Equilibrium between point defects and crystallographic shear planes

Abstract

Thermodynamic data and electron microscopy observations concerning WO_3-x can be understood if it is assumed that point defects and C.S.P. can coexist within a single phase. A very simple model is proposed. An interesting feature is that the variation of the partial molar-free energy is only slightly affected by the presence of crystallographic shear planes (C.S.P.) in opposition with partial enthalpies and entropies. The application of this model to similar systems (TiO_2-x and Nb₂O_5-x) is discussed. C.S.P. observed in Nb₂O_5-X have a quite different origin and cannot be explained by the present model.