@article {610,
	title = {Influence of F content on the composition of Al-rich synthetic phlogopite: Part II. Probing the structural arrangement of aluminum in tetrahedral and octahedral layers by Al-27 MQMAS and H-1/F-19-Al-27 HETCOR and REDOR experiments},
	journal = {American Mineralogist},
	volume = {88},
	number = {7},
	year = {2003},
	note = {ISI Document Delivery No.: 699FDTimes Cited: 10Cited Reference Count: 28},
	month = {Jul},
	pages = {1046-1054},
	type = {Article},
	abstract = {The influence of F substitution on the local structure of Al in the tetrahedral and octahedral sheets of synthetic Al-rich phlogopite samples with nominal gel compositions of K(Mg3-xAlx)[Al1+xSi3-xO10] (OH)(y)(F)(2-y) between 0.0 less than or equal to x less than or equal to 0.8 and 0.5 less than or equal to y less than or equal to 1.8, was studied by Al-27 MAS, MQMAS, {H-1/F-19} {\textendash}> Al-27 2D CPMAS (HETCOR) and {H-1/F-19} Al-27 REDOR solid-state NMR and by IR spectroscopy. Changes in intensity of the absorption bands in the OH-stretching region of the IR spectra clearly indicate the incorporation of octahedral Al. Signals from the different phases can be separated in the Al-27 MQMAS NMR spectra by generation of an isotropic dimension in F1. The Al-27 quadrupolar parameters of the four phases were estimated from Al-27 MAS NMR spectra obtained at 104.26 and 208.42 MHz. The quadrupolar coupling constant and isotropic chemical shift increases with increasing Al content for the Al-IV site in phlogopite. The Al-VI site shows a clear increase of the asymmetry parameter and C-Q with increasing F content. The estimated Al-27 signal areas show the lowest amount of impurity phases at high OH contents and a stabilization of Al-VI sites by hydroxyl groups. The {H-1} {\textendash}> Al-27 2D CPMAS (HETCOR) NMR experiment at short contact times provides information about site neighborhoods of tetrahedral Al sites and Mg3OH as well as Mg2AlOH sites, whereas magnetization is only transferred to the octahedral At sites from hydroxyl groups in Mg2AlOH sites. The {F-19} {\textendash}> Al-27 2D CPMAS (HETCOR) NMR spectrum is dominated by Al-IV sites coupled to the Mg3F complex in phlogopite. Resonances from Mg2AlF complexes are not observed. Finally, the {H-1/F-19} Al-27 REDOR experiments support the results of the 2D CPMAS (HETCOR) experiments.},
	keywords = {ANGLE-SPINNING NMR, DOUBLE-RESONANCE, F-19 MAS-NMR, FLUORINE, HIGH-FIELD, NMR, QUADRUPOLAR NUCLEI, SI-29, SOLID-STATE NMR, SPECTRA, SUBSTITUTION},
	isbn = {0003-004X},
	url = {<Go to ISI>://000184045300013},
	author = {Fechtelkord, M. and Behrens, H. and Holtz, F. and Bretherton, J. L. and Fyfe, C. A. and Groat, L. A. and Raudsepp, M.}
}
@article {5081,
	title = {Solid-state NMR characterization of the mineral searlesite and its detection in complex synthesis mixtures},
	journal = {Inorganic Chemistry},
	volume = {40},
	number = {23},
	year = {2001},
	note = {ISI Document Delivery No.: 488JRTimes Cited: 5Cited Reference Count: 34},
	month = {Nov},
	pages = {5906-5912},
	type = {Article},
	abstract = {The mineral searlesite (NaBSi2O5(OH)(2)) was synthesized and characterized by H-1, B-11, Na-23, and Si-29 magic-angle spinning (MAS) NMR spectroscopy. From these spectra, the B-11 and Na-23 quadrupole coupling parameters and isotropic chemical shifts and the Si-29 chemical shift anisotropies have been precisely determined. These parameters are all consistent with the local environments obtained from the crystal structure for searlesite from X-ray diffraction, and they demonstrate that the synthetic sample has a high degree of both short- and long-range order. Furthermore, these anisotropic parameters are found to provide a unique fingerprinting of searlesite in complex mixtures where the presence of this mineral is not anticipated. This is demonstrated for product mixtures formed in attempts to incorporate boron in the structures of the layer silicates magadiite and kenyaite. These. mixtures have been investigated by B-11, Na-23, and Si-29 MAS NMR which clearly reveal that the samples are mixtures of searlesite and magadiite/kenyaite and that searlesite production consumes all of the boron in these synthesis mixtures. However, the Si-29 MAS NMR spectra of these mixtures indicate that the presence of boron in the reaction mixtures nevertheless has an important influence on the quality of the magadiite and kenyaite layer silicates produced.},
	keywords = {BORATE, BORON, ISOMORPHOUS SUBSTITUTION, LAYERED SILICATES, MAGADIITE, MAS NMR, QUADRUPOLAR NUCLEI, SATELLITE, SILICON, TRANSITIONS},
	isbn = {0020-1669},
	url = {<Go to ISI>://000171932500026},
	author = {Fyfe, C. A. and Skibsted, J. and Schwieger, W.}
}
@article {5079,
	title = {Solid-state NMR detection, characterization, and quantification of the multiple aluminum environments in US-Y catalysts by Al-27 MAS and MQMAS experiments at very high field},
	journal = {Journal of the American Chemical Society},
	volume = {123},
	number = {22},
	year = {2001},
	note = {ISI Document Delivery No.: 438ETTimes Cited: 47Cited Reference Count: 25},
	month = {Jun},
	pages = {5285-5291},
	type = {Article},
	abstract = {The detection of all of the aluminum present in steamed zeolite H-Y catalysts by Al-27 MAS NMR at 14.4 T (600 MHz for H-1) end 18.8T (800 MHz for H-1) is reported. Further, it is shown that it is possible Al MAS and MQMAS NMR measurements to clearly identify four separate aluminum environments which are characteristic of these materials and to unambiguously assign their coordinations. Average chemical shift and quadrupolar coupling parameters are used to accurately simulate the Al-27 MAS NMR spectra at 9.4 T (400 MHz for H-1), 14.4 T (600 MHz for H-1) and 18.8 T (800 MHz for H-1) in terms of these four aluminum environments. In addition, these:average chemical shift and quadrupolar coupling parameters are used to calculate peak positions in the Al-27 MQMAS isotropic dimension that are in good agreement with the experimental data acquired at 9.4 and 18.8 T.},
	keywords = {ACID SITES, ANGLE-SPINNING NMR, QUADRUPOLAR NUCLEI, SPECTROSCOPY, zeolites},
	isbn = {0002-7863},
	url = {<Go to ISI>://000169041300015},
	author = {Fyfe, C. A. and Bretherton, J. L. and Lam, L. Y.}
}
@article {4549,
	title = {Characterization of Na5P3O10 polymorphs by Na-23 MAS, Na-23 MQMAS, and P-31 MAS NMR spectroscopy},
	journal = {Inorganic Chemistry},
	volume = {38},
	number = {1},
	year = {1999},
	note = {ISI Document Delivery No.: 157MUTimes Cited: 20Cited Reference Count: 42},
	month = {Jan},
	pages = {84-92},
	type = {Article},
	abstract = {The two anhydrous polymorphs of Na5P3O10 have been characterized by Na-23 and P-31 MAS NMR spectroscopy, The Na-23 multiple-quantum (MQ) MAS NMR spectrum of the low-temperature form (phase II) displays three resonances for which the quadrupole coupling parameters and isotropic chemical shifts have been accurately determined from the MAS NMR spectra of the central transition. Thereby, discrepancies between recently reported Na-23 MQMAS spectra of this phase and the crystal structure have been clarified. The Na-23 resonances observed for the low-temperature form are assigned to the crystallographically nonequivalent Na sites in the crystal structure using point-monopole calculations of the electric-field gradient tensors. Three Na-23 resonances have also been observed for the high-temperature form (phase I), with two signals having very similar quadrupolar couplings and isotropic chemical shifts indicating similar coordination environments for the corresponding Na sites, in disagreement with the reported single-crystal structure. Point-monopole calculations of the electric-field gradient tensors based on the crystal structure fail to reproduce the experimental values. The P-31 chemical shielding anisotropies, obtained from P-31 MAS NMR spectra, show that the terminal P atoms of the P3O105- ions have a negative shielding anisotropy parameter (delta(sigma) = delta(iso) - delta(33)) in agreement with similar observations reported for diphosphates. This characteristic feature has been used in the assignment of the three P-31 resonances observed for the hexahydrate Na5P3O10. 6H(2)O.},
	keywords = {2-SPIN SYSTEMS, ANGLE-SPINNING NMR, CHEMICAL SHIELDING, CONDENSED PHOSPHATES, DIPOLAR, NUCLEAR-MAGNETIC-RESONANCE, QUADRUPOLAR NUCLEI, SODIUM TRIPHOSPHATE, SOLID-STATE, SPECTRA, TENSORS},
	isbn = {0020-1669},
	url = {<Go to ISI>://000078066900013},
	author = {Fyfe, C. A. and Altenschildesche, H. M. Z. and Skibsted, J.}
}
@article {3339,
	title = {DIPOLAR-BASED AL-27-]SI-29 SOLID-STATE NMR CONNECTIVITY EXPERIMENTS IN ZEOLITE MOLECULAR-SIEVE FRAMEWORKS},
	journal = {Journal of Physical Chemistry},
	volume = {99},
	number = {21},
	year = {1995},
	note = {ISI Document Delivery No.: RA147Times Cited: 64Cited Reference Count: 38},
	month = {May},
	pages = {8707-8716},
	type = {Article},
	abstract = {In this work we present the results of a systematic investigation of a set of dipolar-based Al-27 {\textendash}> Si-29 connectivity experiments for a series: of representative zeolite molecular sieve frameworks: zeolites A, X, Y, and Omega. Coherence transfer from quadrupolar Al-27 (I = 5/2) to Si-29 (I = 1/2) nuclei through cross polarization and transferred-echo double-resonance (TEDOR) experiments is. observed, and an experimental investigation of the parameters controlling the efficiency of both experiments is presented. Rotational-echo double-resonance (REDOR) and dipolar-dephasing difference experiments are also demonstrated. These experiments utilize the heteronuclear dipolar couplings, whose magnitudes are proportional to the inverse third power of the internuclear distance and are therefore extremely sensitive to the separation of the coupled spins. In addition, we demonstrate that for these dipolar-based experiments, there is a relative enhancement of a given resonance which is approximately linear with the number of aluminum atoms in the neighboring tetrahedral sites. Two-dimensional extensions of the cross-polarization and TEDOR experiments are also possible and will be of use for complex mixtures or where several resonances are observable in the one-dimensional spectra of the two nuclei.},
	keywords = {ANGLE, CROSS-POLARIZATION, DOUBLE-ROTOR, ECHO DOUBLE-RESONANCE, INORGANIC SOLIDS, MAS-NMR, NMR, NUCLEAR MAGNETIC-RESONANCE, QUADRUPOLAR NUCLEI, SPECTROSCOPY, VPI-5},
	isbn = {0022-3654},
	url = {<Go to ISI>://A1995RA14700041},
	author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y. and Grondey, H. and Mueller, K. T.}
}
