Controlling Metallurgical Phase Separation Reactions of the Ge<sub>0.87</sub>Pb<sub>0.13</sub>Te Alloy for High Thermoelectric Performance

Gelbstein, Yaniv; Davidow, Joseph; Girard, Steven N.; Chung, Duck Young; Kanatzidis, Mercouri G.

doi:10.1002/aenm.201200970

Cited by 216 publications

(215 citation statements)

References 34 publications

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“…These alloys undergo a soft optical mode transition between the rocksalt and rhombohedral phases as a function of the composition and temperature [23], and have high ZT [19,20,[24][25][26][27]. Our first principles virtual-crystal calculations show that the phase transition minimizes the anharmonic component of κ due to extremely soft optical modes which maximize the anharmonic acoustic-optical coupling, especially for lowfrequency phonons.…”

Section: Introductionmentioning

confidence: 80%

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

et al. 2017

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Type of publicationArticle (peer-reviewed) We show how tuning the proximity to the soft optical mode phase transition via chemical composition affects the lattice thermal conductivity κ of Pb 1−x Ge x Te alloys. Using first-principles virtual-crystal simulations, we find that the anharmonic contribution to κ is minimized at the phase transition due to the maximized acoustic-optical anharmonic interaction. Mass disorder significantly lowers and flattens the dip in the anharmonic κ over a wide composition range, thus shifting the κ minimum away from the phase transition. The total κ and its anharmonic contribution vary continuously between the rocksalt and rhombohedral phases as expected for the second-order phase transition. The actual phase and its strength of resonant bonding play a less prominent role in reducing the κ of Pb 1−x Ge x Te alloys than the proximity to the phase transition and the atomic mass. Our results show that alloys with soft optical mode transitions are promising materials for achieving low thermal conductivity and possibly high thermoelectric efficiency.

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Section: Introductionmentioning

confidence: 80%

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

et al. 2017

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“…37,38 Recently, Pb dopants in GeTe were successfully used to optimize the carrier concentration and form sub-micron phase separation domains to reduce the thermal conductivity, which resulted in a ZT of~2 for Pb x Ge 1 − x Te. 39 Bi 2 Te 3 -doped Pb x Ge 1 − x Te has also been reported with an excellent ZT of~1.9. 40 Sb x Ge 1 − x Te compounds showed a similar ZT of~1.85 and high mechanical stability.…”

Section: Introductionmentioning

confidence: 92%

Resonant level-induced high thermoelectric response in indium-doped GeTe

et al. 2017

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Resonant levels are promising for high-performance single-phase thermoelectric materials. Recently, phase-change materials have attracted much attention for energy conversion applications. As the energetic position of resonant levels could be temperature dependent, searching for dopants in phase-change materials, which can introduce resonant levels in both low and high temperature phases, remains challenging. In this study, possible distortions of the electronic density of states due to group IIIA elements (Ga, In, Tl) in GeTe are theoretically investigated. Resonant levels induced by indium dopants in both rhombohedral and cubic phase GeTe have been demonstrated. The experimental Seebeck coefficients of In x Ge 1 − x Te exhibit a large enhancement compared with those observed for other prior dopants. Indium dopants reduce the defect concentrations in GeTe, and thus, they lower the carrier concentrations and suppress the electronic component of the total thermal conductivity. The enhanced Seebeck coefficient, together with the suppressed thermal conductivity, leads to a reasonably high ZT of 1.3 at a temperature near 355°C in In 0.02 Ge 0.98 Te. The corresponding average ZT is enhanced by~70% across the entire temperature range of the rhombohedral and cubic phases. These observations indicate that indium-doped GeTe is a promising base material for achieving an even higher thermoelectric performance.

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“…The lack of a detailed investigation of GeTe has also hindered the understanding of some GeTe-based alloys with decent TE properties, such as GeTe-AgSbTe (TAGS), [42][43][44][45] (GeTe) n Sb 2 Te 3 (GST), [46][47][48] (Bi 2 Te 3 ) x (GeTe) 1 − x 49-52 and Ge 1 − x Pb x Te. [53][54][55][56][57][58] Therefore, it is of great importance to reveal the essence of the superior electronic performance in GeTe, particularly from the perspective of the electronic structure.…”

Section: Introductionmentioning

confidence: 99%

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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Controlling Metallurgical Phase Separation Reactions of the Ge_0.87Pb_0.13Te Alloy for High Thermoelectric Performance

Cited by 216 publications

References 34 publications

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

Resonant level-induced high thermoelectric response in indium-doped GeTe

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

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Controlling Metallurgical Phase Separation Reactions of the Ge0.87Pb0.13Te Alloy for High Thermoelectric Performance

Cited by 216 publications

References 34 publications

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

Ferroelectric phase transition and the lattice thermal conductivity of Pb1−xGexTe alloys

Resonant level-induced high thermoelectric response in indium-doped GeTe

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

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Controlling Metallurgical Phase Separation Reactions of the Ge_0.87Pb_0.13Te Alloy for High Thermoelectric Performance