Effect of bismuth incorporation on thermal properties of quaternary chalcogenide glass Se80Te15-xCd5Bix (x=0,5,10) alloys

Differential scanning calorimetry has been employed to investigate the thermal properties of Se80Te15-xCd5Bix (x = 0, 5, 10) glass system. The Variation of characteristic temperatures such as glass transition temperature (T-g), onset crystallization temperature (T-c), peak crystallization temperature (T-p) and melting temperature (T-m) are studied as a function of composition and heating rate. A stepwise increase in values of characteristic temperatures has been observed with the increase in heating rate. Further, obtained values of characteristic temperatures display decreasing trend with increase in bismuth concentration. The compositional and heating rate dependence of Thermal parameters such as glass forming ability (Delta T), thermal stability (H-g), enthalpy (Delta H) and entropy (Delta S) has been investigated. It has been observed that Delta T and H-g have lowest and highest values for Se80Te5Cd5Bi10 and Se80Te15Cd5 compositions respectively. Avrami index (n) and activation energy for crystallization (E-c) have been calculated for all the samples. Values of n obtained for Se80Te15Cd5, Se80Te15Cd5Bi5 and Se80Te5Cd5Bi10 compositions are found to be 1.44, 2.16 and 2.16 respectively. Based on the obtained values of n, the nucleation process in alloys is discussed. It is noteworthy to mention that least value of E-c is observed for the alloy Se80Te5Cd5Bi10 containing the highest amount of bismuth. Furthermore, calculated thermal parameters are used to anticipate the electrical switching behavior of the alloys.