title: Hydrothermal Synthesis and Characterization of Ni-Al Montmorillonite-Like Phyllosilicates.
abstract: This work describes the first hydrothermal synthesis in fluoride medium of Ni-Al montmorillonite-like phyllosilicates, in which the only metallic elements in the octahedral sheet are Ni and Al. X-ray diffraction, chemical analysis, thermogravimetric and differential thermal analysis, scanning electron microscopy and transmission electron microscopy confirm that the synthesized samples are montmorillonite-like phyllosilicates having the expected chemical composition. The specific surface areas of the samples are relatively large (>100 m² g-¹) compared to naturally occurring montmorillonites.29Si and27Al nuclear magnetic resonance (NMR) indicate substitutions of Al for Si in the tetrahedral sheet.19F NMR and NiK-edge extended X-ray absorption fine structure (EXAFS) local probes highlight a clustering of the metal elements and of the vacancies in the octahedral sheet of the samples. These Ni-Al phyllosilicates exhibit a higher local order than in previously synthesized Zn-Al phyllosilicates. Unlike natural montmorillonites, where the distribution of transition metal cations ensures a charge equilibrium allowing a stability of the framework, synthetic montmorillonites entail clustering and instability of the lattice when the content of divalent element in the octahedral sheet exceedsca.20%. Synthesis of Ni-Al montmorillonite-like phyllosilicates, was successfully achieved for the first time. These new synthetic materials may find potential applications as catalysts or as materials with magnetic, optical or staining properties.
authors.affiliation: Université de Poitiers, CNRS UMR 7285 IC2MP, ENSIP-Bât. B1, 1 Rue Marcel Doré, F-86022 Poitiers cedex, France. marc.reinholdt@univ-poitiers.fr.
authors.forename: Marc X
authors.initials: MX
authors.lastname: Reinholdt
authors.affiliation: Université de Haute Alsace (UHA), CNRS, Equipe Matériaux à Porosité Contrôlée (MPC), Institut de Science des Matériaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse, France. jocelyne.brendle@uha.fr.
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Brendlé
authors.affiliation: Université de Haute Alsace (UHA), Laboratoire Physique et Mécanique Textile (LPMT), EA 4365 (conventionnée au CNRS), F-68093 Mulhouse, France. marie-helene.tuilier@uha.fr.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Tuilier
authors.affiliation: Chimique, Université Laval, 1065 ave. de la Médecine, Québec, QC G1V 0A6, Canada. serge.kaliaguine@gch.ulaval.ca.
authors.forename: Serge
authors.initials: S
authors.lastname: Kaliaguine
authors.affiliation: Université de Haute Alsace (UHA), CNRS, Equipe Matériaux à Porosité Contrôlée (MPC), Institut de Science des Matériaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse, France. emmanuelle.ambroise@uha.fr.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Ambroise
keywords: EXAFS; clay; fluoride medium; montmorillonite; solid-state NMR; synthesis