High-Resolution Powder Diffractometry to Study the Phase Transition of h-BaTiO 3

High-resolution powder diffraction experiments of hexagonal BaTiO 3 were performed at BL02B1 of SPring-8 to determine the symmetry and the lattice form in the low temperature phases. The best resolution achieved was 0.0085° as FWHM even for the powder diffraction. The symmetry of the lowest ferroelectric phase was determined to be a monoclinic associated with small distortion. The deviation from 120° was only 0.05°. The intermediate phase was orthorhombic as was reported. Based on these analysis, both results on the high-resolution X-ray single crystal experiments performed at the home laboratory and the high-resolution powder neutron scattering experiments performed at JRR3M were interpreted.