Japanese scientists have recently discovered a low-temperature thermoelectric material that can display thermoelectric effects more than 100 times higher than that of lanthanum-based thermoelectric materials at low temperatures. Experiments show that the larger the crystal size of this iron compound, the greater the actual electrothermal effect.
The thermoelectric conversion material can directly convert electric energy and heat energy, and can be used for waste heat power generation and a refrigeration apparatus not using Freon. In the thermoelectric conversion materials, germanium compounds are relatively common, and the cryogenic thermoelectric conversion original devices required for the operation of superconducting materials have not yet been practically applied, and a new low-temperature thermoelectric material needs to be designed.
To solve this problem, researchers from Tokyo University, Nagoya University and Osaka University conducted a joint study. They discovered an iron-based compound "FeSb2" that showed a thermoelectric effect more than 100 times higher than that of the bismuth-based thermoelectric material at a low temperature of -260 degrees Celsius, which made it an extremely desirable low-temperature electric heat. The materials are expected to provide new ideas for designing thermoelectric conversion devices in low temperature environments.
However, researchers do not understand why FeSb2 exhibits a huge thermoelectric effect, so it is impossible to design components with higher thermoelectric performance. To this end, they synthesized ultra-high-purity FeSb2 single crystals, and measured the resistivity, Seebeck coefficient, and thermal conductivity using five different size single crystals. As a result, it was found that the crystal size increases, the thermal conductivity and the Seebeck coefficient also increase, and high thermal conductivity is achieved at the maximum crystal size. Through the cyclotron resonance test, they found that the electron effective mass was 5 times higher than that of free electrons. Finally, it was confirmed that the giant Seebeck coefficient and the output factor of FeSb2 observed were caused by the interaction of a phonon with a long mean free path of grain boundary scattering and an electron with a large effective mass.
Related papers were published in the recently published "Nature and Communications" magazine. (Reporter Chen Chao)
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