Structural and magnetic properties of zinc- and aluminum-substituted cobalt ferrite prepared by co-precipitation method

Spinal ferrites having the general formula Co_{1 − x} Zn _x Fe_{2 − x} Al _x O₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were prepared using the wet chemical co-operation technique. The samples were annealed at 800°C for 12 h and were studied by means of X-ray diffraction, magnetization and low field AC susceptibility measurements. The X-ray analysis showed that all the samples had single-phase cubic spinel structure. The variation of lattice constant with Zn and Al concentration deviates from Vegard’s law. The saturation magnetization σ _s and magneton number n _B measured at 300 K using high field hysteresis loop technique decreases with increasing x, suggesting decrease in ferrimagnetic behaviour. Curie temperature T _C deduced from AC susceptibility data decreases with x, suggesting a decrease in ferrimagnetic behaviour.