Tunable thermopower and thermal conductivity in Lu doped In2O3

Abstract

Lu-doped polycrystalline (In_1−xLu_x)₂O₃ (x = 0, 0.025, 0.05, 0.10, 0.15) materials were prepared by co-precipitation method followed by spark plasma sintering processing. The large and heavy Lu³⁺ was strategically selected to replace In³⁺ in order to lower the thermal conductivity while minimizing changes to the electronic structure of In₂O₃. The resulting samples had an average grain size of 200–400 nm at a density of ∼90% of the theoretical mass density. Lu doping was found to increase the thermopower of In₂O₃, however the electrical resistivity was also increased, primarily due to the remarkable decrease in carrier concentration. The thermal conductivity of In₂O₃ was significantly reduced by the substitution of In by Lu.