Influence of temperature on structural and magnetic properties of Co0.5Mn0.5Fe2O4 ferrites

Co0.5Mn0.5Fe2O4 ferrites have been synthesized using a single-step sol gel auto-combustion method in which the metal nitrate (MN)-to-citric acid (CA) ratio was adjusted to 0.5: 1 and pH to 7, respectively. The structural and magnetic properties of as-burnt and annealed samples were studied as a function of temperature. The inverse spinel structure was confirmed by X-ray diffraction (XRD) and crystallite size was estimated by the most intense peak (311) using Scherrer's formula. Contrary to earlier studies reported in the literature, both as-burnt and annealed samples exhibit crystalline behaviour. Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to 10 +/- kOe. Lattice constant and crystallite size increased as the annealing temperature was increased. However, the coercivity (H-c) initially increased and then decreased with the increase of crystallite size. The variation in coercivity is ascribed to the transition from a multi-domain to a single-domain configuration.