First-principles calculations and experimental studies of <i>XYZ</i><sub>2</sub> thermoelectric compounds: detailed analysis of van der Waals interactions

Pöhls, Jan-Hendrik; Luo, Zhe; Aydemir, Umut; Sun, Jon‐Paul; Hao, Shiqiang; He, Jiangang; Hill, Ian G.; Hautier, Geoffroy; Jain, Anubhav; Zeng, Xiaoqin; Wolverton, Chris; Snyder, G. Jeffrey; Zhu, Hong; White, Mary Anne

doi:10.1039/c8ta06470a

Cited by 20 publications

(12 citation statements)

References 82 publications

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“…On the other hand, hybrid functionals do not affect the curvature of band edges but widen the band gap, as seen in Figure S12 (Supporting Information). In agreement with our findings, previous studies have shown that hybrid-DFT calculations are not superior to the DFT for the calculation of transport properties in TE materials. − …”

Section: Methodssupporting

confidence: 92%

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Shahabfar

2021

Chem. Mater.

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To realize the widespread use of thermoelectric (TE) applications, developing low-cost, eco-friendly, and high-performance TE materials with an optimal band gap is essential. We find that the lapieite grouprock-forming minerals buried deep in the earthwith the general formula MCuPnQ3 (M = Ni, Pt, and Pd; Pn = Sb and Bi; and Q = S and Se) comprise the key metrics to become “Thermoelectric Rockstars”. Our detailed chemical and phonon analyses show that the coexistence of weak covalent, partially ionic, and metavalent bonds and the stereoactive lone-pair electrons on Pn benefit the thermoelectric performance of the lapieite group. In PdCuBiSe3, for example, the elongated and soft Cu–Q and Pn–Q bonds along the c-axis synergistically suppress the lattice heat transport (κL) to 0.3 W m–1 K–1 and improve the power factor to 3 mW m–1 K–2 at 600 K, approaching the so-called “phonon-glass electron-crystal” paradigm. Likewise, the other members of the lapieite group achieve a high TE performance. The band structure and Fermi surface analyses indicate that the high band degeneracy (N v = 11) contributes to their high TE performance. Thus, the minerals of the lapieite group, having nontoxic and earth-abundant elements, such as the Ni-based ones, open up a quick path for developing new practical TE materials, awaiting further experimental validations.

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Section: Methodssupporting

confidence: 92%

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Shahabfar

2021

Chem. Mater.

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“…Among those, CuTmTe 2 , AgTmTe 2 , and AgBiSe 2 − are experimentally established good thermoelectric materials. First-principles calculations also predicted other related “112” (such as YAgTe 2 , YCuTe 2 ) compounds as promising thermoelectric materials …”

Section: Introductionmentioning

confidence: 83%

“…The Pauli paramagnetism, low Seebeck coefficient, and high thermal conductivity indicate that CuNiSb 2 is not a potential magnetic or thermoelectric material. However, CuNiSb 2 represents a rare case of “112” in ternary pnictides and provides a reference for further study of “112” compounds of which many are predicted to be promising thermoelectrics . More “112” ternary pnictides such as T 1 T 2 Pn 2 or RTPn 2 (T = transition metal, R = rare-earth metal) with metal-ordered NiAs-derived structure require further exploration using solid-state methods at ambient and high pressure and/or other synthetic methods including Sb, Bi, and salt fluxes.…”

Section: Discussionmentioning

confidence: 99%

Ambient and High Pressure CuNiSb₂: Metal-Ordered and Metal-Disordered NiAs-Type Derivative Pnictides

et al. 2020

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The mineral Zlatogorite, CuNiSb2, was synthesized in the laboratory for the first time by annealing elements at ambient pressure (CuNiSb2-AP). Rietveld refinement of synchrotron powder X-ray diffraction data indicates that CuNiSb2-AP crystallizes in the NiAs-derived structure (P m1, #164) with Cu and Ni ordering. The structure consists of alternate NiSb6 and CuSb6 octahedral layers via face-sharing. The formation of such structure instead of metal disordered NiAs-type structure (P63/mmc, #194) is validated by the lower energy of the ordered phase by first-principle calculations. Interatomic crystal orbital Hamilton population, electron localization function, and charge density analysis reveal strong Ni-Sb, Cu-Sb, and Cu-Ni bonding and long weak Sb-Sb interactions in CuNiSb2-AP. The magnetic measurement indicates that CuNiSb2-AP is Pauli paramagnetic. First-principle calculations and experimental electrical resistivity measurements reveal that CuNiSb2-AP is a metal. The low Seebeck coefficient and large thermal conductivity suggest that CuNiSb2 is not a potential thermoelectric material. Single crystals were grown by chemical vapor transport. The high pressure sample (CuNiSb2-8 GPa) was prepared by pressing CuNiSb2-AP at 700 °C and 8 GPa. However, the structures of single crystal and CuNiSb2-8 GPa are best fit with a disordered metal structure in the P m1 space group, corroborated by transmission electron microscopy.

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“…Motivated by the search for new efficient renewable sources of energy, a huge experimental effort has been made towards identifying materials with better thermoelectric properties in the recent years. So far, this intense search has been based mostly on a single particle theoretical description of electrons and standard electron-phonon coupling due to displacement potential, supported by numerical ab-initio simulations [1] [2]. While this research program has had some notable successes [3] it should be also noted that the progress has been slow and so novel pathways are needed.…”

Section: Pacs Numbersmentioning

confidence: 99%

Anharmonic coupling between electrons and TO phonons in the vicinity of a ferroelectric quantum critical point

Chudziński

2020

Phys. Rev. Research

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We explore a novel coupling mechanism of electrons with the transverse optical (TO) phonon branch in a regime when the TO mode becomes highly anharmonic and drives the ferroelectric phase transition. We show that this anharmonicity, which leads to a collective motion of ions, is able to couple electronic and lattice displacement fields. An effective correlated electron-ion dynamics method is required to capture the effect of the onset of the local electric polarization due to this collective behavior close to the quantum critical point. We identify an intermediate temperature range where an emergent phonon drag may contribute substantially to thermoelectric conductivity in this regime. We find that, under optimal conditions, this extra contribution may be larger than values achieved so far in the benchmark material, PbTe. In the last part we make a case for the importance of our results in the generic problem of anharmonic electron-lattice dynamics. PACS numbers:Motivated by the search for new efficient renewable sources of energy, a huge experimental effort has been made towards identifying materials with better thermoelectric properties in the recent years. So far, this intense search has been based mostly on a single particle theoretical description of electrons and standard electron-phonon coupling due to displacement potential, supported by numerical ab-initio simulations[1] [2]. While this research program has had some notable successes [3] it should be also noted that the progress has been slow and so novel pathways are needed. At the same time it has been observed that in several cases good thermoelectrics (TE) are weakly doped semiconductors, such as PbTe[4], SnTe or SrTiO 3 , that are in the vicinity of a ferroelectric quantum critical phase transition (FE-QCP). It is then natural to ask if it is just a pure coincidence, or whether an yet undiscovered mechanism enhances the Seebeck coefficient.As the system approaches the FE-QCP, a crucial role is played by the transverse optical (TO) phonons. In the Landau macroscopic framework the TO mode spectral weight is coupled to the material's electric polarization [5] (the order parameter), so as the FE transition takes place, the TO softening at q = 0 indicates the emergence of a uniform displacement and the polar order. The electrons should be susceptible to this dipole ordering and usually the appearance of the FE is accompanied by a disappearance of the electron pockets. Otherwise the remaining free electrons would screen the FE order. A massive softening at the Γ point implies that the TO branch emerges as a new family of phonons with a very substantial velocity, often comparable to the one of the longitudinal acoustic (LA) branch [6], and so they certainly contribute to the transport properties of the system.The assertion about coupling between electrons and the TO phonons is experimentally confirmed in an incipient FE, PbTe, by observation[7] that i) photoexcited electrons do change the TO phonons frequency and ii) in return these TO phonons do modify th...

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First-principles calculations and experimental studies of XYZ₂ thermoelectric compounds: detailed analysis of van der Waals interactions

Abstract: van der Waals interactions enhanced the prediction of properties in layered thermoelectrics.

Cited by 20 publications

References 82 publications

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Ambient and High Pressure CuNiSb₂: Metal-Ordered and Metal-Disordered NiAs-Type Derivative Pnictides

Anharmonic coupling between electrons and TO phonons in the vicinity of a ferroelectric quantum critical point

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First-principles calculations and experimental studies of XYZ2 thermoelectric compounds: detailed analysis of van der Waals interactions

Abstract: van der Waals interactions enhanced the prediction of properties in layered thermoelectrics.

Cited by 20 publications

References 82 publications

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Mind the Mines: Lapieite Minerals with Ultralow Lattice Thermal Conductivity and High Power Factor for Thermoelectricity

Ambient and High Pressure CuNiSb2: Metal-Ordered and Metal-Disordered NiAs-Type Derivative Pnictides

Anharmonic coupling between electrons and TO phonons in the vicinity of a ferroelectric quantum critical point

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First-principles calculations and experimental studies of XYZ₂ thermoelectric compounds: detailed analysis of van der Waals interactions

Ambient and High Pressure CuNiSb₂: Metal-Ordered and Metal-Disordered NiAs-Type Derivative Pnictides