EFFECT OF THE PREPARATION METHOD ON THE OXIDATION-REDUCTION MECHANISM AND THE CATION DISTRIBUTION OF MN-ZN FERRITES

The cation distribution of manganese-zinc ferrite Mn0.50Zn0.15Fe2.05O4 prepared by a ceramic route and wet method was investigated by derivative thermogravimetry (DTG) and X-ray diffraction analyses. Below about 500°C, these ferrites which are oxidized in cation deficient spinels show an incomplete oxidation of tetrahedral Mn2+ ions leading to a cation distribution (Zn2+0.43 Mn2+0.15Fe3+0.42)A (Fe3+1.54Mn3+0.32 □0.14)BO2−4. With increasing temperature further oxidation of Mn2+ ions results in the appearance of a rhombohedral phase α−(Fe2-zMnz)O3 rich in iron accompanied by a spinel phase containing the totality of zinc. © 1993 Academic Press, Inc.