Electric response and improved dielectric properties in BiCu3Ti3FeO12

BiCu3Ti3FeO12 ceramics, with similar crystal structure as ACu3Ti4O12, were fabricated by a standard solid-state reaction method. By tuning the sintering temperature, the samples with homogeneous grain size and low porosity were obtained. The electric responses of BiCu3Ti3FeO12 were revealed by electric modulus and complex impedance analysis. Interestingly, unlike CCTO materials, BiCu3Ti3FeO12 ceramics did not exhibit low-frequency giant permittivity plateau, which is induced by high grain resistivity. Due to different electronegativity of Ti4+ and Fe3+, Fe3+ is much easier to be reduced to Fe2+ and in turn BiCu3Ti3FeO12 ceramics show a higher Fe2+ content. Higher activation energy for electron hopping between Fe2+ and Fe3+ gives rise to a higher grain resistivity in the samples. By modifying composition, low-frequency giant permittivity plateau was successfully achieved for the samples with low Fe content.