Inherent optical behavior and structural variation in Na_(0.5)Bi_(0.5)TiO_3-6%BaTiO_3 revealed by temperature dependent Raman scattering and ultraviolet-visible transmittance

摘要

Optical properties of Na_(0.5)Bi_(0.5)TiO_3-6%BaTiO_3 (NBT-6%BT) single crystal have been studied by temperature dependent Raman and ultraviolet-visible spectra from 25 to 180 ℃. With increasing the temperature, the absorption edge approximately decreases from 3.13 to 3.04 eV. Moreover, abnormal changes of phonon mode and spectral transmission are observed at 83, 106, and 150 ℃, which can be unambiguously correlated with thermal evolutions of polar nano-regions and phase transition. It indicates that there is an inherent relationship between optical behavior and structural variation of NBT-6%BT, which provides a valid methodology to explore the phase transition of relaxor ferroelectric oxides.