Magnetocapacitance in Dy-doped Ni ferrite

Ferromagnetic and ferroelectric characteristics of Dy substituted nickel ferrite, NiO·Fe1.925Dy0.075O₃, were investigated. The material formed in the cubic inverse spinel phase with a small amount of DyFeO₃ as the additional phase. A small distortion of the cubic lattice was observed upon the substitution of Fe by Dy (in the B site). Substitution of Dy for Fe caused a decrease in the saturation magnetization and Curie temperature of the nickel ferrite. Magnetocapacitance of -4% was observed in NiO·Fe1.925Dy0.075O₃ although the magnetostriction has not significantly changed with Dy substitution. The (high) dielectric constant with frequency is seen to reveal the dispersion in relaxation times.