Hydrogen location in yttrium dihydride by means of NMR measurements

Abstract

The proton magnetic resonance rigid-lattice second moment in ${\mathrm{YH}}_{1.92}$ and ${\mathrm{YH}}_{1.98}$ has been measured in the temperature range 160-200 K. From these the occupancy factors for hydrogen in the octahedral and tetrahedral interstitial sites of the fcc metal lattice have been determined. A significant fraction (≃10-15%) of the octahedral sites are found to be occupied, consistent with features observed in the optical properties of ${\mathrm{YH}}_2$.