Mg Environments in the Octahedral Sheet of 2:1 Talc-Like Hybrid Phyllosilicates: A Comparative XAFS Study
✍ Scribed by Jocelyne Miehé-Brendlé; Marie-Hélène Tuilier; Claire Marichal; Jean-Christophe Gallego; Marc Reinholdt
- Book ID
- 102167320
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 310 KB
- Volume
- 2010
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
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.