40 research outputs found
Non-centrosymmetric Na3Nb4As3O19
A new non-centrosymmetric compound, trisÂodium tetraÂniobium triarsenic nonaÂdecaÂoxide, Na3Nb4As3O19, has been synthesized by a solid-state reaction at 1123â
K. The structure consists of AsO4 tetraÂhedra and NbO6 octaÂhedra sharing corners to form a three-dimensional framework containing two types of tunnels running along the c axis, in which the sodium ions are located. Na+ cations occupying statistically several sites, respectively, are surrounded by seven, six and four O atoms at distances ranging from 2.08â
(1) to 2.88â
(4)â
Ă
. The title structure is compared with those containing the same groups, viz.
M
2XO13 and M
2
X
2O17 (M = transition metal, and X = As or P)
K3VO2(V2As2O12)
A new potassium vanadium arsenate, tripotassium trivanadium bisÂ(arsenate) hexaÂoxide, K3VO2(V2As2O12), was synthesized by a solid-state reaction at 743â
K. The structure is built up from VO5 pyramids, VO4 tetraÂhedra (.m. symmetry) and AsO4 tetraÂhedra linked together by corner-sharing to form a three-dimensional framework. The two crystallographically independent K+ cations, one of which has .m. symmetry, are located in the interÂconnected tunnels running along the a and b directions
Vanadium(V) oxide arsenate(V), VOAsO4
The vanadyl arsenate, VOAsO4, has been isolated by a solid-state reaction. The structure consists of distorted VO6 octaÂhedra and AsO4 tetraÂhedra sharing corners to build up VAsO7 layers parallel to ac linked by edge-sharing of VO6 octaÂhedra, forming a three-dimensional framework
AgNa2Mo3O9AsO4
The title compound, silver disodium trimolybdenum(VI) nonaoxide arsenate, AgNa2Mo3O9AsO4, was prepared by a solid-state reaction at 808â
K. The structure consists of an infinite (Mo3AsO13)n ribbon, parallel to the c axis, composed of AsO4 tetraÂhedra and MoO6 octaÂhedra sharing edges and corners. The Na and Ag ions partially occupy several independent close positions, with various occupancies, in the inter-ribbon space delimited by the one-dimensional framework. The composition was refined to Ag1.06(1)Na1.94(1)Mo3O9AsO4
β-K(VO2)2(PO4)
A new vanadium oxide, potassium bis(dioxovanadyl) phosphate, β-K(VO2)2(PO4), has been synthesized by a solid-state reaction. In the title compound, the [V2PO8] framework is built up from infinite pyramidal [V2O8]∞ and [VPO7]∞ chains linked together by V—O—P bridges, leading to a three-dimensional framework which delimits two types of intersecting tunnels running along [100] and [010] in which the four unique K+ ions, showing coordination numbers of nine and ten, are located