Magnetic-field-induced orientational order in the isotropic phase of hard colloidal platelets

Journal Article · Sat Apr 15 00:00:00 EDT 2006 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PHYSREVE.73.0· OSTI ID:20779237

Beek, D van der; Petukhov, A V; Vroege, G J; Lekkerkerker, H N.W. ^[1]; Davidson, P; Ferre, J; Jamet, J P ^[2]; Wensink, H H ^[3]; Bras, W ^[4]

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1. Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands)
2. Laboratoire de Physique des Solides, UMR 8502 CNRS, Universite Paris-Sud, Batiment 510, 91405 Orsay (France)
3. Institut fuer Theoretische Physik II, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, Gebaeude 25.32, 40225 Duesseldorf (Germany)
4. Netherlands Organisation for Scientific Research (NWO), DUBBLE CRG, European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France)

The magnetic-field-induced orientational order in the isotropic phase of colloidal gibbsite [Al(OH){sub 3}] platelets is studied by means of optical birefringence and small-angle x-ray scattering (SAXS) techniques. The suspensions display field-induced ordering at moderate field strengths (a few Tesla), which increases with increasing particle concentration. The gibbsite particles align their normals perpendicular to the magnetic field and hence possess a negative anisotropy of their diamagnetic susceptibility {delta}{chi}. The results can be described following a simple, Onsager-like approach. A simplified model is derived that allows one to obtain the orientational distribution function directly from the scattering data. However, it leads to an underestimate of the diamagnetic susceptibility anisotropy {delta}{chi}. This accounts for the difference between the {delta}{chi} values provided by the two experimental techniques (SAXS and magneto-optics). The order of magnitude {delta}{chi}{approx}10{sup -22} J/T{sup 2} lies in between that of goethite suspensions and that of suspensions of organic particles.

• OSTI ID: 20779237
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Vol. 73, Issue 4; Other Information: DOI: 10.1103/PhysRevE.73.041402; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM HYDROXIDES
ANISOTROPY
BIREFRINGENCE
COLLOIDS
DIAMAGNETISM
DISTRIBUTION FUNCTIONS
GIBBSITE
GOETHITE
MAGNETIC FIELDS
MAGNETIC SUSCEPTIBILITY
MAGNETO-OPTICAL EFFECTS
PARTICLES
SMALL ANGLE SCATTERING
SUSPENSIONS
X-RAY DIFFRACTION