Phase transition in Ba_2In_2O_5 studied by in situ high temperature X-ray diffraction using synchrotron radiation

摘要

The order-disorder phase transition in Ba_h2n25igh-temOperature Iion_iconductor was systematically studied by in situ high-temperature X-ray diffraction using synchrotron radiation and electrical conductivity. Pure barium indate was prepared by solid state reactions at 1300°C. The room-temperature structural characterization showed a high degree of phase homogeneity in the prepared material. The reduction of the order-disorder phase transition temperature was verified by electrical conductivity and high-temperature X-ray diffraction. The observed features were explained based on Fourier-transform infrared spectroscopy results that revealed the presence of hydroxyl species in the crystal lattice. The increase of the intensity of few diffraction peaks near the phase transition temperature suggests the formation of a superstructure before the orthorhombic-to-tetragonal phase transition.