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VO6 Octahedra (vo6 + octahedron)
Selected AbstractsIsosymmetrical phase transition in ,-YbV4O8ACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2008Karen Friese The structure of YbV4O8 is related to the CaFe2O4 structure type. VO6 octahedra form a three-dimensional framework with tunnels in which the Yb3+ ions are incorporated. Two different polymorphs , and , are known and differ mainly in the arrangement of the Yb ions within the framework. We studied the structure and magnetic properties of ,-YbV4O8 as a function of temperature. At approximately 70,K ,-YbV4O8 undergoes a first-order isosymmetrical phase transition (P21/n,P21/n). While in the high-temperature , phase the three V3+ and one V4+ are disordered over the four symmetrically independent octahedral sites, in the low-temperature ,, phase complete charge ordering is observed. The transition is accompanied by a paramagnetic,paramagnetic anomaly in the magnetic susceptibility data which can be interpreted on the basis of spin-gap formation. The transition mechanism in the , polymorph is very similar to that observed earlier in the , polymorph at 185,K. [source] Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010Romain Gautier Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs2V2O3(PO4)(HPO4), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs2[(VO)3(HPO4)4(H2O)]·H2O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO6 octahedra and PO4 tetrahedra. In (I), infinite chains of corner-sharing VO6 octahedra are connected to V2O10 dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V3O15(H2O) trimers separated by hydrogenphosphate groups. Both structures show three-dimensional frameworks with tunnels in which Cs+ cations are located. [source] The first three-dimensional vanadium hypophosphiteACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Hind A. Maouel The title synthesized hypophosphite has the formula V(H2PO2)3. Its structure is based on VO6 octahedra and (H2PO2), pseudo-tetrahedra. The asymmetric unit contains two crystallographically distinct V atoms and six independent (H2PO2), groups. The connection of the polyhedra generates [VPO6H2]6, chains extended along a, b and c, leading to the first three-dimensional network of an anhydrous transition metal hypophosphite. [source] Nickel vanadium tellurium oxide, NiV2Te2O10ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Dong Zhang Single crystals of nickel(II) divanadium(V) ditellurium(IV) decaoxide, NiV2Te2O10, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound crystallizes in the triclinic system (space group P). The Ni atoms are positioned in the 1c position on the inversion centre, while the V and Te atoms are in general positions 2i. The crystal structure is layered, the building units within a (010) layer being distorted VO6 octahedra and NiO6 octahedra. The metal,oxide layers are connected by distorted TeO4E square pyramids (E being the 5s2 lone electron pair of TeIV) to form the framework. The structure contains corner-sharing NiO6 octahedra, corner- and edge-sharing TeO4E square pyramids, and corner- and edge-sharing VO6 octahedra. NiV2Te2O10 is the first oxide containing all of the cations NiII, VV and TeIV. [source] The high-pressure form of cadmium vanadate, CdV2O6ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2007Alexei A. Belik The crystal structure of a new high-pressure modification of cadmium divanadium hexaoxide, CdV2O6, was refined from X-ray single-crystal data. It contains zigzag chains of edge-sharing VO6 octahedra. Octahedra in adjacent chains share corners and form corrugated layers. Octahedrally coordinated Cd atoms, which lie on twofold axes, are situated between the layers. The columbite-like structure results in a strong distortion of the CdO6 octahedra which may be stabilized only at high pressure. [source] Caesium vanadium selenite, Cs(VO2)3(SeO3)2ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2000William T. A. Harrison Caesium vanadium(V) selenite contains infinite sheets of distorted vertex-sharing VO6 octahedra, capped by selenite groups [dav(V,O) = 1.927,(4),Å and dav(Se,O) = 1.709,(3),Å]. Interlayer caesium cations complete the structure [dav(Cs,O) = 3.365,(4),Å]. [source] | ||||||||||