Contribution of Equilibrium Vacancies to Vanadium Caloric Properties

For the first time, data have been obtained on the parameters of the contribution of equilibrium vacancies to the caloric properties of vanadium: the vacancy formation energy, $E = 1.22$ eV, the vacancy formation entropy, $S = 26.8$ J/(mol K)$^{–1}$, and the temperature dependence of the vacancy concentration (at the vanadium melting temperature, $T_m = 2220$ K, the concentration equals to $c = 4.2\%$). These values are determined on the basis of experimental measurements of the average heat capacity of vanadium. From analysis of the interconnection between the vacancy contribution and the limit temperature of superheating of the beginning of melting, $T_{sh}$, we found that the most reliable vacancy-free straight line of the average heat capacity corresponds to $(T_{sh}/T_m) \approx 1.25$ and may serve as a reliability criterion for calculation of the vacancy contribution in metals.