27Al NMR studies of aluminosilicate solutions : influences of the second coordination sphere on the shielding of aluminium

Abstract Aluminosilicate solutions have been studied by 27 Al NMR to investigate effects of the second coordination sphere on AI shielding. The spectra show four distinct peaks. 27 A1 chemical shifts are compared with 29 Si data. An analogous classification of the 27 Al chemical shifts in terms of A1O 4 units of different environments and different degrees of condensation is proposed Observed resonances are correlated to aliminiumoxygen tetrahedra with different numbers of Si-O-Al bonds.