Structural transformations in the Na{sub 4+x}VO(PO{sub 4}){sub 2} vanadylphosphates

Journal Article · Tue Aug 15 04:00:00 EDT 2006 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.05.013· OSTI ID:20905424

Shpanchenko, Roman V ^[1]; Dikarev, Evgeny V ^[2]; Mironov, Andrey V ^[1]; Mudretsova, Svetlana N ^[1]; Antipov, Evgeny V ^[1]

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1. Department of Chemistry, Moscow State University, 119992 Moscow (Russian Federation)
2. Department of Chemistry, University at Albany, SUNY, Albany, NY 12222 (United States)

The crystal structures of new sodium vanadylphosphate, Na{sub 4.35}VO(PO{sub 4}){sub 2} (a=15.4450(11)A, b=14.7690(10)A, c=6.9870(5)A, Z=8, S.G. Ibam), and new ({gamma}-) modification of Na{sub 4}VO(PO{sub 4}){sub 2} (a=15.4455(15)A, b=14.8433(10)A, c=7.0081(5)A, Z=8, S.G. Pbc2{sub 1}) have been investigated by X-ray single-crystal diffraction. Both structures contain isolated infinite chains of the corner-sharing VO{sub 6} octahedra. The octahedra within the chains are additionally linked to each other by the tetrahedral PO{sub 4} groups. Sodium atoms are situated in the positions between the chains. Depending on the conditions of synthesis, the number of sodium atoms in the unit cell of the Na{sub 4+x}VO(PO{sub 4}){sub 2} compounds may vary resulting in a change of the oxidation state of vanadium atoms and a change of their coordination environment. In Na{sub 4.35}VO(PO{sub 4}){sub 2} vanadium atoms have almost regular octahedral coordination with six close V-O separations and all chains in the structure are equivalent. The crystal structure of {gamma}-Na{sub 4}VO(PO{sub 4}){sub 2} contains two non-equivalent chain types: the first one is similar to that found in Na{sub 4.35}VO(PO{sub 4}){sub 2} whereas the second one contains VO{sub 6} octahedra with the short vanadyl bonds. The charge re-distribution was supposed in the new {gamma}-modification of Na{sub 4}VO(PO{sub 4}){sub 2} where the V{sup 4+{delta}} and V{sup 4-{delta}} cations orderly occupy octahedral positions in different chains. The origin of this phenomena is discussed.

• OSTI ID: 20905424
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 8 Vol. 179; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL-PHASE TRANSFORMATIONS
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PHOSPHATES
SODIUM COMPOUNDS
SYNTHESIS
VANADIUM COMPOUNDS
VANADIUM IONS
X-RAY DIFFRACTION