Trivalent cobalt in nickel-zinc ferrites—I. chemical problems

By using special preparation techniques the amounts of trivalent cobalt present in irondeficient Ni-Zn-Co ferrites have been varied.Co³⁺ concentrations have been measured very accurately by careful chemical analyses. It has been shown that under normal sintering conditions, e.g. 1200°C in oxygen, the amount of Co³⁺ just compensates the iron deficiency. The cation vacancy concentration is low. Cation vacancies are formed at lower temperatures near pores and grain boundaries.