Thermal expansion coefficient of diamond in a wide temperature range

Experimental data for the linear thermal expansion coefficient of diamond available in the literature were analyzed and carefully selected to produce a representative dataset, which was fit with a multi-frequency Einstein model (R. Reeber, 1975) using a limited number of effective independent oscillators. In the temperature range of 10-300 K, the fits were constrained using the high-accuracy data (S. Stoupin and Yu. Shvyd'ko, 2011). It was found that the multi-frequency model precisely describes the available data from 10 K to approximately 1000 K. Above 1000 K, discrepancies were found, which suggest presence of anharmonic effects in diamond and/or influence of defects. The obtained semi-empirical formulas can be used as convenient continuous approximations for the thermal expansion coefficient in modeling thermoelastic behavior of diamond components subjected to large temperature variations.