Crystal structure of two hydrides formed from a Ti-V-MnBCC solid solution alloy studied by time-of-flight neutron powder diffraction - a NaCl structure and a CaF2 structure

We investigated the crystal structures of two hydrides formed from a BCC so lid solution alloy Ti1.0V1.1Mn0.9 by means of neutron and X-ray powder diff raction. The mono-hydride (Ti1.0V1.1Mn0.9)D-2.0 has a pseudo-cubic NaCl str ucture. The lattice constants are a' = 0.41278(4) nm and c' = 0.37685(6) nm , where the c'-axis is 9% shorter than the a'-axis. In this phase the hydro gen atoms occupy octahedral (O) sites surrounded by six metal atoms. The di -hydride (Ti1.0V1.1Mn0.9)D-5.4 has the CaF2 structure (a = 0.431935(5) nm) with hydrogen atoms occupying tetrahedral (T) sites. The mono-hydride found in this study is classified into a new category: "a NaCl-type mono-hydride formed from BCC solid solution". (C) 2001 Elsevier Science B.V. All rights reserved.