Divalent ion exchange of alkaline-earth cations into the triple-layered perovskite RbCa2Nb3O10

Ion exchange reactions between the Dion-Jacobson-type, triple-layered perovskite RbCa2Nb3O10 and calcium, strontium, and barium cations were investigated. Exchange occurs in all systems, but only the strontium and barium systems form stable compounds. The final products, Rb1−xSrx/2Ca2Nb3O10 (x = 0.45) and Rb1−xBax/2Ca2Nb3O10 (x = 0.55), are isostructural with the parent. Unit cells contract upon replacement of rubidium with the smaller, more highly charged cation. The effect of layer contraction in directing the extent of exchange is discussed.