A neutron powder diffraction study of zirconium bromide deuteride, ZrBrD. Two hydrogen atoms in the same metal interstice

Abstract

The D atoms in the double-metal-layered compound ZrBrD have been located and refined by Rietveld analysis of the powder neutron diffraction (IPNS). Interestingly, the D atoms are approximately trigonal planar to Zr, a pair lying 0.25 Å inside opposite triangular faces in the trigonal antiprismatic (“octahedral”) zirconium interstices (d (D−D ) = 2.204 (8) A ̊ ) . Similar trends for single D atoms can be recognized in the structures of the rare earth metal trihydrides. The refinement also shows a small occupation of tetrahedral interstices which are less favourable owing to short H…Br distances. These second nearest neighbour interactions are generally important in hydride structures.