Compositional-induced structural transformation and relaxor ferroelectric behavior in Sr/Nb-modified Bi4Ti3O12 Aurivillius ceramics

This study reports the synthesis of Sr/Nb-modified Bi4Ti3O12 Aurivillius phase, SrxBi4-xTi3-xNbxO12 (x = 0, 0.5, 1, 1.5, and 2) for lead-free relaxor ferroelectric materials using the molten-salt method. The effects of cation substitution (x content) on the structure, morphology, electrical and optical properties was investigated. X-ray diffraction and dielectric measurements revealed that the phase structures of the parent compound Bi4Ti3O12 (x = 0) experienced a gradual transformation from the orthorhombic B2cb phase to the tetragonal I4/mmm phase, for x = 1.5 and 2. Upon increasing the x content, the Curie-Weiss temperature (T-c) and dielectric constant decreased, which are explained in terms of reducing the structural distortion of orthorhombic structure. The cation substitution induced the A-and B-site cation disorder and intensified diffusion and relaxor-ferroelectric behavior. These findings will provide significant impetus for further research on relaxor ferroelectric Aurivillius phases.