Effects of doping materials and heat treatment on the morphology and magnetic properties of M-type barium hexaferrite produced by co-precipitation

Abstract

Undoped and Co-Sn substituted barium ferrite BaFe₁₂₋₂ₓSnₓCoₓ0₁₉ particle with nominal composition x= 0.00, 0.25, 0.50, 0.75 and 1.00 had been synthesized by the co-precipitation method. Mole ratios of Fe/Ba in the range of 8.1-10.1 were used. Powders of the mixtures were then calcinated for 4 hours at 50 ℃ intervals between 950 ℃ and 1200 ℃. The chemical compositions were determined by energy dispersive X-ray spectrometer. It was found that the undoped samples were Fe-rich, while the doped samples were Ba-rich. The particle sizes were determined from the transmission and scanning electron micrographs. The magnetic properties were measured with a vibrating sample magnetometer. It was found that coercivity decreased as the doping increased. It was observed that there was a correlation between the coercivity and the surface area to volume ratio of the grains. The internal magnetic fields were determined by Mossbauer spectroscopy (MS). The MS spectrums showed that the magnetic structure of the doped samples became more ordered as the doping level increased. The optimum temperature for the preparation of BaF for use in magnetic recording was found to be1000 ℃ with nominal dopant levels between 0.25-0.50 since the optimal magnetic properties needed were obtained.