heat treatment effect on eu3+ glass systems with ag...

Research ArticleHeat Treatment Effect on Eu3+ Doped TeO2-BaO-Bi2O3 GlassSystems with Ag Nanoparticles

Tomasz Lewandowski1 MichaBDembski1 MichalinaWalas1 Marcin AapiNski1

Magdalena Narajczyk2 Wojciech Sadowski1 and Barbara KoVcielska1

1Department of Solid State Physics Faculty of Applied Physics and Mathematics Gdansk University of TechnologyGabriela Narutowicza 1112 80-233 Gdansk Poland2Laboratory of Electron Microscopy Faculty of Biology University of Gdansk ul Wita Stwosza 57246 80-952 Gdansk Poland

Correspondence should be addressed to Tomasz Lewandowski tlewandowskimifpggdapl

Received 28 July 2017 Accepted 1 October 2017 Published 30 October 2017

Academic Editor Xuping Sun

Copyright copy 2017 Tomasz Lewandowski et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Glass systems of 73TeO2-4BaO-3Bi2O3-2Eu2O3-xAg (in molar ratio where x = 0 1 2 and 3) compositions have been successfullysynthesized Silver nanoparticles were obtained with the employment of heat treatment (HT) procedure executed at 350∘C Glasstransition temperatures of different compositions have been determined through DSC measurements XRD results presentedcharacteristic amorphous halo indicating lack of long range order in the samples FTIR structural studies revealed that glassmatrix is mainly composed of TeO3 and TeO4 species and is stable after different applied heat treatment times X-ray photoelectronspectroscopy (XPS) measurements confirmed that in selected samples part of Ag ions changed oxidation state to form Ag0 speciesTEMmeasurements revealed nanoparticles of size in the range of 20ndash40 nm UV-vis absorption results demonstrated characteristictransitions of Eu3+ ions Additionally UV-vis spectra of samples heat-treated for 6 12 24 and 48 hours presented bands relatedto silver nanoparticles Photoluminescence (PL) studies have been performed with excitation wavelength of 120582exc = 395 nmObtained spectra exhibited peaks due to 5D0-

7FJ (where 119869 = 2 3 4) and 5D1-7FJ (where 119869 = 1 2 3) transitions of Eu3+ Moreoverluminescence measurement indicated enhancement of rare earth ions emissions in several of the annealed samples Increase ofemission intensity of about 35 has been observed

1 Introduction

Superior properties for instance mechanical and thermalstability high devitrification resistance and suitable infraredtransparency make tellurite glasses promising materials forvariety of applications related to the field of optics forexample light upconversion materials lasers solar cellsor optical amplifiers [1ndash6] Additionally these glasses aresuitable for utilization as luminescentmaterials owing to theirlow phonon energy (700 cmminus1) in comparison to other oxideglasses and wide transmission window This property leadsto minimization of the nonradiative losses Tellurite glassesalso exhibit good solubility of rare earth ions that allows forpossible employment of their f-f transitions in order to obtainefficient light sources with tunable emission color [7 8]

In recent years glasses doped with silver gained muchattention considering possibility of the localized surfaceplasmon resonance (LSPR) phenomenon utilization LSPRis observed in case of nanoparticles with sizes smaller than100 nm Electron excitations creating charge oscillations atthe metal-insulator boundary lead to large local electric fieldenhancement in the vicinity of nanoparticles creating socalled ldquohot-spotsrdquo As a result it is possible to increase theintensity of rare earth ions emissions Formation of silvernanoparticles is facilitated by high mobility of silver ions intellurite glass matrix and suitable redox potential of Ag+ rarrAg0 reduction [9] Silver is reduced through one-step process

Ag+ + 1eminus 997888rarr Ag0 (1)

HindawiJournal of NanomaterialsVolume 2017 Article ID 5075326 12 pageshttpsdoiorg10115520175075326

2 Journal of Nanomaterials

with the reduction potential of 1198640 = 07996V [10] Highlymobile silver ions are form nanoparticles by matrix-assistedreduction process for example by structural elements ofTeO2 matrix with uncompensated charge Silver diffusesinto tellurite glass matrix changes its valance state andforms nanoparticles through Ostwald ripening Thus it ispromising to synthesize the nanoparticles inside glass matrixand in consequence achieve emission enhancement of rareearth ions with employment of metal nanoparticles

One of the first reports on LSPR in glass medium was thework of Malta et al [11] on borosilicate glasses Enhancementof Eu3+ ions emissions has been observed Lately numerousworks concerning silver nanoparticles and emission enhance-ments throughLSPRphenomenonhave been reported in caseof various glass systems [12ndash15] Number of studies describedthe formation of silver nanoparticles in glass matrix throughheat treatment approach While in higher temperaturesmobility of silver ions increases heat treatment approachinvolves annealing of samples usually above glass transitiontemperature to introduce metallic nanoparticles [16] Thatmethod is widely applied in order to create nanoparticlesthrough their agglomeration and to obtain enhancementof rare earth emission intensity Jiao et al examined theluminescence of Eu3+ in borate glasses after addition of silverand mechanisms of Ag ions agglomeration In this caseenhancement of emission intensities has been detected [17]White light emission in europium doped phosphate glasseswas obtained by Fan et al [18] In this study an efficientenergy transfer between nanoparticles and Eu2+ and Eu3+species has been detected Moreover a number of studieswere dedicated to describe silver influence on rare earthsemission intensities inmatrices demonstrating lower phononenergies such as tellurite and tellurite based glasses

Amjad et al [19] studied the influence of silver nanopar-ticles on the luminescence properties of Eu3+ in TeO2-ZnOglass systems and obtained increase of emission intensitiesof europium ions Dousti et al focused on the silver dopedTeO2-PbO glasses [20] Du et al reported tellurite-germanateglasses for solar converters doped with Ag nanoparti-cles to enhance Pr3+ emission intensity [21] Fares et alobtained TeO2-BaO-Nb2O5-Er2O3 glasses with embeddedsilver nanoparticles [22] Enhancement of lifetime and emis-sion intensities of the Er3+ 4I132 rarr

4I152 transition has beenobserved Huang et al studied Er3+Tm3+ codoped TeO2-ZnO-Na2CO3-Er2O3-Tm2O3-AgNO3 glasses doped with sil-ver and observed 185 120583m band fluorescence enhancementmainly attributed to the intensified local field effect inducedby Ag NPs [23] Wu et al presented study on influence ofsilver on Er3+Yb3+ codoped TeO2-Bi2O3-TiO2 glasses [24]

To the best of our knowledge there are no reportson europium doped TeO2-BaO-Bi2O3-Ag (TBBAg) systemswith silver nanoparticles obtained through heat treatmentprocess Similar glass materials have never been studied interms of silver incorporation and its influence on rare earthions emission The aim of this work is the synthesis ofsilver nanoparticles in tellurite glass matrix and to study theinfluence of silver addition on luminescence of europium ionsincorporated into TBBAg glass This novel glass matrix is

promisingmaterial for Eu3+ host with its excellent propertiesSince TeO2 is conditional glass former BaO is introducedto stabilize the glass matrix Heavy metal oxides such asbarium oxide are proven to induce higher devitrificationresistance of glasses [25] Moreover low phonon energy oftellurite glass promotes radiative transitions of rare earth ionsThe aforementioned properties of synthesized glass matrixare the reason that it has been used in this work Silvernanoparticles on the other hand are introduced to studythe rare earth ions emission enhancement through LSPRphenomenon It has never been done before in glass systemof similar composition Since this work is also focused onmatrix influence on luminescence of rare earth ion europiumions have been chosen as a luminescent center since itsemission properties are well understood Additionally studyof the LSPR as a function of different amount of silverin glass is performed Finally influence of heat treatmentprocedure on luminescent properties of obtained materialis discussed TBBAg system is promising material for colortunable phosphors that can be used in LEDs and in lightingindustry

2 Experimental

Synthesis of tellurite glass samples involved mixing andpulverizing of high purity TeO2 BaCO3 Bi5O(OH)9(NO3)4Eu(NO3)3 and AgNO3 raw materials in powder form Con-ventional melt-quenching technique has been used to obtainamorphous glass material Well-mixed batches were placedin porcelain crucibles and were gradually heated to 800∘Cin order to enhance the mixing of ingredients After 30minutes the temperature was reduced to 700∘C for the next30 minutes Afterwards obtained melt was poured onto apreheated steel plate (300∘C) pressed immediately betweensteel plates and then cooled down to room temperature Eachstage of this procedure was carried out in the air atmosphereSuch approach led to synthesis of homogenous transparentsamples

Heat treatment (HT) stage involves annealing of thesamples usually above glass transition temperature In thiswork heat treatment at 350∘C in the air atmosphere hasbeen applied This has been done to initiate the migration ofsilver ions thatwould lead to formation of silver nanoparticlesembedded in glass matrix HT procedure is considered to bethe method of choice in case of solid state samples since it isa simple one-step process that allows controlling annealingparameters Different HT times have been applied in order tostudy the evolution of the glass system and change of sampleproperties HT parameters are presented in Table 1 in detail

Differential scanning calorimetry (DSC) measurementswere executed on Netzsch Simultaneous TGA-DSC STA449 F1 in order to determine the thermal properties ofthe material such as glass transition and crystallizationtemperature Investigations were conducted on powder sam-ples in platinum-rhodium crucibles with heating rate of15∘Cminminus1 in the air atmosphere Structural investigationswere performed using several techniques Examination ofinternal structure of prepared samples was carried out using

Journal of Nanomaterials 3

Table 1 Parameters of heat treatment performed on obtained samples

Sample series Composition (molar ratio) HT (h) T (∘C)Ag0 73TeO2-4BaO-3Bi2O3 mdash mdashAg1 73TeO2-4BaO-3Bi2O3-1Ag 0 3 6 12 24 48 96

350

Ag2 73TeO2-4BaO-3Bi2O3-2Ag 0 3 6 12 24 48 96Ag3 73TeO2-4BaO-3Bi2O3-3Ag 0 3 6 12 24 48 96AgEu1 73TeO2-4BaO-3Bi2O3-2Eu2O3-1Ag 0 3 6 12 24AgEu2 73TeO2-4BaO-3Bi2O3-2Eu2O3-2Ag 0 3 6 12 24AgEu3 73TeO2-4BaO-3Bi2O3-2Eu2O3-3Ag 0 3 6 12 24

conventional X-ray diffraction (XRD) technique Measure-ments were executed on powder samples using PhilipsXrsquoPERT PLUS diffractometer with Cu-K120572 radiation (120582 =0154 nm) Chemical bonds existing in the structural units ofthe glass samples were determined using Fourier TransformInfrared (FTIR) spectroscopy results These measurementswere undertaken on Perkin-Elmer Frontier MIRFIR spec-trometerwithTGSdetector in themidinfrared spectral rangeExamination involved creating pellet-type samples contain-ing mixture of glass with potassium bromide (KBr) in weightratio 1 100 The same amount of ingredients with controlledgrain size was introduced in case of all measured samplesMeasurements were performed with 05 cmminus1 spectral reso-lution X-ray photoelectron spectroscopy analysis (XPS) wascarried out with the employment of X-ray photoelectronspectrometer (Omicron NanoTechnology) with 128-channelcollector Investigated samples were precleaned by Ar ionbeam XPSmeasurement has been done at room temperaturein ultrahigh vacuum conditions below 11 times 10minus8mBar Thephotoelectrons were excited by an Mg-K120572 X-ray source TheX-ray anode was operated at 15 keV and 300W OmicronArgus hemispherical electron analyserwith round aperture of4mm was used for analysing of emitted photoelectrons Thebinding energies were corrected using the background C1sline (2850 eV) as a reference XPS spectra were analysed withCasa-XPS software using a Shirley background subtractionand GaussianndashLorentzian curve as a fitting algorithm Fortransmission electron microscopy TEM samples were placedon copper grids coated with a 2 collodion solution andcarbon Probes were examined using a Tecnai Spirit BioTwin(FEI) electron microscope at 120 kV UV-vis spectra werecollected on Perkin-Elmer Lambda 35 UV-vis spectropho-tometer in the range of 350ndash700 nm Measurements wereconducted in the air atmosphere Photoluminescence (PL)spectra were collected in the 430ndash750 nm range in case ofemission spectra and 250ndash500 nm for excitation spectra usingPerkin-Elmer LS 55 spectrofluorometer Measurements wereperformed using pellet samples mixed with KBr in weightratio of 1 1

Calculations of the extinction coefficients were achievedusing the multireflectance formula [27]

119879 = (1 minus 119877)2 times 119890minus120572119889

((1 minus 119877)2 times 119890minus2120572119889) (2)

where120572 is the extinction coefficient119889 is the sample thicknessR is the reflectance and T is the transmittance For each

Hea

rt fl

ow (a

rb u

nit)

Temperature (∘C)

Tg

Tc1

Tc2

exo up

(a)

(b)

318∘C 387∘C

420∘C

321∘C416∘C

500400300

Figure 1 DSC spectrum of Ag0 (a) and Ag1 (b) glass samples

Table 2 Thermal parameters of Ag0 and Ag1 glass samples

Sample 119879119892 (∘C) 1198791198881 (∘C) 1198791198882 (∘C) TS (∘C)Ag0 321 mdash 416 95Ag1 318 387 420 69

sample values of reflectance and the transmittance weremeasured Extinction coefficient value was calculated bysubtracting the extinction coefficient of the sample withoutsilver addition from that of the annealed samples containingsilver nanoparticles

3 Results and Discussion

31 Structural Studies

311 DSC DSC curves of Ag0 and Ag1 glass samples arepresented in Figure 1((a) and (b)) Glass transition temper-ature 119879119892 is located at 321 and 318∘C respectively In caseof Ag0 sample one clear exothermic peak attributed tothe crystallization process may be distinguished at 416∘COn the other hand DSC curve of Ag1 consists of themain crystallization peak at 420∘C and additionally anotherexothermal peak at 387∘CThermal stability [28] (TS) regionshave been determined and equaled 95∘C in case of Ag0 and69∘C for Ag1 sample Thermal parameters of studied samplesare presented in Table 2


Inte

nsity

(au

)

2Θ (∘)8070605040302010

Figure 2 XRD result of AgEu1 glass sample annealed for 6 hours

These measurements have been performed mainly inorder to investigate the TS region Its range is crucial for silvernanoparticles formation process considering the fact thattheir synthesis is usually performed below the temperatureof the first crystallization peak but above the glass transitiontemperature Above 119879119892 glass properties such as viscosity andionmobility change favoring silver nanoparticles agglomera-tion Additionally such approach prevents the crystallizationof glass matrix which is the case in our work

Therefore synthesis of Ag nanoparticles has been per-formed in the range between 119879119892 and the onset of the firstcrystallization peak at 387∘C It is our consideration that usedtemperature range would be sufficient to initialize migrationof silver ions to form silver nanoclusters This is possible dueto decrease of glass viscosity with increasing temperature

312 XRD XRD results were obtained for glass materialsannealed for 3 6 12 and 24 hours Amorphous halo is evidentindicating that no long range order periodicity existed in thesamples It was not possible to detect any Ag nanoparticlessignals because only 1ndash3mol of silver was introduced intothe samples

On the other hand in case of nanoparticles one canobserve widening of diffraction peaks and due to nanoscalesize such peak can overlap with wide amorphous haloExemplary result of AgEu1 sample heat-treated for 6 hoursis presented in Figure 2

313 FTIR FTIR technique was employed to reveal anystructural alterations induced by heat treatment procedureor by the change of composition Moreover basic structuralelements of the matrix were also revealed Tellurite glassesare usually composed of TeO3 pyramids and TeO4 trigonalbipyramids Obtained measurement results of as-preparedand heat-treated Ag1 samples are presented in Figure 3 Toexamine heat treatment induced changes in tellurite glassmatrix two samples have been chosen for measurement as-prepared and heat-treated for 96 hours Main feature is thewide band visible in the 530ndash850 cmminus1 range This band canbe deconvoluted into two signals positioned at 650 cmminus1 and

Noncrystallized96 h of HT

Wavenumber (cＧminus1)

Tran

smitt

ance

(au

)

1000900800700600500400

Figure 3 FTIR spectrum of Ag1 sample noncrystallized (dottedline) and heat-treated for 96 h (solid line) The pink curve refers tosignal due to vibrations in TeO4 elements while the green one refersto vibration signal in TeO3

730 cmminus1 The first one (pink curve) at 650 cmminus1 came fromTe-O stretching vibrations of TeO4 trigonal bipyramids [29ndash31] The second one (green curve) at approximately 730 cmminus1is associated with oscillations of Te-O in TeO3 trigonalpyramids [30 31] TeO4 derived signal is stronger in bothcases This might indicate that more TeO4 species exist inobtained material

Intensities of the aforementioned bands varied slightly asa function of annealing time Heat treatment for 96 h resultedin increased intensity of these two peaks However observedchanges of FTIR spectra are minor Ratio between intensitiesof TeO4 and TeO3 derived bands remained approximatelyconstant Therefore it is concluded that glass matrix isresistant to heat treatment procedure and stays unchangedeven when long annealing times have been applied It isconsistent with XRD results that indicated no crystallizationof glass matrix after HT process

314 XPS XPS experiment has been performed to provideinsight on valance state of silver in tellurite glass matrixExemplary spectra of as-prepared Ag1 sample Ag1 and Ag3samples crystallized for 6 h are presented in Figure 4(a)Ag3d52 and Ag3d32 photoelectron peaks of silver havebeen observed at 368 and 374 eV respectively Spin orbitcomponents in all cases were separated by distance of 6 eVwhich is characteristic of silver Shape of obtained spectra iscomparable to others published before [32] However it is dif-ficult to distinguish between different silver state componentsof 3d52 peakTherefore definition of silver oxidation state onthe basis of XPSmeasurements is challenging and sometimesimpossible Consequently modified Auger parameter (1205721015840)had to be calculated In order to acquire it kinetic energyvalues of silverM4VVAuger lines are determined (presentedin Figure 4(b)) Their positions equaled 3556 eV 3573 eVand 3576 eV in case of Ag1 (HT = 0 h) Ag1 (HT = 6 h) and


Table 3 Results of XPS measurement performed on Ag1 and Ag3 glass samples

Sample HT (h) Ag3d52 (eV) Ag3d32 (eV) M4VV (eV) 1205721015840 (eV)Ag1 0 3680 3742 3556 7236Ag1 6 3681 3739 3573 7254Ag3 6 3680 3740 3576 7256Value of Auger parameter of metallic silver [26] 7260

CPS

(au

)

Ag1Ag3NC

Binding energy (eV)375370365360

(a)

CPS

(au

)

Ag1Ag3NC

Kinetic energy (eV)360340320300

(b)

Figure 4 Ag3d photoelectron peaks (a) and Auger lines (b) of Ag1 and Ag3 heat-treated samples and noncrystallized (NC) Ag1 sample

Ag3 (HT = 6 h) samples respectively Parameter has beencalculated according to the following equation

1205721015840 = BE (Ag3d52) + KE (Ag M4VV) (3)

where BE(Ag3d52) is the binding energy of Ag3d52 peak andKE(Ag M4VV) is kinetic energy of M4VV Auger line peakParameter1205721015840 formetallic silver equals 726 eV [26] Calculatedresults are presented in Table 3

As-prepared Ag1 sample possessed lowest modifiedAuger parameter which suggests that in case of Ag1 specimenmost of silver exists in ionic form It is indicative that mixtureofmetallic and ionic silver exists in both heat-treated samplessince obtained results are in the range between parameterscharacteristic to AgO species and metallic silver

However some portion of silver ions changed theirvalance state and formed Ag0 species For heat-treated Ag1sample parameter 1205721015840 equaled 7254 eV which means thatmixture of Ag oxidation states existed with the great majorityof Ag0 species Moreover parameter of Ag3 sample is evenhigher and equals 7256 which confirms that most of silverexists in Ag0 form Since the value of parameter for Ag3sample is close to that of metallic silver it is concluded thatratio of Ag0 to other Ag species in that specimen is the highestof all samples

Additional study has been performed on Ag1 sampleheat-treated for 6 hours in order to describe bismuth ionsvalance state There was a possibility of bismuth reductionand nucleation since heat treatment process created envi-ronment propitious for metallic nanoparticles formation Noevidence for bismuth nucleation has been obtained sincebismuth Bi4f signals observed (Figure 5) are characteristicto bismuth in oxide state Peaks possess symmetric shapeand are positioned at 1596 and 1649 eV (for Bi4f72 andBi4f52 resp) Thus it can be concluded that only Bi3+ ionsexist in glass matrix This is consistent with the fact thatBi2O3 is conditional glass former and probably is one of thecomponents creating the amorphous matrix

315 TEM In order to observe the silver nanoparticlesembedded in tellurite glass material TEM measurement hasbeen performed Samples with Ag1 Ag2 and Ag3 designa-tions annealed for 6 hours has been chosen for measurementExemplary TEM images have been presented in Figures 6(a)6(b) and 6(c) As it can be noticed nanoparticles are indeedsynthesized within amorphous tellurite glass matrix Theshape of nanoparticles is spherical However nanoparticlesof different size have been obtained in different samplesIncrease of dimensionswith increasing amount of introducedsilver can be observed In case of Ag1 samples nanoparticles


Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000

Figure 5 Bi4f photoelectron peaks in Ag1 sample heat-treated for 6 h

50nm

(a)

50nm

(b)

50nm

(c)

Figure 6 TEM images of Ag1 Ag2 and Ag3 samples heat-treated for 6 hours ((a) (b) and (c) resp)

50nm

(a)50nm

(b)

50nm

(c)

Figure 7 TEM images of Ag1 samples heat-treated for 3 6 and 12 hours ((a) (b) and (c) resp)

size does not exceed 30 nm whereas in Ag2 and Ag3 samplesizes exceed 30 nm and 40 nm respectively

TEM measurements are strongly supported with theaforementioned XPS results which indicated that majority ofsilver is in metallic form in Ag3 sample Increased number ofAg0 species resulted in formation of larger agglomerates

In Figure 7 exemplary TEM images of Ag1 samples heat-treated for 3 6 and 12 hours have been presented It is worthnoticing that with changing heat treatment time diameterof observed nanoparticles increases with heat treatmentduration In samples heat-treated for 3 hours nanoparticlesare not exceeding 20 nm in diameter On the other hand in


400 450 500

Wavelength (nm)550 600 650

0

20

40

60

80

Tran

smitt

ance

()

Figure 8 UV-vis transmittance spectrum of AgEu1 sample

sample heat-treated for 12 hours nanoparticles of 30ndash40 nmhave been observed It can be thus concluded that changeof heat treatment parameters influences the size of silvernanoparticles embedded in tellurite glass matrix

32 Optical Studies

321 UV-vis UV-vis spectrum of AgEu1 sample is shown inFigure 8 It can be noticed that absorption signals characteris-tic to Eu3+ were present Peaks at 465 and 532 nm due to 7F0-5D2 and

7F0-5D1 transitions have been observed and assigned

on the basis of the energy levels reported in [33]To observe the influence ofAg quantity on silver nanopar-

ticles formation samples without europium addition havebeenmeasured first In Figures 9(a) 9(b) and 9(c) extinctioncoefficient in function of wavelength has been presented forobtained series Through application of different HT condi-tions it is possible to obtain tunable LSPR peak dependingon silver content Position and intensity of LSPR band variedslightly with different HT time applied Samples heat-treatedfor 6 24 and 48 hours are shown Moreover amount ofincorporated silver is also a factor influencing the LSPRband intensity and position It might indicate that silvernanoparticles size can be altered through change of silvercontent and performing different HT procedure Howeverdue to the fact that observed LSPR bands are very wideand amount of introduced silver is small it is difficult toaccurately calculate exact shift value of LSPR bands causedby the changes of nanoparticle sizes

Surface plasmon band is visible in Figures 9(a) 9(b) and9(c) in the range of 500ndash550 nm Silver LSPR peak has beenobserved above 500 nm in [22 34] In tellurite matrix withits refractive index of approximately 2 LSPR band shifts tohigherwavelengths in comparison to silicate glasses [20]Thisis consistent with the following equation [35]

1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)

where119873 is the concentration of free electrons 120576infin is themetaloptical dielectric function 1205760 is the permeability of free space119899 is the refractive index of glass host and 119888 and 119898 are speedof light and electron effective mass respectively One can findthat wavelength of LSPR depends on refractive index of glassmatrix Thus LSPR is red shifted in case of matrices withhigher refractive indices [36]

UV-vis results are consistent with XPS and TEM mea-surements presented in previous section Observation sug-gests the successful nanoparticles formation

322 Photoluminescence In case of excitation spectrummoni-tored at 615 nm several bands corresponding to the 4f -4f tran-sitions of Eu3+ are apparent They were assigned to 7F0-5D4 (362 nm) 7F0-

5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-

5D2 (465 nm) transitions [19 37] Spec-trum of AgEu1 sample is presented in Figure 10

In case of 395 nm excitation number of peaks due totransitions of Eu3+ was observed Starting with low wave-lengths signals at 536 and 557 nm (as a result of 5D1-

7F1and 5D1-

7F2 transitions) and peaks at 588 615 654 and703 nm (5D0-

7F17F27F3 and

7F4 transitions) can be noticed[37ndash40] Additionally matrix spectrum (Ag0 sample) hasbeen obtained as a reference which is included in presentedemission spectra

The same excitation has been used for samples with silvernanoparticles generated through heat treatment processResults are presented in Figures 11(a) 11(b) and 11(c) ForAgEu1 sample annealed for 3 6 and 12 hours increase of Eu3+emission intensities was observed Maximum of 5D0-

7F2band intensity (615 nm) was detected for 6 hours of HT timeThis can be explained by LSPR which enhances europiumions transitions Eu3+ ions lying near silver nanoparticles areinfluenced by increased local field around AgNPs Radiativetransition of 5D0-

7F2 is electric-dipole transition [41] It ishypersensitive to local environment change and modifica-tion of local symmetry Considering this increase of itsintensity may indicate influence of silver nanoparticles Ratiobetween intensities of 5D0-

7F2 peak and 5D0-7F1 magnetic-

dipole transition (588 nm) allows evaluating if the intensitychange of 5D0-

7F2 transition has the origin in electric fieldenhancement This parameter reached the maximum of itsvalue after HT of 6 hours This is indicative for local electricfield influence of AgNPs To visualize interaction betweenrare earth ions and silver nanoparticles energy level diagramof Eu3+ has been presented in Figure 12

However when longer heat treatment times have beenapplied quenching of europium transitions was noticed It isapparent in case of emission spectrum of the AgEu1 sampleannealed for 24 hours This is most likely caused by Eu3+-AgNP energy transfer processes that hinder the radiativetransitions of Eu3+ and promote nonradiative relaxationsAdditionally growth of silver nanoparticles could lead todecrease of Eu3+-AgNP distance that enhances energy trans-fer processes [42] At shorter Eu3+-AgNP distance dipole-dipole interactions become significant resulting in decreaseof europium ions luminescence intensity [43 44] Quenching


0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

(a) LSPR band in Ag1 series

Wavelength (nm)650600550500

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h

(b) LSPR band in Ag2 series


105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h

(c) LSPR band in Ag3 series

Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350

Figure 10 Excitation spectrum of AgEu1 glass sample with 120582em = 615 nm


Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)

Wavelength (nm)612 615 618 621

3 h6 h12 h

24 hAs-prepared

(a) Emission spectra of AgEu1 sample

Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared

(b) Emission spectra of AgEu2 sample

Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared

(c) Emission spectra of AgEu3 sample

Figure 11

can also have its origin in increased absorbance of silvernanoparticles grown for longer time periods

For AgEu2 and AgEu3 glass samples enhancement ofeuropium emission bands is not observed The reason isprobably an excessive amount of silver added to glass sampleQuenching can occur when ratio of RE ions to silver is belowone Energy transfer mechanisms such as Eu3+ rarr AgNPtransfer takes place which ultimately prevents the increase ofeuropium ions emission intensities [9 45] It should be notedthat relative position between AgNPs and Eu3+ ions is crucialsince dipole interactions dominate over local field enhance-ment when distance separating them becomes shorter Dueto possible small separation between ions and nanoparticlesthis quenching mechanism cannot be neglected

Observed lack of enhancement in case of Ag2 and Ag3series is consistent with TEM results At higher concen-trations silver creates larger agglomerates which could beobserved in Figure 6 In case of those samples size ofthe nanoparticles is not optimal for emission enhancementof rare earth ions At this point energy transfer mech-anisms become dominant Moreover absorption of silvernanoparticles may have increased with size and as a resultintensity of rare earth ions emission is decreased In oursystem silver nanoparticles of sizes exceeding approximately30 nm resulted in lack of Eu3+ luminescence enhancementIt is thus concluded that dimensions of silver nanoparticlesshould be strictly controlled in order to avoid quenchingin compositions with higher silver content This could be


LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3

Figure 12 Energy level diagram of Eu3+ ions Observed emissionsrepresented by lines of different colors

CIE 1931 chromaticity diagram08

07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420

Figure 13 CIE chromaticity diagram of AgEu1 (diamond) AgEu2(circle) and AgEu3 (triangle) samples heat-treated for 6 hours

done with introduction of appropriate silver amount andheat treatment time In case of this work best results wereobtained in samples with silver nanoparticles of sizes below30 nm Such nanoparticles have been synthesized in AgEu1series heat-treated for 6 hours

Exemplary CIE diagrams of Ag1 Ag2 and Ag3 samplesheat-treated for 6 hours are presented in Figure 13 Excitationwith 395 nm wavelength resulted in reddish-orange emissionin case of all samples Silver amount did not influence the

emission color significantly For simplicity only samplesannealed for 6 hours are presented since all obtained samplesemitted similar red to orange color

4 Conclusions

Presented XRD results have shown that amorphous materialof 73TeO2-4BaO-3Bi2O3-2Eu2O3-xAg (where x = 1 2 and 3)composition has been successfully obtained No crystalliza-tion of glassmatrix is detected in the as-prepared samples dueto correct conditions of melt-quenching process DSC studyrevealed that glass transition temperature and thermal stabil-ity TS changes only slightly with introduction of silver ionsFor TeO2-BaO-Bi2O3 glass matrix and TeO2-BaO-Bi2O3-Agsample 119879119892 was determined as 321 and 318∘C respectivelyThermal stability parameter was slightly decreased after silveradditionThis is caused by introduction of some nonbridgingoxygen in glass matrix which would lead to slight decreaseof glass transition temperature Thus obtained material isconsidered to be thermally stable FTIR results presentedthat after exposure to heat treatment for excessive time ratioof signal intensities due to TeO3 and TeO4 species doesnot change significantly This in fact confirms that glassmatrix is not influenced by HT process and its structure isheat resistant XPS measurement indicated that in case ofAg1 and Ag3 glass samples annealed for 6 hours most ofsilver changed its valance state to Ag0 Shape position anddistance between Ag3d doublet also corresponds to metallicsilver Highest amount of Ag0 has been determined in caseof Ag3 series probably due to higher silver content Withthe employment of TEM imaging technique round-shapedsilver nanoparticles have been observed in case of sampleswith different silver content and heat treatment time Moreimportantly silver nanoparticles increase their sizes withincreasing silver content Nanoparticles diameters were in therange of 20ndash50 nm UV-vis absorption results additionallyproved that silver nanoparticles have been obtained It isconcluded that change of the silver content together withmodification of heat treatment time can result in tunableLSPR band and silver nanoparticles dimensions It is promis-ing to further study the influence of HT process on silvernanoparticles properties Photoluminescence measurementspresented the enhancement of Eu3+ emission bands in caseof AgEu1 sample Enhancement is observed until 6 hoursof annealing is applied Then for 12 and 24 hours of heattreatment decrease of intensity is observed probably due toEu3+-AgNP energy transfer Obtained materials could findapplication in tunable red to yellow-white light emitters

Conflicts of Interest

The authors declare that they have no conflicts of interest

References

[1] Y Cheng ZWu X Hu TWu andW Zhou ldquoThermal stabilityand optical properties of a novel Tm3+ doped fluorotelluriteglassrdquo Journal of Rare Earths vol 32 no 12 pp 1154ndash1161 2014


[2] H Lin S Tanabe L Lin et al ldquoInfrequent blue and greenemission transitions from Eu3+ in heavy metal tellurite glasseswith low phonon energyrdquo Physics Letters A vol 358 no 5-6 pp474ndash477 2006

[3] Y Gao Q-H Nie T-F Xu andX Shen ldquoStudy of luminescenceproperties of novel Er3+ single-doped and Er3+Yb3+ co-doped tellurite glassesrdquo Spectrochimica Acta Part A Molecularand Biomolecular Spectroscopy vol 61 no 6 pp 1259ndash12622005

[4] E A Lalla U R Rodrıguez-Mendoza A D Lozano-Gorrın ASanz-Arranz F Rull and V Lavın ldquoNd3+-doped TeO2-PbF2-AlF3 glasses for laser applicationsrdquoOptical Materials vol 51 pp35ndash41 2016

[5] Y Lu M Cai R Cao S Qian S Xu and J Zhang ldquoEr3+doped germanate-tellurite glass for mid-infrared 27120583m fiberlaser materialrdquo Journal of Quantitative Spectroscopy amp RadiativeTransfer vol 171 pp 73ndash81 2016

[6] X Pi X Cao Z Fu et al ldquoApplication of Te-Based Glass inSilicon Solar Cellsrdquo Acta Metallurgica Sinica (English Letters)vol 28 no 2 pp 223ndash229 2015

[7] D Li W Xu P Kuan et al ldquoSpectroscopic and laser propertiesof Ho3+ doped lanthanum-tungsten-tellurite glass and fiberrdquoCeramics International vol 42 no 8 pp 10493ndash10497 2016

[8] A Maaoui F Ben Slimen M Haouari A Bulou B Boulardand H Ben Ouada ldquoUpconversion and near infrared emissionproperties of a novel Er3+Yb3+ codoped fluoro-tellurite glassrdquoJournal of Alloys and Compounds vol 682 pp 115ndash123 2016

[9] V A G Rivera Y Ledemi S P A Osorio et al ldquoEfficientplasmonic coupling between Er3 +(AgAu) in tellurite glassesrdquoJournal of Non-Crystalline Solids vol 358 no 2 pp 399ndash4052012

[10] I Soltani S Hraiech K Horchani-Naifer H Elhouichet BGelloz and M Ferid ldquoGrowth of silver nanoparticles stimulatespectroscopic properties of Er3+ doped phosphate glasses Heattreatment effectrdquo Journal of Alloys and Compounds vol 686 pp556ndash563 2016

[11] O L Malta P A Santa-Cruz G F De Sa and F Auzel ldquoFluo-rescence enhancement induced by the presence of small silverparticles in Eu3+ dopedmaterialsrdquo Journal of Luminescence vol33 no 3 pp 261ndash272 1985

[12] M E Camilo T A A Assumpcao D M Da Silva D SDa Silva L R P Kassab and C B De Araujo ldquoInfluence ofsilver nanoparticles on the infrared-to-visible frequency upcon-version in Tm3Er3Yb3 doped GeO 2-PbO glassrdquo Journal ofApplied Physics vol 113 no 15 Article ID 153507 2013

[13] H-R Bahari R Zamiri H A A Sidek A Zakaria and F RM Adikan ldquoCharacterization and synthesis of silver nanos-tructures in rare earth activated GeO2-PbO glass matrix usingmatrix adjustment thermal reduction methodrdquo Entropy vol 15no 5 pp 1528ndash1539 2013

[14] Y Hu J Qiu Z Song et al ldquoSpectroscopic properties of Tm3+Er3+Yb3+ co-doped oxyfluorogermanate glasses containingsilver nanoparticlesrdquo Journal of Luminescence vol 145 pp 512ndash517 2014

[15] S Mohapatra ldquoTunable surface plasmon resonance of silvernanoclusters in ion exchanged soda lime glassrdquo Journal of Alloysand Compounds vol 598 pp 11ndash15 2014

[16] V A G Rivera D Manzani Y Messaddeq L A O Nunes andE Marega Jr ldquoStudy of Er3+ fluorescence on tellurite glassescontaining Ag nanoparticlesrdquo Journal of Physics ConferenceSeries vol 274 no 1 Article ID 012123 2011

[17] Q Jiao X Wang J Qiu and D Zhou ldquoEffect of silver ionsand clusters on the luminescence properties of Eu-doped borateglassesrdquoMaterials Research Bulletin vol 72 pp 264ndash268 2015

[18] S Fan C Yu D He K Li and L Hu ldquoWhite light emissionfrom 120574-irradiated AgEu co-doped phosphate glass under NUVlight excitationrdquo Journal of Alloys and Compounds vol 518 pp80ndash85 2012

[19] R J Amjad M R Dousti M R Sahar et al ldquoSilver nanopar-ticles enhanced luminescence of Eu3+-doped tellurite glassrdquoJournal of Luminescence vol 154 pp 316ndash321 2014

[20] 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

[21] Y Y Du B J Chen E Y B Pun Z Q Wang X Zhao andH Lin ldquoSilver nanoparticles enhanced multichannel transitionluminescence of Pr3+ in heavy metal germanium telluriteglassesrdquo Optics Communications vol 334 pp 203ndash207 2015

[22] H Fares H Elhouichet B Gelloz and M Ferid ldquoSilvernanoparticles enhanced luminescence properties of Er3+ dopedtellurite glasses Effect of heat treatmentrdquo Journal of AppliedPhysics vol 116 no 12 Article ID 123504 2014

[23] B Huang Y Zhou P Cheng Z Zhou J Li and G YangldquoThe 185 120583m spectroscopic properties of Er3+Tm3+co-dopedtellurite glasses containing silver nanoparticlesrdquo Journal ofAlloys and Compounds vol 686 pp 785ndash792 2016

[24] L Wu Y Zhou Z Zhou et al ldquoEffect of silver nanoparticleson the 153 120583m fluorescence in Er3+Yb3+ codoped telluriteglassesrdquo Optical Materials vol 57 pp 185ndash192 2016

[25] G Laudisio and M Catauro ldquoGlass transition temperatureand devitrification behaviour of glasses in the Na2Osdot4GeO2-K2Osdot4GeO2 composition rangerdquo Materials Chemistry andPhysics vol 51 no 1 pp 54ndash58 1997

[26] M Ramstedt and P Franklyn ldquoDifficulties in determiningvalence for Ag0 nanoparticles using XPS - Characterizationof nanoparticles inside poly (3-sulphopropyl methacrylate)brushesrdquo Surface and Interface Analysis vol 42 no 6-7 pp 855ndash858 2010

[27] K Sadecka M Gajc K Orlinski et al ldquoWhen eutectics meetplasmonics Nanoplasmonic volumetric self-organized silver-based eutecticrdquo Advanced Optical Materials vol 3 no 3 pp381ndash389 2015

[28] A Dietzel ldquoGlass structure and glass propertiesrdquoGlastechnischeBerichte-Glass Science and Technology vol 22 pp 41ndash45 1968

[29] E Culea I Vida-Simiti G Borodi E N Culea R Stefanand P Pascuta ldquoEffects of Er3+Ag codoping on structuraland spectroscopic properties of lead tellurite glass ceramicsrdquoCeramics International vol 40 no 7 pp 11001ndash11007 2014

[30] N M Yusoff and M R Sahar ldquoThe incorporation of silvernanoparticles in samarium doped magnesium tellurite glassEffect on the characteristic of bonding and local structurerdquoPhysica B Condensed Matter vol 470-471 pp 6ndash14 2015

[31] M Walas A Pastwa T Lewandowski et al ldquoLuminescentproperties of Ln3+ doped tellurite glasses containing AlF3rdquoOptical Materials vol 59 pp 70ndash75 2016

[32] P Prieto V Nistor K Nouneh M Oyama M Abd-Lefdil andR Dıaz ldquoXPS study of silver nickel and bimetallic silver-nickelnanoparticles prepared by seed-mediated growthrdquo Applied Sur-face Science vol 258 no 22 pp 8807ndash8813 2012

[33] A Dehelean S Rada I Kacso and E Culea ldquoIR UV-vis spectroscopic and DSC investigations of europium doped


tellurite glasses obtained by sol-gel synthesisrdquo Journal of Physicsand Chemistry of Solids vol 74 no 9 pp 1235ndash1239 2013

[34] Y Wu X Shen S Dai et al ldquoSilver nanoparticles enhancedupconversion luminescence in Er 3+Yb 3+ codoped bismuth-germanate glassesrdquoThe Journal of Physical Chemistry C vol 115no 50 pp 25040ndash25045 2011

[35] A N GoldsteinHandbook of Nanophase Materials CRC Press1997

[36] Y Qi Y Zhou L Wu et al ldquoSilver nanoparticles enhanced 153120583m band fluorescence of Er 3+Yb3+ codoped tellurite glassesrdquoJournal of Luminescence vol 153 pp 401ndash407 2014

[37] W Stambouli H Elhouichet B Gelloz and M Ferid ldquoOpticaland spectroscopic properties of Eu-doped tellurite glasses andglass ceramicsrdquo Journal of Luminescence vol 138 pp 201ndash2082013

[38] W A Pisarski L Zur M Kowal and J Pisarska ldquoEnhancementand quenching photoluminescence effects for rare earth -Doped lead bismuth gallate glassesrdquo Journal of Alloys andCompounds vol 651 pp 565ndash570 2015

[39] K Binnemans ldquoInterpretation of europium(III) spectrardquo Coor-dination Chemistry Reviews vol 295 pp 1ndash45 2015

[40] A Dwivedi C Joshi and S B Rai ldquoEffect of heat treatmenton structural thermal and optical properties of Eu3+ dopedtellurite glass formation of glass-ceramic and ceramicsrdquoOpticalMaterials vol 45 pp 202ndash208 2015

[41] C B DeAraujo D Silverio Da Silva T A Alves DeAssumpcaoL R P Kassab and D Mariano Da Silva ldquoEnhanced opticalproperties of germanate and tellurite glasses containing metalor semiconductor nanoparticlesrdquo The Scientific World Journalvol 2013 Article ID 385193 2013

[42] M Reza Dousti and S Raheleh Hosseinian ldquoEnhanced upcon-version emission of Dy3+-doped tellurite glass by heat-treatedsilver nanoparticlesrdquo Journal of Luminescence vol 154 pp 218ndash223 2014

[43] J N Farahani D W Pohl H-J Eisler and B Hecht ldquoSinglequantum dot coupled to a scanning optical antenna a tunablesuperemitterrdquo Physical Review Letters vol 95 no 1 Article ID017402 2005

[44] AChiaseraM FerrariMMattarelli et al ldquoAssessment of spec-troscopic properties of erbium ions in a soda-lime silicate glassafter silver-sodium exchangerdquo Optical Materials vol 27 no 11pp 1743ndash1747 2005

[45] H Mertens A F Koenderink and A Polman ldquoPlasmon-enhanced luminescence near noble-metal nanospheres Com-parison of exact theory and an improved Gersten and Nitzanmodelrdquo Physical Review B Condensed Matter and MaterialsPhysics vol 76 no 11 Article ID 115123 2007

Submit your manuscripts athttpswwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of



with the reduction potential of 1198640 = 07996V [10] Highlymobile silver ions are form nanoparticles by matrix-assistedreduction process for example by structural elements ofTeO2 matrix with uncompensated charge Silver diffusesinto tellurite glass matrix changes its valance state andforms nanoparticles through Ostwald ripening Thus it ispromising to synthesize the nanoparticles inside glass matrixand in consequence achieve emission enhancement of rareearth ions with employment of metal nanoparticles

One of the first reports on LSPR in glass medium was thework of Malta et al [11] on borosilicate glasses Enhancementof Eu3+ ions emissions has been observed Lately numerousworks concerning silver nanoparticles and emission enhance-ments throughLSPRphenomenonhave been reported in caseof various glass systems [12ndash15] Number of studies describedthe formation of silver nanoparticles in glass matrix throughheat treatment approach While in higher temperaturesmobility of silver ions increases heat treatment approachinvolves annealing of samples usually above glass transitiontemperature to introduce metallic nanoparticles [16] Thatmethod is widely applied in order to create nanoparticlesthrough their agglomeration and to obtain enhancementof rare earth emission intensity Jiao et al examined theluminescence of Eu3+ in borate glasses after addition of silverand mechanisms of Ag ions agglomeration In this caseenhancement of emission intensities has been detected [17]White light emission in europium doped phosphate glasseswas obtained by Fan et al [18] In this study an efficientenergy transfer between nanoparticles and Eu2+ and Eu3+species has been detected Moreover a number of studieswere dedicated to describe silver influence on rare earthsemission intensities inmatrices demonstrating lower phononenergies such as tellurite and tellurite based glasses

Amjad et al [19] studied the influence of silver nanopar-ticles on the luminescence properties of Eu3+ in TeO2-ZnOglass systems and obtained increase of emission intensitiesof europium ions Dousti et al focused on the silver dopedTeO2-PbO glasses [20] Du et al reported tellurite-germanateglasses for solar converters doped with Ag nanoparti-cles to enhance Pr3+ emission intensity [21] Fares et alobtained TeO2-BaO-Nb2O5-Er2O3 glasses with embeddedsilver nanoparticles [22] Enhancement of lifetime and emis-sion intensities of the Er3+ 4I132 rarr

4I152 transition has beenobserved Huang et al studied Er3+Tm3+ codoped TeO2-ZnO-Na2CO3-Er2O3-Tm2O3-AgNO3 glasses doped with sil-ver and observed 185 120583m band fluorescence enhancementmainly attributed to the intensified local field effect inducedby Ag NPs [23] Wu et al presented study on influence ofsilver on Er3+Yb3+ codoped TeO2-Bi2O3-TiO2 glasses [24]

To the best of our knowledge there are no reportson europium doped TeO2-BaO-Bi2O3-Ag (TBBAg) systemswith silver nanoparticles obtained through heat treatmentprocess Similar glass materials have never been studied interms of silver incorporation and its influence on rare earthions emission The aim of this work is the synthesis ofsilver nanoparticles in tellurite glass matrix and to study theinfluence of silver addition on luminescence of europium ionsincorporated into TBBAg glass This novel glass matrix is

promisingmaterial for Eu3+ host with its excellent propertiesSince TeO2 is conditional glass former BaO is introducedto stabilize the glass matrix Heavy metal oxides such asbarium oxide are proven to induce higher devitrificationresistance of glasses [25] Moreover low phonon energy oftellurite glass promotes radiative transitions of rare earth ionsThe aforementioned properties of synthesized glass matrixare the reason that it has been used in this work Silvernanoparticles on the other hand are introduced to studythe rare earth ions emission enhancement through LSPRphenomenon It has never been done before in glass systemof similar composition Since this work is also focused onmatrix influence on luminescence of rare earth ion europiumions have been chosen as a luminescent center since itsemission properties are well understood Additionally studyof the LSPR as a function of different amount of silverin glass is performed Finally influence of heat treatmentprocedure on luminescent properties of obtained materialis discussed TBBAg system is promising material for colortunable phosphors that can be used in LEDs and in lightingindustry

2 Experimental

Synthesis of tellurite glass samples involved mixing andpulverizing of high purity TeO2 BaCO3 Bi5O(OH)9(NO3)4Eu(NO3)3 and AgNO3 raw materials in powder form Con-ventional melt-quenching technique has been used to obtainamorphous glass material Well-mixed batches were placedin porcelain crucibles and were gradually heated to 800∘Cin order to enhance the mixing of ingredients After 30minutes the temperature was reduced to 700∘C for the next30 minutes Afterwards obtained melt was poured onto apreheated steel plate (300∘C) pressed immediately betweensteel plates and then cooled down to room temperature Eachstage of this procedure was carried out in the air atmosphereSuch approach led to synthesis of homogenous transparentsamples

Heat treatment (HT) stage involves annealing of thesamples usually above glass transition temperature In thiswork heat treatment at 350∘C in the air atmosphere hasbeen applied This has been done to initiate the migration ofsilver ions thatwould lead to formation of silver nanoparticlesembedded in glass matrix HT procedure is considered to bethe method of choice in case of solid state samples since it isa simple one-step process that allows controlling annealingparameters Different HT times have been applied in order tostudy the evolution of the glass system and change of sampleproperties HT parameters are presented in Table 1 in detail

Differential scanning calorimetry (DSC) measurementswere executed on Netzsch Simultaneous TGA-DSC STA449 F1 in order to determine the thermal properties ofthe material such as glass transition and crystallizationtemperature Investigations were conducted on powder sam-ples in platinum-rhodium crucibles with heating rate of15∘Cminminus1 in the air atmosphere Structural investigationswere performed using several techniques Examination ofinternal structure of prepared samples was carried out using




350







Hea

rt fl

ow (a

rb u

nit)

Temperature (∘C)

Tg

Tc1

Tc2

exo up

(a)

(b)

318∘C 387∘C

420∘C

321∘C416∘C

500400300









Inte

nsity

(au

)

2Θ (∘)8070605040302010









Tran

smitt

ance

(au

)

1000900800700600500400








CPS

(au

)

Ag1Ag3NC


(a)

CPS

(au

)

Ag1Ag3NC


(b)



1205721015840 = BE (Ag3d52) + KE (Ag M4VV) (3)







Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000


50nm

(a)

50nm

(b)

50nm

(c)


50nm

(a)50nm

(b)

50nm

(c)






400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of





350







Hea

rt fl

ow (a

rb u

nit)

Temperature (∘C)

Tg

Tc1

Tc2

exo up

(a)

(b)

318∘C 387∘C

420∘C

321∘C416∘C

500400300









Inte

nsity

(au

)

2Θ (∘)8070605040302010









Tran

smitt

ance

(au

)

1000900800700600500400








CPS

(au

)

Ag1Ag3NC


(a)

CPS

(au

)

Ag1Ag3NC


(b)



1205721015840 = BE (Ag3d52) + KE (Ag M4VV) (3)







Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000


50nm

(a)

50nm

(b)

50nm

(c)


50nm

(a)50nm

(b)

50nm

(c)






400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



Inte

nsity

(au

)

2Θ (∘)8070605040302010









Tran

smitt

ance

(au

)

1000900800700600500400








CPS

(au

)

Ag1Ag3NC


(a)

CPS

(au

)

Ag1Ag3NC


(b)



1205721015840 = BE (Ag3d52) + KE (Ag M4VV) (3)







Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000


50nm

(a)

50nm

(b)

50nm

(c)


50nm

(a)50nm

(b)

50nm

(c)






400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of





CPS

(au

)

Ag1Ag3NC


(a)

CPS

(au

)

Ag1Ag3NC


(b)



1205721015840 = BE (Ag3d52) + KE (Ag M4VV) (3)







Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000


50nm

(a)

50nm

(b)

50nm

(c)


50nm

(a)50nm

(b)

50nm

(c)






400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



Binding energy (eV)

Bi4f72

Bi4f52

170165160155

120000

140000

160000

Cou

nts

180000

200000


50nm

(a)

50nm

(b)

50nm

(c)


50nm

(a)50nm

(b)

50nm

(c)






400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



400 450 500


0

20

40

60

80

Tran

smitt

ance

()



32 Optical Studies






1205822max =21205871198881198981198731198902 (120576infin + 21198992)

1205760 (4)




5L7 (382 nm) 7F0-5L6 (395 nm) 7F1-

5D3(415 nm) and 7F0-



7F1and 5D1-


7F17F27F3 and










0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



0 h6 h

24 h48 h

Wavelength (nm)700650625 675600575550525500475

105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h



105

110

115

120

Extin

ctio

n co

eci

ent (

＝Ｇminus1)

0 h6 h

24 h48 h


Figure 9

Inte

nsity

(au

)

Wavelength (nm)

70-5＄

4

70-57

70-56

70-5＄

3

70-5＄

2

500450400350



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



Inte

nsity

(au

)

500 550 600 650 700

Wavelength (nm)


3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Inte

nsity

(au

)


500 550 600 650 700

Wavelength (nm)

3 h6 h12 h

24 hAs-prepared


Figure 11





LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



LSPR

56

5＄J

7J

NR

395

nm536

nm557

nm588

nm615

nm654

nm703

nm

2

4

6

8

10

12

14

16

18

20

22

24

Ener

gy (1

03

cＧminus1)

1234

5

6

0

1

2

3



07

06

05

04

03

02

01

00

y

x080706050403020100

550

560

570

580

590

600610

630680

540

530

520510

490

480

470

460

420





4 Conclusions




References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


heat treatment effect on eu3+ glass systems with ag...

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