Atomic migration in CoIn0.1Fe1.9O4

Abstract CoIn 0.1 Fe 1.9 O 4 ferrite has been studied with Mossbauer spectroscopy, and X-ray diffraction. The crystal structure is found to be a cubic spinel with the lattice constant a 0 =8.396±0.005 A. Mossbauer spectra of CoIn 0.1 Fe 1.9 O 4 were measured at various absorber temperatures of 17–825 K. Its Neel temperature T N is found to be 765 K. The Mossbauer spectra consist of two six-line patterns corresponding to Fe 3+ at the tetrahedral (A) and octahedral (B) sites. It is found that Debye temperature for the A and B sites of CoIn 0.1 Fe 1.9 O 4 is found to be Θ A =664±5 K and Θ B =207±5 K . The intensity ratio of the A to B patterns is found to increase at low temperatures with increasing temperature due to the large difference of Debye temperatures of the two sites and to decrease at high temperatures due to migration of Fe 3+ ions from A to B sites. Atomic migration of CoIn 0.1 Fe 1.9 O 4 starts near 295 K and increases rapidly with increasing temperature to such a degree that 80% of the ferric ions at the A sites have moved over to the B sites by 700 K.