The diffusion study of oxygen atoms in Cox/3Ni(5−x)/3Sb1/3Fe1O4 ferrite

Abstract The oxygen diffusion in polycrystalline samples Co x /3 Ni (5− x )/3 Sb 1/3 Fe 1 O 4 ( x =0, 1, 2, 3, 4) at an annealing temperature of 823 K for 1 min, was studied. The diffusion coefficient was calculated using the equation D =( σKT / Ne 2 ) t . It was found that the oxygen diffusion is characterized by a relatively small activation energy (0.54 eV) and low pre-exponential factors D 0 ≈10 −13 –10 −14 cm 2 s −1 . These results suggest the oxygen diffusion in ferrite under consideration occurs by means of structural vacancies with their concentration about 10 −11 –10 −13 . The substitution of Co 2+ ions decreases the diffusion coefficient up to x =1 and then increase it. The X-ray analysis showed that the spinel phase was completely formed at 12 h sintered at 1473 K. From the correlation between ionic radius and radius of octahedral and tetrahedral sites, the theoretical lattice parameters were calculated and a suggestion of cation distribution for the given ferrites was determined.