title: Original disorder-order transition related to electronic and magnetic properties in the thermoelectric misfit phase [Ca2CoO3][CoO2]1.62.
abstract: A structural phase transition is shown around 400 K for the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62. This transition is related to a rearrangement of the central [CoO] layer of the [Ca2CoO3] slab of this structure, characterized by a commensurate intrinsic modulation q2 = 2/3a*-1/3c*. The partial residual disorder related to split Co and O atomic sites along the misfit b direction disappears and one can describe this layer with its triple chains as a modulated configuration with a regular and not distorted periodicity along b. This phase transition is associated with small changes observed in the transport and magnetic properties as a function of temperature.
authors.affiliation: CRISMAT-ENSICAEN Laboratory, UMR CNRS 6508, 6 Bd Maréchal Juin, F-14050 Caen CEDEX, France. herve.muguerra@ensicaen.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Muguerra
authors.forename: Dominique
authors.initials: D
authors.lastname: Grebille