Structural and Dielectric Properties of the Lutetium (Lu) and Yttrium (Y) Doped Nickel Ferrite

The structural and dielectric characteristics of NiFe1.925R0.075O4 (R=Lu, Y) were investigated. The material crystallize in the cubic inverse spinel phase with a very small amount of RFeO3 (R=Lu, Y) as the additional phase. Frequency variation of the dielectric constant shows the dispersion that can be modeled with a modified Debye's function, which considers the possibility of more than one ion, contributing to the relaxation. Impedance spectroscopic analysis indicates the different relaxation mechanisms, bulk grain and grain-boundary contributions to the electrical conductivity and capacitance of these materials.