Analysis of thermodynamic functions of silicon at high temperatures

It is for the first time that the results of experimental studies of variation of the enthalpy and heat capacity of silicon are analyzed within the framework of anharmonic expansion of the Debye model with due regard for the temperature dependence of the characteristic Debye temperature $\theta(T)$ in the temperature region above room temperature up to the melting point. The calculation results in a wide range of temperatures $300\le T\le1400$ K are in rather satisfactory agreement with the experimental temperature dependence of the enthalpy variation of the material. However, in the vicinity of the melting point of silicon $T_m=1690$ K, the experimental points lie above the predicted curve. The additional increment of the enthalpy of silicon in the premelting region, established for the first time in this study, is interpreted within the framework of the Frenkel thermal activation model.