Crystal Structure and Magnetic Properties of the Novel Oxide Pb2V5O12

R. V. SHPANCHENKO; V. V. CHERNAYA; A. M. ABAKUMOV; E. V. ANTIPOV; J. HADERMANN; G. VAN TENDELOO; E. E. KAUL; C. GEIBEL; D. SHEPTYAKOV; A. M. BALAGUROV

ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE

Wiley-VCH Verlag GmbH

Lugar: Weinheim; Año: 2001 vol. 627 p. 2143 - 2150

0044-2313

The crystal structure of the new oxide Pb2V5O12 was determined from X-ray single crystal and neutron powder diffraction data. The oxide is monoclinic, space group P2/c with a = 8.408(2), b = 5.017 (1), c = 11.940 (2) Å, b = 98.42(3)°, Z = 2. The crystal structure of Pb2V5O12 consists of isolated layers formed by edge and corner sharing VO5 square pyramids with short vanadyl bonds directed above and below the layers. Six pyramids linked by corner form so-called “tilling plaquettes”. Neighboring plaquettes are linked by edge sharing. the Pb cations are located in the interstitial positions between layers. The structure of Pb2V5O12 is closely related to the MVnIVO2n+1 homologous series known for Ca, Sr and Cd. Electron diffraction and high resolution electron microscopy study confirm the crystal structure data and revealed a phase transition induced by irradiation resulting in the formation of a disordered orthorhombic phase (a ~ 3.75, b ~ 3.79, c ~ 5.03 Å) which corresponds to a sublattice of the plaquette-built structure. The analyses of related structures allowed to suggest a more general formula for this homologous series: MmVm+nO3m+2n. The structures of such compounds may be described by shear planes formed by a shift of the VO2 units over a 1/2* [110] translation starting from the parent “VO2” or “MVO3” structures. Magnetic susceptibility measurements of Pb2V5O12 indicate low dimentsional behavior and a strong antiferromagnetic exchange within the plaquettes with J of the order of 190 K. Anomalies observed in the susceptibility and the specific heat indicate magnetic order at TN = 26 K.