Microstructures and Thermoelectric Properties of (Bi,Te,S) Composites Incorporated with Iodine

• Main Authors: Bo-jung Kuo, 郭柏忠
• Other Authors: Ching-Cherng Wu
• Format: Others
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/sj6wnb

碩士 === 國立東華大學 === 材料科學與工程學系 === 105 === In this study, two groups of composites: (Bi2Te3)1-x /(Bi19S27I3)x (x=0.1、x=0.3) and ((Bi2Te3)0.9/(Bi2S3)0.1)1-y /Iy (y=0.005、y=0.0075、y=0.01) were synthesized by melting and direct quenching method. The compositions and microstructures of all samples were analyzed by X-ray diffraction analysis (XRD), optical microscope (OM) and field emission scanning electron microscope (FE-SEM). The thermoelectric behaviors for these composites were studied by means of thermal and carrier transport measurements. Temperature dependences of resistivity, Seebeck coefficient and thermal conductivity for these composites were analyzed. It reveals that all samples showed n-type electron transport characteristics. It is hard to avoid precipitation of Te in the lattice, which results in degradation of the thermoelectric properties. The results show that the content of Te precipitate in ((Bi2Te3)0.9/(Bi2S3)0.1)1-y /Iy composites are smaller than in (Bi2Te3)1-x /(Bi19S27I3)x composites. The ZT value of (Bi2Te3)1-x /(Bi19S27I3)x composites were not enhanced due to their low Seebeck coefficient. The resistivity and thermal conductivity of ((Bi2Te3)0.9/(Bi2S3)0.1)1-y /Iy composites were decreased with the content of iodine incorporation. The Seebeck coefficient of ((Bi2Te3)0.9/(Bi2S3)0.1)1-y /Iy composites increased with iodine content. As a result, the highest ZT value obtained was 0.22 at 300 K for the incorporation of 0.75％ iodine in (Bi2Te3)0.9/(Bi2S3)0.1 , which is better than that of (Bi2Te3)0.9/(Bi2S3)0.1 with no iodine incorporation. (ZT=0.07)