Hereinwereport a significantly reduced lattice thermal conductivity of Sb-doped Hf0.35Zr0.35 Ti0.3NiSn half-Heusler alloys with sub-micron grains (grain size of ~300 nm). Polycrystalline bulks of Hf0.35Zr0.35Ti0.3NiSn1-xSbx (x = 0.01, 0.02, 0.03) with a complete single half-Heusler phase are prepared using temperature-regulated melt spinning and subsequent spark plasma sintering without a long annealing process. In these submicron-grained bulks, a very low lattice thermal conductivity value of ~2.4Wm-1 K-1 is obtained at 300 K due to the intensified phonon scatterings by highly dense grain boundaries and point-defects (Zr and Ti substituted at Hf-sites). A maximum thermoelectric figure of merit, zT, of 0.5 at 800 K is obtained in Hf0.35Zr0.35Ti0.3NiSn0.99Sb0.01.
Bibliographical noteFunding Information:
This work was supported by the Technology Innovation Program (20000149, Development of non rare half-Heusler thermoelectric alloys for mid to high temperature waste heat recovery) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea). This research was also supported by the Global Frontier Program through the Global Frontier Hybrid Interface Materials (GFHIM) project (Grant 2013M3A6B1078870) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1A6A1A11055660).
© 2020 by the authors.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Process Chemistry and Technology
- Computer Science Applications
- Fluid Flow and Transfer Processes