A 23Na NMR study of mixed cation β-aluminas

The 23Na NMR spectrum of Na, Tl β- and Na, Cd β-alumina can be understood in the same terms of cation site occupation used to interpret the spectrum of the pure Na crystal. The monovalent Tl ion enters the conduction plane and, up to a level of 60% of exchange, occupies the cation site in the singly occupied cell. The divalent Cd ion, on the other hand, moves initially into the doubly occupied cell, the cell that also contains the charge compensating oxygen. This difference in exchange behavior, as observed by NMR, can be related to differences in mixed cation behavior between these two mixed crystals. 14 refs.; 2 figs.; 1 table