Crystal Structures and Lattice Distortions ofσ-Type Layered Vanadium Bronzes:σ-M0.25V2O5·H2O (M=Mg, Co, Ni)

✍ Scribed by Yoshio Oka; Takeshi Yao; Naoichi Yamamoto

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 314 KB
• Volume: 144
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8155

✦ Synopsis

New -type layered vanadium bronzes M 0.25 V 2 O 5 • H 2 O were hydrothermally synthesized for divalent metals of M ‫؍‬ Mg, Co, Ni in addition to the first-reported M ‫؍‬ Zn compound. The -type structures, consisting of V 2 O 5 layers with three octahedral and one tetrahedral V atoms and interlayer M (H 2 O) 4 rectangles, were confirmed by single-crystal X-ray diffractometry. The Ni compound crystallizes in the same P1 phase as the Zn compound while the Mg and Co compounds crystallize in the new P2 1 /a phase of higher symmetry. The P 2 1 /a phases is an undistorted form of the P1 phases, where the distortion is caused by the locations of interlayer water molecules. Among four V atoms one octahedral atom is tetravalent and others are pentavalent, being consistent with the average V 4.75 ؉ valence. The M(H 2 O) 4 is held by two apical oxygens of VO 4 tetrahedra to form a regular MO 6 octahedron and thus M 2 ؉ ions must fit for the octahedral oxygen coordination.