Neutron diffraction study of deuterium ordering in C15 type TaV2Dx (x>1) in the temperature range of 1.5–295 K

Hydrogen jump motion in Laves-phase hydrides: Two frequency scales

“…The ratio of the g-g distances as a function of R A /R B for a number of C15-type deuterides AB 2 D x . The values of r 2 /r 1 are derived from the neutron diffraction data for TaV 2 D x [10], ZrTi 2 D x [24], ZrMo 2 D x [25], [22] and YMn 2 D x [23]. [28] on YMn 2 H x (R A /R B = 1.425, x = 0.4, 0.65 and 1.26) are consistent with these expectations.…”

“…The ratio r 2 /r 1 is determined by the positional parameters (X g and Z g ) of hydrogen atoms at g sites. Using the values X g = 0.055 and Z g = 0.888 derived from the neutron diffraction measurements for TaV 2 D x [10] we obtain r 2 /r 1 = 1.45. This means that the g-site hexagons in TaV 2 H x (D x ) are well separated from each other.…”

“…According to the neutron diffraction data [2,10], hydrogen atoms in TaV 2 H x (D x ) occupy only g sites coordinated by two Ta and two V atoms. The sublattice of g sites consists of hexagons lying in the planes perpendicular to 1 1 1 directions [3].…”

Hydrogen-induced and A-site substitution-dependent structural properties of AB2-type (Ho1−xAx)Co2–hydrogen system (A=Mm and Ti)

“…There are totally 17 tetrahedral interstitial sites per RM 2 formula unit, containing 12 (2R2M)-sites, 4 (1R3M)-sites and 1 4M site [30]. It is found that the most of the hydrogen atom occupation takes place with (2R2M)-sites at lower hydrogen concentrations and (1R3M)-sites start filling at higher hydrogen concentrations [31]. Since (Ho, Mm) atoms having large negative heat of mixing with hydrogen, the hydrogen atoms can stay more stable in the (2R2M)-sites than in (1R3M)-sites [27,32].…”

The possibility of enhancing light squeezing by cascade parametric oscillation

“…The distance r 1 between the nearest-neighbour g sites within the hexagons can be obtained from the structural data. Using the positional parameters of D atoms at g sites in TaV 2 D x (X g = 0.055, Z g = 0.888) [15] and the actual lattice parameter for TaV 2 H 0.65 , we obtain r 1 = 0.98Å. Taking into account that only a fraction p of the H atoms participate in the fast localized motion [3], the elastic incoherent structure factor for the six-site model [12] can be written as…”