Ga,Al andNa solid state MAS NMR of β- and β″-aluminogallates.

Two series of compounds with sodium β- and β″-alumina structure have been studied in which the aluminium is partly replaced by gallium. The level of substitution has been varied from x(Ga/Ga+Al)=0.3 to 0.8. The approximately quantitative analysis of aluminium and gallium NMR of these aluminogallates has allowed us to determine a gallium site occupancy for the different values of x. For sodium, several sites have been shown and a correlation between gallium substitution and sodium positioning has been proposed. The structures are affected by the changes in cation size from aluminium to gallium. The sites occupancy has been determined and allows one to understand the distortions, due to gallium insertion, in the structures. [ABSTRACT FROM AUTHOR]