Uniaxial and biaxial liquid crystal phases in colloidal dispersions of board-like particles

Dispersions of board-like goethite (α-FeOOH) particles with short-range repulsive interaction form a versatile colloidal model system, showing a nematic, smectic A and columnar phase. In high magnetic fields a biaxial nematic phase is induced with the shortest dimension of the particles aligned alon...

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Bibliographic Details
Published in:Liquid crystals 2010-06, Vol.37 (6-7), p.641-651
Main Authors: van den Pol, E., Thies-Weesie, D.M.E., Petukhov, A.V., Byelov, D.V., Vroege, G.J.
Format: Article
Language:English
Subjects:
biaxial phases
Colloids
Columns (structural)
Dispersion
Dispersions
Liquid crystals
Magnetic fields
magnetic particles
Mathematical models
mineral liquid crystals
Nematic
Particle physics
Phases
Scattering
X-ray scattering
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Summary:Dispersions of board-like goethite (α-FeOOH) particles with short-range repulsive interaction form a versatile colloidal model system, showing a nematic, smectic A and columnar phase. In high magnetic fields a biaxial nematic phase is induced with the shortest dimension of the particles aligned along the field. Moreover, if particles have a shape almost exactly in between rod-like and plate-like they can spontaneously, without external magnetic field, form biaxial nematic and biaxial smectic A phases, which is in accordance with theoretical predictions. The macroscopic domains were oriented by a magnetic field and their structure was revealed by small-angle X-ray scattering. Our results suggest that biaxial phases can be readily obtained by a proper choice of the particle shape.
ISSN:0267-8292
1366-5855
DOI:10.1080/02678291003798164