Study On The Relationship Between The Characteristic Temperatures And Composition Of Se-Based Infrared Glass

In this paper, the Se-based infrared glasses GexSe80-xSb20(x=10,12.5,15,22.5,25) and GexSe100-x(x=20,25,30,60) were choosen as the research object, and the amorphous and crystalline samples were prepared by the melt-quenching method. The XRD was used to determine the amorphous degree of the sample, and through the Fourier transform infrared spectroscopy, the sample’s infrared performance was tested. With the DSC thermal analysis method, the glass transition temperature Tg of the sample was measured. According to the VFT equation, the dynamics ideal glass transition temperature Tg0 of the specimen was fitted. The thermodynamics ideal glass transition temperature Tk was determined by the experimental measurement of the specific heat. The kinetic fragility parameter of the sample was calculated finally. The main research results of the paper are as follows:(1) In the 2～15μm wavelength range, the infrared transmittance of GexSe80-xSb20 and GexSe100-x glass samples was about 60%, and the maximum value can reach to 75%, which indicated that the good infrared performance of the samples, and it can be applied to the production of the atmospheric infrared window in 3～5 μm and 8～12μm.(2) The glass transition temperature Tg of GexSe80-xSb20 and GexSe100-x samples was related to the heating rate and the composition of the sample. The glass transition temperature Tg increased with the heating rate and the content of germanium increasing.(3) The dynamics ideal glass transition temperature T0 of GexSe80-xSb20 and GexSe100-x were less than the actual glass transition temperature Tg. With the increasing of the germanium element content and heating rate, the characteristic temperature T0 also showed an increasing trend. But no matter how changed in composition and heating rate, the volume change fraction of maximum conversion rate fp were smaller than 0.6, which meant that the transition process from amorphous glass to crystalline phase transition was according to the growth pattern of anisotropic collision.(4) The fragility parameter m of the GexSes0-xSb20 was in the range from 16.333 to 25.107, suggesting that the GexSe80-xSb20 glasses belonged to the "medium-strength glass". The fragility parameter m of the Ge3oSe7o and Ge25Se75 sample were respectively 12.732 and 15.584, indicating that the two binary chalcogenide glasses belonged to the "strength glass". The reduced temperature Trg of the GexSe80-xSb20 sample were greater than 0.667.(5) The fitting results showed that the specific heat of the undercooled liquid (cp’) was greater than that of the crystal (cpc). By the calculation, the thermodynamics ideal glass transition temperature Tk of the GexSe80-xSb20 can be obtained. When x was equal to 10,12.5,15,22.5,25, the characteristic temperature Tk of GexSe80-xSb20 were respectively 305.32 K,440.57 K,442.79 K,460.56 K, and 465.73 K. Analysis showed that, when fixed the content of Sb elements in the Ge-Se-Sb glass,Tk will increase with the increasing of the Ge content. Comparison of Tk, Tg and T0, the conclusion of Tg>T0>Tk can be obtained.