TY - JOUR
T1 - Magic angle spinning oxygen-17 NMR of aluminum oxides and hydroxides
AU - Walter, Thomas H.
AU - Oldfield, Eric
PY - 1989
Y1 - 1989
N2 -
We have obtained magic angle spinning
17
O nuclear magnetic resonance spectra of
17
O-labeled α-Al
2
O
3
, boehmite (AlO(OH)), bayerite (Al(OH)
3
), and several transitional aluminas, including γ-, η-, δ-, and θ-Al
2
O
3
. Cross polarization from
1
H to
17
O has been used to enhance the hydroxyl oxygen resonances of boehmite and bayerite and to allow the observation of hydroxyl groups on the surface of γ-Al
2
O
3
. The spectra yield nuclear quadrupole coupling constants, electric field gradient tensor asymmetry parameters, and isotropic chemical shifts for each chemically distinct oxygen site. The quadrupole coupling constants for tetrahedrally coordinated oxide sites (OAl
4
) range from 1.2 to 2.2 MHz, while those of trigonally coordinated hydroxide sites (Al
2
OH) are in the 5-6-MHz range. Trigonally coordinated oxide sites (OAl
3
), arising as a result of cation vacancies in the transitional aluminas, are estimated to have quadrupole coupling constants of approximately 4 MHz. It is shown that the observed quadrupole coupling constants and asymmetry parameters are in generally good agreement with the results of electric field gradient calculations based on a point charge model.
AB -
We have obtained magic angle spinning
17
O nuclear magnetic resonance spectra of
17
O-labeled α-Al
2
O
3
, boehmite (AlO(OH)), bayerite (Al(OH)
3
), and several transitional aluminas, including γ-, η-, δ-, and θ-Al
2
O
3
. Cross polarization from
1
H to
17
O has been used to enhance the hydroxyl oxygen resonances of boehmite and bayerite and to allow the observation of hydroxyl groups on the surface of γ-Al
2
O
3
. The spectra yield nuclear quadrupole coupling constants, electric field gradient tensor asymmetry parameters, and isotropic chemical shifts for each chemically distinct oxygen site. The quadrupole coupling constants for tetrahedrally coordinated oxide sites (OAl
4
) range from 1.2 to 2.2 MHz, while those of trigonally coordinated hydroxide sites (Al
2
OH) are in the 5-6-MHz range. Trigonally coordinated oxide sites (OAl
3
), arising as a result of cation vacancies in the transitional aluminas, are estimated to have quadrupole coupling constants of approximately 4 MHz. It is shown that the observed quadrupole coupling constants and asymmetry parameters are in generally good agreement with the results of electric field gradient calculations based on a point charge model.
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U2 - 10.1021/j100355a034
DO - 10.1021/j100355a034
M3 - Article
AN - SCOPUS:33845183740
SN - 0022-3654
VL - 93
SP - 6744
EP - 6751
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 18
ER -