Mossbauer study of Cu0.8Fe2.2O4

Cu0.8Fe2.2O4 has been studied by using Mossbauer spectroscopy and X-ray dif fraction. The crystal is found to have a cubic spinel structure with the la ttice constant a(0) = 8.399 +/- 0.005 Angstrom. It is noteworthy that a 20 % replacement of Cu by Fe in the copper ferrite transforms the crystal stru cture from tetragonal to cubic and decreases the quadrupole shifts drastica lly. The iron ions at both A (tetrahedral) and B (octahedral) sites are fou nd to be in ferric states. Atomic migration between A- and B-sites starts n ear 300 K and increases rapidly with increasing temperature to such a degre e that 78 % of the ferric ions at the A-sites move over to the B sites at 6 00 K.