Effects of Sb-doping on electrical transport properties of Co-based half-Heusler compound

Yasuhiro Ono, Shingo Inayama, Hideaki Adachi, Satoshi Yotsuhashi, Yuzuru Miyazaki, Tsuyoshi Kajitani

Research output: Contribution to journalConference articlepeer-review

Abstract

Electrical transport properties of NbCoSn1-xSbx (x=0, 0.01, 0.02 and 0.05), a half-Heusler compound and its alloys, have been studied in the temperature range from 80 K to 850 K. As-prepared samples exhibit metallic conduction and similar Seebeck coefficients near 300 K (S= -100 μVK-1). Except for NbCoSn0.95Sn0.05, both electrical resistivity, ρ, and the absolute value of S appreciably increase during the annealing for 6 days at 1123 K. Unusual increase in ρ of the annealed NbCoSn sample is found at about 200 K. ρ-T curves of the other annealed samples remain metallic over the measured temperature range and the ρ value noticeably decreases with increasing Sb content, x. Among the annealed samples, the high power factor, 25×10-4Wm -1K-2 at 850 K, is obtained for NbCoSn 0.95Sb0.05. The band structure of NbCoSn is calculated based on the determined crystal structure, indicating that NbCoSn is an indirect transition-type semiconductor with a band gap of approximately 1 eV. This is not consistent with the metallic behavior of ρ observed for the annealed NbCoSn sample above 400 K. Partial disordering of Nb and Co atoms is a conceivable answer.

Original languageEnglish
Pages (from-to)195-200
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume793
DOIs
Publication statusPublished - 2003 Jan 1
EventThermoelectric Materials 2003 - Research and Applications - Boston, MA., United States
Duration: 2003 Dec 12003 Dec 3

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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