Crystal structure and characterization of Ba2V3O9: A vanadyl(IV) vanadate containing rutile-like chains of VO6 octahedra

The crystal structure of Ba2V3O9 has been determined and refined to final R and R(w) values of 0.025 and 0.028 from 1562 independent single crystal reflections, It crystallizes in the space group P2(1)/m with a 9.302(1) Angstrom, b = 5.969(1) Angstrom, c = 8.118(1) Angstrom, and beta = 113.96 (1)degrees, The structure consists of one-dimensional rutile-type chains of edge-sharing VO6 octahedra parallel to the b axis. The VO4 tetrahedra share corners with VO6 octahedra of a single rutile-type chain to form one-dimensional [V3O9](4-)(infinity) columns which are held together by Ba2+ ions, In this mixed valence compound V4+ and V5+ ions are distributed in an ordered way in octahedra and tetrahedra, respectively, In the almost perfect O-6 octahedron the vanadium atom is off-center so that it forms a short vanadyl V=O bond of 1.686(3) Angstrom, typical of a V4+ ion. This compound is a barium vanadyl vanadate Ba-2(VO)(VO4)(2). It is the first example of isolated rutile-type chains found with V4+ ions, Magnetic susceptibility measurements show that this phase is an antiferromagnet with T-N congruent to 58 K. At about 20 K magnetic anisotropy causes a canted spin arrangement. (C) 1996 Academic Press, Inc.