Development and Analysis of Improved Thermoelectric Materials
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Date
2018-12
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The Ohio State University
Abstract
Thermoelectric cooling devices, also called Peltier coolers, are devices based on the
thermoelectric effect of materials and act in cooling mode. By adding an electrical potential on
two sides of the material, a temperature gradient will be created. Thermoelectric cooling devices
have many advantages, when compared to the commonly used compression-used refrigerators.
For example, refrigerant-free, vibration free and compact. However, a vital disadvantage of
thermoelectric cooling device is that it has a much lower device efficiency, comparing to
compressor-based refrigerators. Thermoelectric coolers offer around 10-15% efficiency of ideal
Carnot cycle, while compressor-based refrigerators provide 40-60% efficiency ideal Carnot
cycle. The efficiency of thermoelectric cooler is influenced by the performance of thermoelectric
used. Therefore, the purpose of this project was to improve the thermoelectric performance of
Bi-Sb alloy. Bi-Sb alloys are of interest for thermoelectric cooling devices and it is believed that
their heat pump efficiency can be enhanced by using CuBr resonant impurities. This project
involves the synthesis of polycrystalline Bi-Sb alloys with different amounts of CuBr prepared
via ingot casting. A concentrated master sample, with 0.5% CuBr, was developed first. Then, 2
times, 5 times and 10 times diluted samples was developed by diluting the master sample. After
measurement, the master sample was found to have best thermoelectric performance, with a ZT
of 0.27. The second step was to develop a single-crystalline sample via zone melting with the
master sample mentioned above. The single-crystalline sample was found to have huge
enhancement in thermoelectric performance, the ZT value of it was found to be 0.41. The results
prove that CuBr dopant does enhanced the heat pump efficiency of Bi-Sb alloy. However, it is
not as much as expected. Further effort can be done to improve the efficiency even more.
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Keywords
Theromelectric, Bi-Sb alloy