Temperature Dependence of the Saturation Magnetization of Ferrites with Magnetoplumbite Structure

The anomaly in the saturation magnetization vs temperature dependence of ferrites with magnetoplumbite structure is supposed to be caused by the fact that the superexchange interactions of the five crystallographically distinguished sublattices may be of several kinds in a part of the unit cell. It is shown that the interaction chain can be made to be of one kind only by replacement of the iron ions of one sublattice by nonmagnetic ions, and the conditions under which this replacement can be effected are pointed out. Experimental evidence demonstrates that this can partly be achieved by using $BaTiO3$ instead of $BaCO3$ in the starting mixture, if special precautions as to the sintering conditions are taken.