Microstructure and magnetic properties of Li-Co ferrites

The microstructure and magnetic properties of Li0.5−x/2 Cox Fe2.5−x/2 O4 (where x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7) ferrites have been reported. The ferrite samples were prepared by standard double sintering ceramic technique and structural analysis was carried out using X-ray diffraction. The lattice parameter (a) increases with increase in x. The average grain size obtained from SEM micrographs shows an initial decrease up to x=0.4 and then it increases. The saturation magnetization (Ms) and initial permeability (μi) decrease with cobalt content up to x=0.4 and then a small increase is observed in case of μi. This has been attributed to high positive value of anisotropy constant (k1) for Co2+. The Curie temperature of the samples decreases with increase in the content of cobalt (x) due to reduction in the A–B interaction. The initial permeability of the samples remains almost independent of frequency in the frequency range studied viz. 1 kHz to 1 MHz. The measurement of AC susceptibility with temperature reveals the single domain (SD) state of the samples.