Crystal structure and thermoelectric properties of chimney-ladder compounds in the Ru2Si3-Mn4Si7 pseudobinary system

Norihiko L. Okamoto, Tatsuya Koyama, Kyosuke Kishida, Katsushi Tanaka, Haruyuki Inui

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

Phase relationships of manganese-substituted ruthenium sesquisilicide alloys have been investigated by using X-ray powder diffraction and scanning and transmission electron microscopy. A series of chimney-ladder phases Ru1-xMnxSiy (0.14 ≤ x ≤ 0.97, 1.584 ≤ y ≤ 1.741) are formed over a wide compositional range between Ru2Si3 and Mn4Si7. The compositions of these chimney-ladder compounds deviate slightly from the composition line connecting Ru2Si3 and Mn4Si7, which corresponds to the ideal composition line satisfying VEC (valence electron counting) = 14 rule. The occurrence of this compositional deviation is discussed in terms of the VEC rule and the atomic packing. The thermoelectric properties of the directionally solidified Ru1-xMnxSiy alloys (0.55 ≤ x ≤ 0.90) have also been investigated as a function of the Mn content and temperature. The dimensionless figure of merit (ZT) for those alloys with a high Mn content (x ≥ 0.75) increased with the increase in Mn content. The ZT value for a crystal with x = 0.90 was as high as 0.76 at 874 K.

Original languageEnglish
Pages (from-to)5036-5045
Number of pages10
JournalActa Materialia
Volume57
Issue number17
DOIs
Publication statusPublished - 2009 Oct
Externally publishedYes

Keywords

  • Directional solidification
  • Thermal conductivity
  • Transition metal silicide
  • Transmission electron microscopy
  • X-ray diffraction

ASJC Scopus subject areas

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

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