Statistical model for the non-stoichiometric Cr 2N phase

Abstract

In order to obtain some information on the bonding in the non-stoichiometric Cr 2N 1 − x phase, a statistical thermodynamic approach has been made. The interaction energy between the nitrogen atom and the chromium atom, E N-Cr, was estimated to be −34.4 kcal/mole, and that between chromium atoms, E Cr-Cr, to be −13.4 kcal/mole. The interaction energy between nitrogen atoms, E N-N, was found to have positive values, varying with temperature. These results show that both the metal-metal and metal-nonmetal bonds play an important role in the Cr 2N phase. The atomic partition functions, which have been conventionally put equal to unity in almost all the statistical thermodynamic considerations, were also evaluated for the nitrogen atom and the chromium atom in the Cr 2N lattice. From the evaluated values for these atomic partition functions, the importance of the contribution of the electronic structures to the atomic partition functions may be appreciated.