Towards solving the crystal structure of polytype 3R sub(2) Mg-Al layered double hydroxides

An analysis of the crystal structure of polytype 3R sub(2) layered double hydroxides has been carried out based on XRPD diffractograms. Measurement of the transmission-XRPD pattern carried out in a spinning and tilting capillary using synchrotron radiation has been shown to diminish the preferred or...

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Bibliographic Details
Published in:Applied clay science 2011-11, Vol.54 (1), p.77-82
Main Authors: Budhysutanto, W N, Hendrikx, RWA, Kramer, HJM
Format: Article
Language:English
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Summary:An analysis of the crystal structure of polytype 3R sub(2) layered double hydroxides has been carried out based on XRPD diffractograms. Measurement of the transmission-XRPD pattern carried out in a spinning and tilting capillary using synchrotron radiation has been shown to diminish the preferred orientation effect of the sample. In order to approach the structure of polytype 3R sub(2), structural models, based on possible interlayer anion arrangement as revealed by FT-IR, 27-Al solid state NMR and XRPD, were constructed. A structural model is proposed that is consistent with the by XRPD measured interlayer distance, in which tetrahedral aluminate ions are grafted with their apical oxygen ions onto the octahedral sheet. The presence of a measured extra reflection at 2I value of 6.3, which is not predicted by this structure, can be obtained however by enlargement of the unit cell to a' = asqrt3 = 0.5279 nm and c' = c = 2.1985 nm, which simulates the aluminate anions ordering in the interlayer.
ISSN:0169-1317
DOI:10.1016/j.clay.2011.07.015