Ga<sub>4</sub>C-family crystals, a new generation of star thermoelectric materials, achieved by band degeneracies, valley anisotropy, and strong phonon scattering among others

Lou, Ao; Fu, Hua‐Hua; Wu, Ruqian

doi:10.1039/d2ta09210g

Cited by 3 publications

(1 citation statement)

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“…It has been reported that electrical conductivity can be enhanced and thermal conductivity can be reduced by additional phonon scattering through strain engineering. − For example, in the experiment, the selection of different substrate in the Mg 3 Sb 2 film was able to stretch stress or compression stress in the film middle class, which was the maximum amount of 8%, and the thermoelectric properties were greatly improved . Our theoretical calculation shows that both tensile strain and compressive strain not only increase the power factor but also significantly decrease the lattice thermal conductivity.…”

Section: Resultsmentioning

confidence: 65%

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Cheng,

Yuan,

Yao

et al. 2023

J. Phys. Chem. C

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Using first-principles calculations and the electron–phonon Wannier and Boltzmann transport equation, the electronic and lattice transport properties along with thermoelectric performance of FeOCl-type compounds ScXI (X = S, Se, Te) are investigated. It is found that the transport coefficients that determine the thermoelectric properties are significantly affected by electron–phonon coupling, with optical phonon scattering contributing importantly to the transport properties that produce low lattice thermal conductivity at room temperature. Near the Fermi level, the conductivity and relaxation time of holes are 1 order of magnitude larger than that of electrons, while both of them contribute negligibly to the thermal conductivity. The significantly enhanced power factor of holes along with low lattice thermal conductivity give rise to remarkable thermoelectric performance, with ZT of p-type ScSI reaching 1.02. More importantly, we find that both compressive and tensile strain engineering significantly suppress the lattice thermal conductivity by enhancing the phonon scattering, while retaining the electronic band structures almost unchanged near the Fermi level. As a result, a giant thermoelectric figure of merit is predicted in ScSI with a ZT value as high as 4.56 under isotropic strain ratio (−0.6%), corresponding with a hydrostatic pressure of 1.08 GPa. The present work not only uncovers a new family of high-performance thermoelectric materials but also casts physical insights on optimizing the figure of merits for potential applications.

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Section: Resultsmentioning

confidence: 65%

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Cheng,

Yuan,

Yao

et al. 2023

J. Phys. Chem. C

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Predicting large comprehensive refrigeration performance of plastic crystals by compositing carbon architectures for room temperature application

Li,

Niu,

et al. 2023

Applied Physics Letters

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Plastic crystals PE (pentaerythritol) possess colossal barocaloric effect (BCE) that is promising for solid-state refrigeration; however, the high phase transition temperature (> 400 K) and low thermal conductivity (<0.5 W·m−1·K−1) greatly hinder its practical application at room temperature. Here, we propose to complex plastic crystal (PC) with carbon nanotube/graphene architectures (CNT-Gra) to form [PC/CNT-Gra] composites and investigate the BCE based on molecular dynamics simulations. It is found that phase transition temperature of molecular order to disorder can be tuned by alloying PA (neopentane) or NPG (neopentyl glycol) into PE imbedded in CNT-Gra architectures. Importantly, we find that PE0.8PA0.2/CNT-Gra and PE0.75NPG0.25/CNT-Gra demonstrate both giant isothermal entropy changes ΔS (∼200 J·kg−1·K−1) and adiabatic temperature change ΔT (∼18 K) at room temperature. The large BCE mainly comes from the order–disorder transition of PC molecules imbedded in CNT-Gra architectures through analysis of the dynamic process of the composites. Importantly, the thermal conductivity of these campsites is as high as ∼10 W·m−1·K−1, enabling efficient thermal exchange that is vital for improving cooling performance of the cyclic refrigeration process. This work provides important insights for designing PC-based composites with optimized comprehensive cooling performance for potential room temperature refrigeration.

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Colossal barocaloric effect of plastic crystals imbedded in silicon frame near room temperature: Molecular dynamics simulation

Niu,

Li,

et al. 2024

Applied Physics Letters

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Solid-state refrigeration technology has been attracting tremendous attention in recent decades. Plastic crystal pentaerythritol (PE) is a crucial barocaloric material in the solid-state refrigeration field due to its high entropy. However, its refrigeration temperature range and extremely low thermal conductivity are far from meeting the requirements of practical application. Here, we systematically investigate the barocaloric effect (BCE) of composite PE and silicon frame [consisting of silicon nanotube and silicene architectures (SNT-Sil)] and analyze the effects of different silicon models on the BCE performance based on molecular dynamics simulations and statistical analysis. A colossal BCE of PE/silicon frame composite is observed, and refrigeration temperature can be altered to the room temperature range by alloying neopentane (PA) into the PE matrix. It is found that the composite PE0.8PA0.2/SNT-Sil and PE0.9PA0.1/SNT-Sil demonstrate excellent comprehensive refrigeration performance near room temperature (300–320 K), with large isothermal entropy change ΔS (654–842 J kg−1 K−1), adiabatic temperature ΔT (34–47 K), and thermal conductivity κ (4.0–4.2 W m−1 K−1). The microscopic mechanism is discussed through pressure induced changes in bonding, structural, and vibrational properties. Importantly, the plastic crystal/silicon framework is easy to deform and requires smaller input work in the barocaloric refrigeration process compared to other nanomaterials such as carbon framework. This work provides important guidance on improving plastic crystals with colossal comprehensive refrigeration performance for practical applications.

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Ga₄C-family crystals, a new generation of star thermoelectric materials, achieved by band degeneracies, valley anisotropy, and strong phonon scattering among others

Abstract: Using density functional theory combined with Boltzmann transport equation, we uncover a new class of high-performing thermoelectric material, i.e., supertetrahedral Ga4C-family materials characterized by ultrahigh thermoelectric figure of merit (ZT),...

Cited by 3 publications

References 67 publications

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Predicting large comprehensive refrigeration performance of plastic crystals by compositing carbon architectures for room temperature application

Colossal barocaloric effect of plastic crystals imbedded in silicon frame near room temperature: Molecular dynamics simulation

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Ga4C-family crystals, a new generation of star thermoelectric materials, achieved by band degeneracies, valley anisotropy, and strong phonon scattering among others

Abstract: Using density functional theory combined with Boltzmann transport equation, we uncover a new class of high-performing thermoelectric material, i.e., supertetrahedral Ga4C-family materials characterized by ultrahigh thermoelectric figure of merit (ZT),...

Cited by 3 publications

References 67 publications

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

Predicting large comprehensive refrigeration performance of plastic crystals by compositing carbon architectures for room temperature application

Colossal barocaloric effect of plastic crystals imbedded in silicon frame near room temperature: Molecular dynamics simulation

Contact Info

Product

Resources

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Ga₄C-family crystals, a new generation of star thermoelectric materials, achieved by band degeneracies, valley anisotropy, and strong phonon scattering among others