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Single‐crystal X‐ray diffraction study on the hydrogen ordering in Ta 2 H
Author(s) -
Asano H.,
Ishikawa Y.,
Hirabayashi M.
Publication year - 1978
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889878014260
Subject(s) - monoclinic crystal system , orthorhombic crystal system , crystallography , tantalum , neutron diffraction , diffraction , single crystal , superlattice , crystal structure , hydrogen , lattice (music) , materials science , x ray , chemistry , optics , physics , optoelectronics , organic chemistry , acoustics , metallurgy
A crystal of Ta 2 H with a single ordered domain has been prepared by the reaction of hydrogen gas with a tantalum single‐crystal. Precession and Weissenberg photographs show the superlattice reflections which are indexed in terms of an orthorhombic unit cell with lattice parameters A = a [2(1 +cos γ )] 1/ 2 , B = c and C = a [2(1−cos γ )] 1/2 , where a (= b ) = 3.359, c = 3.398 Å and γ = 90.3° are the parameters of the host monoclinic tantalum lattice. Quantitative intensity measurements indicate that these reflections arise mostly from the systematic displacement of metal atoms caused by the ordered hydrogen arrangement. The amount of displacement has been determined as 0.086 Å, which is a little larger than a previous neutron diffraction result (0.057 Å) on Ta 2 D.