Revisiting kaolinite dehydroxylation: A sup 29 Si and sup 27 Al MAS NMR study

The {sup 29}Si and {sup 27}Al MAS NMR spectra of kaolinite are easily interpreted in terms of a Q{sup 3} environment for silicon and of an octahedral configuration of aluminum. Upon progressive dehydroxylation, these spectra become more complex. For a degree of dehydroxylation ({alpha}) between 1/10...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1989-05, Vol.111:10
Main Authors: Lambert, J.F., Millman, W.S., Fripiat, J.J.
Format: Article
Language:English
Subjects:
360602 > Other Materials-- Structure & Phase Studies
400101 > Activation, Nuclear Reaction, Radiometric & Radiochemical Procedures
ALUMINIUM 27
ALUMINIUM COMPOUNDS
ALUMINIUM ISOTOPES
ALUMINIUM SILICATES
DATA
DATA ANALYSIS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
INFORMATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
ISOTOPES
KAOLINITE
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS SCIENCE
MEASURING INSTRUMENTS
MEASURING METHODS
MINERALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RESONANCE
SILICATE MINERALS
SILICATES
SILICON 29
SILICON COMPOUNDS
SILICON ISOTOPES
STABLE ISOTOPES 360000 > Materials
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Description
Summary:The {sup 29}Si and {sup 27}Al MAS NMR spectra of kaolinite are easily interpreted in terms of a Q{sup 3} environment for silicon and of an octahedral configuration of aluminum. Upon progressive dehydroxylation, these spectra become more complex. For a degree of dehydroxylation ({alpha}) between 1/10 and 9/10, three {sup 27}Al resonances are observed at +3, +28, and +55 ppm. The octahedral component decreases in intensity as {alpha} increases, whereas the other two become dominant. The line at +28 ppm is assigned to pentacoordinated Al, as suggested by Gilson et al. The +55-ppm line is attributed to tetrahedrally coordinated Al. Simultaneously, the {minus}91-ppm (initial) component of the {sup 29}Si spectrum decreases in intensity, while at least two components corresponding to more shielded Si nuclei grow in intensity. As {alpha} increases beyond 9/10, further shifts are observed in the {sup 29}Si spectra as mentioned by Meinhold et al. Ultimately a line at {minus}109 ppm suggests a significant proportion of the {sup 29}Si nuclei being in a Q{sup 4} environment, while the {sup 27}Al spectrum is reminiscent of that of a spinel-like material. The relationships between the {sup 29}Si and {sup 27}Al spectra are discussed and compared with IR data in the 1,200-400-cm{sup {minus}1} range and with earlier results on {sup 1}H (static) NMR.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00192a005