Transforming n=1 members of the Ruddlesden-Popper phases to a n=3 member through metathesis: synthesis of a new layered perovskite, Ca₂La₂CuTi₂O₁₀

Abstract

We report the formation of a new n=3 Ruddlesden-Popper (R-P) layered perovskite oxide, Ca₂La₂CuTi₂O₁₀ (I), in the metathesis reaction between NaLaTiO₄ and Ca₂CuO₂Cl₂ (n=1 R-P phases) at 700°C in air. Rietveld refinement of powder XRD data shows that I is isostructural with Sr₄Ti₃O₁₀ (space group I4/mmm; a=3.8837(5), c=27.727(6) Å), consisting of triple perovskite CuTi₂O₁₀ sheets wherein Cu and Ti are ordered at the central and terminal octahedral sites, respectively. Magnetization data provide support for the presence of strong antiferromagnetically coupled CuO₂ sheets in the structure. I is metastable decomposing at higher temperatures (~950°C) to a mixture of perovskite-like CaLa₂CuTi₂O₉ and CaO. Interestingly, the reaction between NaLaTiO₄ and Sr₂CuO₂C_l2 follows a different metathesis route, 2NaLaTiO₄+Sr₂CuO₂Cl₂→La₂CuO₄+2SrTiO₃+2NaCl, revealing multiplicity of reaction pathways for solid-state metathesis reactions.