Highly fluidic liquid at homointerface generates grain-boundary dislocation arrays for high-performance bulk thermoelectrics

Hyeona Mun, Kyu Hyoung Lee, Seung Jo Yoo, Hyun Sik Kim, Jiwon Jeong, Sang Ho Oh, G. Jeffrey Snyder, Young Hee Lee, Young Min Kim, Sung Wng Kim

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Dislocation arrays embedded in low-angle grain-boundaries have emerged as an effective structural defect for a dramatic improvement of thermoelectric performance by reducing thermal conductivity [1]. A transient liquid-flow assisted compacting process has been employed for p-type Bi0.5Sb1.5Te3 material to generate the dislocation arrays at grain-boundaries. The details of underlying formation mechanism are crucial for the feasibility of the process on other state-of-the-art thermoelectric materials but have not been well understood. Here, we report the direct observation of dislocation formation process at grain-boundaries of Sb2Te3 system as a proof-of-concept material. We found that the formation of homointerface between Te-terminated Sb2Te3 matrix phase and Te liquid atomic-layer of secondary phase is a prerequisite factor to achieve the low-energy liquid-solid homointerface at compacting elevated temperature. We further demonstrate from the successful observations of atomic structure in the intermediate state of the compacted pellet that the high self-diffusion rate of Te atoms at the liquid-solid homointerface facilitates an effective grain rearrangement, generating low-energy grain-boundaries embedded with dense dislocation arrays. These results pave the way to improve thermoelectric performance of various materials where dislocation arrays are generated by transient liquid-flow assisted compacting process using precursors with an interface constructed with the same types of atoms.

Original languageEnglish
Pages (from-to)266-275
Number of pages10
JournalActa Materialia
Volume159
DOIs
Publication statusPublished - 2018 Oct 15

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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