Preparing And Properties Of A New Cobalt Oxide Thermoelectric Material

Thermoelectric materials are those materials that directly convert heat to electricity or conversely, which are prospect using as the thermoelectric generators and cooling devices. The thermoelectric phenomena, history and the recent development progress of thermoelectric materials were reviewed in detailed. Oxide thermoelectric materials were found to have high working temperature, oxidation-resistant, no pollution, simple preparation, long life and have became new candidate materials with a potential to study and applying values. In this dissertation, A new layered oxide Ca2Co2O5 has been selected as this study due to very good thermoelectric performance and its thermoelectric properties were investigated by doping Sm3+ ion. Excellent performances of p-type and n-type thermoelectric materials were selected to fabricate oxide thermoelectric devices.In this dissertation, Thermoelectric materials of pure Ca2Co2O5 and Ca2Co2O2 with doping Sm3+ ion were synthesized by the sol-gel method and sintering at 900℃in air. TG-DTA, IR, XRD, SEM and thermoelectric properties test were used to research the structure, microscopic appearance and thermoelectric properties(such as the Seebeck coefficient, electrical resistivity and power factor) of Ca2Co2O5. Doping Sm3+ ion, which effect on the structure of Ca2Co2O5 was also studied. The p-type Ca1.70Sm0.30 Co2O5 and n-type Ca0.95Sm0.05MnO3 thermoelectric materials were selected to fabricate thermoelectric devices. The experimental results show that the sol-gel method is better than others and the samples have condensed micro structure and better thermoelectric properties. The substitution of trivalent Sm3+for divalent Ca2+ had a remarkable effect on the enhancement of both properties. The performance of the device show that the output voltage and current of the thermoelectric device increase with the temperature.