Study on sintering process and characteristic of nanosized soft magnetic MnZn ferrite powders
ABSTRACT The effect of sintering process (especially the sintering temperature) on the magnetic property and microstructure of sintered sample of nanosized soft magnetic MnZn ferrite powder was investigated. The sintered sample of MnZn ferrite was prepared by both traditional pressing and cool isostatic pressing on MnZn ferrite nanoparticals. The sintering process of which was segmented. The density, microstructure and phase composition of sintered sample were analyzed by Archimedes' law, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The grain growth and densification in sintering process of MnZn ferrite were investigated. The magnetic property was measured by vibrating sample magnetometer (VSM) and Nim2000 magnetic material testing system. The results show that the better sintering temperature is 850 °C, at which the better magnetic property and microstructure of sintered compact were obtained.
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ABSTRACT: The tetrahedral/octahedral site occupancy of non-magnetic zinc ion, added to maximize the net magnetic moment of mixed ferrites has been found to depend on the method of preparation. In this paper, we qualitatively analyze the metal ion distribution in Mn–Zn ferrite particles prepared by co-precipitation and ceramic methods using extended X-ray absorption fine structure (EXAFS) technique. The results suggest that the differences observed in the magnetic properties of the samples prepared by different methods are not only due to the difference in particle size but also due to the difference in cation distribution. The difference in cation distributions between ferrites of similar composition prepared differently has been found to depend on the crystal field stability energies of the metal ion of interest and associated cations.Journal of Magnetism and Magnetic Materials 01/2000; · 1.83 Impact Factor
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ABSTRACT: Energy dispersive X-ray analysis performed on plasma-sprayed MnZn ferrite (MZF) single `splats' shows a variation in zinc content within splats of different sizes after the spray process, even though the powder has the same starting stoichiometry. A simple model indicates that smaller particles have a higher zinc evaporation rate during the in-flight time. However, the significant decrease of zinc in smaller ferrite particles is mainly attributed to their large surface-to-volume ratio. Compositional differences due to a random cation distribution condition results in magnetic property variations among MZF splats. The coating inhomogeneity due to zinc loss increases the coercivity of the plasma-sprayed MnZn ferrites. The magnetic properties of the MnZn ferrites can be improved through long-range (diffusion) and short-range (ordering) cation redistribution upon low temperature annealing.Acta Materialia. 01/2004;
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ABSTRACT: Nanocrystalline Mn0.5Zn0.5Fe2O4 ferrite in SiO2 matrix has been prepared by sol–gel method. X-ray diffraction (XRD) study indicates the presence of single-phase spinel ferrite in the sample. The size of the particles, estimated by a transmission electron microscope (TEM), was found to be less that 20 nm. The magnetization measurement of the sample shows no hysteresis loss. The Mössbauer spectra consist of a sextet due to ferromagnetic particles and a doublet due to superparamagnetic nano-sized ferrite.Applied Surface Science 01/2001; · 2.11 Impact Factor