Synthesis and crystal structure of κ-Zr9V4SH∼23

The Zr9V4SH∼23 hydride was synthesized by saturation from gaseous hydrogen at room temperature and 0.12 MPa hydrogen pressure. The measured hydrogen absorption capacity of the κ-Zr9V4S was 1.77 H/M. The refinement of the hydride structure with the use of X-ray powder diffraction data confirmed the preserved symmetry of the metallic matrix (sp.gr. P63 /mmc, a=9.2715(2), c=9.0756(4)Å, Δa/a=7.3%, Δc/c=6.1%, ΔV/V=22.1%, ΔV/at.H=2.62  Å3). The analysis of interstices in this compound revealed that without positioning hydrogen atoms in triangular Zr3 interstices it is impossible to model the structure of k-hydride with the experimentally observed capacity. Neutron powder diffraction study of the Zr9V4SD∼23 deuteride (sp.gr. P63/mmc, a=9.2779(5), c=9.0779(5)  Å) revealed deuterium atoms filling two tetrahedral and three triangular interstices. A full occupancy of only one site (D4) was observed in our sample giving the refined deuterium content of 20.8(2) D/f.u. Filling of the D4 site causes a displacement of the sulphur atoms from the three-fold axis (splitting of 2c to 6h position).