A study of synthesis of NiCuZn-ferrite sintering in low temperature by metal nitrates and its electromagnetic property

Abstract

The initial NiCuZn synthetic ferrite was synthesized by thermally decomposing the metal nitrates Fe(NO3)(3) (.) 9H(2)O, Zn(NO3)(2)(.)6H(2)O, Ni(NO3)(2)(.)6H(2)O, and Cu(NO3)(2) (.) 3H(2)O at 150degreesC for 24 h, and then we calcined the synthetic ferrite powder at 500degreesC, pulverized each of those for 3, 6, 9, 12, and 15 h in a steel ball mill, sintered each at 700-1000degreesC for I h, and thus studied their microstructures and electromagnetic properties. We could make the initial specimens chemically bonded in liquid at a low-temperature of 150degreesC, by using the low melting points less than 200degreesC of the metal nitrates instead of the mechanical ball-mill pulverization, then narrow a distance between the particles into a molecular one, and thus lower the reaction point of sintering by at least 200-300degreesC. Their initial permeability was 50-400 and their maximum magnetic induction density and coercive force, 2400 G and 0.3-0.5 Oe each, which was similar to those of NiCuZn ferrite synthesized in the conventional process. In the graph of initial permeability versus frequencies, a 180degrees rotation of the magnetic domain, which appears in a broad band of micro-wave before and after the resonance frequency, could be perceived. (C) 2002 Elsevier Science B.V. All rights reserved.