A kinetic analysis on non-isothermal glass-crystal transformation in glassy semiconductors. Application to the Sb0.16As0.29Se0.55 alloy

In the present work, a kinetic analysis on glass-crystal transformation fro m differential scanning calorimetry (DSC) data under non-isothermal conditi on is described. A method has been developed for analyzing the evolution wi th time of the volume fraction crystallized and for calculating the kinetic parameters at non-isothermal reactions in materials involving: formation a nd growth of nuclei. Considering the assumptions of extended volume and ran dom nucleation, a general expression of the fraction crystallized has been obtained, as a function of the temperature in bulk crystallization. The kin etic parameters have been deduced, assuming that the crystal growth rate ha s an Arrhenius-type temperature dependence, and the nucleation frequency is either constant or negligible. The theoretical procedure described has bee n applied to the crystallization kinetics of glassy alloy Sb0.16As0.29Se0.5 5 with and without previous reheating. According to the study carried out, the n-values have been found: 3.1 for the as-quenched glass and 2.1 for the reheated glass. As n decreases with reheating, it is possible to state tha t the annealing causes the appearance of new nuclei. The phases at which th e alloy crystallizes after the thermal process have been identified by X-ra y diffraction, The diffractogram of the transformed material suggests the p resence microcrystallites of Sb2Se3 and AsSe remaining in a residual amorph ous matrix.