Cation distribution, magnetic properties and cubic-perovskite phase transition in bismuth-doped nickel ferrite

摘要

AbstractThe phase transition of bismuth-substituted nickel ferrite, synthesized by using a simple sol-gel autocombustion method, from cubic to perovskite is confirmed from the X-ray diffraction spectrums. The changes in isomer shift, hyperfine field and cation distribution are obtained from the Mossbauer spectroscopy analysis. The cation distribution demonstrates Ni2+cations occupy tetrahedral sites, while Fe3+and Bi3+occupy both tetrahedral as well as octahedral sites. For higher concentrations of bismuth, saturation magnetization is increased whereas, coercivity is decreased which is related to phase change. The variations of dielectric constant, tangent loss and conductivity (ac) with frequency (10 Hz-5 MHz) have been explored with Bi3+-doping i.e. ‘x’. According to Maxwell-Wagener model, there is an involvement of electron hopping kinetics as both dielectric constant and tangent loss are decreased with increasing frequency. Increase of conductivity with frequency (measured at room temperature, 27 °C) is attributed to increase of number of carriers and mobility.Graphical abstractDisplay OmittedHighlights?Due to phase change, for higher concentrations of bismuth, saturation magnetization is increased whereas, coercivity is decreased.?The cation distribution demonstrates Ni2+cations occupy tetrahedral sites, while Fe3+and Bi3+occupy both tetrahedral as well as octahedral sites.?Dielectric constant, tangent loss and conductivity with frequency measurements confirm involvement of electron hopping kinetics.?Increase of number of carriers and mobility are evidenced.]]>