Enhanced thermoelectric properties in a layered rhodium oxide with a trigonal symmetry

We have synthesized an original layered rhodium oxide in the Bi-Sr-Rh-O system with alternately stacked conductive RhOx layer and insulating (Bi0.75Sr0.25)O-1.5 fluorite-type layers. Thermopower, resistivity, Hall coefficient, magnetoresistance, and magnetization measurements evidence high thermoelectric properties with Pauli-like paramagnetism and large carrier concentration (similar to 10(22) cm(-3)). The room-temperature resistivity, thermopower, and power factor are 1.6 m Omega cm, 63 mu V/K, and 2.48 mu W/cm K-2, respectively, which are comparable with those of the best existing p-type thermoelectric oxides, the misfit-layered cobalt oxides with the hexagonal CdI2-type CoO2 layer. In these crystals, the temperature dependence of the resistivity and the magnetic susceptibility suggest the presence of strong electron-electron interaction. This two-dimensional material emphasizes the potential of the transition-metal oxides for thermoelectric applications.