Moessbauer study of the substitution of iron by chromium in Mn-Zn ferrites

The Mnsub(0.7)Znsub(0.3)Crsub(x)Fesub(2-x)O4 (0 <= x <= 1) ferrite system is studied by Moessbauer spectroscopy. At liquid nitrogen temperature the average hyperfine field slightly decreases with increasing chromium concentration. On the contrary at room temperature the field strongly decreases for x ranging between 0 and 0.9 and then becomes zero for x = 1. The variations in the Curie temperature are in agreement with the previous behaviour. Spectra taken under a 6 T applied field show that the collinear character of the magnetic structure is preserved at least up to x = 0.5. Finally, the study of the site occupancy has demonstrated a notable Fe3+ amount at tetraedral sites which leads to an important inversion degree in these ferrites. (author)