The perfect crystal, thermal vacancies and the thermal expansion coefficient of aluminium

The thermal expansion coefficient of an Al perfect crystal is predicted by our alpha(V)K(T)V model. Thermal defect contributions and their formation parameters are determined by subtracting model results from various macroscopic expansion coefficient measurements. The results are compared with extensive theoretical and experimental determinations of the vacancy formation parameters for Al. The formation parameters obtained here are 0.67 eV for the enthalpy and 2.66k for the entropy. The vacancy concentration estimated at the melting point is 3.4 x 10(-3) Our approach provides a basis for the calculation of the high-temperature-pressure properties of Al and serves as a guide for other defect-free theoretical calculations. The method can be extended to other fee crystals.