Investigation of magnetic properties of Ba3Ni2-xZnxFe24O41 hexaferrites

Abstract

Various Ba3Ni2-xZnxFe24O41 (x=0.0, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5 and 1.7) hexaferrites were prepared by a conventional solid state reaction technique. Stoichiometric amounts of BaCO3, Fe2O3, NiO and ZnO were milled for 12 h. After milling, composition was subjected to calcining wherein it was controlled at 900°C and calcined powder was crushed into fine powder. The prepared fine powder was pressed into pellets and was sintered at 1200, 1250 and 13000C for 5 h. The X-ray diffraction (XRD) patterns for different compositions were analyzed and compared with previously reported XRD patterns of Z-type hexaferrites. This comparison confirms the formation of the Z type hexaferrites. The lattice parameters „a’ and „c‟, and c/a ratio for all samples are calculated. The values of lattice parameters are close to the reported values. The lattice parameters increase due to Zn substitution. The increase in lattice parameters with increasing Zn content can be explained on the basis of the ionic radii. The bulk density of the samples is observed to be decreased slightly with increasing Zn content. This decrease in density with increasing Zn content can be explained on the basis of the atomic weight and unit cell volume. The optical micrographs show that the average grain size increases with Zn content. The ac magnetic properties of the hexaferrites are characterized within the frequency range 100 kHz- 120 MHz. The real part of the complex initial permeability (  ) for different compositions indicates that   decreases with increasing frequency. It is observed that real part of initial complex permeability increases with the increase in Zn content up to x = 1.1 for all sintering temperatures and then it decreases. The saturation magnetization increases with Zn content up to x = 1.3 and then decreases.