title: First experimental evidence of potassium ordering in layered k4co7o14.
abstract: The layered P2-K4Co7O14 oxide has been prepared and characterized by means of X-ray diffraction, electrical conductivity, thermopower, and magnetic measurements. The crystal structure of K4Co7O14 (P6(3)/m space group, Z=2, a=7.5171(1) A, and c=12.371(1) A) consists of a stacking of slabs of edge-shared CoO6 octahedra with K+ ions occupying ordered positions in the interslab space, leading to a a0 radical7xa0 radical7 supercell. Potential energy calculations at 0 K are in good agreement with the ordered distribution of potassium ions in the (ab) plane. This oxide is metallic, and the magnetic susceptibility is of Pauli-type, which contrasts with the Curie-Weiss behavior of the homologous NaxCoO2 (x approximately 0.6) oxide with close alkali content. The thermopower at room temperature is about one-third that of polycrystalline Na0.6CoO2.
authors.affiliation: Institut de Chimie de la Matière Condensée de Bordeaux, ICMCB-CNRS, 87, avenue du Dr. Schweitzer, 33608 Pessac Cedex, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Blangero
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Decourt
authors.forename: Dany
authors.initials: D
authors.lastname: Carlier
authors.forename: Gerbrand
authors.initials: G
authors.lastname: Ceder
authors.forename: Michael
authors.initials: M
authors.lastname: Pollet
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Doumerc
authors.forename: Jacques
authors.initials: J
authors.lastname: Darriet
authors.forename: Claude
authors.initials: C
authors.lastname: Delmas