Thermal stability and high temperature polymorphism of topochemically-prepared Dion-Jacobson triple-layered perovskites

The thermal stability of six Dion-Jacobson-related triple layered perovskites, ACa(2)Nb(3)O(10) (A = H, NH4, Li, Na, K, CuCl), was explored to 1000 degrees C. Each compound was produced topochemically by low-temperature (<500 degrees C) ion exchange from RbCa2Nb3O10. The thermal behavior of the series was examined by variable temperature X-ray powder diffraction experiments in tandem with thermogravimetric analysis and differential scanning calorimetry. Five of the species were found to be low temperature/metastable phases, decomposing below 900 degrees C, where the stability of the series decreased with decreasing interlayer cation size. The compounds, A = Li, Na, K, exhibited high temperature polymorphism, with a completely reversible transition evident for KCa2Nb3O10. (C) 2015 Elsevier B.V. All rights reserved.