Distillation And Purification Of Infrared Glass Raw Material And Its Physical Properties

Chalcogenide glass is a material with high performances,such as the advantages of high chemical stability,wide infrared transmission range,easy precision molding and so on.It is a good candidate material for a new generation of temperature-adaptive optical lens.However,its own weak chemical bond,poor mechanical properties,the presence of impurities in the vitreous absorption peak and other shortcomings limit its development.The purification of glass raw materials can effectively improve its optical properties,and setting the appropriate heat treatment temperature can effectively improve the mechanical properties of glass.In this paper,through the design of chalcogenide glass distillation purification device,the use of new equipment prepared glass.X-ray diffraction(XRD)analysis,differential scanning calorimetry(DSC)analysis,fourier transform infrared spectroscopy,hardness and density analysis,thermal expansion properties and specific heat analysis methods are used to analyze the purification process,infrared properties,density,hardness and thermal properties of Ge/3Se67Sb10,pure Selenium,and Ge-Se chalcogenide glass.The conclusions are drawn as following:The Ge23Se67Sb10 chalcogenide glass with high density and bright surface was prepared by a combination of distillation and reagent purification methods.After purification,the absorption peak of Se-H impurity at 4.56 ?m was obviously weakened,the infrared transmittance and thermal stability of the glass sample by adding GaCl3 are better than that by adding titanium,AICl3 and TeCl4.the infrared transmittance is more than 60%,and the density is 4.5063 g·cm-3,hardness is 169.92 kgf·mm-2,Tg of the glass transition point is 253.9 ?.the parameters that characterize the thermal stability ?T,H,S are 202.5 ?,0.80,14.52,respectively,which shows that samples with the adding of GaCl3 have good thermal stability and glass-formation ability.The relationship between distillation rate of Ge23Se67Sb10 chalcogenide glass and temperature is:V=0.54-16.93(?).Fitting the relaxation enthalpy of Ge23Se67Sb10 chalcogenide glass by formula ?H(T(?))=?Heq{1-exp[(t(?)/?)?]} and then obtain three coefficients in the formula.the value of ?Heq is 2.057 J/g,the ? is 18.025 s,the is 0.548.The thermal properties of pure Se glass were studied.characteristic temperature,heat of crystallization AH and the melting enthalpy AHm of the sample of pure selenium glass were measured.Then the specific heat capacity of the sample was analyzed by the stepwise method,and three new models are brought forward to predict the thermal capacity difference ?Cp between the crystalline and supercooled liquid.At last,the Gibbs free energy change ?G and entropy change ?S are calculated from the specific heat.Then get the curves of ?G and ?S with temperature,and the Kauzmann temperature Tk is determined.It is found that ?H increases with increasing heating rate R,and ?Hm decreases with increasing R.At the same time,considering the experimentally measured specific heat capacity,then fit the equations of supercooled liquid phase and crystal,that is Cp1 =-0.0024T + 0.5598 and Cpc=0.000094T + 0.22944,so that the?Cp is 0.165 JK-1g-1.After comparison,it is found that the ACp predicted by the new model is in good agreement with the experimental results,and the error is no more than 5%.Kauzmann temperature Tk is 221 K.The thermal expansion coefficient of Ge4Se96,Ge7.4Se92.6 and Ge14Se86 decreases with the increase of Ge content.The glass transition temperature,yield point temperature,softening point temperature increase while the Ge content rises.The Tg measured by DSC is slightly lower than that measured by TMA.