Thermoelectric Properties of Si2Ti-Type Al-(Mn,Cr,Fe)-Si Alloys

• Published in: Journal of electronic materials 2011-05, Vol.40 (5), p.1052-1056
• Main Authors: Toyama, Yasuhiro, Hazama, Hirofumi, Asahi, Ryoji, Takeuchi, Tsunehiro
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Cross-disciplinary physics: materials science; rheology; Electronic transport in condensed matter; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Optical and Electronic Materials; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; Solid State Physics; Thermoelectric and thermomagnetic effects
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-011-1531-2

To optimize the thermoelectric properties of Si 2 Ti-type Al 32 Mn 34 Si 34 ( C 54-phase), which possesses a large absolute Seebeck coefficient | S | exceeding 300  μ V/K with negative sign, we partially substituted Cr and Fe for Mn, and succeeded in decreasing the number of valence electrons (in the case of Cr) without observing precipitation of secondary phases. A large, positive Seebeck coefficient exceeding 200  μ V/K was observed for Al 32 Cr x Mn 34− x Si 34 (1 ≤  x  ≤ 2.5), which consists almost solely of the C 54-phase. The increase of hole concentration caused by Cr substitution for Mn was confirmed by both the reduction in electrical resistivity and the sign reversal of the Seebeck coefficient. The largest ZT -value for positive Seebeck coefficient ( p -type behavior) was obtained for Al 32 Cr 2.5 Mn 31.5 Si 34 , with the resulting ZT -value reaching a magnitude twice as large as the largest ZT -value of the ternary compound Al 33 Mn 34 Si 33 possessing p -type behavior.