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 p arameters are determined by subtracting model results from various macrosco pic expansion coefficient measurements. The results are compared with exten sive theoretical and experimental determinations of the vacancy formation p arameters for Al. The formation parameters obtained here are 0.67 eV for th e enthalpy and 2.66k for the entropy. The vacancy concentration estimated a t the melting point is 3.4 x 10(-3) Our approach provides a basis for the c alculation of the high-temperature-pressure properties of Al and serves as a guide for other defect-free theoretical calculations. The method can be e xtended to other fee crystals.