Synthesis and structure of novel layered perovskite oxides: Li2La1.78Nb0.66Ti2.34O10, and a new family, Li2[A0.5nBnO3n + 1]

Abstract

Several new members (n = 2, 3, 4 members) of the family of layered perovskites Li₂[A_xB_nO_{3n + 1}] (A = Ca, Sr, La; B = Nb, Ta, Ti, Fe) have been synthesized for the first time. The structure analysis of Li₂SrNb₂O₇ and Li₂SrTa₂O₇ determined by powder X-ray diffraction (XRD), and of Li₂La_1.78Nb_0.66Ti_2.34O₁₀ and Li₂Sr₂Nb_3.97Fe_0.03O_12.97 determined by single crystal XRD data, shows that these novel phases are related to the Ruddlesden–Popper series of compounds, A′₂[A_{n – 1}M_nO_{3n + 1}]. While the structures of n = 2 members are identical to the RP series, in the higher members the A sites are partially occupied. Interestingly, the compounds for A = Ca, Sr and B = Nb, Ta, Fe indicate the formation of a new family of oxides of general formula Li₂A_0.5nB_nO_{3n + 1} where different members of the family can be synthesized with the same set of A and B atoms.