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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

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 (US)
Pages (from-to)266-275
Number of pages10
JournalActa Materialia
Volume159
DOIs
StatePublished - Oct 15 2018

Keywords

  • Dislocation arrays
  • Grain-boundary
  • Homointerface
  • Thermal conductivity
  • Thermoelectrics

ASJC Scopus subject areas

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

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