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Sustainable Thermoelectric Materials Fabricated by Using Cu2Sn1-xZnxS3 Nanoparticles as Building Blocks

 Japan Advanced Institute of Science and Technology (JAIST) announced on January 4, 2018 that the research group led by Professor Shinya Maenosono from Materials Chemistry Area of the Institute has succeeded in creating sustainable nanostructured thermoelectric materials by sintering chemically synthesized Cu2Sn1-xZnxS3 nanoparticles as building blocks in collaboration with National Institute of Advanced Industrial Science and Technology (AIST) and Nippon Shokubai Co., Ltd. Details were published in Applied Physics Letters*.

 Electric power generation from waste heat from steel plants and incinerators, for instance, is attracting attention as a possible means for efficient energy consumption to cope with greenhouse gases. Fabrication of thermoelectric material is a challenging issue and its figure of merit ZT is proportional to electrical conductivity and the inverse of thermal conductivity.

 The research group chemically synthesized uniform Cu2Sn1-xZnxS3(x=0-0.2) nanoparticles (NPs) with a characteristic size of about 40nm and sintered NPs to form nanostructured pellets by the pulse electric current sintering technique. Crystal structure of NPs changed from wurtzite to zinc blende, keeping crystal size of about 20nm.

 Among all samples, the pellets of x=0.05 and 0.15 exhibited the highest ZT value (0.37 at 670K) which is 10 times higher than that of a non-nanostructured Cu2SnS3 bulk crystal. The improvement is attributed to effective phonon scattering by nanograins, phase change to zinc blende crystal structure, and the increase in hole carrier density by Zn doping.

*Wei Zhou, Chiko Shijimaya, Mari Takahashi, Masanobu Miyata, Derrick Mott, Mikio Koyano, Michihiro Ohta, Takeo Akatsuka, Hironobu Ono, and Shinya Maenosono, "Sustainable thermoelectric materials fabricated by using Cu2Sn1-xZnxS3 nanoparticles as building blocks", Applied Physics Letters, 111, 263105 (2017); doi. 10.1063/1.5009594; Published Online: 28 December 2017