Reentrant phenomenon in the diffuse ferroelectric BaSn0.15Ti0.85O3: Local structural insights and first-order reversal curves study

From the phase diagram proposed by Lei et al. [J. Appl. Phys. 101, 084105 (2007)], BaSn0.15Ti0.85O3 is chosen. It also exhibits a diffuse phase transition between cubic and rhombohedral (C-R) near room temperature. Dielectric analysis confirms a phase transition near room temperature (T-C approximate to 290 K). In addition, frequency dispersion in the dielectric constant, concomitantly, a loss peak is observed at low temperatures (T < T-C). Furthermore, in the similar temperature range, a decrease in remanent polarization is seen upon lowering the temperature. All of these findings point to a reentering phenomenon in the system. First-order reversal curves P(E-r, E) are measured at different temperatures and analyzed to better understand the system's interactions and polarization evolution. It was found that the relaxor nature present in the system is responsible for the reentrant behavior. Local probe techniques such as x-ray absorption near-edge spectroscopy, Raman spectroscopy, and Mossbauer spectroscopy are employed to investigate the local environment changes that are associated with the reentrant behavior. A simple ferroelectric exchange model explaining the low-temperature reentrant behavior is presented from these results.