Abstract
Values of K1, the first order anisotropy constant, have been measured by torque methods from 120 °K to 400 °K for seven crystals of gallium or aluminium substituted magnetic. The ionic distribution in these crystals has been carefully determined from other physical and chemical measurements and a preliminary analysis has been made of the results to decide the relative importance of the mechanism contributing to the anomalous variation of the anisotropy energy in magnetic