Variation of the degree of preferential crystallographic orientation and magnetic properties of texturized barium ferrite permanent magnets during sintering

Abstract

1. A study was made of the effect of sintering temperature on the magnetic properties and demagnetization curves of anisotropic barium ferrite magnets along their texture axis and at right angles to it. 2. It is shown that, during the sintering of texturized barium ferrite, its grains grow in a direction at right angles to the preferential direction of hexagonal axes and that its texture is appreciably improved as a result of grain growth at sintering temperatures above 1220°C. A quantitative evaluation is given of the changes in the degree of texture of such magnets induced by the sintering process. 3. It is demonstrated that the increase in the remanent induction of texturized barium ferrite during sinteringis brought about mainly by an increase in its density at sintering temperatures of up to 1220°C and by an improvement in its texture at temperatures ranging from 1220 to 1300°C. 4. On the basis of an experimentally established relation between the relative coercive force and its absolute magnitude, the hypothesis is put forward that magnetic polarity reversal has a predominantly single-domain character for barium ferrite withIHC > 2900 Oe and a predominantly multidomain character atIHC ≤ 2000 Oe.