Orientational microdynamics and magnetic-field-induced ordering of clay platelets detected by 2H NMR spectroscopy.
The orientation of montmorillonite clays induced by a static magnetic field is quantified by using (2)H NMR spectroscopy. Indeed, the residual quadrupolar splitting of the (2)H resonance line measured for heavy water is a direct consequence of the specific orientation of the clay platelets in the static magnetic field. In the dilute regime, this residual splitting increases linearly with clay concentration, which confirms that the clay/clay electrostatic repulsions remain negligible by comparison with the diamagnetic coupling of these anisotropic platelets. At higher concentration, the electrostatic repulsion between clay particles markedly enhances the detected splitting. Such enhancement is well predicted by numerical simulations. By varying the size of the clay platelets and the strength of the static magnetic field, it is possible to evaluate the order of magnitude of the diamagnetic susceptibility of these anisotropic colloids.
Porion
Patrice
P
Centre de Recherche sur la Matière Divisée, CNRS-Université d'Orléans, UMR6619, 45071 Orléans Cedex 02, France. porion@cnrs-orleans.fr
Faugère
Anne Marie
AM
Michot
Laurent J
LJ
Paineau
Erwan
E
Delville
Alfred
A
D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D000077215:Clay; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D010316:Particle Size; D013499:Surface Properties; D013816:Thermodynamics
D000538:Aluminum Silicates; D001546:Bentonite; D003903:Deuterium; D000077215:Clay