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Temperature dependence of the lattice constant in metallic sodium
Author(s) -
Abe H.,
Ohshima K.,
Sukuki T.,
Watanabe Y.
Publication year - 1994
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/s0021889894008642
Subject(s) - lattice constant , full width at half maximum , diffraction , atmospheric temperature range , neutron diffraction , condensed matter physics , materials science , metal , lattice (music) , bragg's law , chemistry , analytical chemistry (journal) , crystallography , crystal structure , optics , thermodynamics , physics , metallurgy , optoelectronics , chromatography , acoustics
The temperature dependence of the lattice constant for the parent phase in metallic sodium, which has a body‐centred cubic (b.c.c.) structure, has been measured by an X‐ray single‐crystal diffraction method over a range of 20 to 293 K. An abnormal change of the lattice constant at around 40 K is shown, which is attributed to small regions of the low‐temperature phase. On the other hand, the value of the full width at half‐maximum (FWHM) for the (110) b.c.c. Bragg reflection increased gradually with decreasing temperature and then changed drastically at around 40 K. This result was inconsistent with the neutron diffraction one: the value was constant down to the phase‐transition temperature and changed drastically at that temperature. The FWHM for the X‐ray experiment is very sensitive to the size of the specimen and sample mount because the external strain originating from contraction of the sample holder is often introduced into the specimen.