Influence of periodic table in designing solid-state metal chalcogenides for thermoelectric energy conversion

Rathore, Ekashmi; Dutta, Moinak; Biswas, Kanishka

doi:10.1007/s12039-019-1704-8

Cited by 8 publications

(3 citation statements)

References 36 publications

(53 reference statements)

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“…The distortion is favored when the stabilization from the s/p mixing offsets the reduced electrostatic stabilization from the lower coordination number. The relative energy difference between the Bi 6 s and S 3 p orbitals is the smallest, resulting in a stronger interaction, and Bi 2 S 3 therefore preferentially adopts the low-symmetry Pnma phase with an active lone pair and remains stable even under pressure. , On the other hand, the poorer energy match between the Bi 6 s and Se 4 p /Te 5 p orbitals leads to weaker interactions that cannot stabilize an active lone pair, resulting in “quenching” and a preference for the higher-symmetry R 3̅ m phase.…”

Section: Resultsmentioning

confidence: 99%

Structural Dynamics and Thermal Transport in Bismuth Chalcogenide Alloys

2021

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We present a detailed study of the structural dynamics, energetic and dynamical stability, and thermal transport of the bismuth chalcogenides Bi 2 S 3 , Bi 2 Se 3 , and Bi 2 Te 3 and their alloys. The active Bi lone pairs lead to competition between orthorhombic Pnma and rhombohedral R3̅ m phases, with the latter favored by the heavier chalcogens, while the reported nonambient Bi 2 Se 3 and Bi 2 Te 3 phases show phonon instabilities under ambient conditions. The Pnma structure has intrinsically weaker chemical bonding and stronger phonon anharmonicity than the R3̅ m phase, resulting in lower lattice thermal conductivity. A thermodynamic model of Bi 2 (Se 1−x S x ) 3 indicates that the R3̅ m structure is energetically favored only at low S content, but the stability window may be extended with lower formation temperatures. R3̅ m Bi 2 (Se 1−x Te x ) 3 is a nonideal solid solution due to a strong preference for the Se and Te atoms to occupy the interior and exterior sites, respectively, in the constituent quintuple layers. Strain-field fluctuations from chemical bonding inhomogeneities are shown to play an important role in the heat transport in the alloys, and chalcogen disorder is found to be an important factor in the lower thermal conductivity of Bi 2 SeTe 2 compared to Bi 2 Te 3 . The microscopic insight from this study provides a new theoretical perspective on bismuth chalcogenides and their alloys to inform ongoing research on the thermoelectric performance of these and related systems.

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Section: Resultsmentioning

confidence: 99%

Structural Dynamics and Thermal Transport in Bismuth Chalcogenide Alloys

2021

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“…On the other hand, the poorer energy match between the Bi 6s and Se 4p/Te 5p leads to weaker orbital interactions that are insufficient to stabilize an active lone pair, resulting in "quenching". 66 Bi2Se3 and Bi2Te3 therefore preferentially adopt the higher-symmetry R3 ̅ m phase. relatively high energies, we therefore conclude that these phases are highly unlikely to be formed under ambient conditions.…”

Section: Resultsmentioning

confidence: 99%

Structural Dynamics and Thermal Transport in Bismuth Chalcogenide Alloys

Cen

Pallikara

Skelton

2021

Preprint

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We present a detailed study of the structural dynamics, energetic and dynamical stability and thermal transport of the bismuth chalcogenides Bi2S3, Bi2Se3 and Bi2Te3 and their alloys. The differing activities of the Bi cation lone pairs in Bi2S3, Bi2Se3 and Bi2Te3 lead to competition between orthorhombic Pnma and rhombohedral R-3m phases, with the latter favored by heavier chalcogen atoms, while the reported non-ambient phases of Bi2Se3 and Bi2Te3 show phonon instabilities under ambient conditions. The Pnma structure has weaker chemical bonding and stronger phonon anharmonicity than the R-3m phase, resulting in an intrinsically lower lattice thermal conductivity. A thermodynamic model of Bi2[Se(1-x)S(x)]3 indicates that the R-3m structure is energetically favored only for low S content, but the stability window can potentially be extended at lower formation temperatures. Bi2[Se(1-x)Te(x)]3 in the R-3m phase shows substantial deviation from ideal solid-solution behavior, due to a strong energetic preference for the Se and Te atoms to occupy the interior and exterior sites, respectively, in the constituent quintuple layers. Strain-field fluctuations induced by inhomogeneities in the chemical bonding are shown to play a significant role in determining the heat transport in the alloy systems, and chalcogen disorder away from the preferred symmetric structure is found to be an important factor in the reduced thermal conductivity of Bi2SeTe2 compared to the Bi2Te3 endpoint. The microscopic insight from these modelling studies provides new insight into the bismuth chalcogenides and their alloys, which may inform ongoing research to optimize the thermoelectric performance of these and related materials.

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“…which are met by the binary/ternary/multinary phases of the elements from the p-block of the periodic table. 424 To move the existing frontiers in thermoelectrics, we call for a conceptual advancement by deviating from the conventional approaches and look for new theories or approaches that can decouple the electrical and thermal transport so that they can be independently optimized. This would also lead to novel thermoelectric compounds.…”

Section: Future Outlookmentioning

confidence: 99%