High temperature Bi-based ferroelectric solid-solution with enhanced dielectric properties and magnetic order

Substitution of Fe3+ at B-site in 0.45(BiMg0.5Zr0.5O3)–0.55(PbTiO3) (BMZ–PT) solid solution [(BiMg0.5(1−x)Zr0.5(1−x)FexO3)0.45–(PbTiO3)0.55, for x=0.30, 0.35, 0.45 and 0.50] enhances the tetragonality (c/a ratio), dielectric constant (ε׳), ferroelectric curie temperature (TC) and polarization values with increasing Fe content. We show that the samples fall in the category of Bi(B′B″B′′′)O3–PbTiO3 type solid solutions possessing high TC (highest being ~434 °C for x=0.50). The variations of c/a ratio and ferroelectric TC with Fe content show non-linear trends. Using impedance spectroscopy, a single relaxation process (solely due to grains) could be identified in these solid solutions. However, detailed study of ac conductivity indicates that the conduction mechanism is dependent on frequency as well as Fe content. The ac conductivity measurements also point out that the small and large polaron hopping conduction is responsible for enhancement in dielectric constant in these samples. The sample with largest Fe content also shows magnetic ordering.