Effects of heat treatment temperature and time on structure and static magnetic property of W-type ferrite hollow microspheres

Abstract

Hollow spheres of hexagonal ferrite BaCo₂Fe₁₆O₂₇ were fabricated through a spray pyrolysis technique using co-precipitation ferrite powder precursor as materials, followed by calcinations in an air atmosphere. The phase composition, micro-morphology, and static magnetic property of the particles were measured by XRD, SEM, and VSM. The results indicate that the method for preparation of ferrite hollow microspheres (FHM) results in a broad particles size distribution. The density of FHM decreased from 5.31 g/cm³ to 2.31 g/cm³. When the heating rate was 5 °C/min, and temperature was 1 200 °C for 4 hours, pure W-type ferrites were formed. With the heat treatment temperature and time increasing, the crystal structure becomes perfect, the saturation magnetization is increased and the coercive force is decreased.

Keywords

microwave absorber / ferrite / hollow microspheres / spray pyrolysis

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