J. Phys. IV France 7 (1997) C2-829-C2-830
Structural Studies of Hydroxy-Ga Pillared Clays by Ga K-Edge X-Ray AbsorptionE. Montarges1, L. Michot1 and Ph. Ildefonse2
1 Laboratoire Environnement et Minéralurgie, rue du doyen Marcel Roubault, BP. 40, 54501 Vandoeuvre cedex, France
2 Laboratoire de Minéralogie-Cristallographie, Universités Paris 6 et 7, 4 place Jussieu, 75252 Paris cedex 05, France
A natural montmorillonite clay was intercalated by hydroxy-Ga polycations (Ga13), obtained by basis hydrolysis of metal salts. These species are structural analogues of Al13. The clay interlayer cations were exchanged in Ga13 solutions containing various amounts of organic polymer. The synthesized materials were aged and/or calcined to 150 and 500°C. In a first approach, Ga-K edge experiments were carried out to investigate the local environment of Ga atoms intercalated into the interlayer space. The study of the first nearest neighbours, oxygen atoms, revealed a decrease in the average bond distance after calcination, which traduced dehydroxylation of the Gal3 pillas. By studying the second nearest neighbours, gallium atoms, the Fourier transforms indicate the presence of the central tetrahedrally coordinated gallium of the Ga13 polycations whose contribution disappears upon ageing or calcination.
© EDP Sciences 1997