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A1: Low temperature materials

Thermoelectric Property Studies in Bi0.5Sb1.5Te3 Composites with Silicon Inclusions

T.W. Lan1,2, C.C. Chang2, C.M. Tseng2, T.K. Lee2, M.K. Wu2, Y.Y. Chen2
1Department of Physics, National Taiwan University, Taipei 106, Taiwan 2Institute of Physics, Academia Sinica, Nankang, Taipei 115, Taiwan

In the last few years, the thermoelectric (TE) materials have been broadly investigated due to their potential application in energy saving by generating electricity from waste heat. Bismuth antimony telluride (BiSbTe) and its alloys are is one of the most promising commercial thermoelectric materials near the room temperature. To enhance the thermoelectric performance, the most effective way is to optimize power factor of BiSbTe composites.

Hence, in this work, the effects of silicon(Si) inclusion on Bi0.5Sb1.5Te3 has been studied, exhibited figure of merit (ZT) over ~1.2 for a wide temperature range of 320 to 440 K and with a peak ZT = 1.3 at 375 K is obtained in SixBi0.5Sb1.5Te3 with x=0.03 by introducing an optimal carrier concentration of 2 x 1019 cm-3. The SixBiSbTe composites with varied x can be achieved through Bridgman method, milling and spark plasma sintering (SPS) process. Partial substitution of Si for Bi or Sb site results in an increase of carrier concentration and lattice constant. Compared with the Bi0.5Sb1.5Te3 alloy, zT value has been significantly improved in the composites with Si inclusions mainly due to the increased power factor by increasing Seebeck coefficient. The consequence can be explained through carrier concentration and mobility confirmed by the Hall measurement.