Research & Reviews: Journal of Material Sciences
MenuISSN:2321-6212
ISSN:2321-6212
Pee-Yew Lee
Institute of Materials Engineering-NTOU, Taiwan
Posters & Accepted Abstracts: Res. Rev. J Mat. Sci
During mechanical alloying of Bi, Sb and Te elemental powder mixture, the Bi0.4Sb1.6Te3 compound phase can be obtained after 2 hours of mechanical alloying treatment. The as-milled Bi0.4Sb1.6Te3 powders were further mixing with Ti50Cu28Ni15Sn7 amorphous particles to form Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 composite powders after 30 minutes ball milling. The Ti50Cu28Ni15Sn7/ Bi0.4Sb1.6Te3 composite powders were consolidated into bulk samples with a diameter of 20 mm and thickness of 10mm by using vacuum hot pressing. The nano-/microstructured structure were observed for Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 bulk samples. TEM bright-field image shows that the Ti50Cu28Ni15Sn7 amorphous phase with particle size of about 50 nm were homogeneously distributed along the grain boundary of Bi0.4Sb1.6Te3 matrix with grain size around 0.5~2.0 �¼m. The thermoelectric properties of Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 samples were measured. The results indicated, either use high purity (99.999%) or low purity (99.5%) Sb and Te as starting materials, the values of figure of merit (ZT) for the Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 bulk composite samples were found to increase with temperature in the range from 298 K to 580 K. It is the first time that such specific behavior has been observed. For 3 wt.% amorphous Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 specimen use high purity Sb and Te powders as starting materials, the maximum ZT value is only 0.9 at 473 K but is expected to reach 1.18 when the ZT curve is extended from 473K to 580K. For 1.75 wt. % amorphous Ti50Cu28Ni15Sn7/Bi0.4Sb1.6Te3 specimen fabricated from low purity Sb and Te powders, the maximum ZT value is 1.08 at 580 K, which is the highest ZT values among the existing typical low temperature thermoelectric materials has been measured at 580 K.
E-mail:
pylee@ntou.edu.tw