Abstract
The structural transformations in PbBi4Ti4O15 (PBT) induced by decreasing the temperature from 850 to 120 K were investigated using Raman spectroscopy. The temperature evolution of phonon modes revealed structural alterations in PBT occurred near 800, 600, and 400 K. The paraelectric-ferroelectric phase transition at 800 K was clearly observed in the temperature behavior of the low-energy phonon mode at 60 cm−1 that has been previously attributed to a displacement of the Bi2O2 plane with respect to the Aurivillius perovskite-like block, emphasizing that this is the phonon mode driving the system into a ferroelectric state. The structural transformation near 600 K was identified from the mode at 40 cm−1 related to Pb/Bi vibrations in the perovskite-like block as well as modes at 130 and 220 cm−1 caused by octahedral tilting of TiO6. The temperature of this structural alteration matches the second anomaly observed in the dielectric permittivity of PBT, so it causes minor spontaneous polarization in this material. The temperature dependence of the mode at 60 cm−1 also revealed a structural transformation at 400 K that is not related to the ferroelectric properties of PBT.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call