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

Abstract

Solid solutions of the formula, A_2–xLa₂Ti_3–xNb_xO₁₀(A = K, Rb), exist for the range 0⩽x⩽1.0, bridging n= 3 members of the Ruddlesden–Popper series (A₂La₂Ti₃O₁₀) and the Dion–Jacobson series (ALa₂Ti₂NbO₁₀). For 0⩽x⩽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, H_2–xLa₂Ti_3–xNb_xO₁₀, which are prepared by ion exchange, retain the structural difference of the parent phases. A difference in the Brønsted acidity of the protonated derivatives revealed by intercalation experiments with organic bases seems to be related to this structural difference.