The diffusion of tracer oxygen atoms in Ni ferrites

Abstract

Oxygen tracer diffusion in polycrystalline nickel ferrites Ni (1-x)Fe(2+x)O(4) (x=0.1; 0.2; 0.4) at temperatures of 450-700°C was studied. The number of 18O atoms diffusing to the sample was determined using the 18O(p,α) 15N nuclear reaction at the energy of the primary beam particles equal to 762 keV. The nuclear physical experiments were performed on a 2 MV Van de Graaff accelerator. It has been established the oxygen diffusion is characterized by relatively small activation energy (0.89 eV for x=0.2) and low pre-exponential factors (∼10-13 cm2/s for x=0.2). These results suggest that oxygen diffusion in the ferrites under consideration occurs by means of structural vacancies with their concentration about 10 -9-10-11. © 1998 American Institute of Physics.