Raman study of the relationship between room-temperature tetragonality and the Curie point of barium titanate

Variable-temperature Raman spectroscopy showed that, in progressively finer BaTiO3 powders, the Curie point increased as the room temperature tetragonality decreased. The influence of crystallite size distribution on the range of tetragonalities present in a powder was clearly evident in both phase transitions, as observed by Roman spectroscopy and room-temperature X-ray diffraction patterns, Titanium K-edge X-ray absorption spectroscopy could not distinguish between the cubic and tetragonal structures of BaTiO3, at 300 degrees C and room temperature, respectively.