Viscosity and heat capacity of As₂Se₃ connected via Adam–Gibbs model

Abstract

The viscosity data measured by penetration and parallel‐plate methods for As2Se3 glass and undercooled melt were compared with literature data. The MYEGA equation (log η0 = −4.67 ± 0.12, m = 43.2 ± 0.4, and T12 = 441.7 ± 0.3 K) was used for the description of the selected viscosity data, including melt region (15 orders of magnitude). The heat capacity data for As2Se3 glass, undercooled melt, and melt, as well as for crystalline As2Se3 were determined for low and medium‐range temperature intervals. These data were compared with previously reported data. Equations that describe the heat capacity of As2Se3 in a broad temperature interval were formulated. The values of the standard molar enthalpy, Δ0THm0, and entropy, Δ0TSm0, at T = 298.15 K are 26.202 kJ·mol−1 and 193.8 J·mol−1·K−1, respectively. The heat capacity data determined from very low temperatures were used for the calculation of crystal, glass, and melt entropies. These heat capacity temperature dependencies were used both for the estimation of the Kauzmann temperature (TK = 292.5 K) and the glass entropy at 0 K (S0 = 25.96 J·mol−1·K−1), and for the determination of the excess entropy. The proportionality between the viscosity of the As2Se3 melt and the excess entropy clearly indicates the applicability of the Adam–Gibbs (AG) model.