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Mechanical Properties and Crystallization Behavior of GeS 2 Sb 2 S 3 In 2 S 3 Chalcogenide Glass Lei Ying, Changgui Lin, §,Qiuhua Nie, Zhuobin Li, Yinsheng Xu, § Feifei Chen, and Shixun Dai ,The School of Information Science and Engineering, Ningbo University, Ningbo 315211, China § The School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, China 54GeS 2 36Sb 2 S 3 10In 2 S 3 glass-ceramics were prepared by heat-treating the base glass above T g for different durations. The results of Raman spectra and XRD patterns show that the first precipitated crystals during the heat treatment are In 2 S 3 and the crystallization of the Sb 2 S 3 and GeS 2 subsequently occurs. Bulk samples heat-treated at 295°C for different heat- ing rates and durations are used to study the crystallization mechanism and evolution of the three crystallization peaks (CPs). It is found that three CPs partly overlap with each other and then separate with increasing heat-treating durations. I. Introduction C HALCOGENIDE glasses have received considerable interest in the development of pertinent materials operating in mid-infrared (IR) spectral region of 210 lm wavelength range for various applications such as thermal imaging, opti- cal fibers for chemical and biological sensing, optical modu- lator and optical communications. 13 In addition, their advantages over currently used single crystalline germanium are associated with the relatively low-cost of raw materials and the possibility of producing complex optics by mold- ing. 4,5 However, the excellent IR transmitting material has not been fully exploited due to their intrinsic weakness such as poor resistance to crack propagation and thermal shocks. Fortunately, the generation of crystals inside a glass matrix is a proven technique for improving the mechanical proper- ties of glasses to balance shock sensitivity and inhibit crack propagation. 6,7 As far as optical properties are concerned, the formation of grains inside glass matrix can be a source of optical loss due to light scattering. Consequently, main chal- lenge in glass-ceramic science is to discover glassy systems exhibiting soft balance in glass to crystal transformation and keeping good transparency. In the past several years, crystallization behavior of some chalcogenide glasses, e.g., GeS 2 Ga 2 S 3 CsCl, 8 GeSe 2 Sb 2 Se 3 RbI 9 and GeS 2 Sb 2 S 3 CsCl 10 have been systematically investigated. These relatively suitable systems are based on glasses of the GeS 2 Sb 2 S 3 or GeS 2 Ga 2 S 3 , combined with metallic halide in which the size of the metallic ion is large enough to be used as the compatible modifier cations. Previ- ous studies have been conducted in using CsCl, CsBr, CsI, RbI, CuI, PbI 2 . 911 Unfortunately, controllable and repro- ducible crystals growth in the above mentioned chalcogenide glassesstill suffer from the difficulty to control the nucleation of nanometer size and species. In addition, the introduction of relatively high-halide content leads to poor chemical dura- bility. In this case, metallic halide is substituted by a similar large-metallic sulfide In 2 S 3 ,which plays a role in the forma- tion of the glassy framework other than modifier. Mean- while, the element In located at the same main group and the next period of the elemental period table as Ga, In-con- tained chalcogenide glasses should have similar superior properties, such as high solubility of rare earth ions. Further- more, the substitution of Ga for heavier metal In would increase the refractive index, leading to high quantum effi- ciencies for rare earth ions transition in chalcogenide glass. 12 In this work, we focus on the crystallization behavior of glasses based on the GeS 2 In 2 S 3 Sb 2 S 3 system which has been well-investigated in our previous research. 13 As crystalli- zation of a chalcogenide glass is a highly exothermic process, differential scanning calorimetry (DSC) is a very suitable technique for obtaining the parameters of crystallization. The results on the precipitated crystal phases, physical properties, and crystallization behavior of GeS 2 In 2 S 3 Sb 2 S 3 glass- ceramics are presented and discussed. Based on the DSC, X- Ray diffraction (XRD), and Raman results, the crystalliza- tion mechanism for three crystal phases of In 2 S 3 , Sb 2 S 3 , and GeS 2 is elucidated in detail. II. Experimental Bulk glass with a composition of 54GeS 2 36Sb 2 S 3 10In 2 S 3 was synthesized using polycrystalline germanium, indium, antimony, and sulfur (all of 5 N) as starting materials. Appropriate quantity (10 g) of each component was weighed according to the stoichiometric glass composition and intro- duced into a silica tube, which was sealed under a vacuum of ~10 3 Pa and then it was reacted at 950°C for 13 h in a rocking furnace. Tube containing the melt was moved out and subsequently quenched in cold water. The reference polycrystalline In 2 S 3 sample was also prepared with very slow cooling rate in a vacuum silica tube. The obtained glass rod was annealed below glass transition temperature (T g ) for 5 h to minimize inner stress. Specimens were cut into disks of ~10 mm in diameter and 1.5 mm in thickness, and pol- ished both sides for optical measurements. The crystallization of the as-prepared glass was conducted by heating at 2°C/ min to a designed temperature (T HT ), holding for various durations, and then cooling slowly to room temperature. The glass transition temperatures (T g ) and crystallization temperatures (T x ) of as-prepared glasses were determined by DSC at a heating rate of 10°C/min with a temperature accu- racy of ± 1°C (TA Q2000). To study the crystallization behavior, bulk samples heat-treated at T HT (T g + 20°C) for different durations were placed in hermetic aluminum pans and heated from room temperature until crystallization com- pleted. The densities were measured, according to Archime- des principle using de-ionized water as an immersion liquid. Transmission spectra were obtained with a Lambda 950 UV- VIS-NIR spectrophotometer (Perkin-Elmer, Inc., Waltham, MA) in visible and near-IR spectral region and Nicolet 381 J. Heo—contributing editor Manuscript No. 30209. Received August 21, 2011; approved January 18, 2012. Authors to whom correspondence should be addressed. e-mails: linchanggui@nbu. edu.cn and [email protected] 1320 J. Am. Ceram. Soc., 95 [4] 1320–1325 (2012) DOI: 10.1111/j.1551-2916.2012.05117.x © 2012 The American Ceramic Society J ournal

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MechanicalPropertiesandCrystallizationBehaviorofGeS2Sb2S3In2S3ChalcogenideGlassLeiYing,ChangguiLin,,QiuhuaNie,ZhuobinLi,YinshengXu,FeifeiChen,andShixunDai,TheSchoolofInformationScienceandEngineering,NingboUniversity,Ningbo315211,ChinaTheSchoolofMaterialsScienceandChemicalEngineering,NingboUniversity,Ningbo315211,China54GeS236Sb2S310In2S3glass-ceramics were prepared byheat-treating the base glass above Tgfor dierent durations.TheresultsofRamanspectraandXRDpatternsshowthattherst precipitatedcrystals duringthe heat treatment are In2S3and the crystallization of the Sb2S3and GeS2subsequentlyoccurs. Bulksamplesheat-treatedat 295Cfordierent heat-ing rates and durations are used to study the crystallizationmechanismand evolution of the three crystallization peaks(CPs). It is found that three CPs partly overlap with eachotherandthenseparatewithincreasingheat-treatingdurations.I. IntroductionCHALCOGENIDEglasses havereceivedconsiderableinterestinthe development of pertinent materials operatinginmid-infrared (IR) spectral region of 210lmwavelengthrangeforvariousapplicationssuchasthermal imaging, opti-cal bersforchemical andbiological sensing, optical modu-lator and optical communications.13In addition, theiradvantages over currentlyusedsinglecrystalline germaniumare associatedwiththe relatively low-cost of rawmaterialsand the possibility of producing complex optics by mold-ing.4,5However, the excellent IRtransmitting material hasnot beenfullyexploitedduetotheirintrinsicweaknesssuchaspoorresistancetocrackpropagationandthermal shocks.Fortunately, the generationof crystals inside aglass matrixis aproventechniquefor improvingthemechanical proper-ties of glasses tobalanceshocksensitivityandinhibit crackpropagation.6,7As far as optical properties are concerned,theformationofgrainsinsideglassmatrixcanbeasourceofoptical lossduetolightscattering. Consequently, mainchal-lenge in glass-ceramic science is to discover glassy systemsexhibitingsoftbalanceinglasstocrystal transformationandkeepinggoodtransparency.Inthepast several years, crystallizationbehaviorof somechalcogenide glasses, e.g., GeS2Ga2S3CsCl,8GeSe2Sb2Se3RbI9and GeS2Sb2S3CsCl10have been systematicallyinvestigated. These relatively suitable systems are basedonglasses of the GeS2Sb2S3or GeS2Ga2S3, combined withmetallichalideinwhichthesizeof themetallicionis largeenoughtobeusedasthecompatiblemodiercations. Previ-ous studies have beenconductedinusingCsCl, CsBr, CsI,RbI, CuI, PbI2.911Unfortunately, controllable and repro-duciblecrystalsgrowthintheabovementionedchalcogenideglassesstill suerfromthedicultytocontrol thenucleationof nanometer sizeandspecies. Inaddition, theintroductionofrelativelyhigh-halidecontentleadstopoorchemical dura-bility. Inthiscase, metallichalideissubstitutedbyasimilarlarge-metallic sulde In2S3,whichplays arole inthe forma-tion of the glassy framework other than modier. Mean-while, the element Inlocatedat the same maingroupandthenext periodof theelemental periodtableasGa, In-con-tained chalcogenide glasses should have similar superiorproperties,suchashighsolubilityofrareearthions.Further-more, the substitution of Ga for heavier metal In wouldincrease the refractive index, leading tohighquantume-cienciesforrareearthionstransitioninchalcogenideglass.12Inthis work, we focus onthe crystallizationbehavior ofglasses based on the GeS2In2S3Sb2S3systemwhich hasbeenwell-investigatedinourpreviousresearch.13Ascrystalli-zationofachalcogenideglassisahighlyexothermicprocess,dierential scanning calorimetry (DSC) is a very suitabletechniqueforobtainingtheparametersofcrystallization.Theresultsontheprecipitatedcrystal phases, physical properties,and crystallization behavior of GeS2In2S3Sb2S3glass-ceramicsarepresentedanddiscussed. BasedontheDSC, X-Ray diraction(XRD), andRamanresults, the crystalliza-tionmechanismforthreecrystal phasesofIn2S3, Sb2S3, andGeS2iselucidatedindetail.II. ExperimentalBulk glass with a composition of 54GeS236Sb2S310In2S3was synthesized using polycrystalline germanium, indium,antimony, and sulfur (all of 5N) as starting materials.Appropriatequantity(10g)ofeachcomponentwasweighedaccordingtothestoichiometricglasscompositionandintro-ducedintoasilicatube,whichwassealedunderavacuumof~103Pa and then it was reacted at 950Cfor 13h in arocking furnace. Tube containing the melt was moved outand subsequently quenched in cold water. The referencepolycrystalline In2S3sample was also prepared with veryslowcoolingrateinavacuumsilicatube. Theobtainedglassrodwasannealedbelowglasstransitiontemperature(Tg)for5htominimize inner stress. Specimens were cut intodisksof ~10mmindiameter and1.5mminthickness, andpol-ishedbothsidesforopticalmeasurements.Thecrystallizationof the as-preparedglass was conductedby heating at 2C/min to a designed temperature (THT), holding for variousdurations,andthencoolingslowlytoroomtemperature.The glass transitiontemperatures (Tg) andcrystallizationtemperatures(Tx) of as-preparedglassesweredeterminedbyDSCataheatingrateof10C/minwithatemperatureaccu-racy of 1C (TA Q2000). To study the crystallizationbehavior, bulksamples heat-treatedat THT(Tg+20C) fordierent durations were placedinhermetic aluminumpansandheatedfromroomtemperatureuntil crystallizationcom-pleted. The densities weremeasured, accordingtoArchime-des principleusingde-ionizedwater as animmersionliquid.TransmissionspectrawereobtainedwithaLambda950UV-VIS-NIRspectrophotometer (Perkin-Elmer, Inc., Waltham,MA) invisibleandnear-IRspectral regionandNicolet 381J.HeocontributingeditorManuscriptNo.30209.ReceivedAugust21,2011;approvedJanuary18,2012.Authorstowhomcorrespondenceshouldbeaddressed. e-mails: [email protected]@nbu.edu.cn1320J.Am.Ceram.Soc.,95[4]13201325(2012)DOI:10.1111/j.1551-2916.2012.05117.x2012TheAmericanCeramicSocietyJournalFourier Infrared spectrophotometer (Thermo Nicolet Cor-poration, Madison, WI) inthe mid-IRregionrangingfrom2.5 to 16lm, respectively. Crystals in glassy matrix wereobservedbya scanning electric microscope (SEM) andthemarks andcracks made byindentationwere observedwithoptical microscope (VHX-1000E; Keyence Corporation,Osaka, Japan). XRD data were collected using a D8Advance X-Ray diractometer (Voltage 36kV, current20mA, CuKa; BrukerAXS, Madison, WI). Ramanspectrawereconductedat roomtemperatureusingback(180) scat-teringcongurationbyLaser Co-focal RamanSpectrometer(Renishaw,inVia)withexcitationwavelengthof488nm.Theresolutioninthefrequenciesis0.5cm1.Vickersmicroind-enter (Everone MH-3, Everone Enterprises. Ltd., Shanghai,China) was usedtoobtainhardness withachargeof 100gfor 5s. All the characteristics were averagedover measure-menton10indentationspersample.III. ResultsandDiscussionThe DSCcurve of the 54GeS236Sb2S310In2S3glass at aheatingrateof10C/minisshowninFig. 1.Anobviousexo-thermicpeakcanbeobserved, andthecharacteristictemper-atures of TgandTxarealsolistedinFig. 1. Evidently, theexothermicpeakisoverlappedbyseveral peaksasshownintheinset.TheexothermicpeakcanbedecomposedbyGauss-ianfunctionswiththreepeaksrangingfrom370Cto415C,suggestingdierent kindsof crystallization. Withtheknowl-edgeof thermal results andprevious study,14,15afairlylowTHTof 295C(Tg+20C) was chosenas heat-treatedtem-perature for crystallization process. The base glasses wereplacedina ventilatedfurnace at 295Cfor dierent dura-tionsrangingfrom20to120h.Itshouldbepointedoutthatthe shape andparallelismof the studiedsamples were notchanged after the heat-treatment. To investigate whethermechanical propertieswouldbeimprovedafterceramizationprocess, Vickers indentations were performed on the well-polishedsamples. AsshowninFig. 2, themarksandcracksmade by indentationwere observedwithanoptical micro-scope. The propagation of cracks is greatly inhibited withincreasingheat-treatment durations, indicatingaprogressivestrengthening of the samples by generating crystals insideglassymatrix. Some physical andmechanical properties arelistedinTableI.Furthermore, theVis-NIRtransmissionspectra, whicharevery sensitive to the presence of crystals, are shown inFig. 3(a)forthebaseandcrystallizedglasses.AsindicatedinTableI, it canbeclearlyseenthat thecut-oedgeof shortwavelength is red-shifted as a function of heat-treatmentdurations. It is well knownthat thechangedepends largelyonthe size andconcentrationof the crystals, andthat theoptical attenuation decreases rapidly when the wavelengthincrease.16Surprisingly, as showninFig. 3(b), thetransmit-tanceis not impairedstronglyinthemid-IRspectral regionfrom2to10lm. It canbe concludedthat the presence ofsmall crystalsintheglassymatrixdoesnotimpairthetrans-parencyintheapplicationwindowlocatedatmid-IRspectralregion. Then, SEMimagesshowninFig. 4indicatethat theinnercrystalsareof sizeabout 60nm, whichcauseMiedif-fusiontoshift thecut-oedgeof short wavelength, andnonotablechangeofsizeisobservedintherangeof60h.How-ever, samples heat-treated for 120h at 295Cshowa dis-tinctlydecrease inthe maximumof transmissionfrom65%to50%. Thisphenomenonshowsthepresenceof largecrys-talsthatdeterioratethetransparencyofthematerial rapidly,leadingprogressivelytoitswholeopacityintheIRrange.Toidentify the species of the precipitatedcrystal, X-raydiractioniscarriedoutonthepolycrystallineIn2S3andthe54GeS236Sb2S310In2S3baseglassheat-treatedfordierentdurations. Figure5 presents the XRDpatterns collectedat295Cduring120honpowdersamples. Athree-stepcrystal-lization mechanismcan be clearly recognized fromtheseXRDpatterns. Duringtherststep, whichendsafter~20hof annealing at 295C, no obvious diusion signature isobservedandthe matrixremains mostlyamorphous. How-ever, afterabout 40h, several peaks(2h=27, 33, 43and47) appear and then growslowly and continuously. TheFig. 1. DSCcurve for bulkglass of 54GeS236Sb2S310In2S3at aheatingrateof10C/min. TheexothermicpeakisttedbyGaussianFunctionsintheinset.(a) (b)(c) (d)Fig. 2. Optical microscope pictures of the dierent samples afterVickers indentation(a) Base glass, glasses crystallizedat 295Cfor(b)20h,(c)40h,and(d)60h,respectively.TableI. SomePhysicalandMechanicalPropertiesofthe54GeS236Sb2S310In2S3GlassandGlass-CeramicsSamplesCut-oedge(1nm)Density, (0.002gcm3)Hardness,Hv(2Kgmm2)Base 637 3.595 17720h 643 3.671 17540h 825 3.794 18060h 1027 3.790 18690h 1273 3.732 194120h 1608 3.867 193April2012 GeS2-Sb2S3-In2S3ChalcogenideGlassandGlassCeramics 1321positions of these peaks are in good agreement with theIn2S3indexation(JCPDScardno. 25-0390) andtheirbroad-ness conrms the nanosize of the particles. The thirdstep,startingfromabout 50h, corresponds totheappearanceofnewsharpones(2h=22, 41), relatedtonewcrystal phaseSb2S3(JCPDScardno.42-1393).Inaddition,theGeS2phase(2h=30, 31) is alsopresent inthe60hheat-treatedsam-ple. Therefore, the species of crystal phases are roughlyrevealedbytheXRDpatterns.Inaddition,normalizedRamanspectraoftheglassceram-ics andIn2S3polycrystallinearepresentedinFig. 6, furtherconrmingthatthecrystalsofIn2S3andSb2S3wereprecipi-tated. With the increasing of the heat-treatment durations,the bands around140and310cm1whichis attributedtothevibrationsof [S3InInS3] ethane-likeunitsand[InS4] tet-rahedra17are graduallyenhancedat the beginningof 20h.Moreimportantly, thelittleprominenceat140cm1becomesharp with the elongation of heat-treatment whereas thebandat 310cm1has almost nochange. It canbeascribedthat the vibration of the homopolar bond of InInin theIn2S3crystal graduallydominatesinthecrystallizedsamples.Inaddition,themainRamanpeakat300cm1corresponding(a)(b)Fig. 3. Transmissioncurves of 54GeS236Sb2S310In2S3glass andglasses ceramics heat-treated at 295Cfor dierent durations: (a)near-infrared transmitting spectral region, and (b) the wholetransmitting spectral region. The inset of (b) is the photographofthebaseglassandglassesceramics.(a)(b)Fig. 4. SEMimages for samples crystallizedat 295Cfor dierentdurations:(a)40h9100000,and(b)60h9100000,respectively.Fig. 5. XRDpatterns of In2S3polycrystalline, 54GeS236Sb2S310In2S3baseglassandglassceramicsobtainedbyheat-treatment at295Cfordierentdurations,respectively.Fig. 6. Raman spectra of In2S3polycrystalline, 54GeS236Sb2S310In2S3glassandglassesceramicsheat-treatedat295Cfordierentdurations.1322 JournaloftheAmericanCeramicSocietyYingetal. Vol.95,No.4tothevibrationofthe[Sb2S3]pyramidunitisalsosharpenedafter60hheat-treatment, suggestingtheSb2S3crystalshaveappearedduring the crystallizationprocess. Regretfully, wedid not observe the characteristic vibration band of GeS2crystalsinFig. 6,whichmaybeduetotheRamanspectraofasmall amountofGeS2crystalsundistinguishablefromthatof GeS2glass.18Basedontheabove-mentionedanalysis, thespecies andsequenceof crystallizationarecoincident totheXRDresults.IR-transmitting 54GeS236Sb2S310In2S3glass-ceramicswith improved mechanical properties have been fabricatedthrough a reproducible and controllable crystallization.Meanwhile, the species, size, and sequence of precipitatedcrystals were determined. Hence, inthefollowing, themainpurpose is to study the crystallization mechanismof thisglass. ThepresenceofthreeCPsinFig. 1maybeduetothepresenceofdierentcrystallizationmechanism. Furthermore,asshowninFigs. 5and6, threecrystal phaseswereprecipi-tatedinthe glass matrix, successively. Therefore, it canbesupposedthatthesethreeCPsareoriginatedfromtheprecip-itationofIn2S3,Sb2S3,andGeS2crystals,respectively.Despite the goodknowledge onthe distinct phase trans-formationforthethreeCPsachieved, thereasonsmainlyforthe crystallization of In2S3crystals in 54GeS236Sb2S310In2S3glass at 295Care still ambiguous. As shown inFig. 7, avariableheatingrateDSCmethodwasemployedtoevaluatethekineticparametersforcrystallizationofthestud-ied glass. In TableII are listed the characteristic tempera-tures of the studied chalcogenide glass at an increasedheatingrate, b=1, 5, 10, 15and20C/min. Thecrystalliza-tionbehaviorofthethreeglassphasescanbeunderstoodbythe following kinetic parameters: the activation energy forthecrystallizationEc, thefrequencyfactorK0, andthecrys-tallizationrateconstantK. Toobtainthekineticparameters,the kinetic model of Bansal and Hyatt19is used andexpressedasfollows:lnbT2c EcRTclnRK0Ec (1)Where Ris the ideal gas constant (8.314Jmol1K1), andTcis the characteristic temperature in Kelvin, respectively.Plots of lnb=T2c against 1000/Tcfor thechalcogenideglassgivealinearbehaviorasshowninFig. 8. Consequently, theEcandK0valuesarecalculatedfromtheslopesoftheselinescorrespondingtoEc/R, listedinTableIII. Nevertheless, theparametersofEcandK0arestill notsucienttounderstandwhytheIn2S3crystalphaseismucheasiertobefullycrystal-Fig. 7. DSCcurves of the 54GeS236Sb2S310In2S3glasses heat-treatedat 295Cfor dierent heatingrates from1C/minto20C/min.TableII. CharacteristicTemperaturesofTg,TxandTpfor54GeS236Sb2S310In2S3GlassHeatingrates, b(oC/min) Tg(1C) Tx(1C)1 265 3395 281 37010 283 37715 284 38420 286 389Fig. 8. Plotsoflnb=T2cvs(1000/Tc).TableIII. CrystallizationKineticsParametersfor54GeS236Sb2S310In2S3GlassCrystallizationpeaks Ec(kJmol1) K0(s1) K295C(s1)First(In2S3) 152.30 6.8910123.499103Second(Sb2S3) 155.34 1.1910122.689103Third(GeS2) 160.84 0.5910122.639103Fig. 9. DSCcurves of the 54GeS236Sb2S310In2S3glasses heat-treatedat295Cfordierentdurations.April2012 GeS2-Sb2S3-In2S3ChalcogenideGlassandGlassCeramics 1323lizedthanSb2S3andGeS2at 295C. Hence, thecrystalliza-tionrate constant Kshouldbe considered. In general, thecrystallization rate constant Kincreases exponentially withtemperatureindicatingthat thecrystallizationis athermallyactivatedprocess. It canbecomputedwithEcandK0, andmathematicallyexpressedas:K K0 exp EcRT (2)These Kvalues for the In2S3, Sb2S3, and GeS2phaseslistedinTableIII were analyzedusingthe above equation.Where T corresponding to the annealing temperature(568.15K), and the values of Ecand K0are used fromTableIII, respectively. The Kvalue for the In2S3phase isabout two times larger than that of the Sb2S3and GeS2phase, suggestingamucheasiercrystallizationmechanismofIn2S3phase. Thus, it isnot surprisingthat theIn2S3crystalsareeasilyprecipitatedbytheheattreatmentsat295C.Tostudythecrystallizationbehaviorofthesethreephases,DSCcurves of base glass and glass ceramics which wereheat-treatedat 295Cfor dierent durations were recordedas showninFig. 9. After heat-treatment at 295Cfor 20h,themainbroadpeakbeginningsplit upintothreeexothermpeaks gradually. Byincreasingtheheat-treatment durations,thethreeCPsshiftstowardslowertemperature. Itispossiblydue tothe increasing number of nuclei inthe glass matrixafterheat-treatment, subsequentlyleadingtoaneasycrystal-lization. Meanwhile, the height of the rst CP obviouslydecreases with the elongation of heat-treatment durationsand vanishes after 40h heat-treatment indicating the totalcrystallization of associated phase. During this period, thesecondandthe thirdCPs dissociatedbydegrees as well astheincreasingheight of theCPs. After 60hheat-treatment,thesecondCPalmost disappeared, indicatingthetotal crys-tallization of the related phase. Moreover, the third CPbehavesinasimilarwaybyfurtherincreasingtheheat-treat-ment time. CombinedwiththeresultsontheXRDpatternsandRamanspectra, the precipitationof In2S3is completedattherst ~40h,correspondingtotheevolutionofrstCP.Consequently, the crystal phase of In2S3is responsible fortherstCPinthepresentglass. Inaddition, theXRDspec-trarecordedthat the crystal phase of Sb2S3whichprecipi-tatedprior toGeS2are inagreement withthe sequence ofphasetransformationinGeSbSglass ceramics.20,21There-fore, the Sb2S3crystal phase is related to the second CPwhereastheGeS2crystalphaseiscorrespondingtothetrans-formationofthethirdCP.Basedonthe above analysis, the crystallizationof In2S3,Sb2S3, andGeS2phase inthe glass matrix is schematicallyillustratedinFig. 10. Forthe54GeS236Sb2S310In2S3glass,theglassnetworkmainlyconsistsof[SbS3] pyramids, [GeS4],and[InS4] tetrahedra ina stochastic manner. Accordingtothecognitionof therst crystallizationof In2S3crystalsandthenanophasecontainingInInbondsintheglassnetwork,[S3InSInS3] unitsarespeciedtopresent thepossiblecon-guration of In-related units to formIn2S3nuclei, whichnallygrowintoIn2S3crystals.Similarcrystallizationprocessfor theformationof Ga2S3nanocrystals intheGeS2Ga2S3glasshasbeenreportedbyLinetal.22Withtheincreasingofheat-treatment durations, theSb2S3andGeS2crystal is pre-cipitatedsubsequently.IV. ConclusionInthiswork, wedemonstratethat reproducibleglassceram-ics were obtainedfrom54GeS236Sb2S310In2S3chalcogen-ideglass. Theobtainedglass-ceramicsarehighlytransparentinthemid-IRregion. Inaddition, thecrystallizationbehav-iorsoftheIn2S3,Sb2S3,andGeS2phasehavebeensystemati-callyinvestigatedbyXRD,Raman,andDSCanalysis.Basedontheresults, theevolutionofthethreeCPsforthecrystal-lizedbulkindicatesthattheprecipitationofIn2S3andSb2S3crystal phaseareresponsiblefortherstandthesecondCP,andthatofGeS2phaseforthethirdoneinDSCcurves.ThelowervalueofactivationenergyEcandhighervalueofcrys-tallization rate constant Kfor the rst CP illustrates themucheasiercrystallizationmechanismofIn2S3. Theseresultsallowedus todeducethat the[S3InSInS3] units arespeci-edtopossible nearest-neighbor congurationof In-relatedunits,whicharedemixedfromthenetworkbackbone.AcknowledgmentsThis work is partially supported by Natural Science Foundation of China(Grant No. 61108057), Zhejiang Provincial Natural Science Foundation ofChina (Grant Nos. R1101263 and Y4110322), Program for InnovativeResearch Teamin Ningbo City (Grant No. 2009B21007), Natural ScienceFoundationofNingboCity(GrantNo.2011A610091),ProgramforNewCen-turyExcellentTalentsinUniversity(GrantNo. NCET-10-0976), andtheout-standingDissertationEngagement FoundationofGraduateSchool ofNingboUniversity(Grant No. PY20100010).Inaddition, it wasalsosponsoredbyK.C.WongMagnaFundinNingboUniversity.References1M.Baudrier-Raybaut,R.Haidar,P.Kupecek,P.Lemasson,andE.Rosen-cher, RandomQuasi-Phase-MatchinginBulkPolycrystallineIsotropicNon-linearMaterials,Nature,432[7015]3746(2004).2J.S.SangheraandI.D.Aggarwal,ActiveandPassiveChalcogenideGlassOptical FibersforIRApplications: AReview,J. Non-Cryst. Solids, 256-257,616(1999).3A. ZakeryandS. R. Elliott, Optical PropertiesandApplicationsofChal-cogenideGlasses:AReview,J.Non-Cryst.Solids,330[1-3]112(2003).4X.H. Zhang, Y.Guimond,andY. Bellec, ProductionofComplexChal-cogenideGlass Optics byMoldingfor Thermal Imaging,J. Non-Cryst. 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