Research ArticleGreen Emission of Tellurite Based Glass Containing ErbiumOxide Nanoparticles

Azlan Muhammad Noorazlan Halimah Mohamed KamariSharudin Omar Baki and Daud W Mohamad

Physics Department Faculty of Science University Putra Malaysia (UPM) 43400 Serdang Selangor Malaysia

Correspondence should be addressed to Halimah Mohamed Kamari hmk6360gmailcom

Received 28 July 2015 Revised 29 September 2015 Accepted 8 October 2015

Academic Editor Fei Meng

Copyright copy 2015 Azlan Muhammad Noorazlan et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Investigation on green emission and spectral intensity of tellurite based glass containing erbium oxide NPs is one of the crucialissues Tellurite based glass containing erbium oxide NPs with the composition of [(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

has been prepared by using conventional melt-quenching method The structural and optical properties of the glass sample werecharacterized by using XRD FTIR UV-Vis absorption and PL spectroscopy The amorphous structural arrangement was provedthrough XRDmethodThe formation of TeO

3and BO

3units was revealed by FTIR analysis Five transition states of excitation were

shown inUV-Vis spectra which arise from the ground state 4I152

to the excited states 4G112

+ 2H92

+ 4F52

+ 4F72

+ 2H112

+ 4S32

+4F92

+ 4I92

+ 4I112

The intensity parameters Ω119905(119905 = 2 4 6) are calculated and follow the trend of Ω

2gt Ω4gt Ω6 Broad green

emission at 559 nm under 385 nm excitation was obtained

1 Introduction

Judd-Ofelt theory was first introduced by Judd and Ofelt in1962 to explore the spectral intensities at 4f-4f transitionsof the rare earth ions [1 2] In present years Judd-Ofeltanalysis has become a very important tool to estimate theluminescence and laser efficiency of materials Rare earthions consist of very strong intensities and sharp spectralcharacteristic in 4f transitions [3] Based on this character-istic rare earth ions become the most needed materials todevelop excellent luminescence and laser applicability Judd-Ofelt analysis consists of three parameters which are Ω

2

Ω4 and Ω

6[1 2] The three Judd-Ofelt intensity parameters

are determined empirically from the room temperature (RT)absorption spectrum by minimizing the differences betweencalculated and experimental transition line (or oscillator)strengths of a series of excited multiplets by standard least-squares or chi square method [4] Lately the luminescenceand upconversion properties of Er3+ ions have been con-sidered due to their intense green and red emission [5 6]These emissions provide an excellent application in many

areas from high density optical storage and optoelectronicsto medical applications

Tellurite based glass is widely being used as the mainhost materials to attain excellent optical and dielectric prop-erties It is well known that tellurite based glass possessesa high quality of glass forming ability wide transmissionband fast optical switches excellent linear and nonlinearoptical properties and exceptional optical fibers for fiber-optical communications Based on these properties it is ofinterest to investigate the new tellurite glass system withvarious compositions The formation of tellurite glass systemacquires glass stabilizer to obtain stable and reliable glasssystem Borate oxide is the most interesting compound tobe used as glass stabilizer which is due to its low meltingtemperature and good rare earth ion solubility Furthermoreborate matrix consists of BO

3(trigonal structure) and BO

4

(tetrahedra structure) which generate 4 stable borate groupssuch as diborate and triborate The insertion of zinc oxidein the glass system provides low rates of crystallization andcontributes to a significant growth of glass forming abilityMoreover tellurite based glass has a good compatibility with

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 952308 9 pageshttpdxdoiorg1011552015952308

2 Journal of Nanomaterials

200nm

(a)

200nm

(b)

Figure 1 TEM image of erbium oxide NPs before (a) and after (b) the glass formation

rare earth ions since they provide low phonon energy (700ndash800 cmminus1) environment to minimize the nonradiative losseswhich are lower compared to the other oxide glass such assilicates borates phosphates and germinates [7ndash9]

Tellurite glass containing nanoparticles system has a greatattraction especially to study the effect of nanosize particleson optical behavior Nowadays special attention has beengiven to enhance the luminescence properties of materialsby using silver and gold nanoparticles [10ndash13] However theinvestigations on the tellurite glass containing rare earthnanoparticles have not been well explored Erbium oxide hasvery special properties especially in luminescence and laserapplications Lately the investigations of luminescence andspectral intensity of tellurite glass containing erbium oxidesystem have been extensively studied [14 15] Neverthelessthe research on tellurite glass system containing erbiumoxideNPs seems not to be available Nanoparticles are very usefulto improve the quantum efficiency of laser materials Awanget al 2013 stated that nanoparticles may enhance the weakoptical transitions by generation of intense electric fieldsupon electromagnetic excitation where plasmonic metalnanostructures in the vicinity of the rare earth (RE) ionsalter their free space spectroscopic properties [12] Hence it isextremely demanding to further explore the spectral intensityand green emission of tellurite based glass containing erbiumoxide NPs

2 Experimental Methodology

The tellurite based glass containing Er3+ NPs was prepared byusing melt-quenching method with chemical composition of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The highpurity of rawmaterials (9999 purity grade) of erbium (III)oxide nanoparticles Er

2O3NPs (20ndash30 nm Nanostructured

and Amorphous Materials Inc) tellurium (IV) oxide TeO2

(Puratronic Alfa Aesar) zinc oxide ZnO (Assay Alfa Aesar)and boron oxide B

2O3(Assay Alfa Aesar) was used to

fabricate the glass sample The chemical composition of

about 13 g was weighted and mixed thoroughly and placedin alumina crucible The homogenous mixture was thentransferred to the electrical furnace of 400∘C in about 1 hourto remove the excess water molecule

The mixture was transferred to the electrical furnace of900∘C in about 2 hours for the melting process The meltwas poured onto a preheated stainless steel split mouldThe mould was kept in an electrical furnace of 400∘C inabout 1 hour to remove strain and improve the mechanicalstrength After that the furnace was turned off to cool downat room temperature The glass sample was cut by usingIsomet Buehler low speed saw machine to obtain 2mmthickness of the glass sample The sample was polished withvarious types of sand papers 1500 grit 1200 grit and 1000grit to obtain flat and smooth surface The density of theglass sample was measured through Archimedes principleby using acetone as immersion liquid The FTIR XRD andEDX analysis were performed by using EDX-720800HS Shi-madzu Xpert Highscore PANalytical X-ray diffractometersand PerkinElmer Spectrum 100 Series FT-IR spectrometersThe refractive index of the glass sample was carried out byusing EL X-02C high precision ellipsometer with the angleof the incident at 70∘ and wavelength of the beam laser120582 = 635 nm The absorption analysis of the glass sample wasmeasured by using UV-1650PC UV-Vis Spectrophotometer(Shimadzu) with the wavelength of 190ndash1100 nm

3 Result and Discussions

31 Transmission Electron Microscopy (TEM) Figure 1 illus-trates the TEM image for erbium oxide NPs before andafter the glass formation It is clear from the figure that thepure erbium oxide nanoparticles exhibit three-dimensionalspherical-shaped structuresThe average size of nanoparticlesbefore the glass formation is found in the range 18 nm It canbe seen fromFigure 1 that the erbiumoxideNPs exist after theglass formationThe average size of the nanoparticles is foundin the range 28 nm with three-dimensional spherical-shapedstructures It can be seen that the average size of nanoparticles

Journal of Nanomaterials 3

0

100

200

300

400

500

600

20 23 27 30 33 37 40 43 46 50 53 56 60 63 66 70 73 76 79C

ount

Position (2120579)

005

Figure 2 XRD spectra of [(TeO2)070(B2O3)030]07(ZnO)

03095

(Er2O3)005

B

OEr

Zn

Te

020406080

100120140160180

0 5 10 15 20 25 30

(cps

)

Energy (keV)

Figure 3 EDX spectra of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

is increased after the glass formation This may be due to theparticle sintering and grain growth as a result of the high-temperature thermal treatment in which the smaller particlestend to form larger particles

32 X-Ray Diffraction and EDX Analysis The noncrys-tallinity of the glass system was confirmed by using X-raydiffraction (XRD) method The X-ray diffraction pattern ofthe tellurite based glass containing Er3+ NPs was recorded atroom temperature in the range of 20∘ le 120579 le 80∘ The XRDspectra are shown in Figure 2 and it is clear from the figurethat the spectra possess broad diffusion at lower scatteringangle indicating the long range disorder arrangementThis isin accordance with the characteristic of glass materials whichpossess amorphous structural arrangement The absenceof sharp peaks recommends that the glass sample exhibitnoncrystalline phase The energy dispersion X-ray (EDX)analysis was performed to determine the exact compositionof the glass materialsThe EDX spectra are shown in Figure 3and the measured weight composition of the glass sample istabulated in Table 1 It can be seen from Figure 3 that all theelements of zinc erbium oxide NPs boron and tellurite existin the glass systemThere is no sign of foreign elements in theEDX spectra which indicates that the glass sample is free fromcontamination

Table 1 Calculated and EDX-measured weight of oxides of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Oxides Experimental weight Calculated weightTeO2

58062 56929B2O3

17073 17772ZnO 8806 10643Er2O3

16059 14656

33 Fourier Transform Infrared Analysis Fourier transforminfrared analysis (FT-IR) is used to understand the char-acteristic of the local structure and functional groups forparticular materials The transmission spectra were recordedat room temperature in the range of 280ndash2400 cmminus1 Theobtained data of transmission spectrawere plotted in Figure 4and tabulated in Table 2 It can be seen from Figure 4 thatthe existence of intense absorption bands was centered at645 cmminus1 1223 cmminus1 and 1331 cmminus1 The transmission bandof the local structure of pure TeO

2glass was centered at

640 cmminus1 [22] Tellurite oxide containing glass possessestwo types of structural arrangement which are trigonalpyramidal TeO

3and trigonal bipyramidal TeO

4 These two

types of structural arrangements can be identified throughthe transmission band at 600ndash700 cmminus1 The transmission

4 Journal of Nanomaterials

645

12231331

0

20

40

60

80

100

120

280535790104513001555181020652320

Tran

smiss

ion

T (

)

Wavenumber (cmminus1)

Figure 4 FTIR spectrum of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Table 2 Assignment of infrared transmission bands of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

NumberPosition (cmminus1) Assignments

1 1331 Trigonal B-O bond stretching vibrationsin isolated trigonal BO

3units

2 1223 Trigonal B-O bond stretching vibrationsof BO

3units from boroxyl groups

3 645 TeO3group exists in tellurite containing

glass

band centered at 600ndash650 cmminus1 is due to the formationof trigonal bipyramidal TeO

4while that at 650ndash700 cmminus1

corresponds to the formation of trigonal pyramidal TeO3

respectively Based on Figure 4 the existence of transmissionband located at 656ndash664 cmminus1 correlates to the formationof trigonal pyramidal TeO

3structural arrangement This is

the indication of the formation of nonbridging oxygen inthe glass network which contributes to the high frequencyposition of TeO

3compared to TeO

4

Borate glass B2O3 possesses boroxyl ring structural

arrangement located at 806 cmminus1 However this band disap-peared after the glass formation which indicates the absenceof boroxyl ring in the glass system Furthermore the trigonalBO3and tetrahedral BO

4are taking place after the glass

formation Previous research reported that the transmissionband of borate network is mainly active in only three spectralregions [23 24] The first band of borate network is locatedin the range of 1200ndash1600 cmminus1 This correlates with theasymmetric stretching vibration of the B-O band in trigonalBO3units [25] The second band of borate network lies

in the range of 800ndash1200 cmminus1 which corresponds to thestretching vibrations of B-O band in tetrahedral BO

4units

The third group of borate network is positioned in the rangeof 700 cmminus1 which correlates to bending vibrations of B-O-B in trigonal BO

3units It can be seen from Figure 4 that

the intense absorption bands of borate network are located at1233 cmminus1 and 1343 cmminus1 These two bands are attributed tothe symmetric stretching vibrations of B-O in trigonal BO

3

units

minus001001003005007009011013015

250 350 450 550 650 750 850 950

Opt

ical

den

sity

Wavelength 120582 (nm)

Figure 5 Optical density spectra of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The characteristic of ZnO4unit is located at 418 cmminus1

However the ZnO4unit is absent from the present glass

system This indicates that the zinc lattice is completelybroken down and may be formulated as ZnB

4O7[26] It can

be seen from Figure 4 that no sign of erbium unit appearedThis is due to the low concentration of erbium ions that couldnot be detected by the instrument

34 Optical Density and Extinction Coefficient The opticalabsorption studies give information to understand the elec-tronic transitions of the materials The absorption spectra oftellurite based glass containing erbium oxide NPs recordedat room temperature in the UV-Vis region are shown inFigure 5 It can be seen from the figure that the absorptionspectra consist of several bands which is due to the charac-teristic of Er3+ ions Furthermore erbium ions consist of 4felectrons which are shielded by the outer 5s and 5p bondingelectrons which result from the sharp absorption bandsThese bands correspond to the 10 transitions originatingfrom the 4I

152ground state The transitions arise from the

intraconfigurational (f-f) transitions from the ground state4I152

to the excited states 4G112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

[27] The absorptionband below 300 nm could not be determined which is dueto the rapid increases of the electronic absorption edge

Journal of Nanomaterials 5

Table 3 Optical coefficient and extinction coefficient of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Samples Absorption coefficient(cmminus1)

Extinction coefficient(119896) 10minus8

005 13359 66110

The absorption coefficient (120572) has been obtained by using thefollowing relation

120572 (120582) = 2303119860

119889 (1)

where 119860 is the absorbance and 119889 is the thickness of theglass sample The obtained value of absorption coefficient ispresented in Table 3 The absence of clear sharp absorptioncoefficient edge recommends that the glass sample is amor-phous in nature Besides that the absorption edge depends onthe oxygen bond strength of the glass sample The variety ofoxygen bond strength will affect the absorption characteristicof the materials

The hallmark of the Er3+-ligand bonds can be determinedthrough the nephelauxetic ratio and bonding parameters(120573 120575) of the glass sampleThe value of nephelauxetic ratio canbe expressed by the following relation

120573 =V119888

V119886

(2)

where V119888correspond to the wavenumber (in cmminus1) for

the single excited states transition of Er3+ and V119886is the

wavenumber (in cmminus1) for the same position of excited statestransitions in aquo-ion [27] The bonding parameter 120575 of theglass sample can be determined by considering the averagevalues of 120573 through the following formula

120575 =1 minus 120573

120573times 100 (3)

The obtained values of nephelauxetic ratio and bondingparameter for the title glass were tabulated in Table 4 Theionic or covalent characteristic of the materials can bepredicted by negative or positive sign value of the bondingparameter It can be seen from the table that the bondingparameter is in negative sign which indicates that the glasssample is ionic in nature The ionic nature of the metal-ligand is affected by the chemical composition of the glassmaterials The existence of trivalent electron of erbium oxideNPs contributes to the strong ionic characteristic of the glasssample Previous research on glass containing erbium oxidereported the same ionic behavior with this work [28]

35 Judd-Ofelt Analysis The introduction of Judd-Ofelt the-ory [2 16] provides the information of transition behaviourbetween 4f-4f electronic configuration and calculation oftransition probabilities branching ratio oscillator strengthand intensity parameters (Ω

1 Ω2 and Ω

3) Judd-Ofelt the-

ory is an important approach to analyze and investigatethe spectral properties of tellurite glass system containing

Table 4 Band positions and bonding parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition(from 4I

152) Wavenumber (cmminus1) Wavenumber in

aquo-ion (cmminus1) [16]4F52

22201 223004F72

20435 206002H112

19120 192704S32

18349 185504F92

15291 153904I92

12516 12400120573 24830120575 minus59726

erbium ions The Judd-Ofelt analysis acquires the preciseintegrated absorption cross section measurement over therange of wavelength and transition state of excitation Theexperimental oscillator strength for each transition state ofexcitation can be expressed by the following relation

119891exp =2303119898119888

2

1198731205871198902int 120576 (120590) 119889120590 (4)

where 119873 is the concentration of Er3+ ions in cmminus1 and120576(120590) is the molar absorptivity in L(molsdotcm) obtained fromthe measured absorbance of the glass system The molarabsorptivity 120576(120590) at a given energy is computed from Beer-Lambert Law as shown in the following

120576 (120590) =1

119888119897log1198680

119868 (5)

where 119888 is the concentration of Er3+ ion (mol) 119897 is thethickness of the glass sample (cm) and log(119868

0119868) is the

optical density (OD) According to the Judd-Ofelt theorythe estimation of theoretical oscillator strength of an electricdipole transition from (119878119871)119869 to (11987810158401198711015840)1198691015840 is determined by thefollowing expression

119891cal =81205872

3ℎ (2119869 + 1)

(1198992+ 2)2

9119899120590

sdot sum120582=246

Ω120582

10038161003816100381610038161003816⟨(119878119871119869)

10038171003817100381710038171003817119880(120582)10038171003817100381710038171003817(119878101584011987110158401198691015840)⟩10038161003816100381610038161003816

2

(6)

where ℎ is Plankrsquos constant 119899 is the refractive index and119880120582 is the doubly reducedmatrix elements of the unit tensor

operatorThe obtained values of experimental and calculatedoscillator strength were tabulated in Table 5 The Judd-Ofelt parameter is computed by using least-square fittingprocedure which gives the best fit between experimentaland calculated oscillator strength Meanwhile according tothe Judd-Ofelt theory the line strength 119878

119898can be found

from an integrated absorption cross section by the followingexpression [29]

119878119898=3119888ℎ (2119869

2+ 1)

812058731198902120582119899 (

3

1198992 + 2)2

intmanifold

OD (120582) 119889120582 (7)

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

2 Journal of Nanomaterials

200nm

(a)

200nm

(b)

Figure 1 TEM image of erbium oxide NPs before (a) and after (b) the glass formation

rare earth ions since they provide low phonon energy (700ndash800 cmminus1) environment to minimize the nonradiative losseswhich are lower compared to the other oxide glass such assilicates borates phosphates and germinates [7ndash9]

Tellurite glass containing nanoparticles system has a greatattraction especially to study the effect of nanosize particleson optical behavior Nowadays special attention has beengiven to enhance the luminescence properties of materialsby using silver and gold nanoparticles [10ndash13] However theinvestigations on the tellurite glass containing rare earthnanoparticles have not been well explored Erbium oxide hasvery special properties especially in luminescence and laserapplications Lately the investigations of luminescence andspectral intensity of tellurite glass containing erbium oxidesystem have been extensively studied [14 15] Neverthelessthe research on tellurite glass system containing erbiumoxideNPs seems not to be available Nanoparticles are very usefulto improve the quantum efficiency of laser materials Awanget al 2013 stated that nanoparticles may enhance the weakoptical transitions by generation of intense electric fieldsupon electromagnetic excitation where plasmonic metalnanostructures in the vicinity of the rare earth (RE) ionsalter their free space spectroscopic properties [12] Hence it isextremely demanding to further explore the spectral intensityand green emission of tellurite based glass containing erbiumoxide NPs

2 Experimental Methodology

The tellurite based glass containing Er3+ NPs was prepared byusing melt-quenching method with chemical composition of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The highpurity of rawmaterials (9999 purity grade) of erbium (III)oxide nanoparticles Er

2O3NPs (20ndash30 nm Nanostructured

and Amorphous Materials Inc) tellurium (IV) oxide TeO2

(Puratronic Alfa Aesar) zinc oxide ZnO (Assay Alfa Aesar)and boron oxide B

2O3(Assay Alfa Aesar) was used to

fabricate the glass sample The chemical composition of

about 13 g was weighted and mixed thoroughly and placedin alumina crucible The homogenous mixture was thentransferred to the electrical furnace of 400∘C in about 1 hourto remove the excess water molecule

The mixture was transferred to the electrical furnace of900∘C in about 2 hours for the melting process The meltwas poured onto a preheated stainless steel split mouldThe mould was kept in an electrical furnace of 400∘C inabout 1 hour to remove strain and improve the mechanicalstrength After that the furnace was turned off to cool downat room temperature The glass sample was cut by usingIsomet Buehler low speed saw machine to obtain 2mmthickness of the glass sample The sample was polished withvarious types of sand papers 1500 grit 1200 grit and 1000grit to obtain flat and smooth surface The density of theglass sample was measured through Archimedes principleby using acetone as immersion liquid The FTIR XRD andEDX analysis were performed by using EDX-720800HS Shi-madzu Xpert Highscore PANalytical X-ray diffractometersand PerkinElmer Spectrum 100 Series FT-IR spectrometersThe refractive index of the glass sample was carried out byusing EL X-02C high precision ellipsometer with the angleof the incident at 70∘ and wavelength of the beam laser120582 = 635 nm The absorption analysis of the glass sample wasmeasured by using UV-1650PC UV-Vis Spectrophotometer(Shimadzu) with the wavelength of 190ndash1100 nm

3 Result and Discussions

31 Transmission Electron Microscopy (TEM) Figure 1 illus-trates the TEM image for erbium oxide NPs before andafter the glass formation It is clear from the figure that thepure erbium oxide nanoparticles exhibit three-dimensionalspherical-shaped structuresThe average size of nanoparticlesbefore the glass formation is found in the range 18 nm It canbe seen fromFigure 1 that the erbiumoxideNPs exist after theglass formationThe average size of the nanoparticles is foundin the range 28 nm with three-dimensional spherical-shapedstructures It can be seen that the average size of nanoparticles

Journal of Nanomaterials 3

0

100

200

300

400

500

600

20 23 27 30 33 37 40 43 46 50 53 56 60 63 66 70 73 76 79C

ount

Position (2120579)

005

Figure 2 XRD spectra of [(TeO2)070(B2O3)030]07(ZnO)

03095

(Er2O3)005

B

OEr

Zn

Te

020406080

100120140160180

0 5 10 15 20 25 30

(cps

)

Energy (keV)

Figure 3 EDX spectra of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

is increased after the glass formation This may be due to theparticle sintering and grain growth as a result of the high-temperature thermal treatment in which the smaller particlestend to form larger particles

32 X-Ray Diffraction and EDX Analysis The noncrys-tallinity of the glass system was confirmed by using X-raydiffraction (XRD) method The X-ray diffraction pattern ofthe tellurite based glass containing Er3+ NPs was recorded atroom temperature in the range of 20∘ le 120579 le 80∘ The XRDspectra are shown in Figure 2 and it is clear from the figurethat the spectra possess broad diffusion at lower scatteringangle indicating the long range disorder arrangementThis isin accordance with the characteristic of glass materials whichpossess amorphous structural arrangement The absenceof sharp peaks recommends that the glass sample exhibitnoncrystalline phase The energy dispersion X-ray (EDX)analysis was performed to determine the exact compositionof the glass materialsThe EDX spectra are shown in Figure 3and the measured weight composition of the glass sample istabulated in Table 1 It can be seen from Figure 3 that all theelements of zinc erbium oxide NPs boron and tellurite existin the glass systemThere is no sign of foreign elements in theEDX spectra which indicates that the glass sample is free fromcontamination

Table 1 Calculated and EDX-measured weight of oxides of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Oxides Experimental weight Calculated weightTeO2

58062 56929B2O3

17073 17772ZnO 8806 10643Er2O3

16059 14656

33 Fourier Transform Infrared Analysis Fourier transforminfrared analysis (FT-IR) is used to understand the char-acteristic of the local structure and functional groups forparticular materials The transmission spectra were recordedat room temperature in the range of 280ndash2400 cmminus1 Theobtained data of transmission spectrawere plotted in Figure 4and tabulated in Table 2 It can be seen from Figure 4 thatthe existence of intense absorption bands was centered at645 cmminus1 1223 cmminus1 and 1331 cmminus1 The transmission bandof the local structure of pure TeO

2glass was centered at

640 cmminus1 [22] Tellurite oxide containing glass possessestwo types of structural arrangement which are trigonalpyramidal TeO

3and trigonal bipyramidal TeO

4 These two

types of structural arrangements can be identified throughthe transmission band at 600ndash700 cmminus1 The transmission

4 Journal of Nanomaterials

645

12231331

0

20

40

60

80

100

120

280535790104513001555181020652320

Tran

smiss

ion

T (

)

Wavenumber (cmminus1)

Figure 4 FTIR spectrum of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Table 2 Assignment of infrared transmission bands of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

NumberPosition (cmminus1) Assignments

1 1331 Trigonal B-O bond stretching vibrationsin isolated trigonal BO

3units

2 1223 Trigonal B-O bond stretching vibrationsof BO

3units from boroxyl groups

3 645 TeO3group exists in tellurite containing

glass

band centered at 600ndash650 cmminus1 is due to the formationof trigonal bipyramidal TeO

4while that at 650ndash700 cmminus1

corresponds to the formation of trigonal pyramidal TeO3

respectively Based on Figure 4 the existence of transmissionband located at 656ndash664 cmminus1 correlates to the formationof trigonal pyramidal TeO

3structural arrangement This is

the indication of the formation of nonbridging oxygen inthe glass network which contributes to the high frequencyposition of TeO

3compared to TeO

4

Borate glass B2O3 possesses boroxyl ring structural

arrangement located at 806 cmminus1 However this band disap-peared after the glass formation which indicates the absenceof boroxyl ring in the glass system Furthermore the trigonalBO3and tetrahedral BO

4are taking place after the glass

formation Previous research reported that the transmissionband of borate network is mainly active in only three spectralregions [23 24] The first band of borate network is locatedin the range of 1200ndash1600 cmminus1 This correlates with theasymmetric stretching vibration of the B-O band in trigonalBO3units [25] The second band of borate network lies

in the range of 800ndash1200 cmminus1 which corresponds to thestretching vibrations of B-O band in tetrahedral BO

4units

The third group of borate network is positioned in the rangeof 700 cmminus1 which correlates to bending vibrations of B-O-B in trigonal BO

3units It can be seen from Figure 4 that

the intense absorption bands of borate network are located at1233 cmminus1 and 1343 cmminus1 These two bands are attributed tothe symmetric stretching vibrations of B-O in trigonal BO

3

units

minus001001003005007009011013015

250 350 450 550 650 750 850 950

Opt

ical

den

sity

Wavelength 120582 (nm)

Figure 5 Optical density spectra of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The characteristic of ZnO4unit is located at 418 cmminus1

However the ZnO4unit is absent from the present glass

system This indicates that the zinc lattice is completelybroken down and may be formulated as ZnB

4O7[26] It can

be seen from Figure 4 that no sign of erbium unit appearedThis is due to the low concentration of erbium ions that couldnot be detected by the instrument

34 Optical Density and Extinction Coefficient The opticalabsorption studies give information to understand the elec-tronic transitions of the materials The absorption spectra oftellurite based glass containing erbium oxide NPs recordedat room temperature in the UV-Vis region are shown inFigure 5 It can be seen from the figure that the absorptionspectra consist of several bands which is due to the charac-teristic of Er3+ ions Furthermore erbium ions consist of 4felectrons which are shielded by the outer 5s and 5p bondingelectrons which result from the sharp absorption bandsThese bands correspond to the 10 transitions originatingfrom the 4I

152ground state The transitions arise from the

intraconfigurational (f-f) transitions from the ground state4I152

to the excited states 4G112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

[27] The absorptionband below 300 nm could not be determined which is dueto the rapid increases of the electronic absorption edge

Journal of Nanomaterials 5

Table 3 Optical coefficient and extinction coefficient of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Samples Absorption coefficient(cmminus1)

Extinction coefficient(119896) 10minus8

005 13359 66110

The absorption coefficient (120572) has been obtained by using thefollowing relation

120572 (120582) = 2303119860

119889 (1)

where 119860 is the absorbance and 119889 is the thickness of theglass sample The obtained value of absorption coefficient ispresented in Table 3 The absence of clear sharp absorptioncoefficient edge recommends that the glass sample is amor-phous in nature Besides that the absorption edge depends onthe oxygen bond strength of the glass sample The variety ofoxygen bond strength will affect the absorption characteristicof the materials

The hallmark of the Er3+-ligand bonds can be determinedthrough the nephelauxetic ratio and bonding parameters(120573 120575) of the glass sampleThe value of nephelauxetic ratio canbe expressed by the following relation

120573 =V119888

V119886

(2)

where V119888correspond to the wavenumber (in cmminus1) for

the single excited states transition of Er3+ and V119886is the

wavenumber (in cmminus1) for the same position of excited statestransitions in aquo-ion [27] The bonding parameter 120575 of theglass sample can be determined by considering the averagevalues of 120573 through the following formula

120575 =1 minus 120573

120573times 100 (3)

The obtained values of nephelauxetic ratio and bondingparameter for the title glass were tabulated in Table 4 Theionic or covalent characteristic of the materials can bepredicted by negative or positive sign value of the bondingparameter It can be seen from the table that the bondingparameter is in negative sign which indicates that the glasssample is ionic in nature The ionic nature of the metal-ligand is affected by the chemical composition of the glassmaterials The existence of trivalent electron of erbium oxideNPs contributes to the strong ionic characteristic of the glasssample Previous research on glass containing erbium oxidereported the same ionic behavior with this work [28]

35 Judd-Ofelt Analysis The introduction of Judd-Ofelt the-ory [2 16] provides the information of transition behaviourbetween 4f-4f electronic configuration and calculation oftransition probabilities branching ratio oscillator strengthand intensity parameters (Ω

1 Ω2 and Ω

3) Judd-Ofelt the-

ory is an important approach to analyze and investigatethe spectral properties of tellurite glass system containing

Table 4 Band positions and bonding parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition(from 4I

152) Wavenumber (cmminus1) Wavenumber in

aquo-ion (cmminus1) [16]4F52

22201 223004F72

20435 206002H112

19120 192704S32

18349 185504F92

15291 153904I92

12516 12400120573 24830120575 minus59726

erbium ions The Judd-Ofelt analysis acquires the preciseintegrated absorption cross section measurement over therange of wavelength and transition state of excitation Theexperimental oscillator strength for each transition state ofexcitation can be expressed by the following relation

119891exp =2303119898119888

2

1198731205871198902int 120576 (120590) 119889120590 (4)

where 119873 is the concentration of Er3+ ions in cmminus1 and120576(120590) is the molar absorptivity in L(molsdotcm) obtained fromthe measured absorbance of the glass system The molarabsorptivity 120576(120590) at a given energy is computed from Beer-Lambert Law as shown in the following

120576 (120590) =1

119888119897log1198680

119868 (5)

where 119888 is the concentration of Er3+ ion (mol) 119897 is thethickness of the glass sample (cm) and log(119868

0119868) is the

optical density (OD) According to the Judd-Ofelt theorythe estimation of theoretical oscillator strength of an electricdipole transition from (119878119871)119869 to (11987810158401198711015840)1198691015840 is determined by thefollowing expression

119891cal =81205872

3ℎ (2119869 + 1)

(1198992+ 2)2

9119899120590

sdot sum120582=246

Ω120582

10038161003816100381610038161003816⟨(119878119871119869)

10038171003817100381710038171003817119880(120582)10038171003817100381710038171003817(119878101584011987110158401198691015840)⟩10038161003816100381610038161003816

2

(6)

where ℎ is Plankrsquos constant 119899 is the refractive index and119880120582 is the doubly reducedmatrix elements of the unit tensor

operatorThe obtained values of experimental and calculatedoscillator strength were tabulated in Table 5 The Judd-Ofelt parameter is computed by using least-square fittingprocedure which gives the best fit between experimentaland calculated oscillator strength Meanwhile according tothe Judd-Ofelt theory the line strength 119878

119898can be found

from an integrated absorption cross section by the followingexpression [29]

119878119898=3119888ℎ (2119869

2+ 1)

812058731198902120582119899 (

3

1198992 + 2)2

intmanifold

OD (120582) 119889120582 (7)

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanomaterials 3

0

100

200

300

400

500

600

20 23 27 30 33 37 40 43 46 50 53 56 60 63 66 70 73 76 79C

ount

Position (2120579)

005

Figure 2 XRD spectra of [(TeO2)070(B2O3)030]07(ZnO)

03095

(Er2O3)005

B

OEr

Zn

Te

020406080

100120140160180

0 5 10 15 20 25 30

(cps

)

Energy (keV)

Figure 3 EDX spectra of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

is increased after the glass formation This may be due to theparticle sintering and grain growth as a result of the high-temperature thermal treatment in which the smaller particlestend to form larger particles

32 X-Ray Diffraction and EDX Analysis The noncrys-tallinity of the glass system was confirmed by using X-raydiffraction (XRD) method The X-ray diffraction pattern ofthe tellurite based glass containing Er3+ NPs was recorded atroom temperature in the range of 20∘ le 120579 le 80∘ The XRDspectra are shown in Figure 2 and it is clear from the figurethat the spectra possess broad diffusion at lower scatteringangle indicating the long range disorder arrangementThis isin accordance with the characteristic of glass materials whichpossess amorphous structural arrangement The absenceof sharp peaks recommends that the glass sample exhibitnoncrystalline phase The energy dispersion X-ray (EDX)analysis was performed to determine the exact compositionof the glass materialsThe EDX spectra are shown in Figure 3and the measured weight composition of the glass sample istabulated in Table 1 It can be seen from Figure 3 that all theelements of zinc erbium oxide NPs boron and tellurite existin the glass systemThere is no sign of foreign elements in theEDX spectra which indicates that the glass sample is free fromcontamination

Table 1 Calculated and EDX-measured weight of oxides of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Oxides Experimental weight Calculated weightTeO2

58062 56929B2O3

17073 17772ZnO 8806 10643Er2O3

16059 14656

33 Fourier Transform Infrared Analysis Fourier transforminfrared analysis (FT-IR) is used to understand the char-acteristic of the local structure and functional groups forparticular materials The transmission spectra were recordedat room temperature in the range of 280ndash2400 cmminus1 Theobtained data of transmission spectrawere plotted in Figure 4and tabulated in Table 2 It can be seen from Figure 4 thatthe existence of intense absorption bands was centered at645 cmminus1 1223 cmminus1 and 1331 cmminus1 The transmission bandof the local structure of pure TeO

2glass was centered at

640 cmminus1 [22] Tellurite oxide containing glass possessestwo types of structural arrangement which are trigonalpyramidal TeO

3and trigonal bipyramidal TeO

4 These two

types of structural arrangements can be identified throughthe transmission band at 600ndash700 cmminus1 The transmission

4 Journal of Nanomaterials

645

12231331

0

20

40

60

80

100

120

280535790104513001555181020652320

Tran

smiss

ion

T (

)

Wavenumber (cmminus1)

Figure 4 FTIR spectrum of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Table 2 Assignment of infrared transmission bands of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

NumberPosition (cmminus1) Assignments

1 1331 Trigonal B-O bond stretching vibrationsin isolated trigonal BO

3units

2 1223 Trigonal B-O bond stretching vibrationsof BO

3units from boroxyl groups

3 645 TeO3group exists in tellurite containing

glass

band centered at 600ndash650 cmminus1 is due to the formationof trigonal bipyramidal TeO

4while that at 650ndash700 cmminus1

corresponds to the formation of trigonal pyramidal TeO3

respectively Based on Figure 4 the existence of transmissionband located at 656ndash664 cmminus1 correlates to the formationof trigonal pyramidal TeO

3structural arrangement This is

the indication of the formation of nonbridging oxygen inthe glass network which contributes to the high frequencyposition of TeO

3compared to TeO

4

Borate glass B2O3 possesses boroxyl ring structural

arrangement located at 806 cmminus1 However this band disap-peared after the glass formation which indicates the absenceof boroxyl ring in the glass system Furthermore the trigonalBO3and tetrahedral BO

4are taking place after the glass

formation Previous research reported that the transmissionband of borate network is mainly active in only three spectralregions [23 24] The first band of borate network is locatedin the range of 1200ndash1600 cmminus1 This correlates with theasymmetric stretching vibration of the B-O band in trigonalBO3units [25] The second band of borate network lies

in the range of 800ndash1200 cmminus1 which corresponds to thestretching vibrations of B-O band in tetrahedral BO

4units

The third group of borate network is positioned in the rangeof 700 cmminus1 which correlates to bending vibrations of B-O-B in trigonal BO

3units It can be seen from Figure 4 that

the intense absorption bands of borate network are located at1233 cmminus1 and 1343 cmminus1 These two bands are attributed tothe symmetric stretching vibrations of B-O in trigonal BO

3

units

minus001001003005007009011013015

250 350 450 550 650 750 850 950

Opt

ical

den

sity

Wavelength 120582 (nm)

Figure 5 Optical density spectra of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The characteristic of ZnO4unit is located at 418 cmminus1

However the ZnO4unit is absent from the present glass

system This indicates that the zinc lattice is completelybroken down and may be formulated as ZnB

4O7[26] It can

be seen from Figure 4 that no sign of erbium unit appearedThis is due to the low concentration of erbium ions that couldnot be detected by the instrument

34 Optical Density and Extinction Coefficient The opticalabsorption studies give information to understand the elec-tronic transitions of the materials The absorption spectra oftellurite based glass containing erbium oxide NPs recordedat room temperature in the UV-Vis region are shown inFigure 5 It can be seen from the figure that the absorptionspectra consist of several bands which is due to the charac-teristic of Er3+ ions Furthermore erbium ions consist of 4felectrons which are shielded by the outer 5s and 5p bondingelectrons which result from the sharp absorption bandsThese bands correspond to the 10 transitions originatingfrom the 4I

152ground state The transitions arise from the

intraconfigurational (f-f) transitions from the ground state4I152

to the excited states 4G112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

[27] The absorptionband below 300 nm could not be determined which is dueto the rapid increases of the electronic absorption edge

Journal of Nanomaterials 5

Table 3 Optical coefficient and extinction coefficient of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Samples Absorption coefficient(cmminus1)

Extinction coefficient(119896) 10minus8

005 13359 66110

The absorption coefficient (120572) has been obtained by using thefollowing relation

120572 (120582) = 2303119860

119889 (1)

where 119860 is the absorbance and 119889 is the thickness of theglass sample The obtained value of absorption coefficient ispresented in Table 3 The absence of clear sharp absorptioncoefficient edge recommends that the glass sample is amor-phous in nature Besides that the absorption edge depends onthe oxygen bond strength of the glass sample The variety ofoxygen bond strength will affect the absorption characteristicof the materials

The hallmark of the Er3+-ligand bonds can be determinedthrough the nephelauxetic ratio and bonding parameters(120573 120575) of the glass sampleThe value of nephelauxetic ratio canbe expressed by the following relation

120573 =V119888

V119886

(2)

where V119888correspond to the wavenumber (in cmminus1) for

the single excited states transition of Er3+ and V119886is the

wavenumber (in cmminus1) for the same position of excited statestransitions in aquo-ion [27] The bonding parameter 120575 of theglass sample can be determined by considering the averagevalues of 120573 through the following formula

120575 =1 minus 120573

120573times 100 (3)

The obtained values of nephelauxetic ratio and bondingparameter for the title glass were tabulated in Table 4 Theionic or covalent characteristic of the materials can bepredicted by negative or positive sign value of the bondingparameter It can be seen from the table that the bondingparameter is in negative sign which indicates that the glasssample is ionic in nature The ionic nature of the metal-ligand is affected by the chemical composition of the glassmaterials The existence of trivalent electron of erbium oxideNPs contributes to the strong ionic characteristic of the glasssample Previous research on glass containing erbium oxidereported the same ionic behavior with this work [28]

35 Judd-Ofelt Analysis The introduction of Judd-Ofelt the-ory [2 16] provides the information of transition behaviourbetween 4f-4f electronic configuration and calculation oftransition probabilities branching ratio oscillator strengthand intensity parameters (Ω

1 Ω2 and Ω

3) Judd-Ofelt the-

ory is an important approach to analyze and investigatethe spectral properties of tellurite glass system containing

Table 4 Band positions and bonding parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition(from 4I

152) Wavenumber (cmminus1) Wavenumber in

aquo-ion (cmminus1) [16]4F52

22201 223004F72

20435 206002H112

19120 192704S32

18349 185504F92

15291 153904I92

12516 12400120573 24830120575 minus59726

erbium ions The Judd-Ofelt analysis acquires the preciseintegrated absorption cross section measurement over therange of wavelength and transition state of excitation Theexperimental oscillator strength for each transition state ofexcitation can be expressed by the following relation

119891exp =2303119898119888

2

1198731205871198902int 120576 (120590) 119889120590 (4)

where 119873 is the concentration of Er3+ ions in cmminus1 and120576(120590) is the molar absorptivity in L(molsdotcm) obtained fromthe measured absorbance of the glass system The molarabsorptivity 120576(120590) at a given energy is computed from Beer-Lambert Law as shown in the following

120576 (120590) =1

119888119897log1198680

119868 (5)

where 119888 is the concentration of Er3+ ion (mol) 119897 is thethickness of the glass sample (cm) and log(119868

0119868) is the

optical density (OD) According to the Judd-Ofelt theorythe estimation of theoretical oscillator strength of an electricdipole transition from (119878119871)119869 to (11987810158401198711015840)1198691015840 is determined by thefollowing expression

119891cal =81205872

3ℎ (2119869 + 1)

(1198992+ 2)2

9119899120590

sdot sum120582=246

Ω120582

10038161003816100381610038161003816⟨(119878119871119869)

10038171003817100381710038171003817119880(120582)10038171003817100381710038171003817(119878101584011987110158401198691015840)⟩10038161003816100381610038161003816

2

(6)

where ℎ is Plankrsquos constant 119899 is the refractive index and119880120582 is the doubly reducedmatrix elements of the unit tensor

operatorThe obtained values of experimental and calculatedoscillator strength were tabulated in Table 5 The Judd-Ofelt parameter is computed by using least-square fittingprocedure which gives the best fit between experimentaland calculated oscillator strength Meanwhile according tothe Judd-Ofelt theory the line strength 119878

119898can be found

from an integrated absorption cross section by the followingexpression [29]

119878119898=3119888ℎ (2119869

2+ 1)

812058731198902120582119899 (

3

1198992 + 2)2

intmanifold

OD (120582) 119889120582 (7)

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

4 Journal of Nanomaterials

645

12231331

0

20

40

60

80

100

120

280535790104513001555181020652320

Tran

smiss

ion

T (

)

Wavenumber (cmminus1)

Figure 4 FTIR spectrum of [(TeO2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Table 2 Assignment of infrared transmission bands of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

NumberPosition (cmminus1) Assignments

1 1331 Trigonal B-O bond stretching vibrationsin isolated trigonal BO

3units

2 1223 Trigonal B-O bond stretching vibrationsof BO

3units from boroxyl groups

3 645 TeO3group exists in tellurite containing

glass

band centered at 600ndash650 cmminus1 is due to the formationof trigonal bipyramidal TeO

4while that at 650ndash700 cmminus1

corresponds to the formation of trigonal pyramidal TeO3

respectively Based on Figure 4 the existence of transmissionband located at 656ndash664 cmminus1 correlates to the formationof trigonal pyramidal TeO

3structural arrangement This is

the indication of the formation of nonbridging oxygen inthe glass network which contributes to the high frequencyposition of TeO

3compared to TeO

4

Borate glass B2O3 possesses boroxyl ring structural

arrangement located at 806 cmminus1 However this band disap-peared after the glass formation which indicates the absenceof boroxyl ring in the glass system Furthermore the trigonalBO3and tetrahedral BO

4are taking place after the glass

formation Previous research reported that the transmissionband of borate network is mainly active in only three spectralregions [23 24] The first band of borate network is locatedin the range of 1200ndash1600 cmminus1 This correlates with theasymmetric stretching vibration of the B-O band in trigonalBO3units [25] The second band of borate network lies

in the range of 800ndash1200 cmminus1 which corresponds to thestretching vibrations of B-O band in tetrahedral BO

4units

The third group of borate network is positioned in the rangeof 700 cmminus1 which correlates to bending vibrations of B-O-B in trigonal BO

3units It can be seen from Figure 4 that

the intense absorption bands of borate network are located at1233 cmminus1 and 1343 cmminus1 These two bands are attributed tothe symmetric stretching vibrations of B-O in trigonal BO

3

units

minus001001003005007009011013015

250 350 450 550 650 750 850 950

Opt

ical

den

sity

Wavelength 120582 (nm)

Figure 5 Optical density spectra of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

The characteristic of ZnO4unit is located at 418 cmminus1

However the ZnO4unit is absent from the present glass

system This indicates that the zinc lattice is completelybroken down and may be formulated as ZnB

4O7[26] It can

be seen from Figure 4 that no sign of erbium unit appearedThis is due to the low concentration of erbium ions that couldnot be detected by the instrument

34 Optical Density and Extinction Coefficient The opticalabsorption studies give information to understand the elec-tronic transitions of the materials The absorption spectra oftellurite based glass containing erbium oxide NPs recordedat room temperature in the UV-Vis region are shown inFigure 5 It can be seen from the figure that the absorptionspectra consist of several bands which is due to the charac-teristic of Er3+ ions Furthermore erbium ions consist of 4felectrons which are shielded by the outer 5s and 5p bondingelectrons which result from the sharp absorption bandsThese bands correspond to the 10 transitions originatingfrom the 4I

152ground state The transitions arise from the

intraconfigurational (f-f) transitions from the ground state4I152

to the excited states 4G112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

[27] The absorptionband below 300 nm could not be determined which is dueto the rapid increases of the electronic absorption edge

Journal of Nanomaterials 5

Table 3 Optical coefficient and extinction coefficient of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Samples Absorption coefficient(cmminus1)

Extinction coefficient(119896) 10minus8

005 13359 66110

The absorption coefficient (120572) has been obtained by using thefollowing relation

120572 (120582) = 2303119860

119889 (1)

where 119860 is the absorbance and 119889 is the thickness of theglass sample The obtained value of absorption coefficient ispresented in Table 3 The absence of clear sharp absorptioncoefficient edge recommends that the glass sample is amor-phous in nature Besides that the absorption edge depends onthe oxygen bond strength of the glass sample The variety ofoxygen bond strength will affect the absorption characteristicof the materials

The hallmark of the Er3+-ligand bonds can be determinedthrough the nephelauxetic ratio and bonding parameters(120573 120575) of the glass sampleThe value of nephelauxetic ratio canbe expressed by the following relation

120573 =V119888

V119886

(2)

where V119888correspond to the wavenumber (in cmminus1) for

the single excited states transition of Er3+ and V119886is the

wavenumber (in cmminus1) for the same position of excited statestransitions in aquo-ion [27] The bonding parameter 120575 of theglass sample can be determined by considering the averagevalues of 120573 through the following formula

120575 =1 minus 120573

120573times 100 (3)

The obtained values of nephelauxetic ratio and bondingparameter for the title glass were tabulated in Table 4 Theionic or covalent characteristic of the materials can bepredicted by negative or positive sign value of the bondingparameter It can be seen from the table that the bondingparameter is in negative sign which indicates that the glasssample is ionic in nature The ionic nature of the metal-ligand is affected by the chemical composition of the glassmaterials The existence of trivalent electron of erbium oxideNPs contributes to the strong ionic characteristic of the glasssample Previous research on glass containing erbium oxidereported the same ionic behavior with this work [28]

35 Judd-Ofelt Analysis The introduction of Judd-Ofelt the-ory [2 16] provides the information of transition behaviourbetween 4f-4f electronic configuration and calculation oftransition probabilities branching ratio oscillator strengthand intensity parameters (Ω

1 Ω2 and Ω

3) Judd-Ofelt the-

ory is an important approach to analyze and investigatethe spectral properties of tellurite glass system containing

Table 4 Band positions and bonding parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition(from 4I

152) Wavenumber (cmminus1) Wavenumber in

aquo-ion (cmminus1) [16]4F52

22201 223004F72

20435 206002H112

19120 192704S32

18349 185504F92

15291 153904I92

12516 12400120573 24830120575 minus59726

erbium ions The Judd-Ofelt analysis acquires the preciseintegrated absorption cross section measurement over therange of wavelength and transition state of excitation Theexperimental oscillator strength for each transition state ofexcitation can be expressed by the following relation

119891exp =2303119898119888

2

1198731205871198902int 120576 (120590) 119889120590 (4)

where 119873 is the concentration of Er3+ ions in cmminus1 and120576(120590) is the molar absorptivity in L(molsdotcm) obtained fromthe measured absorbance of the glass system The molarabsorptivity 120576(120590) at a given energy is computed from Beer-Lambert Law as shown in the following

120576 (120590) =1

119888119897log1198680

119868 (5)

where 119888 is the concentration of Er3+ ion (mol) 119897 is thethickness of the glass sample (cm) and log(119868

0119868) is the

optical density (OD) According to the Judd-Ofelt theorythe estimation of theoretical oscillator strength of an electricdipole transition from (119878119871)119869 to (11987810158401198711015840)1198691015840 is determined by thefollowing expression

119891cal =81205872

3ℎ (2119869 + 1)

(1198992+ 2)2

9119899120590

sdot sum120582=246

Ω120582

10038161003816100381610038161003816⟨(119878119871119869)

10038171003817100381710038171003817119880(120582)10038171003817100381710038171003817(119878101584011987110158401198691015840)⟩10038161003816100381610038161003816

2

(6)

where ℎ is Plankrsquos constant 119899 is the refractive index and119880120582 is the doubly reducedmatrix elements of the unit tensor

operatorThe obtained values of experimental and calculatedoscillator strength were tabulated in Table 5 The Judd-Ofelt parameter is computed by using least-square fittingprocedure which gives the best fit between experimentaland calculated oscillator strength Meanwhile according tothe Judd-Ofelt theory the line strength 119878

119898can be found

from an integrated absorption cross section by the followingexpression [29]

119878119898=3119888ℎ (2119869

2+ 1)

812058731198902120582119899 (

3

1198992 + 2)2

intmanifold

OD (120582) 119889120582 (7)

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

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BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanomaterials 5

Table 3 Optical coefficient and extinction coefficient of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Samples Absorption coefficient(cmminus1)

Extinction coefficient(119896) 10minus8

005 13359 66110

The absorption coefficient (120572) has been obtained by using thefollowing relation

120572 (120582) = 2303119860

119889 (1)

where 119860 is the absorbance and 119889 is the thickness of theglass sample The obtained value of absorption coefficient ispresented in Table 3 The absence of clear sharp absorptioncoefficient edge recommends that the glass sample is amor-phous in nature Besides that the absorption edge depends onthe oxygen bond strength of the glass sample The variety ofoxygen bond strength will affect the absorption characteristicof the materials

The hallmark of the Er3+-ligand bonds can be determinedthrough the nephelauxetic ratio and bonding parameters(120573 120575) of the glass sampleThe value of nephelauxetic ratio canbe expressed by the following relation

120573 =V119888

V119886

(2)

where V119888correspond to the wavenumber (in cmminus1) for

the single excited states transition of Er3+ and V119886is the

wavenumber (in cmminus1) for the same position of excited statestransitions in aquo-ion [27] The bonding parameter 120575 of theglass sample can be determined by considering the averagevalues of 120573 through the following formula

120575 =1 minus 120573

120573times 100 (3)

The obtained values of nephelauxetic ratio and bondingparameter for the title glass were tabulated in Table 4 Theionic or covalent characteristic of the materials can bepredicted by negative or positive sign value of the bondingparameter It can be seen from the table that the bondingparameter is in negative sign which indicates that the glasssample is ionic in nature The ionic nature of the metal-ligand is affected by the chemical composition of the glassmaterials The existence of trivalent electron of erbium oxideNPs contributes to the strong ionic characteristic of the glasssample Previous research on glass containing erbium oxidereported the same ionic behavior with this work [28]

35 Judd-Ofelt Analysis The introduction of Judd-Ofelt the-ory [2 16] provides the information of transition behaviourbetween 4f-4f electronic configuration and calculation oftransition probabilities branching ratio oscillator strengthand intensity parameters (Ω

1 Ω2 and Ω

3) Judd-Ofelt the-

ory is an important approach to analyze and investigatethe spectral properties of tellurite glass system containing

Table 4 Band positions and bonding parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition(from 4I

152) Wavenumber (cmminus1) Wavenumber in

aquo-ion (cmminus1) [16]4F52

22201 223004F72

20435 206002H112

19120 192704S32

18349 185504F92

15291 153904I92

12516 12400120573 24830120575 minus59726

erbium ions The Judd-Ofelt analysis acquires the preciseintegrated absorption cross section measurement over therange of wavelength and transition state of excitation Theexperimental oscillator strength for each transition state ofexcitation can be expressed by the following relation

119891exp =2303119898119888

2

1198731205871198902int 120576 (120590) 119889120590 (4)

where 119873 is the concentration of Er3+ ions in cmminus1 and120576(120590) is the molar absorptivity in L(molsdotcm) obtained fromthe measured absorbance of the glass system The molarabsorptivity 120576(120590) at a given energy is computed from Beer-Lambert Law as shown in the following

120576 (120590) =1

119888119897log1198680

119868 (5)

where 119888 is the concentration of Er3+ ion (mol) 119897 is thethickness of the glass sample (cm) and log(119868

0119868) is the

optical density (OD) According to the Judd-Ofelt theorythe estimation of theoretical oscillator strength of an electricdipole transition from (119878119871)119869 to (11987810158401198711015840)1198691015840 is determined by thefollowing expression

119891cal =81205872

3ℎ (2119869 + 1)

(1198992+ 2)2

9119899120590

sdot sum120582=246

Ω120582

10038161003816100381610038161003816⟨(119878119871119869)

10038171003817100381710038171003817119880(120582)10038171003817100381710038171003817(119878101584011987110158401198691015840)⟩10038161003816100381610038161003816

2

(6)

where ℎ is Plankrsquos constant 119899 is the refractive index and119880120582 is the doubly reducedmatrix elements of the unit tensor

operatorThe obtained values of experimental and calculatedoscillator strength were tabulated in Table 5 The Judd-Ofelt parameter is computed by using least-square fittingprocedure which gives the best fit between experimentaland calculated oscillator strength Meanwhile according tothe Judd-Ofelt theory the line strength 119878

119898can be found

from an integrated absorption cross section by the followingexpression [29]

119878119898=3119888ℎ (2119869

2+ 1)

812058731198902120582119899 (

3

1198992 + 2)2

intmanifold

OD (120582) 119889120582 (7)

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

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BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

6 Journal of Nanomaterials

Table 5 Integrated areas dipole line strengths 119878 oscillator strength 119891 and calculated JO intensity parameters of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 intOD(120582)119889120582 Line strength 119878 (times10minus20 cm2) Oscillator strengths 119891 (times10minus20 cm2)(from 4I

152) (nm) (10minus7) cm Measured 119878meas Calculated 119878calc Measured 119878meas Calculated 119878calc

4F52

452 505 0051 0051 0144 01444F72

489 1160 0108 0066 0285 01732H112

527 2197 0191 0202 0473 04994532

654 2597 0180 1037 0354 20394F92

800 1080 0061 0075 0096 01194I92

977 1471 0069 0008 0091 0011Ω2 = (1223 plusmn 0021) times 10minus20 cm2Ω4 = (0400 plusmn 0104) times 10minus20 cm2Ω6 = (0037 plusmn 0112) times 10minus20 cm2 and Δ119878rms = 00537 times 10minus20 cm2

Table 6 JO intensity parameters Ω119905(119905 = 2 4 6) for various glass systems

Glass system Ω119905(times10minus21 cm2) References

Ω2

Ω4

Ω6

TeO2-ZnO-Na

2O-B2O3-GeO

2-Er2O3

575 502 111 [17]TeO2-B2O3-CdO-Li

2O-Er2O3

521 193 105 [18]B2O3-TeO2-MgO-Er

2O3

374 274 186 [19]PbBr2-TeO2-Er2O3

313 125 073 [20]ErYb-GeO

2-PbO-Bi

2O3

329 134 302 [21]Er2O3(NPs)-ZnO-B

2O3-TeO2

1223 0400 0037 This work

where 1198691015840 is the total angular momentum of the lower state 120582is the mean wavelength and OD(120582)119889120582 is the optical densityover the range of wavelength The theoretical expression ofelectric dipole line strength is given by

119878ED = sum119905=246

Ω119905

10038161003816100381610038161003816⟨119891119899[119878119871] 119869

1003817100381710038171003817100381711988011990510038171003817100381710038171003817119891119899[11987810158401198711015840] 1198691015840⟩10038161003816100381610038161003816

2

(8)

where Ω119905is the Judd-Ofelt parameters The reduced matrix

element 119880120582 can be calculated in the intermediate-couplingapproximation and is invariant of environment A Judd-Ofeltanalysis minimizes the square of the difference between 119878

119898

and 119878ED with Ω119905as adjustable parameters [29] The validity

of fitting has been obtained by comparing the experimentaland calculated line strength which is listed in Table 5 Usingthe least-square fittingmethod the Judd-Ofelt parametersΩ

119905

(119905 = 2 4 6) of erbium oxide NPs together with various typesof glass system from earlier reported literature [17ndash21] weresummarized in Table 6 The data of Judd-Ofelt parametersfrom previous literature will be used for comparison with thepresent glass It can be seen from Table 6 that the obtainedvalues of Judd-Ofelt parameters are as followsΩ

246= 1223

0400 and 007 respectively in units of 10minus20 cm2The values of Ω

2and Ω

4parameters correspond to the

asymmetry of the local environment of Er3+ ions sites whichdepends on the covalency between Er3+ ions and ligandanions Meanwhile the value ofΩ

6parameter is linked to the

local basicity of Er3+ ions and inversely proportional to thecovalency of the Er-O bond It can be seen that the Judd-Ofeltparameters behavior of most of the glass system is followingthe trend of Ω

2gt Ω4gt Ω6 The relatively small value of

Ω2and Ω

4was found for tellurite glass containing erbium

oxide NPs compared to the other glass system According

to the Judd-Ofelt theory the Ω2and Ω

4parameters are

strongly sensitive to the local environment symmetry of rareearth ions The small value of Ω

2and Ω

4indicates that the

glass system possesses the lower asymmetric nature of thelocal environment around Er3+ sites This has also shown theionic nature of the chemical bond between Er3+ ions and theligands Furthermore this effect is reflected to the inorganicligand field character of the glass matrix [30]

Compared with Ω2and Ω

4parameters Ω

6parameter

does not depend on the local structure It can be seen fromTable 6 that the obtained value of Ω

6parameter of present

glass is lower compared to the other glass system containingerbium oxide This indicates that the prepared glass systempossesses a high number in Er-O covalency compared to theother glass system The high number of covalency is due tothe high number of nonbridging oxygen ions (NBOs) aroundthe host matrix In addition the presence of a high number ofNBOs leads to producing higher number of electron densityof the ligand ions It can be concluded that the tellurite glasscontaining Er3+ (NPs) possesses a relatively strong covalencyand lower asymmetry around Er3+ sites

The Judd-Ofelt parameters (Ω120582 120582 = 2 4 6) can be used

to compute the radiative transition probability 119860 rad (electricdipole transition probability 119860ED and magnetic dipole tran-sition probability 119860MD) fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions [31] The radiativetransition probability119860 rad (also called Einstein coefficient forspontaneous emission) for any excited transition state can beexpressed by the following relation

119860 rad =6412058731198902

3ℎ (2119869 + 1) 1205823[119899(

1198992+ 2

3)

2

119878ED + 1198993119878MD] (9)

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanomaterials 7

Table 7 Calculated transition probabilities and branching ratio of[(TeO

2)070

(B2O3)030

]07(ZnO)

03095

(Er2O3)005

Transition 120582 (nm) 119860MD (Sminus1) 119860ED (Sminus1) 120573 Lifetime (ms)4I132

4I152

1535 17063 1177 1000 130704I112

4I132

2680 3070 04434I152

976 2225 0557 25014

4I92

4I112

4406 1002 0190 00374I132

1666 3370 00514I152

799 6026 0912 15136

4F92

4I92

3604 1199 1710 00164I112

1982 4791 8910 00494I132

1139 2338 00564I152

654 36865 0879 2384

4S32

4I92

1714 927 00904I112

1234 283 00274I132

845 2696 02614I152

545 6417 0622 9688

2H112

4F92

2611 1064 00034I92

1514 3476 00114I112

1127 2739 00094I132

793 4326 00144I152

523 298646 0963 0322

4F72

4F92

1938 236 00034I92

1260 2178 00314I112

980 6867 00994I132

718 20115 02894I152

489 40270 0578 1435

2G92

4F72

2532 457 00072H112

1894 772 00114F92

1098 727 00104I92

841 1715 00244I112

707 12187 01744I132

559 43297 06174I152

410 11025 0157 1425

The magnetic dipole line strength 119878MD is neglected since theexcitation bands are essentially electric dipole in nature Thecalculated radiative transition probabilities were tabulated inTable 7 It can be seen that the radiative probability 119860 rad ofEr3+ 2H

112[ 4I152

transition possesses a high value whichis beneficial to the green emission

The quality of the fitting between 119878ED and 119878meas wasperformed by the following expression [30]

Δ119878rms = [(119902 minus 119901)minus1

sum(119878ED minus 119878meas)2

]12

(10)

where 119902 is the number of the spectral bands analyzed and119901 is the number of JO parameters calculated The obtainedvalue of rms deviation was 00537 times 10minus20 cm2 which showsa good agreement with calculated and experimental dataand consequently a good precision in the determination ofintensity parameters The branching ratio 120573 and radiative

0

20

40

60

80

100

120

535 540 545 550 555 560 565 570 575 580

PL in

tens

ity (a

u)

Wavelength (nm)

I4 32 S4 32

120582exc = 385nm

120582peak = 559nm

FWHM = 968nm

Figure 6 Green emission spectrum of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

lifetime 120591rad of Er3+ can be evaluated by using the following

equation

120573 (119869 997888rarr 1198691015840) =

119860 rad (119869 997888rarr 1198691015840)

[sum119860 rad (119869 997888rarr 1198691015840)]

120591rad =1

[sum119860 rad (119869 997888rarr 1198691015840)]

(11)

The obtained results for fluorescence branching ratio 120573 andradiative lifetime 120591rad of Er3+ (NPs) ions are tabulated inTable 7 The lifetime is an important information for opticalamplifiers and lasers application especially at the 15 120583mband The longer lifetime at transition of 4I

132level gives

advantage to the population inversion between 4I132

and4I152

levels [32]

36 Green Photoluminescence Figure 6 shows the room tem-perature photoluminescence spectra of zinc borotelluriteglass system containing erbium oxide NPs under 385 nmexcitation wavelength Two main peaks were observed at559 nm and 539 nm which are attributed to 4S

32and 2H

112

levels to the ground state at 4I152

The observed bands aredue to the stark splitting effects which correspond to thelow symmetry of the local environment around Er3+ sites[33] This can be proved by the previous data of Ω

2intensity

parameter at the lower number The electronic configurationschematic diagram is shown in Figure 7 to determine themechanism of emission and energy transfer The emissionpeaks at 559 nm and 539 nm can be ascribed to the visiblelight emissions by transitions of excited optical centers in thedeep levels [33]

It can be seen from Figure 7 that the excitation occursfrom the ground state (4I

152) by absorbing a photon

(25 974 cmminus1) from the excitation beam (GSA (ground stateabsorption) 385 nm) and makes a transition to 4G

112level

The electrons at 4G112

decay nonradiatively (NR) by multi-phonon relaxation to populate 2H

92 4F52

and 4F72

levelsThe electrons at 4F

72level were then relaxed nonradiatively

and populate level 2H112

while the latest state (2H112

) is inthermal equilibrated population with 4S

32excitation levels

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

8 Journal of Nanomaterials

ET

NR

0

5

10

15

20

25

30

GSA

385

nm

Ener

gy (1

03

cmminus1)

Er3+

G4 112

H2 92

F4 52 F4 32

F4 72

H2 112

S4 32

F4 92

I4 92

I4 112

I4 132

I4 152

(538

nm)

(559

nm)

Figure 7 The schematic diagram of[(TeO

2)070(B2O3)030]07(ZnO)

03095(Er2O3)005

and possiblemechanism for visible emissions

[34] The electrons at the excited states of 2H112+4S32

thendecay radiatively to the ground states 4I

152 and produce

green emissionThemechanism of red emission could be alsoexplained by the energy transfer (ET) process between twoadjacent Er3+ electrons through this process

ET1 Er3+(4I

132) + Er3+(4I

112) rarr Er3+(4F

92) +

Er3+(4I152)

ET2 Er3+(4I

112) + Er3+(4I

132) rarr Er3+(4F

92) +

Er3+(4I152)

The energy transfer rate strongly depends on the distance oftwo Er3+ ions which means that the concentration of Er3+affects the efficiency of energy transfer Furthermore theemission peaks of red emission are strongly influenced byenergy transfer process However there is absence of redemission peak of the graph in the present glass system whichis due to the low concentration of Er3+ ions

4 Conclusion

In summary the quaternary composition of TeO2-B2O3-

ZnO-Er2O3NPs glasswas successfully prepared and analyzed

for structural and optical properties The noncrystallinityof the glass sample was confirmed by XRD analysis Theexistence of all glass elements with their exact compositionwas proved by EDX analysis FT-IR analysis revealed theformation of TeO

3indicating the existence of nonbridging

oxygen The bands of BO3units at 1233 and 1343 cmminus1 were

also shown which correspond to the symmetric stretchingvibrations of B-O in trigonal BO

3units The absorption

spectra consist of 10 transitions originating from the groundstate 4I

152to the excited states 4G

112+2H92+4F52+4F72+

2H112+4S32+4F92+4I92+4I112

The extinction coefficientis found to be decreased with increasing wavelength due to

the decreasing number of absorption coefficient Theobtained value of nephelauxetic ratio and bonding parametersuggest that the present glass system is ionic in nature TheJudd-Ofelt parameter was shown to follow the trend ofΩ2gt Ω4gt Ω6 The obtained value of Judd-Ofelt parameter

recommends that the present glass system possesses arelatively strong covalency and lower asymmetry aroundEr3+ sites The quenched green emission of the present glasssystem is shown by the photoluminescence spectra Theexistence of green emission peaks at 559 nm and 539 nmwhich are attributed to 4S

32and 2H

112 is observed which

is due to the stark splitting effect The obtained result ofJudd-Ofelt and photoluminescence shows that the glasssample is very useful in green laser application with highlifetime and strong spectral intensity

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors appreciate the financial support for the workfrom the Ministry of Higher Education of Malaysia throughGPIBT (9411800)

References

[1] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[2] G S Ofelt ldquoIntensities of crystal spectra of rare-earth ionsrdquoTheJournal of Chemical Physics vol 37 no 3 pp 511ndash520 1962

[3] B G Wybourne ldquoThe fascination of the rare earths - then nowand in the futurerdquo Journal of Alloys and Compounds vol 380no 1-2 pp 96ndash100 2004

[4] W Luo J Liao R Li andXChen ldquoDetermination of Judd-Ofeltintensity parameters from the excitation spectra for rare-earthdoped luminescent materialsrdquo Physical Chemistry ChemicalPhysics vol 12 no 13 pp 3276ndash3282 2010

[5] A F da SilvaD SMoura A S Gouveia-Neto et al ldquoIntense redupconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphorrdquo Optics Commu-nications vol 284 no 19 pp 4501ndash4503 2011

[6] A Egatz-Gomez O G Calderon S Melle F Carreno M AAnton and E M Gort ldquoHomogeneous broadening effect ontemperature dependence of green upconversion luminescencein erbium doped fibersrdquo Journal of Luminescence vol 139 pp52ndash59 2013

[7] F Chen T Xu S Dai et al ldquoLinear and non-linear characteris-tics of tellurite glasses within TeO

2-Bi2O3-TiO2ternary systemrdquo

Optical Materials vol 32 no 9 pp 868ndash872 2010[8] M JWeber FromGalileorsquos lsquoOcchialinorsquo to Optoelectronics edited

by P Mazzoldi World Scientific Singapore 1993[9] G Lakshminarayana R Vidya Sagar and S Buddhudu ldquoNIR

luminescence fromEr3+Yb3+ Tm3+Yb3+ Er3+Tm3+ andNd3+ions-doped zincborotellurite glasses for optical amplificationrdquoJournal of Luminescence vol 128 no 4 pp 690ndash695 2008

[10] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treated

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanomaterials 9

silver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[11] M R Dousti M R Sahar M S Rohani et al ldquoNano-silverenhanced luminescence of Eu3+-doped lead tellurite glassrdquoJournal of Molecular Structure vol 1065-1066 no 1 pp 39ndash422014

[12] A Awang S K Ghoshal M R Sahar M Reza Dousti R JAmjad and F Nawaz ldquoEnhanced spectroscopic properties andJuddndashOfelt parameters of Er-doped tellurite glass effect of goldnanoparticlesrdquo Current Applied Physics vol 13 no 8 pp 1813ndash1818 2013

[13] R de Almeida D M da Silva L R P Kassab and C Bde Araujo ldquoEu3+ luminescence in tellurite glasses with goldnanostructuresrdquoOptics Communications vol 281 no 1 pp 108ndash112 2008

[14] M S Figueiredo F A Santos K Yukimitu et al ldquoLuminescencequantum efficiency at 15 120583m of Er3+-doped tellurite glassdetermined by thermal lens spectroscopyrdquo Optical Materialsvol 35 no 12 pp 2400ndash2404 2013

[15] Y Ma Y Guo F Huang L Hu and J Zhang ldquoSpectroscopicproperties in Er3+ doped zinc- and tungsten-modified telluriteglasses for 27 120583m laser materialsrdquo Journal of Luminescence vol147 pp 372ndash377 2014

[16] B R Judd ldquoOptical absorption intensities of rare-earth ionsrdquoPhysical Review vol 127 no 3 pp 750ndash761 1962

[17] F Ren Y-Z Mei C Gao L-G Zhu and A-X Lu ldquoThermalstability and Judd-Ofelt analysis of optical properties of Er3+-doped tellurite glassesrdquo Transactions of Nonferrous MetalsSociety of China (English Edition) vol 22 no 8 pp 2021ndash20262012

[18] K V Raju C N Raju S Sailaja and B S Reddy ldquoJudd-Ofeltanalysis and photoluminescence properties of RE3+ (RE = Eramp Nd) cadmium lithium boro tellurite glassesrdquo Solid StateSciences vol 15 pp 102ndash109 2013

[19] K Selvaraju and K Marimuthu ldquoStructural and spectroscopicstudies on concentration dependent Er3+ doped boro-telluriteglassesrdquo Journal of Luminescence vol 132 no 5 pp 1171ndash11782012

[20] R Rolli M Montagna S Chaussedent A Monteil V KTikhomirov and M Ferrari ldquoErbium-doped tellurite glasseswith high quantum efficiency and broadband stimulated emis-sion cross section at 15120583mrdquoOptical Materials vol 21 no 4 pp743ndash748 2003

[21] H-R Bahari Poor H A A Sidek and R Zamiri ldquoUltrasonicand optical properties and emission of Er3+Yb3+ doped leadbismuth-germanate glass affected by Bi+Bi2+ ionsrdquo Journal ofLuminescence vol 143 pp 526ndash533 2013

[22] D Souri ldquoDSC and FTIR spectra of tellurite-vanadate glassescontaining molybdenumrdquo Middle-East Journal of ScientificResearch vol 5 no 1 pp 44ndash48 2010

[23] B Karthikeyan R Philip and S Mohan ldquoOptical and non-linear optical properties of Nd3+-doped heavy metal borateglassesrdquo Optics Communications vol 246 no 1ndash3 pp 153ndash1622005

[24] B Karthikeyan and S Mohan ldquoStructural optical and glasstransition studies on Nd3+-doped lead bismuth borate glassesrdquoPhysica B Condensed Matter vol 334 no 3-4 pp 298ndash3022003

[25] M Farouk A Samir F Metawe and M Elokr ldquoOpticalabsorption and structural studies of bismuth borate glassescontaining Er3+ ionsrdquo Journal of Non-Crystalline Solids vol 371-372 pp 14ndash21 2013

[26] M E Zayas H Arizpe S J Castillo et al ldquoGlass formation areaand structure of glassy materials obtained from the ZnO-CdO-TeO2ternary systemrdquo Physics and Chemistry of Glasses vol 46

no 1 pp 46ndash57 2005[27] W T Carnall P R Fields and K Rajnak ldquoSpectral intensities

of the trivalent lanthanides and actinides in solution II Pm3+Sm3+ Eu3+ Gd3+ Tb3+ Dy3+ and Ho3+rdquo The Journal ofChemical Physics vol 49 article 4424 1968

[28] K Maheshvaran S Arunkumar V Sudarsan V Natarajanand K Marimuthu ldquoStructural and luminescence studies onEr3+Yb3+ co-doped boro-tellurite glassesrdquo Journal of Alloys andCompounds vol 561 pp 142ndash150 2013

[29] B M Walsh N P Barnes D J Reichle and S Jiang ldquoOpticalproperties of Tm3+ ions in alkali germanate glassrdquo Journal ofNon-Crystalline Solids vol 352 no 50-51 pp 5344ndash5352 2006

[30] S O Baki L S Tan C S Kan H M Kamari A S M Noorand M A Mahdi ldquoStructural and optical properties of Er3+-Yb3+ codoped multicomposition TeO

2-ZnO-PbO-TiO

2-Na2O

glassrdquo Journal of Non-Crystalline Solids vol 362 no 1 pp 156ndash161 2013

[31] D Yin Y Qi S Peng et al ldquoEr3+Tm3+ codoped telluriteglass for blue upconversionmdashstructure thermal stability andspectroscopic propertiesrdquo Journal of Luminescence vol 146 pp141ndash149 2014

[32] Y Fang L HuM Liao and LWen ldquoEffect of bismuth oxide onthe thermal stability and JuddndashOfelt parameters of Er3+Yb3+co-doped aluminophosphate glassesrdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 68 no 3 pp542ndash547 2007

[33] P Ren X Liu K Zhang et al ldquoGreen photoluminescence fromerbium-doped molybdenum trioxiderdquo Materials Letters vol122 pp 320ndash322 2014

[34] Z Ashur SaidMahraz M R Sahar S K Ghoshal M R Doustiand R J Amjad ldquoSilver nanoparticles enhanced luminescenceof Er3+ ions in boro-tellurite glassesrdquoMaterials Letters vol 112pp 136ndash138 2013

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials