Article ID Journal Published Year Pages File Type
5420766 Solid State Nuclear Magnetic Resonance 2009 5 Pages PDF
Abstract
27Al solid-state NMR has been applied to study the local structure of pristine and chemically modified aluminium layered double hydroxides (LDH). The pristine LDH only shows six-fold coordinated, octahedral, aluminium, while the calcined and subsequently surfactant treated LDH sample shows a significant fraction of four-fold coordinated tetrahedral aluminium. The co-existence of two types of octahedral sites with different quadrupolar parameters is clearly observed in both samples. Quadrupolar coupling constants and isotropic chemical shifts have been measured from the 27Al triple-quantum MAS NMR allowing to fit the 27Al MAS spectra and quantify the different species in the samples. The quantitative analysis reveals that 30% of the aluminium is in four-fold coordination in the surfactant-modified LDH. We show that this chemical modification retains the two types of AlO6 sites with a decreased intensity of the site showing the lowest quadrupolar coupling constant.
Related Topics
Physical Sciences and Engineering Chemistry Physical and Theoretical Chemistry
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