AC Conductivity in Bismuth Oxide Doped Nickel-Zinc Ferrites

Abstract

Substituted nickel zinc ferrites have been prepared in the composition series Ni 0.5 Zn 0.5 Bi x Fe 2.0- x O 4 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 Fe 2+ ions. The latter are created because a substantial amount of Bi 3+ gets oxidized to the Bi 5+ state.