Ba₂VO₄Br

Abstract

Single crystals of dibarium vanadate(V) bromide, Ba 2 VO 4 Br, were grown from a melt of Ba 3 (VO 4 ) 2 and BaBr 2 . Ba 2 VO 4 Br crystallizes in the space group Pbcm and is isotypic with the structure of chlorspodiosite, Ca 2 PO 4 Cl. Although the ionic radii in chlorspodiosite are different from those in dibarium vanadate bromide, the structures are very similar to one another. The V atom is coordinated by four O atoms, forming a slightly distorted tetrahedron. The Ba atoms occupy two different sites and are coordinated by six O atoms and three or four Br atoms, depending on the site occupied. Structure descriptionThis work is part of investigations or reinvestigations of compounds with the general formula A 2 BO 4 X (A = alkaline earth metal; B = P, As, V or other pentavalent atoms; X = halogen atom). The intention behind the current work is to understand conditions of the stability of the different structure types and to search for new structure types with this general formula.The title compound Ba 2 VO 4 Br crystallizes isotypically with chlorspodiosite, Ca 2 PO 4 Cl (Mackay, 1953), despite of different ionic radii and the existence of other structure types with the same general formula (Haberkorn et al., 2014). The crystal structure of Ca 2 PO 4 Cl was published by Greenblatt et al. (1967). For an easier comparison of both structures, the atomic sites were normalized and sorted in the same manner as for the title compound