BRIDGING THE RUDDLESDEN-POPPER AND THE DION-JACOBSON SERIES OF LAYERED PEROVSKITES - SYNTHESIS OF LAYERED OXIDES, A2-XLA2TI3-XNBXO10 (A=K, RB), EXHIBITING ION-EXCHANGE

Solid solutions of the formula, A2-xLa2Ti3-xNbxO10 (A=K, Rb), exist for the range 0 less-than-or-equal-to x less-than-or-equal-to 1.0, bridging n = 3 members of the Ruddlesden-Popper series (A2La2Ti3O10) and the Dion-Jacobson series (ALa2Ti2NbO10). For 0 less-than-or-equal-to x less-than-or-equal-to 0.75, the phases possess body-centred structures characteristic of the Ruddlesden-Popper phases, while the x = 1 members are isostructural with KCa2Nb3O10 (A = K) and CsCa2Nb3O10 (A = Rb). Protonated derivatives, H2-xLa2Ti3-xNbxO10, which are prepared by ion exchange, retain the structural difference of the parent phases. A difference in the Bronsted acidity of the protonated derivatives revealed by intercalation experiments with organic bases seems to be related to this structural difference.