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Abstract Eu5Sn2As6is a Zintl phase crystalizing in the orthorhombic space groupPbamwith one‐dimensional chains of corner‐shared SnAs4tetrahedra running in thec‐direction. Eu5Sn2As6has an impressive room temperature Seebeck of >100 μV/K and < – 100 μV/K at 600 K crossing fromp‐ ton‐type at 650 K. The maximum thermoelectric figure of merit,zT, for Eu5Sn2As6is small (0.075), comparable to that of the Zintl phase Ca5Al2Sb6whose thermoelectric performance was improved by doping Na onto the Ca sites. In this study, we show that the thermoelectric properties of Eu5Sn2As6can be improved by substituting with K or La. The series Eu5‐xKxSn2As6provides an increase in maximumzTof 0.22 forx=0.15 due to a decrease resistivity while the onset of bipolar conduction systematically increases in temperature. Upon La substitution, Eu5‐xLaxSn2As6results in a newn‐type Zintl phase across the temperature range of 300–800 K.
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Enhanced Thomson and Unusual Nernst Coefficients in 1T‐ TiSe2 Due to Bipolar Transport and CDW Phase Transition
Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid‐state cooling but their efficiency is hindered by material limitations. Alternative routes based on the Thomson and Nernst effects offer new possibilities. Here, we present a comprehensive investigation of the thermoelectric properties of 1T‐TiSe2, focusing on these effects around the charge density wave transition (≈200 K). The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450 μV K−1at 184 K, surpassing the Seebeck coefficient. Furthermore, 1T‐TiSe2exhibits a remarkably broad temperature range (170–400 K) with a Thomson coefficient exceeding 190 μV K−1, a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges. Additionally, the Nernst coefficient exhibits an unusual temperature dependence, increasing with temperature in the normal phase, which we attribute to bipolar conduction effects. The combination of solid–solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.
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- PAR ID:
- 10568887
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ENERGY & ENVIRONMENTAL MATERIALS
- Volume:
- 8
- Issue:
- 4
- ISSN:
- 2575-0356
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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