Relaxor ferroelectricity driven by 'A' and 'B' site off-centered displacements in cubic phase with Pm3m space group

Abstract

The present report leads to the development of a lead-free perovskite system (Ba1-xCax)(Sn0.11Zr0.05Ti0.84)O3 (BCSZTx); 0≤ x ≤0.20, exhibiting relaxor ferroelectric behaviour in an average cubic structure. The x-ray diffraction measurements have shown a simple cubic phase with Pm3m space group for all the compositions. Despite having a centrosymmetric cubic phase, a slim hysteresis loop has been observed via PE loop measurements. Raman spectroscopic measurements have revealed the presence of local ordering in the macroscopic cubic matrix, corresponding to 'A' and 'B' sites. The cooperative behaviour of 'A' and 'B' site off-centered (local) atoms leading to microscopic polar symmetry in the macroscopically cubic matrix is held responsible for the observed relaxor ferroelectric nature. Owing to the aforementioned contrapositive behaviour, these ceramics have exhibited a high value of dielectric constant. Eventually, we have clearly observed a decisive role of Ca2+ dopant at 'A' site in BCSZTx ceramic system leading to the enhancement in the relaxor ferroelectric behaviour and dielectric properties. The presence of a slim hysteresis loop along with broad and diffuse dielectric nature makes these ceramics, a potential candidate for energy storage applications. © 2021 IOP Publishing Ltd.