Effect of chloride on the magnetic properties of isotropic strontium ferrite

Abstract

The effects of chloric ion on the magnetic properties of isotropic strontium ferrite were studied. The hematite obtained from waste pickle liquor was used. It contained 0.1-0.3 wt% chloric ion as chloride.
Chloric ion in the hematite was reduced. to one half of the initial amount by washing with water. Though the green density remained unchanged after dechlorination, it was found that sintered density of ferrite obtained from the dechlorinated hematite was 5-10% higher than that of as received. Remanence and maximum energy product of the ferrite produced from the dechlorinated hematite were 10-15% higher and intrinsic coercive force was about 10% lower than those from non-dechlorinated ferrite.
In the case of the ferrites obtained from hematite contatining 0.2-5.0 wt% chloric ion as added in the form of ferrous chloride, magnetic properties of those having molar ratio of both 2 Fe/Sr=6.00 and 2 Cl/Sr=1.00 were improved 15-20% over those from not compensated ferrites. The maximum values of the magnetic properties were obtained in the range of 0.8-1.0 wt% chloric ion.
The chloric ion was found to exist as strontium chloride by X-ray diffraction. It was considered that the effects of chloric ion on the magnetic properties are due to the improved densification caused by liquid phase sintering of strontium chloride.