Atomic migration in CoIn0.1Fe1.9O4

CoIn0.1Fe1.9O4 ferrite has been studied with Mossbauer spectroscopy, and X- ray diffraction. The crystal structure is found to be a cubic spinel with t he lattice constant a(0) = 8.396 +/- 0.005 Angstrom. Mossbauer spectra of C oIn0.1Fe1.9O4 were measured at various absorber temperatures of 17-825 K. I ts Neel temperature T-N is found to be 765 K. The Mossbauer spectra consist of two six-line patterns corresponding to Fe3+ at the tetrahedral (A) and octahedral (B) sites. It is found that Debye temperature for the A and B si tes of CoIn0.1Fe1.9O4 is found to be Theta (A) = 664 +/- 5 K and Theta (B) = 207 +/- 5 K. The intensity ratio of the A to B patterns is found to incre ase at low temperatures with increasing temperature due to the large differ ence of Debye temperatures of the two sites and to decrease at high tempera tures due to migration of Fe3+ ions from A to B sites. Atomic migration of CoIn0.1Fe1.9O4,, starts near 295 K and increases rapidly with increasing te mperature to such a degree that 80% of the ferric ions at the A sites have moved over to the B sites by 700 K. (C) 2001 Elsevier Science B.V. All righ ts reserved.