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 Rh Ox layer and insulating (Bi0.75 Sr0.25) O1.5 fluorite-type layers. Thermopower, resistivity, Hall coefficient, magnetoresistance, and magnetization measurements evidence high thermoelectric properties with Pauli-like paramagnetism and large carrier concentration (∼ 1022 cm-3). The room-temperature resistivity, thermopower, and power factor are 1.6 mΩ cm, 63 μV/K, and 2.48 μW/cm K2, respectively, which are comparable with those of the best existing p -type thermoelectric oxides, the misfit-layered cobalt oxides with the hexagonal Cd I2 -type Co O2 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.