Effect of Sn-substitution on the electrical conductivity of SrFe12-xSnxO19 (0.0 ≤ x ≤ 1.0) hexaferrite

Abstract

Herein, we present a study about the effect of Sn-substitution on the electrical conductivity of SrFe12O19 hexaferrite synthesized by the solid-state reaction method. For samples containing Sn4+cations, the complex impedance curves showed the existence of conductive processes. The electrical response studied from the equivalent circuit model, provided grain boundary resistance values higher, in one order, in relation to the grain values, which agrees with the Koop model. For the Sn-doped SrM ceramics samples, the conductivity values increase with the dopant cations content. In addition, the Sn4+ cations insertion in the SrM crystal structure contributes to the emergence of two conductive processes: a DC-conductivity process at low frequency and a second frequency-dependent conductive process at high frequency. From the activation energy, the existence of a small polarons tunneling mechanism with long-range mobility and low frequency, that spontaneously occurring with negative activation energy and an electron hopping mechanism that follows a correlated barrier model and activation energy from 0.135 to 0,355 eV were found.