Dispersion of dielectric constant of oxygen deficient copper ferrospinel

Abstract

Both copper and lithium ions can be used to generate oxygen deficiency. The materials (1)CuFe₂O₄, (2)CuFe₂O₄: CuO and (3)CuFe₂O₄ : 0.75 LiAlHU₄ have been synthesized by usual ceramic technique. Dispersion of dielectric conatant and tan δ of these samples have been studied in the frequency range from 400 Hz to 1 MHz. The dispersion is in accordance with Koop's model. The oxygen deficient copper ferrospinel exhibit larger dielectric constants and tan δ values compared to CuFe₂O₄. The plot of relative loss factor versus relative dielectric constant indicates distribution of relaxation time in the range 140μs - 300μs arising out of and suggests heterogeneities interfacial polarisation. On the basis of these results, it is concluded that the existance of (Cu⁺¹, Cu⁺²) and (Fe⁺², Fe⁺³) ionic pairs, oxygen deficiency and availability of vacant sites in a spinel structure contribute to interfacial polarisation.