Changes in crystal texture of barium ferrite upon sintering

The texture of oriented specimens of barium ferrite sintered at temperatures between 1100 and 1350°C was measured radiographically and magnetically. Upon sintering, the large, better oriented crystallites grow, at the expense of the smaller ones whose orientation is not as good. The changes this involves in the crystal texture were determined quantitatively. The crystallites are arranged in the form of a simple, normal fibre-texture, with the axis as the fibre axis and with the lattice in random azimuthal position around the axis. The frequency of the axes in the preferred direction amounted to about 14 with the 1100°C specimen and to about 41 with the 1350°C specimen (measured in units of the non-oriented specimen). From the texture, the remanence and its angular dependence can be calculated on the assumption that, upon de-energizing of the saturating field, the vectors of magnetization in the individual crystallites swing back into the nearest axis and there is no interaction between neighboring crystallites. Densely sintered specimens showed good agreement between theory and experiment. If, however, porosity cannot be neglected, for instance 15 percent, the measured angular dependence of the remanence is less pronounced than the calculated one which indicates the effect of anisotropic internal demagnetization.