Application of Gibbs-Duhem's equation to a pure p-type semiconducting oxide and to its solid solutions with oxides containing homovalent or heterovalent cations

Abstract

The Gibbs-Duhem equation, relating the chemical potentials of the different species in a multicomponent system, is applied to an oxide presenting a p-type semiconductivity and to the ternary systems formed by dissolving in it another oxide having a cation with a valency either equal or different from that of the base metal ion. A relationship between the activities of the neutral forms of the various components is obtained by considering first the application of Gibbs-Duhem's equation to the actual components of the oxide lattice, i.e., the ions, and then relating their activities to the corresponding values for the neutral species, taking into account the mechanism of incorporation of the different species in the oxide. It is shown that the relationships so obtained are in agreement with those derived from the equilibrium conditions for the formation of the pure oxides.