Neutron diffraction study of the location of deuterium in the deuterium-stabilized HfTi2D4 phase

The location of D atoms in the new deuterium-stabilized HfTi2D4 phase with the C15-type host lattice has been studied by neutron diffraction in the te mperature range 1.5-293 K. It is found that D atoms occupy two types of sit es of the space group Fd (3) over bar m: 32e (HfTi3) and 96g (Hf2Ti2). Most of the D atoms are located in the 32e sites. The occupancy of these sites is found to increase from 0.79 at 293 K to 0.93 at 1.5 K. Thus, as the temp erature decreases, the HfTi2D4 system approaches the fully ordered state wi th the completely occupied sublattice of 32e sites. (C) 1999 Elsevier Scien ce S.A. All rights reserved.