X-ray diffraction cell for studying solid-gas reactions under gas pressures to 100 bar

A pressure cell designed for high-energy X-ray diffraction in transmission mode is described. The cell is intended for use at temperatures up to 573 K with samples that are large enough to permit the real-time determination of the amount of absorbed gas by measuring the gas pressure. The design is driven by the need to ensure that the sample temperature is constant and uniform, despite the heat flow accompanying the reaction between the gas and the sample. The use of the cell is illustrated by its application to elucidating the hydriding phase transformation in the LaNi₅-H₂ system.