Synthesis and structure determination of reduced tantalates, Li2LaTa2O7, Li2Ca2Ta3O10 and Na2Ca2Ta3O10, with a layered perovskite structure

New reduced tantalates, Li2LaTa2O7, Li2Ca2Ta3O10 and Na2Ca2Ta3O10, with a l ayered perovskite structure have been synthesized by a chemical or an elect rochemical intercalation reaction of the alkali metal cations with the pare nt Dion-Jacobson series compounds. The crystal structures of these compound s were determined by Rietveld analysis of powder X-ray diffraction patterns , and found to be analogous to those of the parent compounds. The intercala tion of the lithium ion leads to a large contraction along the stacking dir ection of perovskite layers because of a higher interlayer charge density. These intercalation compounds are the first example of reduced tantalates w ith a layered perovskite structure.