High-field boron-11 magic-angle spinning NMR characterization of boron nitrides

1991 ◽  
Vol 3 (3) ◽  
pp. 482-486 ◽  
Author(s):  
Paul S. Marchetti ◽  
Daekeun Kwon ◽  
Wayde R. Schmidt ◽  
Leonard V. Interrante ◽  
Gary E. Maciel
Keyword(s):  
High Field ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Boron Nitrides ◽  
Nmr Characterization ◽  
Angle Spinning

Characterization of metallurgical-grade aluminas and their precursors by 27Al NMR and XRD

2007 ◽  
Vol 85 (10) ◽  
pp. 889-897 ◽  
Author(s):  
Linus M Perander ◽  
Zoran D Zujovic ◽  
Tania Groutso ◽  
Margaret M Hyland ◽  
Mark E Smith ◽  
...  
Keyword(s):  
Solid State ◽  
High Field ◽  
Structural Complexity ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Nmr Studies ◽  
Transition Alumina ◽  
Angle Spinning ◽  
Alpha Alumina

The structure of metallurgical- or smelter-grade aluminas (MGAs) is complex and poorly understood. Ultra-high-field solid-state 27Al NMR results on industrial as well as on laboratory-prepared aluminas are discussed in relation to XRD results. It is demonstrated that high-field NMR can effectively be used to quantify the proportion of the thermodynamically stable alpha-alumina phase in these materials. The results demonstrate that 27Al NMR is a vital adjunct to XRD methods to quantify the transition alumina phases that invariably dominate the MGAs. The nature of the disorder in these materials, determined by 27Al NMR, is also compared with literature data, such as XANES and EXAFS studies, on typical laboratory-prepared materials. The utility of 27Al NMR studies to provide new insight into the structural complexity of metallurgical aluminas is shown.Key words: solid-state magic-angle-spinning NMR, metallurgical-grade alumina, transition alumina, gamma-alumina, coordination number.

Solid State NMR Characterization of Crosslinked Brominated Poly(Isobutylene-co-4-Methylstyrene)

1993 ◽  
Vol 66 (1) ◽  
pp. 109-120 ◽  
Author(s):  
R. R. Eckman ◽  
I. J. Gardner ◽  
H-C. Wang
Keyword(s):  
Solid State ◽  
Functional Groups ◽  
Solid State Nmr ◽  
Phenyl Ring ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Crosslinked Polymers ◽  
Nmr Characterization ◽  
Angle Spinning

Abstract The curing of brominated poly(isobutylene-co-4-methylstyrene) was studied using solid-state magic-angle-spinning NMR, a technique which is uniquely suited to investigate cured or crosslinked polymers. This brominated copolymer contains 4-bromomethylstyryl and 4-methylstyryl functional groups and was compression cured with pure ZnO. It was proposed that a precomplex is formed between zinc and the 4-bromomethylstyryl group, which generates a benzylic carbocationic intermediate. Crosslinking predominantly occurs by alkylation of the phenyl ring of another 4-bromomethylstyryl group by the benzylic intermediate. The ZnO brings the two bromides of these groups into proximity. The dependence of the cure chemistry on the concentration of 4-bromomethylstyryl functional groups was studied. Conversion of some 4-bromomethylstyryl groups to oxygenated species upon curing was also observed.

A Cross-Polarization Magic-Angle Spinning 13C NMR Characterization of the Stable Solid-State Forms of Cimetidine

1997 ◽  
Vol 86 (12) ◽  
pp. 1400-1402 ◽  
Author(s):  
David A. Middleton ◽  
Cecile S. Le Duff ◽  
Frederic Berst ◽  
David G. Reid
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
Nmr Characterization ◽  
Angle Spinning
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