Pulsed neutron powder diffraction at high pressure by a capacity-increased sapphire anvil cell

Abstract

A new design of opposed anvil cell for time-of-flight neutron powder diffraction was prepared for use at advanced pulsed sources. A couple of single-crystal sapphire sphere anvils and a gasket of fully hardened Ti-Zr null alloy were combined to compress 35 mm 3 of sample volume to 1 GPa and 11 mm 3 to 2 GPa of pressures, respectively. A very high-quality powder diffraction pattern was obtained at Japan Proton Accelerator Research Complex for a controversial high pressure phase of methane hydrate. The counting statistics, resolution, absolute accuracy and d-value range of the pattern were all improved to be best suitable for precise structure refinement. The sample is optically accessible to be measured by Raman and fluorescence spectroscopy during and after compression. The current cell will be an alternative choice to study hydrogenous materials of complex structures that are stable at the described pressure regime.

Hydrogen site analysis of hydrous ringwoodite in mantle transition zone by pulsed neutron diffraction

“…Deuterium in the ringwoodite was analyzed using the Engineering Materials Diffractometer “TAKUMI” installed at Materials and Life Science Experimental Facility at Japan Proton Accelerator Research Complex (J‐PARC) [ Harjo et al ., ]. The powder was loosely placed into a cylindrical container composed of hardened Ti‐Zr null alloy with neutron transparency in which the outer and inner diameters were 3.0 mm and 2.4 mm, respectively [ Okuchi et al ., ]. Radial collimators of 5 mm gauge volume were applied to shield background neutrons from air or other scatterers.…”

Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

“…We used a newly designed high-pressure cell that was optimized for neutron-scattering measurements with strong pulsed-neutron sources [21,22]. In brief, two anvils composed of single-crystal moissanite and sintered polycrystalline diamond with 5 mm culets were used to compress a powdered Mg(OD)2 sample, which was confined within the f-TiZr gasket (initial thickness = 1 mm) and then compressed between the two anvils to 9 GPa.…”