First experimental evidence of potassium ordering in layered K4Co7O14

Maxime Blangero (1) , Rodolphe Decourt (1) , Dany Carlier-Larregaray (1) , Gerbrand Ceder (2) , Michaël Pollet (1) , Jean-Pierre Doumerc (1) , Jacques Darriet (1) , Claude Delmas (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 Department of Materials Science and Engineering

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 (P63/m space group, Z = 2, a = 7.5171(1) Å, and c = 12.371(1) Å) consists of a stacking of slabs of edge-shared CoO6 octahedra with K+ ions occupying ordered positions in the interslab space, leading to a a0V7×a0V7 supercell. Potential energy calculations at 0 K are ivn 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~0.6) oxide with close alkali content...

Mots clés: Thermoelectric power; NaxCoO2; Bronzes; NaCo2O4; Sodium

Domaines: Matériaux

Maxime Blangero, Rodolphe Decourt, Dany Carlier-Larregaray, Gerbrand Ceder, Michaël Pollet, et al.. First experimental evidence of potassium ordering in layered K4Co7O14. Inorganic Chemistry, 2005, 44 (25), pp.9299-9304. ⟨10.1021/ic0514804⟩. ⟨hal-00019053⟩