Investigation of the new P′3-Na_0.60VO₂ phase: structural and physical properties

Olivier Szajwaj (1) , Etienne Gaudin (1) , François Weill (1, 2) , Jacques Darriet (1) , Claude Delmas (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 CREMEN - Centre de Ressources en Microscopie Electronique et Microanalyse

A new layered phase Na_0.60VO₂ was synthesized by chemical deintercalation of sodium from the pristine compound O3-NaVO₂. The Na_0.60VO₂ compound exhibits a distorted P′3-type oxygen stacking (AABBCC) with an average monoclinic unit cell containing a = 4.9862(14) Å, b = 2.8708(8) Å, c = 5.917(2) Å, and β = 104.36(3)°. A modulated structure was observed by transmission electron microscopy and X-ray diffraction (XRD) measurements. Indexation of the XRD pattern was achieved by using the q vector equal to 0.44b*, and the 4D superspace group C2/m (0 β 0) s0 was then deduced. The specific heat measurement showed a strong correlated system with a γ value of around 20 mJ·mol⁻¹·K⁻². The electrical conductivity shows a semiconductor-like behavior with an activation energy of 0.52 eV. A paramagnetic behavior of the susceptibility is observed below room temperature with a Curie constant equal to C = 0.076 emu·K⁻¹·mol⁻¹·Oe⁻¹. To explain this small value, a model of pseudotriangular clusters of vanadium with a random distribution of V³⁺ and V⁴⁺ was considered.

Domaines: Matériaux

Olivier Szajwaj, Etienne Gaudin, François Weill, Jacques Darriet, Claude Delmas. Investigation of the new P′3-Na_0.60VO₂ phase: structural and physical properties. Inorganic Chemistry, 2009, 48 (19), pp.9147-9154. ⟨10.1021/ic9008653⟩. ⟨hal-00426246⟩