The specific heat of aluminum from 330 to 890°K and contributions from the formation of vacancies and anharmonic effects

Abstract

The specific heat of high purity aluminum has been measured from 330 to 890°K with an estimated accuracy of ± 0.7 per cent, using dynamic adiabatic calorimetry. Identical data were obtained for the sample annealed or quenched in ice water from 600°C. The experimental specific heat at constant pressure was converted to that at constant volume using experimental data of molar volume, volume expansivity and isothermal compressibility reported in the literature. A theoretical specific heat at constant volume was obtained by using the Debye specific heat, with a single Debye temperature, to which an electronic specific heat was added. The excess specific heat was determined by the difference between the specific heat converted from the experimental data and the calculated specific heat. The excess specific heat was about 10 per cent of the total specific heat at 930°K. The formation of equilibrium monovacancies accounts for only about one per cent of the excess specific heat at 930°K. The remaining excess specific heat is assumed to be due to anharmonic lattice effects. and the temperature dependence agrees approximately with the theoretical predictions for aluminum.