The role of simultaneous substitution of Cr and Ru on the thermoelectric properties of defect manganese silicides MnSiδ (1.73<δ<1.75)
Autor: | Donald T. Morelli, Terry M. Tritt, V. Ponnambalam, Sriparna Bhattacharya |
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Rok vydání: | 2013 |
Předmět: |
Materials science
Condensed matter physics business.industry Mechanical Engineering Metals and Alloys Analytical chemistry chemistry.chemical_element Manganese Thermoelectric materials Thermal conductivity Semiconductor chemistry Mechanics of Materials Electrical resistivity and conductivity Hall effect Seebeck coefficient Thermoelectric effect Materials Chemistry business |
Zdroj: | Journal of Alloys and Compounds. 580:598-603 |
ISSN: | 0925-8388 |
Popis: | Defect manganese silicides have been substituted with Cr and Ru, in order to study the role of these substitutions on the resulting resistivity ( ρ ), Seebeck ( α ) and Hall coefficients and thermal conductivity. The resistivity and Seebeck coefficient measurements suggest that these compounds are degenerate semiconductors. The Hall measurements indicate that the carrier concentration increases in Cr and Ru substituted compounds. The majority carriers are holes and the change of hole concentration is only marginal. While the hole concentration ( p ) of MnSi 1.74 is ∼2.1 × 10 21 cm −3 , in heavily substituted Mn 0.65 Cr 0.2 Ru 0.15 Si 1.74 , p increases only to ∼4.5 × 10 21 cm −3 . The increase in p is presumably due to Si precipitation. One interesting feature is the low lattice thermal conductivity ( κ L ) which is ∼2–2.5 W/m K at 300 K depending upon the composition. In addition, κ L shows a weak temperature dependence. Because of the combination of high power factor ( α 2 / ρ ) ∼ 2 mW/m K 2 and low thermal conductivity ∼2.5–2.7 W/m K, Mn 0.95 Cr 0.5 Si 1.74 and Mn 0.97 Cr 0.3 Si 1.74 exhibit highest ZT of 0.6 at 850 K. For other compounds, a moderate ZT value of 0.3–0.5 is realized at 850 K. In Ru substituted compounds, the ZT is not improved beyond 0.5, due to the decrease of charge carrier mobility. |
Databáze: | OpenAIRE |
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