MAGNETIC AND ELECTRICAL-PROPERTIES OF NICKEL-ZINC FERRITES DOPED WITHBISMUTH OXIDE

Bismuth-substituted nickel-zinc ferrites have been synthesized by a so lution route in the composition range Ni0.5Zn0.5BixFe2.0-xO4, with 0 l ess than or equal to x less than or equal to 0.2. X-ray diffraction da ta indicate that bismuth most likely exists in the Bi5+ state within t he spinel structure. The saturation magnetization is found to decrease as the bismuth concentration is enhanced. This can be explained on th e basis of two sublattices in the spinel structure, with Bi5+ ions rep lacing some of the Fe2+ ions. The variation of the electrical conducti vity with temperature is explained using small polaron hopping between Fe2+ and Fe3+ sites.