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 language | English |
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Pages (from-to) | 5036-5045 |
Number of pages | 10 |
Journal | Acta Materialia |
Volume | 57 |
Issue number | 17 |
DOIs | |
Publication status | Published - 2009 Oct |
Externally published | Yes |
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