title: Structural studies and electrical properties of Cs/Al/Te/O phases with the pyrochlore structure.
abstract: A series of polycrystalline and single crystal cesium aluminum tellurates with the pyrochlore structure have been prepared and characterized. The variations in cell edge for the Cs/Al/Te/O phases range from 10.06 Å for the Al rich limit to 10.14 Å for the Te rich limit. Rietveld structural analyses based on both X-ray and neutron diffraction data were performed on 5 different compositions. Single crystals of 3 compositions were prepared and studied by X-ray diffraction. The anharmonic component of the thermal motion for Cs was small but became significant on replacing Cs with Rb. A maximum in the electrical conductivity of about 0.1 S/cm is found in the middle of this range close to the ideal composition of CsAl(1/3)Te(5/3)O(6). The conductivity is attributed to filled Te 5s states associated with Te(4+) lying just below the conduction band based on empty Te 5s states associated with Te(6+). The relatively large Te(4+) ion is compressed by the lattice, and as this compression increases the filled 5s states approach the conduction band and thereby increases conductivity.
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Theeranun
authors.initials: T
authors.lastname: Siritanon
authors.forename: Judith K
authors.initials: JK
authors.lastname: Stalick
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Sleight
authors.forename: M A
authors.initials: MA
authors.lastname: Subramanian