In situ high temperature powder x-ray diffraction technique using a sapphire single-crystal flat cell

Understanding the behaviors of materials in their operating and manufacturing environments is essential not only in the scientific field, but also in the context of designing industrial materials for target applications. In this study, we developed a high-temperature x-ray diffraction (XRD) system, using a small microscope heating stage at the BL02B2 beamline in SPring-8. Newly designed sample cells composed of sapphire single crystals were employed to perform XRD experiments using powdered samples at high temperatures and under oxidization/reduction gas atmospheres, with a short sample exchange time. More specifically, XRD experiments were conducted under vacuum, air, inert gas (maximum temperature: ∼1400 °C), and reduction gas flow conditions (maximum temperature: ∼900 °C). In addition, to monitor the changes in the exhausted gas composition during the chemical reactions, the developed heating system was combined with in situ gas-analysis tools (a remote gas-pressure control system, gas chromatograph, and mass spectrometer), which allowed analysis of the gas-adsorption/desorption and solid-gas reaction processes. Several heating experiments, such as the observation of the reduction of Fe oxides, phase transitions of ZrO2 and BaCO3, and synthesis of BaZrO3, demonstrated the validity and usefulness of this system.