Ba/Ag双掺杂对Ca_3Co_4O_9基热电氧化物热传输性能的影响

Effect of double substitution of Ba and Ag on thermal transport of Ca_3Co_4O_9-based thermoelectric oxide

采用溶胶-凝胶结合放电等离子烧结的方法制备了Ba,Ag双掺杂的BaxAgyCa2.8Co4O9块体热电氧化物材料,利用X射线衍射仪,扫描电子显微镜和热参数测试仪分析了所得样品的物相、微观组织结构和热输运性能.结果表明,通过Ba,Ag双掺杂有效调制了Ca3Co4O9的热传输性能,增加Ba掺杂量能有效降低其热导率.分析结果表明,Ba,Ag双掺杂对热导率的调制来源于对晶格热导率的调制,其中Ba,Ag等量掺杂所得样品热导率最低,其总热导率和晶格热导率在973 K时分别达到了1.43 W/mK和1.10 W/mK.

The Ba and Ag co-doped BaxAgyCa2.sCo409 thermoelectric bulk materials are fabricated by acid sol-gel and spark plasma sinter- ing method. The phase compositions, microstructures and thermal transport properties of the resulting bulk materials are analyzed by X-ray diffraction, scanning electron microscopy and the thermal transport constant measurement apparatus. The results show that the thermal conduction behavior for the titled system can be effectively tuned by Ba and Ag co-doping, and the thermal conductivity could be reduced by increasing the Ba doping content. The analysis results show that the total thermal conduction suppressing comes from the lattice thermal conduction confinement. The Ba0.1Ag0.~Ca2.8C0409 bulk material is found to have the lowest thermal conductivity with total thermal conductivity and lattice thermal conductivity reaching 1.43 W/mK and 1.10 W/mK at 973 K, respectively.