Development of in situ synchrotron X-ray total scattering setup under pressurized hydrogen gas

We have developed an in situ gas‐loading sample holder for synchrotron X‐ray total scattering experiments, particularly for hydrogen storage materials, designed to collect diffraction and pair distribution function (PDF) data under pressurized hydrogen gas. A polyimide capillary with a diameter and thickness of 1.4 and 0.06 mm, respectively, connected with commercially available fittings was used as an in situ sample holder. Gas-leakage tests confirmed that this sample holder allows 3 MPa of hydrogen gas pressure and 393 K to be achieved without leakage. Using the developed in situ sample holder, significant background and Bragg peaks from the sample holder were not observed in the X‐ray total scattering patterns and their signal‐to‐noise ratios were sufficiently good. The results of Rietveld and PDF refinements of Ni powder are consistent with those obtained using a polyimide capillary (1.0 mm diameter and 0.04 mm thickness) that has been used for ex situ experiments. In addition, in situ synchrotron X‐ray total scattering experiments under pressurized hydrogen gas up to 1 MPa were successfully demonstrated for LaNi4.6Cu

In-situ measurement of average and local structures of hydrogen absorbing alloys using synchrotron radiation x-rays

Hydrogen absorbing alloys are widely investigated to develop high-performance hydrogen absorbing alloys because they are considered as potential hydrogen storage materials for several applications including fuel cell vehicles as well as stationary energy storage system. The hydrogen absorbing states of materials usually arise under the pressurized hydrogen gas environment. Hence, in-situ measurement is necessary to investigate the hydrogen absorbing states as well as hydrogen absorption/desorption processes. We have investigated structural changes of hydrogen absorbing alloys on hydrogen absorption/desorption processes using an in-situ x-ray diffraction measurement setup installed at BL22XU in SPring-8. By using a large area detector and high energy x-ray about 70 keV, we are capable of performing x-ray total scattering experiments to obtain the atomic pair distribution function, and can investigate the change in both average and local structures to discuss the degradation mechanism of the reversible hydrogen storage capacity.9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM9