Electronic Resource
Copenhagen
:
International Union of Crystallography (IUCr)
Applied crystallography online
13 (1980), S. 486-493
ISSN:
1600-5767
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Geosciences
,
Physics
Notes:
Both superlattice and fundamental reflections have been used in an X-ray determination of the vanadium-atom displacements induced by selected ordering of interstitial deuterium in a multi-domain crystal of V2D. The magnitudes of these displacements along X and Z directions of the pseudo-tetragonal (b.c.t.) unit cell are designated DAX and DAZ respectively, where Z is along the tetragonal c axis. Measurements of the lattice parameters yield DAX ∼0.03 and DAZ ∼0.17 Å. From intensity measurements, the best values for the displacements are DAX = 0.03±0.01 and DAZ = 0.15±0.02 Å, and the purely thermal Debye–Waller factor was found to be 2B = 0.025 Å2. The temperature dependences of both the long-range-order parameter, S, and the lattice parameters of the b.c.t. unit cell were also investigated. Both verify that the phase transition from β (monoclinic) to α (b.c.c.) is first order in character with no intervening ε (tetragonal) phase as in V2H. There is additional evidence that the disordering process includes random occupancy of both Z octahedral and random tetrahedral sites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0021889880012642
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