Effect of Zn2+ and Nd3+ substitution on magnetisation and AC susceptibility of Mg ferrite

Polycrystalline ferrites ZnxMg1-xFe2-yNdyO4 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0; y=0.00, 0.05 and 0.10) were prepared by standard ceramic method and studied for magnetisation and AC susceptibility. The dependence of saturation magnetisation on Zn2+ content suggests that, A-A and B-B superexchange interactions are comparable, leading to non-colinear spin arrangement. The substitution of Nd3+ ion affects magnetisation adversely. Variation of AC susceptibility with temperature shows the existence of single domain structure for x=0.00 and y=0.00 and exhibits transition from single domain to multidomain structure with Zn2+ content. On substitution of Nd3+ the domain structure changes from single domain to multidomain for x≤0.4 and exhibits superparamagnetic structure for x=0.6. The samples for x=0.8 and 1.0 show paramagnetic behaviour