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 Cd1−xErxO (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.