Thermal expansion and specific heat capacity of wurtzite AlN

Abstract

Based on density function theory and density function perturbation theory, the thermal expansion coefficient and molar specific heat at constant pressure with temperature of wurtzite AlN are calculated by first principles. The results show that the coefficient of thermal expansion along the a direction is higher than that along the c direction in the whole temperature range. In general, in the low temperature range, the calculated molar heat capacity at constant pressure is in good agreement with the available experimental data, but in the high temperature range, the calculated results and the available experimental value are quite different, which is caused by anharmonic effect, and the sample itself will produce more defects at high temperature.