Speaker
Eric Martin
(University of Tennessee)
Description
Magnesium-doped rhodium oxides with formula unit Cu Rh_{1-x} Mg_x O_2 and delafossite-type structure exhibit a high thermoelectric figure of merit at elevated temperatures. The electronic structure of Cu Rh_{1-x} Mg_x O_2 has been studied with x-ray emission spectroscopy (XES), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The data reveal that the states at the Fermi level are Rh-derived. Measurements carried out by changing the orientation of the linear photon polarization further indicate that the Rh states have a more localized character along the c-axis, consistent with the layered crystal structure. Given the similarity of the electronic configurations of Co and Rh, these data provide solid experimental evidence that the orbital degrees of freedom of the d^6 ionic configuration of the states rooted in transport are key for explaining the thermoelectric properties of oxide materials.
Co-authors
Christine Cheney
(University of Tennessee at Knoxville)
Norman Mannella
(University of Tennessee at Knoxville)
Paolo Vilmercati
(University of Tennessee at Knoxville)
Takao Sasagawa
(University of Tennessee at Knoxville)
