Arrhenius plots for oxide samples under conditions of constant pressure and the theory of defect equilibrium

It is shown that a family of Arrhenius lines or similar plots which exhibit a linear relationship between intercept values and slopes intersect, on extrapolation, at a point which defines a unique temperature which can be related to other important properties of the sample. The example of an oxide semiconductor exposed to oxygen is considered and it is shown that the energy of formation of neutral vacancies is pressure-dependent. The implications of this on the interpretation of electrical conductivity data for oxides measured as a function of oxygen pressure are discussed. It is suggested that the behaviour of other systems which exhibit compensation may be similarly explained.