Evolution of structural (α) relaxation time anomalies in Ge_xSe_1−x chalcogenide glasses

We examine enthalpy relaxation across the chalcogenide glass series Ge_xSe_1−x, prepared over close-by compositions using conventional melt-quenching technique. We estimate the timescale τ(T_g) characterizing enthalpic relaxation near the kinetic glass transition temperature, using the non-reversing heat-flow data obtained from modulated differential scanning calorimetry measurements over a wide range of compositions (2.1 ≤ r ≤ 2.8, r = 2x + 2). Anomalies in the enthalpy-relaxation characteristic-times τ_g(r) are identified with three rigidity-transitions encountered in successive Ge-doping of polymeric selenium chains. (paper)