Magnetic and dielectric properties of the spinel ferrite system Ni 0.65Zn0.35Fe2-xMn xO4

Abstract

The recent development of a high-magnetization nickel-zinc ferrite with stress-insensitive square hysteresis loop achieved through substitution of Mn3+ ions has prompted a study of the family Fe 3+0.65Zn2+0.35 [Ni2+0.65Fe3+1.35-xMn3+x]O4. The magnetic and dielectric properties of compositions with x ranging from 0 to 0.4 were measured to determine the effects of the manganese substitutions over this concentration range. As anticipated, the saturation magnetizations decreased gradually with increasing x because of reduced magnetic moments in the B sublattice. Of greater importance, however, was the observation that maximum hysteresis loop squareness and minimum stress sensitivity occurred with x∼0.2. A single-ion magnetostriction model is used to interpret this result. Since the electrical resistivity remained above 106 Ω cm and the dielectric loss tangent stayed below 10 -3 for the entire series, Fe2+ ion formation is probably negligible.