On the thermoelectric and magnetic properties, hardness, and crystal structure of the higher boride YbB66

Philipp Sauerschnig, Kantaro Tsuchiya, Takaho Tanaka, Yuichi Michiue, Oksana Sologub, Shu Yin, Akira Yoshikawa, Toetsu Shishido, Takao Mori

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

In this work we report the results of our investigation of YbB66 as a potential high-temperature thermoelectric material. A high-quality single crystal has been grown by the optical floating zone method. Thermoelectric transport properties were measured in a temperature range of 373–973 K YbB66, like REB66 compounds in general, is a p-type semiconductor whose electrical properties can be described by Mott's variable range hopping mechanism. It shows very large Seebeck coefficient ranging from 588 μV K−1 at 373 K to 241 μV K−1 at 973 K and an electrical resistivity ρ that decreases by almost 4 orders of magnitude from 9.4×10−1 Ω m to 2.4 × 10−4 Ω m. Together with the low thermal conductivity of 2.6 W m−1 K−1 a maximum ZT close to 0.1 around 1000 K was determined with trend of sharp increase toward higher temperatures, which is similar to the previous report of SmB66, and significantly larger than previously reported for Y and Er phases of REB66. However, unlike SmB66, the effective magnetic moment suggests a trivalent state for Yb instead of mixed valence, which was determined by measuring the magnetic susceptibility from 2 to 300 K. The composition of YbB66 was indicated to be metal-rich, which actually may be the origin of the good performance.

Original languageEnglish
Article number152182
JournalJournal of Alloys and Compounds
Volume813
DOIs
Publication statusPublished - 2020 Jan 15

Keywords

  • Boride
  • Crystal structure
  • Hardness
  • Magnetic
  • Thermoelectric

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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