The influence mechanism of high-valence rare earth element doping on the thermoelectric properties of ZnO

The mechanism of the influence of high-valence rare earth element Ce on the thermoelectric properties of ZnO was investigated here. The samples were prepared by high-energy mechanical alloying and high-temperature discharge plasma sintering methods. The results showed that the electrical conductivity and power factor of ZnO samples were significantly improved after Ce doping, obtaining the maximum value of similar to 297 Scm(-1) and similar to 9.917 mu Wcm(-1) K-2 at 873 K, which is similar to 290% and similar to 75% higher that of the undoped ZnO. This is mainly attributed to the narrowing of the band gap and the increase in the density of states after Ce doping. The increase in density of states is mainly due to the introduction of impurity levels and the increase in the density of states of Zn and O atoms after Ce doping. The thermal conductivity decreases due to the decrease in Young's modulus and the strengthening of impurity scattering. The ZT value significantly increases with a maximum value of similar to 0.436.