AC Conductivity in Bismuth Oxide Doped Nickel-Zinc Ferrites

Abstract

Substituted nickel zinc ferrites have been prepared in the composition series Ni_0.5Zn_0.5Bi_xFe_2.0-xO₄ with x having values in the range 0.05--0.2. The electrical conductivity of the samples has been measured over the temperature range 150 to 300, K at frequencies ranging from 1, kHz to 1, MHz. The ac conductivity shows a variation of ω ^s where ω is the angular frequency and s is an exponent having values in the range 0.6 to 0.8. Correlated barrier hopping model is found to be satisfactory in explaining the conductivity which arises due to the presence of Fe²⁺ ions. The latter are created because a substantial amount of Bi³⁺ gets oxidized to the Bi⁵⁺ state.