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Phase behavior of platelet‐shaped nanosilicate colloids in saline solutions – a small‐angle X‐ray scattering study
Author(s) -
Fonseca D. M.,
Méheust Y.,
Fossum J. O.,
Knudsen K. D.,
Måløy K. J.,
Parmar K. P. S.
Publication year - 2007
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/s0021889807010825
Subject(s) - scattering , small angle x ray scattering , materials science , colloid , phase (matter) , dispersity , eccentricity (behavior) , optics , intensity (physics) , small angle scattering , molecular physics , condensed matter physics , chemistry , physics , polymer chemistry , law , organic chemistry , political science
A study of polydisperse suspensions of fluorohectorite clay in saline solutions is presented. The suspended clay colloids consist of stacks of nanosilicate sheets several tenths of a nanometre thick. They are polydisperse both with respect to the number of stacked nanolayers and with respect to their extension along the sheets. Due to this polydispersity, a spontaneous gravity‐induced vertical segregation occurs in the sample tubes and results in the presence of up to four different phases on top of each other. Precise characterization of the phase diagram of the samples as a function of salt concentration and vertical position in the tubes, based on small‐angle X‐ray scattering data, is presented. The vertical positions of the phase boundaries were monitored by analyzing the eccentricity of elliptic fits to iso‐intensity cuts of the scattering images. The intensity profiles along the two principal directions of scattering display two power‐law behaviors with a smooth transition between them and show the absence of positional order in all phases.