High-Temperature Specific Heats of Ge, Si, and Ge-Si Alloys

Abstract

The specific heats of Ge, Si, and Ge‐Si alloys were determined in the temperature range 300° to 1000°K, by a novel temperature‐modulation technique. The specific heat at constant pressure c_p exceeds appreciably the Dulong‐Petit value c_DP at high temperature. Above the Debye temperature θ_D the divergence can be represented by $c_p{\mathrm{/c}}_{\mathrm{DP}}{\text{=0.95+αT/θ}}_{\mathrm{D}}$ where T is the absolute temperature and α=0.081 is a coefficient independent of alloy composition. This result is in disagreement with the current theory of the anharmonic contribution to the specific heat at high temperatures, which predicts α=0.016 for Ge, and α=0.030 for Si.