The O tracer diffusivity in polycrystalline samples of Ni1-xFe2+xO4, where x was equal to 0.1, 0.2 or 0.4, was measured at temperatures ranging from 450 to 700C. The number of 18O atoms which diffused to the sample was determined by exploiting the 18O(p,α)15N nuclear reaction. It was established that O diffusion, for x = 0.2, was characterized by a relatively low activation energy of 0.89eV. The corresponding pre-exponential factor was also low (10-13cm2/s). The results suggested that O diffusion in these ferrites occurred via structural vacancies with a concentration of between 10-9 and 10-11.

V.B.Fetisov, G.A.Kozhina, A.J.Fishman, T.E.Kurennykh, V.B.Vykhodets: Journal of Applied Physics, 1998, 83[11], 6876-8