Crystallization kinetics and thermal stability in Se85-xTe15Sbx chalcogenide glasses

Crystallization process of Se_85-xTe₁₅Sb_x (x = 2.7, 7.5, 10 and 15 at %) chalcogenide glasses has been studied by using differential scanning calorimetry (DSC) with different heating rates. These glasses are found to have a double glasses transition and overlapped crystalline phases for Se₇₀Te₁₅Sb₁₅ glass while single glasses transition and single crystallization stage for other glasses. Glass transition temperature, T_g, onset crystallization temperature, T_c, and peak crystallization temperature, T_p, are found to be dependent on composition and heating rates. Values of various kinetic parameters such as activation energy of glass transition, E_g, activation energy of crystallization, E_c, Hurby number, H_r, thermal stability, S_p, rate constant, K_p, and Avrami exponent, n, are determined for the present systems. Results indicate that rate of crystallization is dependent on thermal stability and glass-forming ability. Crystallization mechanism occurs in two dimensions for studied compositions. Crystalline phases resulting from DSC and scanning electron microscopy have been identified by using X-ray diffraction.