(Invited) Precise structural analysis through high-temperature neutron and synchrotron powder diffractometry

Both neutron and synchrotron powder diffraction techniques are powerful to study the crystal structure and phase transformations in inorganic materials at high temperatures. Here we briefly review our recent works on the precise structural analysis through high-temperature neutron and synchrotron powder diffractometry. Our group devised, fabricated and developed new furnaces for neutron diffraction measurements in air at high temperatures up to 1860 K. This system enabled the measurements of high-quality neutron diffraction data with high signal/noise ratio and without any extra peaks, leading to precise structural analysis. Positional disorder and diffusion path of oxide ions in Bi2O3, CeO2, and (La0.8Sr0.2)(Ga(0.8)Mg(0.1)5Co(0.05))O3-delta were studied through the nuclear density distribution obtained by a combined technique including a Rietveld refinement, a maximum-entropy method (MEM) and MEM-based pattern fitting (MPF) of the neutron powder diffraction data measured at high temperatures with this system. We also devised, fabricated and developed a new furnace for synchrotron powder diffraction measurements in air at high temperatures up to 1900 K. This system enabled the measurements of high-quality synchrotron diffraction data with high signal/noise ratio and without any extra peaks, leading to precise structural analysis. Electron-density distribution of calcium titanate perovskite was investigated through a combined technique of a Rietveld method, MEM and MPF of the synchrotron diffraction data measured at high temperatures with this system.