A Study of Nonstoichiometric Empirical Formulas for Semiconductive Metal Oxides

摘要

An empirical formula for semiconductive metal oxides is proposed relating nonstoichiometric value x to a temperature or an oxygen partial pressure such that experimental data can be represented more accurately by the formula than by the well-known Arrhenius-type equation. The proposed empirical formula is log x = A + B· 1000/T + C·exp(- D·1000/T) for a temperature dependence and log x = a + b·log PO2 + c·exp(- d·log PO2) for an oxygen partiral pressure dependence. The A, B, C, D and a, b, c, d are parameters which are evaluated by means of a best-fitting method to experimental data. Subsequently, this empirical formula has been applied to the n-type metal oxides of Zn1+xO, Cd1+xO, and PrO1.8003-x and the p-type metal oxides of CoO1+x, FeO1+x, and Cu2O1+x. It gives a very good agreement with the experimental data through the best-fitted parameters within 6% of relative error. It is also possible to explain approximately qualitative characters of the parameters A, B, C, D and a, b, c, d from theoretical bases.