Magnetic behaviour of nano-sized and coarse powders of Cd-Ni ferrites synthesized by wet-chemical route

60-64Nano particles having particle size in the range (80 -100Å) for compositions (x = 0.2, 0.4, 0.6, 0.8) of CdxNi₁₋xFe₂O₄ spinel ferrite system are prepared by chemical co-precipitation route. The structural and magnetic properties have been studied by X-ray diffraction, magnetization, susceptibility and ⁵⁷Fe Mössbauer spectroscopy measurements, before and after high temperature annealing. The magnetic behaviour is explained by invoking the concept of superparamagnetism assuming core-shell structure of the nano-particles