Abstract
The series of compounds CuCr2-xFexO4 with x=0.02, 0.04, 0.10 and 0.20 has been studied by Mossbauer spectroscopy between 77 and 873K. In all samples, Fe2+ and Fe3+ ions are observed. The occurrence of Fe2+ ions, the variation in the quadrupole splitting and the isomer shift with temperature are discussed in terms of a band model for CuCr2O4 with exchange of an electron occurring between two Fe3+ ions through the conduction band and a relaxation of the Jahn-Teller distortion between the three space directions. The superposition of these two processes implies phonon-electron interactions. The Neel temperature, deduced from the Mossbauer spectra does not vary significantly with the iron content and a value of 130K is obtained, in agreement with the value of 135K deduced from magnetic measurements on CuCr2O4. As expected, the hyperfine field of the Fe3+ ions follows the Brillouin curve for S=5/2.
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