The Thermoelectric Property Of Transition Metallic Oxide CdCoO And CdO

Thermoelectric materials are special types of functional materials which can directly convert heat into electricity and vice versa. The oxide thermoelectric materials have some unique advantages such as good stability in high temperature oxidizing atmosphere, non-toxic or involving rare element. In this thesis, we investigated the thermoelectric properties of the transition metal Cd-based oxide ceramics. The content of this thesis mainly consists of three parts:1. The thermoelectric properties of CdxCo4Oy(x=1,2,3,4) ceramics, which were synthesized by a conventional solid-state reaction method, were investigated. The thermoelectric measurements revealed that sample Cd3Co4Oy had the best power factor and its dimensionless figure-of-merit ZT was about0.035at900K.2. Porous CdO ceramics were prepared by a chemical technique combined with the solid phase reaction sintering method. A high ZT of0.47was obtained at970K in the sample with bulk density of5.5g/cm3. This value is comparable to the best reported ZT for the n-type oxide ceramic thermoelectric materials.3. The effect of Er doping on the high temperature thermoelectric properties of Cd1-xErxO (x=0,0.005,0.01,0.015) ceramics were studied. The results showed that the substitution of Er3+for Cd2+leaded to a remarkable decrease in resistivity while keeping Seebeck coefficient almost unchanged, resulting in the improvement in power factor. Moreover, small addition (0.5%) of Er can decrease the thermal conductivity. The0.5%Er-doped CdO sample exhibited the best ZT and it was0.2at about723K.