Synthese und Kristallstruktur von BaVo2,5

Single crystals of BaVO_2,5 were prepared by high temperature LASER-technique under a hydrogen atmosphere. The X-ray investigation leads to a trigonal symmetry (a=571.8;c=1161.3 pm, space group C _3v ¹ -P3m 1). BaVO_2,5 consists of a closest sphere packing of oxygen with a sequence of cubic and hexagonal layers of the type ... ccchh ... The consequences in respect to the coordination of Ba²⁺ and V³⁺ are discussed.