The bond energy and the composition of metal oxides

Abstract

The relation between the bond energy of metal oxides and their composition has been discussed. To compare the bond energy of oxides of various compositions the cohesive enthalpy per one mole of oxygen atoms was used. The value of this enthalpy was calculated from thermochemical data. A linear relation between the cohesive energy and the composition was found for oxide phases of the same metal. The reasons for the lack of stability of oxides of type MO and M 2O3 where M is Mo, W, Re, Ru, Os etc. have been indicated. The criteria for the formation of the above oxides have been given. Furthermore, minimum cohesive enthalpies needed to obtain thermodynamically stable phases have been calculated. The dependence of cohesive enthalpy on melting temperature and melting heat has been discussed.