The Mössbauer spectra and X-ray diffraction patterns of CuCrxFe2-xO4, where x ranged from 0.1 to 0.8, were studied with especial regard to the atomic distribution and Debye temperature. At room temperature, the crystal structure was found to be a cubic spinel for x-values of 0.2 to 0.8, and was tetragonal for an x-value of 0.1. The increasing intensity ratio of tetrahedral to octahedral patterns, with increasing temperature at temperatures below 250K, was explained in terms of large differences in the Debye temperature of tetrahedral and octahedral sites. A decreasing intensity ratio at high temperatures was attributed to the migration of Fe ions from tetrahedral to octahedral sites, which was found to increase sharply with increasing temperature and Cr content. Even at 150K, atomic migration began for an x-value of 0.2 and increased - with increasing x-value - to such an extent that about 10% of the Fe3+ ions at tetrahedral sites migrated to the octahedral sites when x was equal to 0.6. The atomic migration increased markedly with increasing temperature, and about 50% of the Fe3+ ions at tetrahedral sites migrated at 300K when x was equal to 0.5.

Y.K.Kim: Japanese Journal of Applied Physics - 1, 1997, 36[10], 6339-43