It was shown that the crystal structures of this compound and of related hexagonal perovskites could be interpreted as being mixed-layer structures which consisted of the inter-growth of structural blocks or lamellae of 2 other hexagonal perovskites: -Ba2ScAlO5 and Sc4Ba3O9. The block sequences were imaged directly by means of high-resolution electron microscopy. The characteristic geometrical features of the structural blocks permitted an unambiguous identification to be made of the various sequences. The structures could also be considered to be interface-modulated structures which were derived from a cubic stacking of close-packed BaO3 layers into which periodic stacking faults and twin boundaries were introduced. These interfaces were stabilized by B cations.

R.V.Shpanchenko, L.Nistor, G.Van Tendeloo, S.Amelinckx, E.V.Antipov, L.M.Kovba: Journal of Solid State Chemistry, 1994, 113[1], 193-204