High-speed magic-angle spinning

Dec, Steven F.; Wind, Robert A.; Maciel, Gary E.; Anthonio, F.E

doi:10.1016/0022-2364(86)90023-5

Cited by 37 publications

(12 citation statements)

References 8 publications

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“…High-speed 11 B MAS NMR spectroscopy was carried out at 14.0 T on a Bruker AM-600 spectrometer using a high-speed MAS probe built in-house and tuned to 192.55 MHz. − Samples were spun in 4.5 mm o.d. cylindrical Vespel rotors at a speed of 12−14 kHz.…”

Section: Experimental Methodsmentioning

confidence: 99%

Poly(borosilazane) Precursors to Ceramic Nanocomposites

et al. 1999

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Single-component polymeric precursors to SiC/Si 3 N 4 /C/BN and Si 3 N 4 /BN ceramic nanocomposites were synthesized via hydroboration and dehydrocoupling of vinyl-containing cyclotrisilazanes. The polymer-to-ceramic conversion process was investigated by 13 C, 29 Si, and 11 B solid-state magic-angle spinning (MAS) NMR spectroscopy, FTIR spectroscopy, thermal analysis, elemental analysis, X-ray diffraction (XRD), and transmission electron microscopy. The yields, processibility, and resulting microstructure of the ceramics were dependent on the starting Si/B ratio in the polymers and the atmosphere used for pyrolysis. Thermal conversion of the polymers from 200 to 600 °C involved loss of vinyl functionality, an increase in the amount of B-N environments, and possibly some degradation of the silazane ring structure. Conversion of the polymeric environment to that of mixed-phase ceramic was complete between 600 and 1000 °C; XRD, however, showed the products to be amorphous even after heating to 1600 °C. Heating the N 2 pyrolyzed products to 1800 °C resulted in β-Si 3 N 4 , β-SiC, and t-BN peaks in the XRD powder patterns, while R-Si 3 N 4 and β-Si 3 N 4 peaks were observed for the NH 3 pyrolyzed products.

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Section: Experimental Methodsmentioning

confidence: 99%

Poly(borosilazane) Precursors to Ceramic Nanocomposites

et al. 1999

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“…This paper will not deal with the use of very fast MAS with spin-1/2 nuclei to attenuate moderately strong dipolar interactions [23][24][25][26][27][28][29]. Similarly, this paper will not deal with the inherent difficulties in obtaining reliable cross polarization signal intensities when the spinning speed and dipolar interactions are comparable [26,27].…”

Section: Outline Of the Papermentioning

confidence: 99%

Critical factors in obtaining meaningful fast MAS NMR spectra of non-integral spin quadrupolar nuclei. A review with particular emphasis on27Al MAS NMR of catalysts and minerals

Alemany

1993

Appl. Magn. Reson.

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In the last decade, magic angle spinning (MAS) NMR has become an extremely important method for studying the structure of inorganic solids. Advances in NMR technology have greatly aided in understanding the structure of catalysts, minerals, clays, ceramics, glasses, etc. Obtaining meanin~ul MAS spectra of spin-1/2 nuclei such as 29Si and 31p is relatively straightforward and well understood. In contrast, obtaining meaningful MAS spectra is far from simple with non-integral spin quadrupolar nuclei such as 11B (I= 3/2), 170 (I=5/2), 23Na (I= 3/2), 27A1 (I= 5/2), 69Ga (I= 3/2), and 71Ga (I= 3/2) -to name some of the most commonly studied nuclei. Many additional factors have to be considered. This paper will deal with these factors and the utility of vely fast MAS for studying non-integral spin quadrupolar nuclei in inorganic solids.

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“…25 We have recently reported on the development of such high-speed MAS technology. 26 Results obtained on Kel-F (3M corporation), a homopolymer of trifluorochloroethylene (-CF2CFC1-) have shown that high-resolution solid-state 19F MAS NMR spectra can be obtained at spinning speeds greater than about 14 kHz for this type of polymer system. 26 Here we report further and more detailed results on high-speed MAS 19F NMR studies of copolymers of vinylidene fluoride (CH2CF2) and hexafluoropropene (CF3CFCF2), copolymers of CH2CF2 and CF2CFC1, and terpolymers of CH2CF2, CF3CFCF2, and tetrafluoroethene (CF2CF2).…”

Section: Solid-state Fluorine-19 Nuclear Magnetic Resonance Study Of ...mentioning

confidence: 99%