New Kinetic Theory and New Equations for Lattice and Electronic Heat Capacities, Enthalpies and Entropies of Solids: Application to Tungsten

Abstract

New equations for heat capacities, entropies and enthalpies were applied to the experimental constant volume and constant pressure heat capacity data of tungsten. The heat capacity CP max was predicted to be 24.96 J/molK at 400 K. The temperatures Theta(V) and Theta(P) were found to be 78.5 K. The relationships between dimension and Theta(V) and Debye temperature were given. Tungsten shows the dimensionality crossover from 3 to 2 at about 80 K. Temperature dependences of Debye temperature, Theta(V) and Theta(P) and non-monotonic behavior were discussed. The heat capacity and entropy values predicted by the proposed models were compared with the values predicted by the Debye models. The results have shown that the proposed models fit the data better than the Debye models. The enthalpy values predicted by the proposed models were compared with the values predicted by the polynomial model and good fitting was obtained. The proposed models have shown that the constant pressure heat capacity data can be used to calculate enthalpies, entropies and heat capacities of tungsten.