The Preparation and Thermoelectric Properties of The BaGaGe Clathrates Prepared by Powder Metallurgy

• Main Authors: Yu Ru Tsai, 蔡雨儒
• Other Authors: 張立信
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/81176366685781235256

碩士 === 國立中興大學 === 材料科學與工程學系所 === 100 === In this study, Type - I Ba-Ga-Ge alloy powder with stable composition were prepared by arc melting and powder metallurgy. The effects of sintering time and temperature on thermoelectric properties were studied, and the optimal sintering parameters were found. Homogeneous BaGaGe alloy powder was successfully prepared. The X-ray diffraction analysis showed that the BaGaGe powder was composed of Type - I BaGaGe and Ge phases. The density of specimen increases with increasing sintering time. In consistency, from the observation of electron microscopy, more dense regions were found in sample with more sintering time. In general, the Seebeck coefficient and electrical conductivity increase while thermal conductivity decreases with increasing environmental temperature. However, the Seebeck coefficient decreases and thermal conductivity increases after 500 ℃, The overall thermal conductivity are less than 1 W/mk. The Seebeck coefficient changes not much but electrical conductivity increases with increasing sintering time. The optimal Seebeck coefficient and thermal conductivity can be found between room temperature and 600 ° C. The sample sintered at 800 ℃ for 64 hr has the optimal thermoelectric figure-of-merit 1.16 at 500 ℃.