Doping effects of BiFeO3 in layered perovskite SrBi2Nb2O9

Nanocrystallites of ferroelectric xBiFeO3–(1−x)SrBi2Nb2O9 (SBFN) with x ranging from 0 to 0.2 were synthesized by mechanical activation of mixed oxides at room temperature. The resulting SBFN exhibit nanocrystalline particles, which consist of layered perovskite crystallites in the range 14–24 nm, depending on the level of BiFeO3 doping in SBN. Sintered SBFN exhibited a single-phase layered perovskite structure with no detectable secondary phase being present during crystallization. The grain morphology changes from a lamellar structure in SBN to a granular structure at x=0.2. Lattice dimensions of SBN are decreased slightly by doping with BiFeO3, which also leads to a lower sintering temperature, while the Curie point was shifted upwards with increasing BiFeO3 doping. The peak impedance of SBFN decreases with frequency and increases with increase level of BiFeO3 doping in SrBi2Nb2O9. A dielectric enhancement was observed in 0.2BiFeO3–0.8SrBi2Nb2O9.