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Na3V4+O(PO4)(HPO4), a New Phase in the Na/V/P/H2O System under Hydrothermal Conditions at 473 K

โœ Scribed by Michael Schindler; Werner Joswig; Werner H. Baur

Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
218 KB
Volume
145
Category
Article
ISSN
0022-4596

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โœฆ Synopsis

A new examination of the Na/V/P/H 2 O systems at 473 K under hydrothermal conditions yielded in a pH range between 6.5 and 7.6 and at synthesis times longer than 10 days a new blue Na 3 VO(PO 4 )(HPO 4 ) phase. It crystallizes in space group P2 1 /m with a โ€ซุโ€ฌ 9.6402(7) A s , b โ€ซุโ€ฌ 6.4075(5) A s , c โ€ซุโ€ฌ 6.2637(6) A s , and โ€ซุโ€ฌ 104.861(7)3. The crystal structure is composed of VOPO 4 layers, with additional HPO 4 tetrahedra between the layers. A symmetry supergroup/subgroup examination of all compounds containing VOXO 4 layers shows that all space groups of these compounds can be derived by reducing the symmetry elements of the aristotypic space group I4/mmm. The Na ุ‰ cations occupy every second possible position between the vanadium and the phosphate polyhedra of the VOPO 4 layers. This is in contrast to the class of MVOPO 4 ' nH 2 O (M โ€ซุโ€ฌ Na, K, Rb, Ca, Sr, Pb, Ba) (n โ€ซุโ€ฌ 3+4) compounds, where only every fourth possible position is occupied.

๐Ÿ“œ SIMILAR VOLUMES

The Hydrothermal NH4/V/P/H2O and K/V/P/N
The Hydrothermal NH4/V/P/H2O and K/V/P/N(C2H5)3/H2O Systems at 473 K and the Crystal Structures of NH4VOPO4and (NH4)3V2O3(VO)(PO4)2(HPO4)
โœ Michael Schindler; Werner Joswig; Werner H. Baur ๐Ÿ“‚ Article ๐Ÿ“… 1997 ๐Ÿ› Elsevier Science ๐ŸŒ English โš– 333 KB

4ุ‰ , and As 5ุ‰ , but none of them crystallize in space group Pn2n. In the K/V/P/N(C 2 H 5 ) 3 / H 2 O system, three different K phases were found: K 0.5 VOPO 4 โ€ข 1.5H 2 O, KVOPO 4 , and K-FVP-1 (Frankfurt vanadium phosphate, one, or for short, FVP-1). The microporous K-FVP-1 compound was synthesize