PECULIARITIES ACCOMPANYING THE ENTHALPY RECOVERY DURING STRUCTURAL RELAXATION OF CHALCOGENIC GLASSES

Chemical short range ordering (CSRO) structural relaxation of slowly cooled Ge10(Se85Te15) glass isothermaly and isochronally heat-treated in the vicinity of glass transition region was studied by the use of differential scanning calorimetery. The recovery of excess enthalpy, DELTAH(excess) (DELTAE(AES)*), and of the temperature of maximum of the excess apparent specific heat, T(max) (DELTAE(AES)*), plotted versus the activation energy, DELTAE(AES)* = RT(a) ln(nu0t(a)), showed unique master curves independent of annealing temperature, T(a), or annealing time, t(a). DELTAH(excess)(T(a), t(a)), which is proportional to the instantaneous degree of local order, alpha(T(a), t(a)), represents the true kinetic equation for the studied structural relaxation but the relation between T(max)(T(a), t(a)) and alpha(T(a), t(a)) is not simple. From the DELTAH(excess)(DELTAE(AES)*) master curve, isothermal and isochronal relaxation effects consistent with experimental data were simulated. DELTAH(excess,t(a)=infinity)(T(a)) = const1 + const2/T(a) characterizing the equilibrium of CSRO not reached in the experimental timescale was determined.