Crystal Structures of Hydrated Vanadium Oxides withδ-Type V2O5Layers:δ-M0.25V2O5·H2O,M=Ca, Ni

✍ Scribed by Yoshio Oka; Takeshi Yao; Naoichi Yamamoto

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 718 KB
• Volume: 132
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7467

✦ Synopsis

Single crystals of hydrated vanadium oxides with layered structures containing divalent Ca or Ni were hydrothermally grown, and their structural characterization was focused on the interlayer sites. Both compounds are formulated by M 0.25 V 2 O 5 • H 2 O, M ‫؍‬ Ca, Ni and crystallize in the monoclinic system C2/m with Z ‫؍‬ 4: a ‫؍‬ 11.692(2), b ‫؍‬ 3.564(1), c ‫؍‬ 10.986(2) A s , b ‫؍‬ 105.42(1)°for M ‫؍‬ Ca; a ‫؍‬ 11.756(1), b ‫؍‬ 3.649(1), c ‫؍‬ 10.364(2) A s , ‫؍‬ 95.03(1)°for M ‫؍‬ Ni. The structures consist of -type V 2 O 5 layers stacking along the c axis and interlayer hydrated M 2؉ ions; the refers to the V 2 O 5 layer of -Ag 0.68 V 2 O 5 after which the compounds are designated -M 0.25 V 2 O 5 • H 2 O. The M atoms partially occupy interlayer sites of the 2c position for M ‫؍‬ Ni and the 4i position for M ‫؍‬ Ca, to each of which four water molecules (O w ) are attached forming MO w4 rectangles.

M and O w site occupancies indicate that the MO w4 rectangles are distributed so that they do not interact with each other, and the above stoichiometric formula correspond to the maximum occupancies. Bonding to three apical oxygens of the V 2 O 5 layers, the Ca atom forms a CaO 7 polyhedron, and to two apical oxygens the Ni atom forms a NiO 6 octahedron, due to the Ca 2؉ ion being larger than that of Ni 2؉ ion. This is the first single-crystal study on the structures of hydrated -type vanadium oxide bronzes.