Study on the physical mechanism of thermoelectric transport on the properties of ZnO ceramics

Abstract

Herein, ZnO is used as the matrix while La as the doping element, and the band structure of the oxide system is calculated by first-principles. The La doped series oxides are synthesized by powder-metallurgy method. The first-principles calculation results show that La doping can converge the energy band and significantly increase the density of states near the Fermi level, enhanced by the hybridization between d-orbits of La atoms and d-orbits of Zn atoms and p-orbits of O atoms. With the increase of La element content, the electrical conductivity of the oxide gradually increases, and the Seebeck coefficient decreases to a certain extent, which is consistent with the first - principle calculation. As the doping of La element increases, the thermal conductivity of the oxide has been greatly reduced, resulting in a substantial improvement in the thermoelectric properties of the oxide. The best ZT value of ∼ 0.401 (873 K) can be obtained through proper amount of La doping (x = 0.04), which is ∼ 4.09 times as ∼ 0.098 of the pristine oxide ZnO at the same temperature.