The electronic structure of the CuRh_(1-x)Mg_xO _2 thermoelectric materials: An X-ray photoelectron spectroscopy study

摘要

A detailed X-ray photoelectron spectroscopy study has been performed for the CuRh_(1-x)Mg_xO_2 (x=0, 0.04 and 0.10) series for a better understanding of the role of the Mg2 substitution on the electrical properties and the value of the Seebeck coefficient. This study is based on an analysis of different compounds such as Rh_2O_3, Sr_2RhO_4 and CuCrO_2 in order to characterize different oxidation states (Rh~3 and Rh~4 in octahedral oxygen environment and Cu in a dumbbell OCuO coordination). The Cu2p signal of copper in the non-doped compounds CuCrO_2 and CuRhO_2 reveals different electronic structures. An evolution of the Cu2p core signal with the increase of Mg~2 content in the CuRh_(1-x)Mg _xO_2 is highlighted by XPS. The differences observed, especially for the Cu2p core peaks are discussed for the non-doped compounds CuCrO_2 and CuRhO_2 as for the CuRh_(1-x)Mg _xO_2 series upon Mg~2 substitution.