Ca_3Co_4O_9陶瓷的制备和热电性能

FABRICATION AND THERMOELECTRIC PROPERTIES OF Ca_3Co_4O_9 CERAMICS

氧化物半导体陶瓷材料是新型的中、高温热电材料。采用传统固相合成法和溶胶 -凝胶法成功地制备了Ca3Co4O9陶瓷。对它们的显微结构和热电性能 (Seebeck系数、电导率和热导率 )进行了研究。实验结果表明 ,由两种方法制备得到的Ca3Co4O9陶瓷具有类似的热电性能。Ca3Co4O9陶瓷为取向无规则片状结构 ,属于 p型半导体热电材料 ,其热电品质因子随温度升高而增大。Ca3Co4O9陶瓷具有大的Seebeck系数和低的热导率 ,但它的电导率仍然偏低 。

Oxide semiconductor ceramics are new thermoelectric materials used at mid_or high_temperature for potential application in power generation from waste heat. In this work, Ca 3Co 4O 9 ceramics were fabricated by a traditional solid reaction and sol-gel method. The microstructures of the ceramic samples were characterized by using XRD and SEM. The thermoelectric properties were determined by measuring electrical conductivity, thermal conductivity and Seebeck coefficient. The thermoelectric properties of the ceramic samples prepared from the sol-gel method are similar to those from the solid reaction method. Ca 3Co 4O 9 ceramics contain randomly_oriented plate_shaped grains with layered structure, and are p_type semiconductor and the figure of merit increases with increasing temperature. There are high Seebeck coefficient and low thermal conductivity for Ca 3Co 4O 9 ceramics, but its electrical conductivity is still low, which leads to its lower value of the figure of merit than the traditional thermoelectric alloys.