As-S系およびAs-S-Te系ガラスにおける化学結合種と熱的性質

抄録

Thermal conductivities and specific heats of vitreous materials in the system As-S-Te (composition: 12.7-38.8 at % As, 39.8-87.3 at % S and 0-30.6 at % Te) were measured in the temperature range from 25 to 80°C by a comparative method and an adiabatic calorimeter.
Thermal conductivity at 40°C, λ₄₀, decreased with increasing Te content introduced into As-S parent glasses. The values of λ₄₀ of As-S glasses, which have been reported previously, as well as those of As-S-Te glasses increased with covalent bond concentration, [v]. The bond concentration is defined as the total moles of all kinds of covalent bonds in unit volume of the glasses. Comparison of λ₄₀ for the glasses with same [v] and the same amount of cross-linking indicated that the value for As-S-Te glass was lower than that for As-S glass.
The heat capacity at 40°C per gram formular weight of AsS_xTe_y, C(AsS_xTe_y), can be estimated by the following bond additivity relation,
C(AsS_xTe_y)=5.1[A]+5.9[B]
where[A]is the total moles of As-S and As-Te bonds and [B] the moles of Te-S, Te-Te and S-S bonds per gram formular weight of AsS_xTe_y. The agreement of the values of heat capacities estimated by the above relation with the observed values for As-S-Te glasses was slightly worse than that in the case of As-S glasses. The present result suggests that the bond contribution by each bond species should be determined to improve the accuracy of the additivity relation.