The effect of Er3+ doping on the structure and thermoelectric properties of CdO ceramics

The effect of Er³⁺ doping on the structure and thermoelectric transport properties of CdO ceramics was investigated. The solubility limit of Er³⁺ in CdO was very small and that additions of more than about 0.5 at% Er³⁺ resulted in the presence of Er₂O₃. With the addition of Er³⁺, the average grain size of Cd_1?xEr_xO (0 ≤ x ≤ 0.015) decreased and the carrier concentration as well as mobility increased at room temperature. A small amount of Er³⁺ doping resulted in a marked increase of electric conductivity and a moderate decrease of Seebeck coefficient. Although Er³⁺ doping also leaded to an increase in thermal conductivity, a large ZT of 0.2 was achieved in x = 0.005 sample at 723 K due to the obvious improvement of power factor. The results demonstrate that CdO:Er is a new promising n-type thermoelectric material.