The ordering of hydrogen in β-vanadium hydride

Abstract

Electron microscope specimens of vanadium, thinned by a technique known to add hydrogen, showed evidence for ordering in β‐vanadium hydride. Extra half‐order reflections were observed and concluded to be due to scattering from hydrogen. The transformation between the ordered and disordered phases occurs reversibly at a specific temperature in the range 160 to 190 °C depending on the specimen. The reciprocal lattice as determined by electron diffraction was shown to be in the monoclinic Laue group. Indirect evidence places the composition of the ordered phase in the vicinity of V2H. The possible monoclinic structures consistent with observations place the hydrogens in tetrahedral sites on alternate (101)b. c. t. planes.

Hydride phase equilibria in V–Ti–Ni alloy membranes

“…BCT with c/a = 1.1 [17], but also reported to be monoclinic (a = 91°) [19] Occupancy in O Z1 octahedral sites [18,20] Exists in the range VH 0.41 -VH 0.61 below 175°C [21] e Called b 2 by Fukai [22] Equal [16] g Probably similar to b but with higher degree of order [16] counting statistics the NiTi 2 -rich alloy was examined independently. Fig.…”

Structural transitions at low temperatures in vanadium deuterides

“…Simultaneous studies (Somenkov, ]~ntin, Chervyakov, Wanagel, Sass & Batterman, 1972;Arons, Bohn & Lfitgemeier, 1972) including the present work demonstrate amply that the fl phase exists as monoclinic with the D atoms in octahedral sites. This same composition can have D largely in tetrahedral sites at elevated temperatures in the region.…”

“…5, can be described as a b.c.c, lattice distorted to a b.c.t, with the e of the tetragonal cell in the horizontal direction. The D atoms are shown along alternate (T01) planes, as suggested by Wanagel, Sass & Batterman (1972), but octahedral sites have been chosen for the D's, rather than tetrahedral sites, for reasons that will become obvious below.…”

“…Wanagel, Sass & Batterman (1972) used electron diffraction to determine the sublattice of hydrogen in VzH, but, unable to ascertain the exact sites occupied by hydrogen relative to the lattice of metal atoms, they suggested certain tetrahedral sites. The present study was undertaken with X-ray and neutron-diffraction techniques to specify the crystal structures of V2D and WaD 3 at various temperatures, and to determine whether the observed transitions could be explained on the basis of ordering.…”

Lattice location of hydrogen in β1-V2H (tetragonal)

“…On the basis of neutron, electron and X-ray diffraction experiments it had been reported that the crystal structure of a vanadium hydride ␤ 1 -V 2 H is body-centred monoclinic [1][2][3][4][5][6][7], or body-centred tetragonal [8,9], with an ordered arrangement of hydrogen atoms. This monoclinic structure is a pseudotetragonal one with an axial ratio of c 0 /a 0 ∼ 1.1 (c 0 and a 0 ; lattice parameters in the c-direction and the a-direction, respectively) and a slight inclination of the c 0 axis (α 0 ∼ 90.3 • ).…”