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

Several new members (n = 2, 3, 4 members) of the family of layered perovskites Li2[AxBnO3n+1] (A = Ca, Sr, La; B = Nb, Ta, Ti, Fe) were synthesised for the first time. Structural analysis of Li2SrNb2O7 and Li2SrTa2O7 determined by powder XRD, and of Li2La1.78Nb0.66Ti2.34O10 and Li2Sr2Nb3.97Fe0.03O12.97 determined by single crystal XRD data, shows that these novel phases are related to the Ruddlesden-Popper series of compounds, A'2[An-1MnO3n+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 Li2A0.5nBnO3n+1 where different members of the family can be synthesised with the same set of A and B atoms. 37 refs.