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Realizing High Power Factor and High Figure-of-Merit in Half-Heusler Compounds

Date: 2018-01-12
Time: 10:00
Venue: 中科院物理研究所D-210报告厅
Speaker: Dr. Ran He

Leibniz Institute for Solid State and Materials Research Dresden - IFW Dresden, Germany

Dr. Ran He(何然)currently works as a postdoc fellow at IFW-Dresden. He got his Bachelor degree in material physics in 2011 from Northeastern University, P. R. China. He studied physics at Boston College till the end of 2012, and then transferred to the University of Houston and obtained his Ph.D. in physics in 2016. His study mainly focuses on the transport properties of electron and phonon in mid-to-high temperature thermoelectric materials. He is a recipient of C. W. Chu scholarship at the Texas Center for Superconductivity at the University of Houston.

Heat can be converted into electricity through the thermoelectric (TE) effect. For an ideal TE device, the conversion efficiency is governed by the figure-of-merit (ZT); meanwhile the output power density is related to the power factor (PF) of the TE materials. In the application for waste-heat recovery, high PF is considered equally important as high ZT. However, most of the reported high ZTs were realized in TE materials with extremely low thermal conductivity, yet a combination of high ZT and high PF are much less reported. In this talk, I will present the enhancement of ZT in the half-Heusler based compounds through boosting the PF. The mechanisms of the enhancement such as improving the band degeneracy, tuning the carrier scattering mechanism, and nanostructuring, etc. are discussed in detail. Based on the optimized compositions, a high heat-to-power conversion efficiency of ~9%, as well as a record-high output power density of 22 W cm-2 were realized. These work mark the half-Heusler based compounds promising candidate for thermoelectric applications.

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