Direct Observation of Inherent Atomic-Scale Defect Disorders responsible for High-Performance Ti1-xHfxNiSn1-ySby Half-Heusler Thermoelectric Alloys

作者：Kim Ki Sung; Kim Young Min; Mun Hyeona; Kim Jisoo; Park Jucheol; Borisevich Albina Y; Lee Kyu Hyoung; Kim Sung Wng

来源：Advanced Materials, 2017, 29(36): 1702091.

DOI：10.1002/adma.201702091

• nanostructuring
• thermoelectrics
• thermal conductivity

Structural defects often dominate the electronic- and thermal-transport properties of thermoelectric (TE) materials and are thus a central ingredient for improving their performance. However, understanding the relationship between TE performance and the disordered atomic defects that are generally inherent in nanostructured alloys remains a challenge. Herein, the use of scanning transmission electron microscopy to visualize atomic defects directly is described and disordered atomic-scale defects are demonstrated to be responsible for the enhancement of TE performance in nanostructured Ti1-xHfxNiSn1-ySby half-Heusler alloys. The disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving the power factor. It is observed that the Ni interstitial and Ti,Hf/Sn antisite defects are collectively formed, leading to significant atomic disorder that causes the additional reduction of lattice thermal conductivity. The Ti1-xHfxNiSn1-ySby alloys containing inherent atomic-scale defect disorders are produced in one hour by a newly developed process of temperature-regulated rapid solidification followed by sintering. The collective atomic-scale defect disorder improves the zT to 1.09 +/- 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy. These results provide a promising avenue for improving the TE performance of state-of-the-art materials.

• 出版日期2017-9-27