Optik 122 (2011) 259262

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Synthe lusemior ith

P. MaadeDepartment of 1 020

a r t i c l

Article history:Received 4 JunAccepted 24 N

Keywords:ThiosemicarbaGrowth from sCharacterizatiFluorescenceNonlinear opti

SLC]en grof then of tIR spUVC. To uo

1. Introduction

For the past few decades organic nonlinear optical crystals havebeen the major focus of numerous scientic interests attractingmuch attention owing to their non-linearity quick response, tai-lorabilty and exibility [14]. Organic crystals fall short of vitaltechnologicical stabilitIn order toals, some ndeveloped [earity in inodevice gradto adopt alof hybrid ohigh efciesemiorganiorganic mo[68].

Recentlybeen explorwhen coordmaterial tothenonline

CorresponE-mail add

attracted a great deal of interest. The aspiringmetalorganicmate-rials have the potentials for combining high optical nonlinearityand the chemical exibility of organics with thermally stable andmechanically robust inorganic molecules resulting in useful non-linear optical properties.

In the present study lithium chloride is combined with

0030-4026/$ doi:10.1016/j.al properties including mechanical strength, chem-y and performance at low and high temperature.overcome the shortcoming of the organic materi-ew classes of metalorganic NLO crystal have been5]. The limitations on the maximum attainable nonlin-rganic materials and the moderate success in growinge organic single crystals have egged on scientiststernate strategies. Obviously began the developmentrganicinorganic materials. The achievement to havent optical quality organic based NLO materials inc class is to form compound in which a polarizablelecule is stoichiometrically bonded to inorganic host

metal complexes of thiourea derivative analogs haveed. Thiourea derivative is a centrosymmetric molecule,inate with metal ion it becomes non-centrosymmetricexhibit non-linear optical activity. In the recent past,ar optical properties of products of thiourea [912] have

ding author. Tel.: +91 422 2692461; fax: +91 422 2693812.ress: mades saamy@yahoo.co.in (P. Maadeswaran).

thiosemicarbazide to form a new semiorganic (metalorganic)nonlinear optical material. This paper reports the synthesis, crys-tal growth and characterization studies of TSLC single crystalgrown by solution method. The title compound subjected toX-ray diffraction, absorption, NLO studies, thermal analysis, FTIR, elemental and photoluminescence are presented and dis-cussed.

2. Experimental technique

The new semiorganic material thiosemicarbazide lithium chlo-ride [TSLC] was synthesized by mixing an aqueous solution oflithium chloride combine with thiosemicarbazide in the ratio 1:2.The chemical reaction is given in Scheme 1.

As thiosemicarbazide has a coordinating capacity to form avariety of metalthiosemicarbazide complexes the mixture of thereactants had tobe stirredwell to avoid co-precipitationofmultiplephases. Care was taken to minimize the temperature uctuationsandmechanical disturbance. The single crystals of TSLCweregrownby slow evaporation technique at room temperature. Transparentcolorless crystals were obtained in 2025 days. The photograph ofthe as-grown crystals is shown in Fig. 1.

see front matter 2010 Elsevier GmbH. All rights reserved.ijleo.2009.11.031sis, growth, spectral, thermal and photoganic NLO crystalThiosemicarbazide l

swaran , J. Chandrasekaran, S. ThirumalairajanPhysics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 64

e i n f o

e 2009ovember 2009

zide lithium chlorideolutionon

cal crystals

a b s t r a c t

Thiosemicarbazide lithium chloride [Tsized. Single crystals by TSLC have betemperature. Chemical compositionPowder X-ray diffraction (XRD) patterin the materials were identied by FTcal transmission was studied throughcrystal and inferred to be stable at 176conrmed using Nd:YAG laser and alsr .de / i j leo

minescence properties of a newium chloride [TSLC]

, Tamil Nadu, India

a new semiorganic nonlinear optical crystal has been synthe-own by slow evaporation solution growth technique at roomsynthesized material was conrmed by elemental analysis.he grown crystal has been studied. Functional groups presentectral analysis ranging between 4000 and 450 cm1. The opti-vis spectrophotometer. Thermal analysis is carried out on thehe second harmonic generation (SHG) of the TSLC crystal wasrescence spectral analysis is carried out for the TSLC crystal.

2010 Elsevier GmbH. All rights reserved.

260 P. Maadeswaran et al. / Optik 122 (2011) 259262

Scheme 1. Chemical reaction of TSLC.

Fig. 1. As-grown TSLC crystals.

Table 1Elemental analysis of TSLC crystals.

Element

CHS

3. Result a

3.1. Elemen

The perpresent in tdeterminedhydrogen avalues are c

3.2. X-ray d

The powpound is sobtained byintending oprominentmany low ipound is co

3.3. FT IR a

The FT Inumber ran

Table 2X-ray powder diffraction data of TSLC crystals.

Peak 2 () d-Value

1 17.7404 4.99552 18.5992 4.76683 24.5045 3.62974 25.4604 3.49565 26.9805 3.30206 28.2169 3.16017 51.6629 1.7678

ectroex coin Fcicredwlightthe cordinn of thiosemicarbazide. Most of the metals form a complexh sulphur [14].he higher energy side there is a broad envelope positioneden 3368 and 3179 cm1 which corresponds to the symmet-asymmetric stretching modes of NH2 grouping of aminoExperimental (%) Theoretical (%)

13.80 11.695.63 4.86

27.05 28.54

nd discussion

tal analysis

centage compositions of the constituent elementshiosemicarbazide lithium chloride [TSLC] crystals wereby Vario EL III Elemental. The percentages of carbon,

nd sulphur are presented in Table 1. The experimentallose to the theoretically values.

iffraction

der X-ray diffraction pattern of the synthesized com-hown in Fig. 2. A JEOL JDX services instrument wasthe X-ray powder diffraction pattern. The observed

f the peaks and its d values are given in Table 2. Thepeak appears at 2 values of 28.2169 and also includesntensity lines. The crystallinity of the synthesized com-

FTIR spcomplshownthe specompato be swhichThe conitrogethroug

In tbetweric andnrmed from the sharp andwell-dened Braggs peaks.

bsorption studies

R spectra of TSLC crystal were recorded in the wavege of 4000 to 450 cm1 employing Thermo Nicolet 200

Fig. 2. Powder XRD patterns of TSLC crystals.

thiourea. Th1532 cm1

scissoring vattributed tbetween 12observed arespectivelfrequency rfunctional g

Table 3FT-IR data of T

Wave numb

326331791620153214831000800500Fig. 3. FT-IR spectrum of TSLC crystals.

meter byKBr pelletmethod in order to reveal themetalordination. The FT IR absorption spectrum of TSLC isig. 3. From the following observations the presence ofgroups are conrmed. The FT IR spectra of TSLC whenith the spectra of thiourea [13], a fewpeakswere found

ly shifted. In the complex, there are two possibilities byoordination of lithium with amniothiourea can occur.ationwith lithiummay occur either through sulphur ore medium and strong bands lying between 1645 andare due to the absorption of the NH2 bending andibration .The absorption of the band at 1483 cm1 iso stretchingvibrationofNCN.Thewell resolvedpeaks85 and 1000 cm1 are due to CN stretching. The bandst 647 and 600 cm1 are assigned to CCl stretchingy. The spectradip lets a shift in frequencyband in the lowegion. The assignments conrm the presence of variousroups present in the material, tabulated in Table 3.

SLC crystals.

er (cm1) Assignments

NH asymmetric stretching vibration of NH2 groupsNH symmetric stretching vibration of NH2 groupsNH2 deformationAsymmetric NCN stretchingAsymmetric C S stretchingSymmetric NCN stretchingSymmetric C S stretchingNCS bending

P. Maadeswaran et al. / Optik 122 (2011) 259262 261

Fig. 4. Electronic absorption spectrum of TSLC crystals.

3.4. Electronic absorption spectrum

The transparency of TSLC crystals given by UVvisible spectrawas recorded using JASCO V-530 dual beam UVvis spectropho-tometer with a scanning speed 200nm/min in the wavelengthrange 200400nm. The percentage of absorption vs wavelengthis shown in Fig. 4. The cut-off wavelength was found to be 237nm.The absence of absorption in the region between 290 and 400nm isa favorablehaving NLO

3.5. Therma

Thermalform by reture rangeundernitro2.9830mg amogravimeand the weobserved frbegins at 16sample temthe event is188.64 C co

The weimay attribu208.64 andto the decweight loss716.676 C.of residue rwith the dethermogramno oxidatiosphere.

uores

exced incorded in the range 375400nm (Fig. 6). The sample wasat 390nm. The emission spectrum (Fig. 7) was measured

range 500580nm. A peak at 531nm was observed in theon spectrum. The results indicate that TSLC crystals havereen uorescence emission. The band gap energy was cal-using the formula Eg =hc/e. Here h, c, and e are constant,

elength of uorescence. The band gap energy calculated is2.336eV for the TSLC crystal.

nlinear properties

second harmonic generation (SHG) behavior of TSLC wased by amodied version of the powder technique developedtz and Perry [15,16]. In this method, the powdered sam-th an average particle size of 100150m was illuminatedying fundamental wavelength of 1064nm with pulse widthe SHG was conrmed by the emission of green radiation.

clusioncircumstance as it is the key requirement for materialsproperties.

l studies

properties of grow crystals were studied in powdercording TGA/DTA thermogram from room tempera-0 to 1300 C using SDT Q 600 V8.3 thermal analyzergenatmosphere. Theamountof sample takenwasaboutnd heating was carried out at a rate of 20 C/min. Ther-tric analysis shows that TSLC is stable up to 208.64 Cight loss starts above this temperature (Fig. 5). It isom the DTA thermogram that an endothermic event8.64 C and then a sharp peak appears at 188.64 C. Theperature remains constant at this temperature untilcompleted. The endothermic event in the sample atrresponds to the melting point.ght percentage of about 96.97% observed at 176.64 Cte to the loss of lattice water. The next stage between319.32 C with a total weight loss of 62.26% is assignedomposition of TSLC. The resulting residue gives afor a wide range of temperature between 319.32 andThe weight loss corresponds to 1.10% and 0.1157mgemains. The endothermic peaks of DTA coincide wellcomposition in the TGA trace. The sharpness of thealso illustrates the purity of the crystal and there is

n peaks since the sample was run in the nitrogen atmo-

3.6. Fl

Therecordwas reexcitedin theemissibeen gculated wavabout

3.7. No

Theanalyzby Kurple wiemplo8ns. Th

4. ConFig. 5. TG and DTA thermograms of TSLC crystals.

Thiosemsuccessfullynique. Thespectroscopare conrmtra reveal tregion withproperty foconstituentFig. 6. Excitation spectrum of TSLC crystals.

Fig. 7. Emission spectrum of TSLC crystals.

cence studies

itation and emission spectra of TSLC crystals wereFP-6500 spectrouorometer. The excitation spectrumicarbazide lithium chloride [TSLC] crystals were grownby solutionmethod employing slow evaporation tech-well-grown crystals are characterized using variousic techniques. The crystalline natures of the materialed from the sharpwell-dened peaks. The UVvis spec-hat the crystals are transparent in the entire visiblecut-off wavelength at 237nm which is a desirous

r NLO application. The composition percentages of thes were found to be in well with the calculated values in

262 P. Maadeswaran et al. / Optik 122 (2011) 259262

the elemental analysis. The presence of characteristic functionalgroups are conrmed in FT-IR analysis and a small shift in thespectrum was seen when compared with that of FT-IR spectrumof thiourea. The second harmonic generation was conrmed withthe emission of green radiation using Nd:YAG laser. The TGA andDTA thermogram predicts the stability of the material decompo-sition and corresponding weight losses. The purity of the crystalis conrmed from the sharpness of the endothermic peaks. Thegreen uorescence emission of the crystal conrmed its uores-cence behavior. From the results, it can be considered that the TSLCcrystal is a potential candidate for opto-elctronic and uorescenceapplications.

Acknowledgments

The authors thank sophisticated analytical Instrumentationfacility, Central Electrochemical Research Institute, Karaikudi forthe help. The authors are grateful to Prof. P.K. Das, IISc., Bangalorefor extending the facilities to measure SHG efciency.

References

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Synthesis, growth, spectral, thermal and photoluminescence properties of a new semiorganic NLO crystalThiosemicarbazide l...IntroductionExperimental techniqueResult and discussionElemental analysisX-ray diffractionFT IR absorption studiesElectronic absorption spectrumThermal studiesFluorescence studiesNonlinear properties

ConclusionAcknowledgmentsReferences