Mg Environments in the Octahedral Sheet of 2:1 Talc‐Like Hybrid Phyllosilicates: A Comparative XAFS Study

Autor: Jean-Christophe Gallego, Claire Marichal, Jocelyne Miehé-Brendlé, Marc Reinholdt, M.H. Tuilier
Rok vydání: 2010
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2010:5587-5591
ISSN: 1099-0682
1434-1948
DOI: 10.1002/ejic.201000221
Popis: Phenethyl and Phenylaminomethyl talc-like hybrid (TLH) materials prepared by a one-step synthetic procedure are investigated by Mg K-edge X-ray absorption fine structure (XAFS) to obtain structural information on the octahedral sheet of these 2:1 phyllosilicates. A comparison of Mg K-edge X-ray absorption spectra of the talc-like hybrids, synthetic montmorillonite containing 20 % Mg and 80 % Al in the octahedral sheet, and MgO is presented. Three peaks are observed in the near-edge XAFS spectra of the phyllosilicates. Their interpretation is drawn from previous multiple scattering, band structure, and molecular cluster simulations of electron energy loss near-edge structures spectra of MgO. Among the theoretical approaches found in the literature, the molecular cluster calculations highlight the dependence of the observed features on Mg-O and Mg-Mg orbital overlaps. Our results reveal a lower Mg-Mg orbital overlap in the hybrid materials than in MgO. The extended XAFS analysis emphasises a deviation from the regular Mg octahedral coordination in the TLHs. Two different Mg-O distances are identified ; the shorter one is found to be significantly higher than predicted in the theoretical talc structure.
Databáze: OpenAIRE
načítá se...