Thermopower enhancement in Pb1−xMnxTe alloys and its effect on thermoelectric efficiency

Pei, Yanzhong; Wang, Heng; Gibbs, Zachary M.; LaLonde, Aaron D.; Snyder, G. Jeffrey

doi:10.1038/am.2012.52

Cited by 227 publications

(249 citation statements)

References 58 publications

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“…In addition to carrier scattering by dopant impurities, 81 the further reduction in the Hall mobility at high Bi-doping levels (low hole concentrations, o~2 × 10 20 cm − 3 ) in GeTe is presumably due to the redistribution of carriers from the high-mobility L band to the low-mobility Σ band. Such a redistribution is normally seen in similar materials including PbTe, 19,23,82 SnTe 83 and PbSe. 27 When the temperature increases, GeTe undergoes a phase transition from a rhombohedral structure (α phase) to one that is cubic (β phase), leading to a switch in energy between the L and Σ bands.…”

Section: Resultsmentioning

confidence: 61%

“…Effective approaches include nanostructuring, 2-7 lattice anharmonicity, 8,9 liquid phonons, 10,11 vacancy [12][13][14] or interstitial 15 point defects and a low sound velocity. 16 Band engineering concepts including a large number of degenerated bands, [17][18][19][20][21][22][23][24][25] a low band effective mass 26 and weak carrier scattering 27 have also proven to be successful in enhancing the TE performance. The knowledge of the band structure is thus critical for band engineering and optimizing the electrical transport of TE materials.…”

Section: Introductionmentioning

confidence: 99%

“…Since band engineering approaches such as band convergence have recently proven to enhance effectively the TE performance of both PbTe 17,21,23,62 and SnTe 63,64 in their p-type forms, it is believed that a detailed investigation of the band structure and the inherent transport properties of GeTe in both its low-and high-temperature phases would be helpful not only for guiding the band/microstructure engineering approaches for further improvements but also for evaluating their net contributions.…”

Section: Introductionmentioning

confidence: 99%

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Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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PbTe and SnTe in their p-type forms have long been considered high-performance thermoelectrics, and both of them largely rely on two valence bands (the first band at L point and the second one along the Σ line) participating in the transport properties. This work focuses on the thermoelectric transport properties inherent to p-type GeTe, a member of the group IV monotellurides that is relatively less studied. Approximately 50 GeTe samples have been synthesized with different carrier concentrations spanning from 1 to 20 × 10 20 cm − 3 , enabling an insightful understanding of the electronic transport and a full carrier concentration optimization for the thermoelectric performance. When all of these three monotellurides (PbTe, SnTe and GeTe) are fully optimized in their p-type forms, GeTe shows the highest thermoelectric figure of merit (zT up to 1.8). This is due to its superior electronic performance, originating from the highly degenerated Σ band at the band edge in the low-temperature rhombohedral phase and the smallest effective masses for both the L and Σ bands in the high-temperature cubic phase. The high thermoelectric performance of GeTe that is induced by its unique electronic structure not only provides a reference substance for understanding existing research on GeTe but also opens new possibilities for the further improvement of the thermoelectric performance of this material.

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Section: Resultsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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“…Explicitly, there are at least two types of band alterations by the defects: (i) altering relative band positions of the matrix (type-I) and (ii) introducing the so-called resonant levels via defect-host interactions (type-II). Numerous experiments [27][28][29][30][31][32] with IV-VI compounds have suggested that the tuning of the relative positions of different pockets by doping on the IV-site (type-I alterations). Some of the beneficial dopants were verified by ab initio band structure calculations, without looking into the mechanisms.…”

Section: Electrical Transport In Thermoelectricsmentioning

confidence: 99%

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

et al. 2016

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During the last two decades, we have witnessed great progress in research on thermoelectrics. There are two primary focuses. One is the fundamental understanding of electrical and thermal transport, enabled by the interplay of theory and experiment; the other is the substantial enhancement of the performance of various thermoelectric materials, through synergistic optimisation of those intercorrelated transport parameters. Here we review some of the successful strategies for tuning electrical and thermal transport. For electrical transport, we start from the classical but still very active strategy of tuning band degeneracy (or band convergence), then discuss the engineering of carrier scattering, and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials. For thermal transport, we summarise the approaches for studying thermal transport based on phonon-phonon interactions valid for conventional solids, as well as some quantitative efforts for nanostructures. We also discuss the thermal transport in complex materials with chemical-bond hierarchy, in which a portion of the atoms (or subunits) are weakly bonded to the rest of the structure, leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures. In this review, we provide a summary of achievements made in recent studies of thermoelectric transport properties, and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment, and point out some challenges and possible directions. INTRODUCTION Thermoelectric (TE) materials are materials that can generate useful electric potentials when subjected to a temperature gradient (known as the Seebeck effect). Conversely, they also transfer heat against the temperature gradient when a current is driven against this potential (known as the Peltier effect). They are promising energy materials with many applications, such as waste heat harvesting, radioisotope TE power generation, and solid state Peltier refrigeration, all of which are driving growing research interest. A key challenge is to improve the TE properties in order to obtain more efficient energy conversion and in turn enable new practical applications. Good TE materials must have excellent electrical transport properties, measured by the TE power factor ( = S 2 σ, where S is the Seebeck coefficient and σ is the electrical conductivity), and also a very low thermal conductivity κ (composed of the electronic contribution κ e , the lattice contribution κ L , and the bipolar contribution κ bi ). Combining the two aspects gives us the dimensionless figure of merit ZT,

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“…[13][14][15][16] Ternary PbTe-rich alloys of PbTe-PbSe 4,17,18 show a higher figure of merit than individual binary PbTe and PbSe systems in the temperature range of 550-800 K, mainly due to alteration of the electronic band structure. 4,18 In contrast, higher zT values of PbTe-PbS [19][20][21][22] compared to the binary systems are credited to the reduction in lattice thermal conductivity, which originates from phonon scattering at the interfaces of secondary phases, as PbS shows very limited solubility in the PbTe matrix.…”

Section: Introductionmentioning

confidence: 99%

Chemical composition tuning in quaternary p-type Pb-chalcogenides – a promising strategy for enhanced thermoelectric performance

Yamini

Wang

Gibbs

et al. 2014

Phys. Chem. Chem. Phys.

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Recently a significant improvement in the thermoelectric performance of p-type ternary PbTe-PbSe and PbTe-PbS systems has been realized through alternating the electronic band structure and introducing nano-scale precipitates to bulk materials respectively. However, the quaternary system of PbTe-PbSe-PbS has received less attention. In the current work, we have excluded phase complexity by fabricating single phase sodium doped PbTe, alloyed with PbS up to its solubility limit which is extended to larger concentrations than in the ternary system of PbTe-PbS due to the presence of PbSe. We have presented a thermoelectric efficiency of approximately 1.6 which is superior to ternary PbTe-PbSe and PbTe-PbS at similar carrier concentrations and the binary PbTe, PbSe and PbS alloys. The quaternary system shows a larger Seebeck coefficient than the ternary PbTe-PbSe alloy, indicative of a wider band gap, valence band energy offset and heavier carriers effective mass. In addition, the existence of PbS in the alloy further reduces the lattice thermal conductivity originated from phonon scattering on solute atoms with high contrast atomic mass. Single phase quaternary PbTe-PbSe-PbS alloys are promising thermoelectric materials that provide high performance through adjusting the electronic band structure by regulating chemical composition.

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Thermopower enhancement in Pb1−xMnxTe alloys and its effect on thermoelectric efficiency

Cited by 227 publications

References 58 publications

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Chemical composition tuning in quaternary p-type Pb-chalcogenides – a promising strategy for enhanced thermoelectric performance

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