Non-stoichiometric NiZn ferrite by sol-gel processing

Non-stoichiometric Ni0.5Zn0.5Fe2-xO4-3/2x, ferrites over a wide range of x=0 similar to 0.8 are synthesized by a sol-gel processing. Phase evolution, crystal structure and crystallite size of spinel ferrites are dependent on annealing temperature and the amount of Fe deficiency. The crystallite size of spinel increases with annealing temperature and grows faster in stoichiometric ferrites than that of non-stoichiometric. Fe deficiency results in the partial reduction of spinet ferrite to zincite ZnO. XRD indicates that the crystallization temperature of ZnO is increased to about 700 degrees C. Zincite reduces the number of ferrite crystallites and disfavors the growth of spinet fertites. The lattice parameters decrease with Fe deficiency and are insensitive to the variation in composition in the samples annealed at lower temperature due to the segregation of ZnO and lattice expansion in the ultrafine crystallites. (c) 2005 Elsevier B.V All rights reserved.