微纳结构Yb0.3Co4Sb12热电材料的制备及性能研究-中国材料进展

文章信息/Info

Title:: Preparation and Thermoelectric Properties of Micro-Nanostructured Yb0.3Co4Sb12

Author(s):: WU Xingguo; ZHOU Beiying; ZHOU Zhenxing; SHEN Hongwei; WANG Lianjun; JIANG Wan; State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,
College of Materials Science and Engineering, Donghua University

摘要:: 采用熔融法结合SPS烧结技术制备了不同Yb含量掺杂的CoSb3块体热电材料，当Yb含量为0.3时，其热电性能最佳，ZT值在800 K达到了1.19。随后采用高能球磨技术，对熔融法合成的Yb0.3Co4Sb12粉体进行球磨得到纳米尺度粉体，利用SPS烧结技术制得Yb0.3Co4Sb12块体热电材料。采用X射线衍射（XRD）、场发射扫描电镜（FESEM）、透射电镜（TEM）、热电测试装置（ZEM-3）及激光热导仪等仪器对样品进行表征。XRD分析结果表明球磨后Yb0.3Co4Sb12粉体没有发生相变和分解。从FESEM和TEM分析结果可以看出，球磨可以显著细化粉体，SPS烧结之后样品的晶粒尺寸小于500 nm，其中部分晶粒小于100 nm。通过对比球磨前后粉体SPS烧结样品的热电性能发现，晶粒尺寸减小之后塞贝克系数有一定程度的增加，热导率下降明显，降低了1/3，但是材料的电导率下降更为显著，降低了10倍左右，因此导致材料最终的ZT值相应下降。

Abstract:: Yb-filled bulk CoSb3 skutterudites were prepared by melting method combining with Spark Plasma Sintering (SPS). Bulk Yb0.3Co4Sb12 compounds with superior thermoelectric properties（ZT=1.19,800 K） were achieved at last. Then high-energy ball milling was employed to prepare nano-sized particles. After that, the nano-sized Yb0.3Co4Sb12 particles were sintered by SPS apparatus to get bulk sample. Particle morphology and microstructure observation were performed by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). The thermoelectric properties of bulk materials were measured by ZEM-3 and LFA427. There were no decomposition and crystal form transition appeared after milling 10 h according to XRD patterns. The particle size decreased greatly according to FESEM and TEM observation and after sintering the grain size was ~500 nm and partly was less than 100 nm. Compared with the bulk without milling, the Seebeck coefficient after milling increased a little and thermal conductivity decreased 1/3. However, at the same time, the electrical conductivity decreased about 10 times so that the ZT of milled bulk Yb0.3Co4Sb12 decreased.