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A Small‐Angle X‐ray Scattering Study of the Lyotropic Nematic Phase of Vanadium Pentoxide Gels
Author(s) -
Davidson P.,
Bourgaux C.,
Sergot P.,
Livage J.
Publication year - 1997
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/s0021889897001064
Subject(s) - small angle x ray scattering , lyotropic , pentoxide , materials science , scattering , liquid crystal , phase (matter) , vanadium , ribbon , crystallography , optics , condensed matter physics , chemistry , composite material , physics , organic chemistry , liquid crystalline , optoelectronics , metallurgy
Aqueous suspensions of vanadium pentoxide (V 2 O 5 ) ribbons, also called Zocher phases, are known to display a lyotropic nematic phase. In this paper, it is shown how the small‐angle X‐ray scattering (SAXS) technique can provide useful information on the building blocks and their organization in this phase. SAXS experiments were performed either on unoriented samples or on samples aligned by a magnetic field or by shear flow. The scattering is comparable to that of the other classic lyotropic nematic phases displayed by stiff organic rod‐like particles such as the tobacco mosaic virus. Scattering studies show that the building blocks have a ribbon shape, that their thickness is 9 (1) Å and indirectly that their width is several 100 Å. Their length is known to be around a few thousand Å and therefore could not be measured by SAXS. By following the average distance between the ribbons as a function of concentration, it is shown that the swelling of the phase is one‐dimensional at large concentrations and two‐dimensional at low concentrations. Finally, estimates of the nematic order parameter of a single domain sample and of samples sheared in a Couette cell have been obtained.