Orbital chemistry of high valence band convergence and low-dimensional topology in PbTe

Brod, Madison K.; Snyder, G. Jeffrey

doi:10.1039/d1ta01273h

Cited by 16 publications

(24 citation statements)

References 78 publications

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“…The thermoelectric performance of Tl-doped PbTe alloyed with PbSe or PbS was investigated by Jaworski et al The ZT parameters estimated for the alloys were somewhat lower compared to the only Tl-doped PbTe in ref and in this work. The last property can be well explained using the recently proposed by Brod and Snyder paradigm . As the s–p splitting energy decreases from S to Se and from Se to Te, tellurium is a better choice for high thermoelectric performance than Se or S at T < 700 K (in the case when the L band is higher than the ∑ band) in p -type PbTe due to higher band degeneracy.…”

Section: Resultsmentioning

confidence: 95%

High Thermoelectric Performance of p-Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening

Parashchuk

Wiendlocha

Cherniushok

et al. 2021

ACS Appl. Mater. Interfaces

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In this work, we show the simultaneous enhancement of electrical transport and reduction of phonon propagation in p-type PbTe codoped with Tl and Na. The effective use of advanced electronic structure engineering improves the thermoelectric power factor S 2 σ over the temperature range from 300 to 825 K. A rise in the Seebeck coefficient S was obtained due to the enhanced effective mass m*, coming from the Tl resonance state in PbTe. Due to the presence of additional carriers brought by Na codoping, electrical conductivity became significantly improved. Furthermore, Tl and Na impurities induced crystal lattice softening, remarkably reducing lattice thermal conductivity, which was confirmed by a measured low speed of sound v m and high internal strain Cε XRD . Eventually, the combination of both the attuned electronic structure and the lattice softening effects led to a very high ZT value of up to ∼2.1 for the Pb 1−x−y Tl x Na y Te samples. The estimated energy conversion efficiency shows the extraordinary value of 15.4% (T c = 300 K, T h = 825 K), due to the significantly improved average thermoelectric figure of merit ZT ave = 1.05. This work demonstrates that the combination of impurity resonance scattering and crystal lattice softening can be a breakthrough concept for advancing thermoelectrics.

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Section: Resultsmentioning

confidence: 95%

High Thermoelectric Performance of p-Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening

Parashchuk

Wiendlocha

Cherniushok

et al. 2021

ACS Appl. Mater. Interfaces

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“…There is a flat band between CBM-X 3 (contributed by the d orbital of the Y atom) and Γ point (Δ E = 0.03 eV), with the CBM-X 2 (contributed by the d orbital of the X atom) close in energy (Δ E = 0.25 eV), which should have a complex Fermi surface with a high band degeneracy. 42,43 The orbital diversity of conduction band edges indicates that larger degeneracy can be achieved by engineering the energy offset.…”

Section: Resultsmentioning

confidence: 99%

Conduction band engineering of half-Heusler thermoelectrics using orbital chemistry

et al. 2022

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“…The TB solution for the energy levels in a diatomic molecule can be a useful tool for understanding complex electronic structures. [ 69 ] Consider the interaction between two orbitals (1 and 2) that are members of the same symmetry representation. The expressions for the resulting bonding (ε − ) and anti‐bonding (ε + ) energy levels are given in Equation ().…”

Section: Avoided Crossings In the Hh Electronic Structurementioning

confidence: 99%

“…In order to extend this simple diatomic molecule model to complex crystal structures, we can adjust the on‐site energies and hopping (interaction) parameters so that they are effective on‐site energies (

(E_{1} (k)

and

(E_{2} (k)

) and interaction parameters (

V (k)

), which are a function of the k ‐vector. [ 69 ] That is, we can write Equation () as a function of k , as shown in Equation (), in order to describe more complex electronic dispersions with a simple diatomic molecule TB model:

\begin{matrix} ε_{\pm} = \frac{1}{2} (E_{1} + E_{2}) \pm \frac{1}{2} \sqrt{{(E_{1} - E_{2})}^{2} + 4 V^{2}} \end{matrix}

\begin{matrix} ε_{\pm} (k) = \frac{1}{2} (E_{1} (k) + E_{2} (k)) \pm \frac{1}{2} \sqrt{{(E_{1} (k) - E_{2} (k))}^{2} + 4 V^{2} (k)} \end{matrix}

…”

Section: Avoided Crossings In the Hh Electronic Structurementioning

confidence: 99%

The Importance of Avoided Crossings in Understanding High Valley Degeneracy in Half‐Heusler Thermoelectric Semiconductors

Brod

Anand

Snyder

2022

Adv Elect Materials

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Half‐Heusler (hH) compounds are promising candidates for inexpensive, low‐toxicity thermoelectric materials. It is well known that engineering electronic bands with high valley degeneracy is an effective approach for enhancing the performance of thermoelectric materials, and there are several routes for achieving high valley degeneracy in hH systems. For instance, there are multiple locations in the first Brillouin zone where the valence band maximum can be found (at the Γ‐, L‐, or W‐point), and there are two competing low‐lying conduction bands at the X‐point, where the conduction band minimum is located. By converging the multiple valence band and conduction band extrema, the valley degeneracy, and hence, performance of these materials can be improved. Here, group theoretical and tight‐binding approaches, in addition to first‐principles density functional theory calculations, are used to study the chemical origins of various band extrema in both the n‐type and p‐type compounds, with particular focus on ZrNiSn and NbFeSb. Specifically, the importance of avoided crossings is explained. The results of this work can be used to better understand and develop design strategies for engineering better performing hH thermoelectrics.

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Orbital chemistry of high valence band convergence and low-dimensional topology in PbTe

Abstract: The tight-binding method provides insight into the orbital interactions that lead to the exceptional thermoelectric performance of PbTe. Using this framework, we can predict strategies to achieve enhanced thermoelectric performance in new alloys.

Cited by 16 publications

References 78 publications

High Thermoelectric Performance of p-Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening

High Thermoelectric Performance of p-Type PbTe Enabled by the Synergy of Resonance Scattering and Lattice Softening

Conduction band engineering of half-Heusler thermoelectrics using orbital chemistry

The Importance of Avoided Crossings in Understanding High Valley Degeneracy in Half‐Heusler Thermoelectric Semiconductors

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