Crystal structure of BaLa4Ti4O15, member n = 5 of the homologous series (Ba, La)nTin−1O3n of cation-deficient perovskite-related compounds

BaLa4Ti4O15 crystallizes in the trigonal system (space group P3c1) with the unit-cell parameters a = 5.5720(10) and c = 22.500(2) إ; Z = 2. The structure has been solved from single crystal X-ray diffraction data to a final R1 = 0.0336. Ba and La atoms are 12-fold coordinated and Ti atoms are 6-fold coordinated. The structure can be described as consisting of identical perovskite-like blocks, four corner-sharing TiO6 octahedra thick, separated by layers of vacant octahedra. The distortion of the cation and anion sublattices has been analyzed and a Ba/La order has been observed.