Mossbauer study of MgCr0.1Fe1.9O4

MgCr0.1Fe1.9O4 has been studied with X-ray diffraction and Mossbauer spectr oscopy. The crystal structure is found to have a cubic spinel structure wit h a lattice constant of a(o)=8.388+/-0.005 Angstrom. The iron ions at both A (tetrahedral) and B (octahedral) sites are found to be in ferric high-spi n states. Its Neel temperature T-N is found to be 687+/-3 K. The Debye temp eratures for the A and the B sites are found to be 515+/-5 K and 265+/-5 K, respectively. Atomic migration from the A to the B sites starts near 350 K and increases rapidly with increasing temperature to such a degree that 50 % of the ferric ions at the A sites have moved over to the B sites by 600 K .