Study On Purification And Property Of Se-based Chalcogenide Glass

As an optical material,chalcogenide glass has the advantages of wide infrared transmission range,high infrared transmittance and high structural stability.It is simple in processing and has lower processing cost compared with conventional single crystal materials.It is an ideal candidate for a new generation of optical lenses.However,the chalcogenide glass itself has defects.For example,the infrared transmittance is greatly affected by impurities,the mechanical properties are poor,and the processing parameters are highly adaptive.These defects limit its application and development.Therefore,this paper designed different purification processes to prepare pure Se glass.By means of X-ray diffraction?XRD?analysis,differential scanning calorimetry?DSC?analysis,fourier transform infrared spectroscopy,hardness and density analysis,thermal expansion property analysis and specific heat analysis,this paper campared the effects of different purification processes on the properties of pure Se glass,studied the mechanical properties,glass forming ability,the law of thermodynamic properties changing with glass composition and crystal kinetics of Se-Sb and Ge-Se glass.Combined with the latest theoretical studies,the specific heat near the crystallization peak was calculated.The specific conclusions obtained are as follows:Compared with different processes,it is found that the Se glass prepared by the distillation purification process of adding TeCl₄ and Al as impurity remover has the best comprehensive performance.The infrared transmittance of the sample prepared by this process in the wavelength range of 2.5-15?m is more than 60%,and the highest is 70%.The[Se-H]peak at 4.3?m and the[Se-O]peak at 12.6?m were effectively removed,and the strong[Se-H]peak at 5.9?m and 6.5?m was also relatively weakened.It has the highest thermal stability,and the density and hardness are second only to Se sample without any impurity.In general,the deoxidation effect of Al is better than that of Mg,and the hydrogen removal effect of TeCl₄ is better than that of Ti.According to the calculation of crystallization activation energy,the effect of different impurity removers on the stability of glass can be obtained:the addition of TeCl₄improves the stability of pure Se glass,the addition of Al reduces the glass stability,and the addition of Ti and Mg has little effect on the stability of the glass.The mechanical properties and thermal properties of Se_100-xSb_x?x=2,4,6,8,10?samples were tested.As the content of Sb increases,the density and hardness of the Se-Sb material increase,the molar volume decreases.The characteristic temperature such as glass transition temperature,thermal stability and glass forming ability of the sample first increase and then decrease with the increase of Sb content,and reach the maximum when the Sb content is 4 at.%.Se Sb₄sample has the best stability.This paper calculate the specific heat of the Se Sb sample,and obtain the specific heat-temperature relationship function of the supercooled liquid phase and the crystal phase:=-0.0012T+1.22891,=0.0003725T+0.48338.A method for calculating the specific heat near the crystallization peak is proposed.The relationship between Gibbs free energy change,entropy difference and temperature is obtioned.The thermodynamic ideal glass transition temperature T_Kis 267.46K.The enthalpy ?C_P^L?Sis 0.1125 JK^-1g^-1,and the specific heat near the crystallization peak is 0.7499 JK^-1g^-1.The error with the experimental measurement is 2%.It is experimentally measured that as the Ge content increases,the characteristic temperature such as the glass transition temperature of the Ge_xSe_100-x?x=4,7.5,20?sample increases,the thermal expansion coefficient decreases,and accordingly,the thermal stability is increased,the glass transition activation energy?crystallization transition activation energy and crystallization peak activation energy decreased,and the frequency factor and reaction rate constant K increased by orders of magnitude.It is indicated that the Ge₂₀Se₈₀0 sample is most susceptible to crystallization during heat treatment,followed by the Ge_7.5Se_92.52.5 sample,the least likely to be crystallized is the Ge₄Se₉₆6 sample.According to the VFT fitting curve,the kinetics ideal glass transition temperature of the Ge-Se sample is lower than the actual glass transition temperature,and the ratio is between 0.9 and 1.The relationship between the kinetics ideal glass transition temperature,the actual glass transition temperature and the content of Ge element is:=4.404x+58.97,=4.85x+60.