Synthesis, microstructure and magnetic properties of Ni-Zn ferrites

Ni-Zn ferrite powders with a nominal composition of Ni0.5Zn0.5Fe2O4 were prepared by combustion synthesis, using urea as fuel. The large quantity of gas that developed inhibited particle aggregation and yielded soft powders suitable for dispersion and use. The as-prepared combustion products, helium pycnometer and BET, which were characterized by XRD, showed a high specific surface area (44.26 m(2)/g) and a very small particle and crystalline phase with atomic level homogeneity. The samples were uniaxially compacted by dry pressing and sintered at 1100degreesC, 1200degreesC, 1300degreesC and 1400degreesC for 2h. The samples were characterized by bulk density, SEM, and B-H loop measurements. Optimum properties were obtained for samples sintered at 1200degreesC. The Ni-Zn ferrite presented a uniform microstructure with small grain size (2.0 mum), high density (95% TD) and significant hysteresis parameter values. (C) 2002 Elsevier Science B.V. All rights reserved.