Effect of Mn4+ substitution on magnetic behaviour of cobalt ferrite

The cation distribution and magnetic properties of Co1+xMnxFe2-2xO4 (x = 0.0-0.5) spinel ferrite system have been studied by means of X-ray diffraction, high field magnetization, low field a.c susceptibility and Fe-57 Mossbauer spectroscopy measurements. The compositional variation of lattice constant violates the Vegard's law while magneton number follows the Neel's collinear spin ordering model. The X-ray intensity, calculations indicate that Mn4+ ions occupy only octahedral sites replacing Fe3+ ions and the added Co2+ ions substitution for B-site Fe3+ ions without disturbing tetrahedral site cations. The Mossbaur spectra at 300K have been fitted with two sextets in the ferrimagnetic state corresponding to Fe3+ at tetrahedral and octahedral sites for x less than or equal to 0.4. The temperature dependence a.c susceptibility behaviour is attributed to magnetic anisotropic Co2+ ion in the system.