Specific Heat and Lattice Anharmonicity in ZnSiP2 and ZnSiAs2

The molar specific heat at constant pressure was measured for ZnSiP₂ in the temperature range from 300 to 400 K and for ZnSiAs₂ from 300 to 500 K. An analysis of the experimental data showed that the contribution to the specific heat due to lattice anharmonicity can be described by a polynomial of third order in the temperature. Predictions are made regarding the expected temperature dependence of the thermal expansion coefficients and compared with existing experimental data.