The influence mechanism of rare earth element doping on the electron/phonon transport performances of In2O3 based thermoelectric materials

Abstract

In2O3 based materials are one of the most promising high-temperature thermoelectric materials for application. Herein, Sm doped In2O3 samples were prepared by mechanical alloying, high-temperature calcination, and discharge plasma sintering, and the influence mechanism of rare earth element doping on the thermoelectric properties of In2O3 based semiconductors was studied. The results indicate that the electrical conductivity increased significantly. Due to the introduction of Sm impurity levels, the density of states near the Fermi level significantly increases. The bandgap widens, and the mobility first decreases and then increases. Due to the increase in carrier concentration, the absolute value of the Seebeck coefficient decreases, but the gain effect caused by the increase in conductivity is greater than the debuff caused by the decrease in the absolute value of the Seebeck coefficient. The power factor increases after Sm doping.The thermal conductivity decreases due to the decrease in Young's modulus, enhanced heterogeneous scattering, and enhanced heavy element scattering. The ZT value was raised to ∼0.327 at 973 K, obtained by Sm doped In2O3 sample with x = 0.060, which is ∼6 times as that of the pristine In2O3 sample.

Keywords

• Impurity level
• Rare-earth element
• Electron transport
• Thermoelectric materials