Point defects and diffusion in NiO

A defect model for NiO is developed and is fit to the electrical-conductivity data 26], the deviation-from-stoichiometry data 7], and the cation-self-diffusion data 14, 17]. This model involves neutral, singly charged, and doubly charged nickel vacancies and charge-compensating electron holes. Both singly and doubly charged cation vacancies are required to explain the data; neutral cation vacancies (if present) are not required by the present data. However, the jump frequencies of the two types of charged cation vacancies are generally not equal; the doubly charged cation vacancy moves with the smaller activation enthalpy. The defect data are quantitatively consistent with the chemical-diffusion data 26] and with a correlation factor?v = 0.75.