Application of27Al NMR techniques to structure determination in solids

Abstract

Abstraer. There have been great improvements in the quality of 27A1 NMR spectra from solids over the last decade. The impact of this technique on structure determination fora wide range of solids is briefly reviewed. Emphasis is placed on the effects arising from the presence of the quadrupolar interaction and strategies that allow unambiguous spectral interpretation. It is demonstrated that in addition to the chemical shift, the quadrupolar interaction itself can be a rich source of local information about solids. The insight obtalned from 27A1 NMR hato atomic level structure often contains surprises, such that previous models of structure and properties have to be reassessed.

Preparation of Silica-Alumina Nanoparticles via Blast-Furnace Slag Dissolution in Low-Concentration Acetic Acid for Carbonation

“…On the other hand, the tetrahedral peak at 54 ppm is more intense and sharper in the spectrum of the nanoparticles. A resonance corresponding to penta-coordinated Al, at 32 ppm, is clearly observable; this peak has been reported to be commonly observed in oxides formed by sol-gel processes [23]. These results confirm that elemental aluminum was incorporated into the silica framework affecting its tetrahedral configuration.…”

The nature and impacts of fines in smelter-grade alumina

“…Another technique that shows considerable promise for examining SGAs is Solid State Magic Angle Spinning NMR (SS MAS NMR) [15]. SS MAS NMR studies gives insight into the structural co-ordination of all the aluminium ions in the structure, irrespective of long range ordering [16], which is key to understanding the forms of alumina. Chemical shift ranges for aluminium in different coordinations with oxygen (or hydroxyls) are typically −10 to 20 ppm for octahedrally coordinated aluminium (AlO 6 ), 30 to 40 ppm for pentahedrally coordinated aluminium (AlO 5 ) and 50 to 80 ppm for tetrahedrally coordinated aluminium (AlO 4 ) [16,17].…”

“…SS MAS NMR studies gives insight into the structural co-ordination of all the aluminium ions in the structure, irrespective of long range ordering [16], which is key to understanding the forms of alumina. Chemical shift ranges for aluminium in different coordinations with oxygen (or hydroxyls) are typically −10 to 20 ppm for octahedrally coordinated aluminium (AlO 6 ), 30 to 40 ppm for pentahedrally coordinated aluminium (AlO 5 ) and 50 to 80 ppm for tetrahedrally coordinated aluminium (AlO 4 ) [16,17]. Several NMR studies explore the transition aluminas [17][18][19][20][21] but the technique has not yet been widely applied to SGAs.…”

Zirconia-Alumina Nanoparticles Prepared by Laser Evaporation: Powder Characterisation by TEM and 27Al MAS NMR

“…Typically Al 3 is found in a pure octahedral co-ordination (like in a-Al 2 O 3 ) or in both, octahedral and tetrahedral co-ordination (like in g-Al 2 O 3 or q-Al 2 O 3 ). CN 5 is also found for oxygen polyhedra around Al 3 [15].…”