Bi_(1.6)Pb_(0.4)Sr_2Co_2O_y/Ag复合块材高温热电性能

High temperature thermoelectric properties of Bi_(1.6)Pb_(0.4)Sr_2Co_2O_y/Ag composite bulks

利用固相反应法制备了Pb-doped Bi2Sr2Co2Oy(Bi1.6Pb0.4Sr2Co2Oy)/Ag多晶复合热电材料,并研究了Ag含量对样品结构和热电性能的影响.X线衍射和X线能谱分析表明,Ag主要以金属单质形式存在于Bi1.6Pb0.4Sr2Co2Oy中.适量的Ag(质量分数25%)复合能显著降低样品的电阻率,而对其塞贝克系数影响很小,从而使Bi1.6Pb0.4Sr2Co2Oy的功率因子大幅提高;继续增大Ag的质量分数(30%),一方面会抑制Bi1.6Pb0.4Sr2Co2Oy晶粒的生长,并使其c轴织构程度变差;另一方面会引起复合物中Ag颗粒的团聚、长大,导致其功率因子下降.Bi1.6Pb0.4Sr2Co2Oy/Ag(质量分数25%)样品973K时功率因子2.72×10-4 W/(m·K2),比相同温度下母体材料Bi2Sr2Co2Oy的功率因子提高了近60%.以上结果表明,在对Bi2Sr2Co2Oy掺杂的基础上同时进行金属Ag颗粒复合是提高其热电性能的有效途径之一.

The effect of Ag on the structure and thermoelectric properties of Pb-doped BizSr2CozOy （Bil.6Pbo.4Sr2Co2Oy）/Ag composite bulks has been investigated. X-ray diffraction and energy dispersive X-ray analyses indicated that metallic Ag mainly precipitates as the second phase in Bil.6 Pb04 Sr2Co2Oy bulks. The appropriate amount of Ag addition results in a significant decrease in resistivity while the see- beck coefficient is hardly affected, leading to a great improvement in power factor. Further addition of Ag will inhibit the grain growth and deteriorate the c-axis texture degree of the sample. In addition, Ag parti- cles tend to agglomerate and become large. This will lead to the decrease in power factor. The 25% Ag- added sample has the power factor of about 2.72X10-4 W/（m ~ K2）at 973 K, which is 60% higher than that of the Bi2Sr2Co20~ bulks. The results suggestthat doping and metallic compositing is a promising method to optimize the thermoelectric per{ormance of Bi2 Sr2 Coz Oy bulks.