Influence of hydrothermal powder morphology on the sintered microstructure of MnZn ferrites

Abstract

The influence of hydrothermal powder morphology on the sintered microstructure of MnZn ferrites has been analysed. Changes in lattice parameter, particle size, density, size and total volume of pores and in the surface area of the particles were studied as functions of hydrothermal temperature and time. The ferrites were sintered at 1250 °C in a dry nitrogen atmosphere. High density and surface homogeneous ceramic bodies were obtained, without zinc loss by volatilisation. It has been observed that small differences on the properties of the hydrothermal powders gave rise to rather different microstructures after sintering. The effects of the surface chemistry of the nanosized ferrite particles and of the sintering atmosphere employed are discussed, in order to explain this behaviour. Finally, the magnetic character of the ferrite powders as well as of the sintered bodies was analysed at different conditions of temperature and applied magnetic field.