Phonon-glass electron-crystals in ZnO-multiwalled carbon nanotube nanocomposites

Nam, Woo Hyun; Kim, Bo Bae; Lim, Young Soo; Dae, Kyun Seong; Seo, Won Seon; Park, Hyung Ho; Lee, Jun Young

doi:10.1039/c7nr03747c

Cited by 16 publications

(16 citation statements)

References 52 publications

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“…solved the problem by introducing coherent phonon scattering into the field. They hypothesized diffraction to be the source of scattering, which adequately explains the decrease of lattice thermal conductivity of other coated grain structures. − To verify their hypothesis, they also synthesized a coated grain structure. The coating of CdTe on SnTe was accomplished on the basis of cation-exchange technique, a method used for core/shell nanoparticles .…”

Section: Extrinsic Scattering: Nanoparticles Nanosized Grains Coated ...mentioning

confidence: 99%

“…on the same material, both studies revealed a reduction in thermal conductivity. To add, reduction in thermal conductivity was also evident in other coated grain structures. − Although people did observe a reduction in thermal conductivities based on a coated grain structure, the exact reason for such reduction was not known since the grain size was rather large, a few μm or 10 μm in size. It was widely known that a large interfacial area per unit volume was required to scatter phonons effectively.…”

Section: Extrinsic Scattering: Nanoparticles Nanosized Grains Coated ...mentioning

confidence: 99%

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Strategies for Manipulating Phonon Transport in Solids

2021

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In this review, we summarize the recent efforts on manipulating phonon transport in solids by using specific techniques that modify their phonon thermal conductivity (i.e., specific heat, phonon group velocity, and mean free path) and phonon thermal conductance (i.e., transmission probability and density of states). The strategies discussed for tuning thermal conductivity are as follows: large unit cell approach and liquidlike conduction for maneuvering specific heat; rattler, minibandgap, and phonon confinement for manipulating phonon group velocity; nanoparticles, nanosized grains, coated grains, alloy (isotope) scattering, selection rules in phonon dispersion, Gruneisen parameter, lone-pair electronics, dynamic disorder, and local static distortion for restricting mean free path. We have also included the discussion on tuning phonon thermal conductance, as thermal conduction can be viewed as a transmission process. Additionally, phonon filtering, ballistic transport, and waveguiding are discussed to alter density of states and transmission probability. We hope this review can bring meaningful insights to the researchers in the field of phonon transport in solids.

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Section: Extrinsic Scattering: Nanoparticles Nanosized Grains Coated ...mentioning

confidence: 99%

Section: Extrinsic Scattering: Nanoparticles Nanosized Grains Coated ...mentioning

confidence: 99%

Strategies for Manipulating Phonon Transport in Solids

2021

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“…According to our developed theory, our coated grains offer much larger phonon-scattering cross sections compared to those of nanodots nanocomposites. The theory successfully explains lattice thermal conductivity of other coated grain structures. − Also, this structure is beneficial for electron transport because (i) electron-impurity scattering can be reduced based on wider interimpurity distances inside the grains ( i.e. , intercoating distance) and (ii) the electron-filtering effect can occur on the basis of the heterostructure barriers created by the coated layers to further enhance the power factor …”

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confidence: 96%

Gigantic Phonon-Scattering Cross Section To Enhance Thermoelectric Performance in Bulk Crystals

et al. 2019

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In thermoelectric energy conversions, thermal conductivity reduction is essential for enhancing thermoelectric performance while maintaining a high power factor. Herein, we propose an approach based on coated-grain structures to effectively reduce the thermal conductivity to a much greater degree when compared to that done by conventional nanodot nanocomposite. By incorporating CdTe coated layers on the surface of SnTe grains, the thermal conductivity is as low as 1.16 W/m-K at 929 K, resulting in a thermoelectric figure of merit, i.e., zT, of 1.90. According to our developed theory, phonons scatter coherently due to the phase lag between phonons passing through and around the coated grain. Such scattering is induced by the acoustic impedance mismatch between the coated layer and the grain, resulting in a gigantic phonon-scattering cross section. The phonon-scattering cross section of the coated grains is several orders of magnitude larger than that of the nanodots with the same impurity concentration. The power factor was also slightly increased by the energy filtering effect at the coated surface and additional minority carrier blocking by the heterointerfaces. This scheme can be utilized for various bulk crystals, meaning a broad range of materials can be considered for thermoelectric applications.

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“…(A) Carrier concentration; (B) Carrier mobility; (C) Density of states effective mass; (D) Calculated Pisarenko plots with different effective mass m d * and experimental results from this work and other reported literature 10,24‐27 in ZnO‐based thermoelectric materials [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Resultsmentioning

confidence: 88%

A sandwich structure assisted by defect engineering for higher thermoelectric performance in ZnO‐based films

Zhou

Zou

et al. 2020

J. Am. Ceram. Soc.

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Gallium (Ga) doping together with low dimensionality has been a promising approach to improve thermoelectric performance of zinc oxide (ZnO) materials, due to the increase of carrier concentration and suppression of phonon transport. So far, the highest power factor of Ga-doped ZnO (GZO) thin films has reached 280 μW m −1 K −2 , which is still limited for practical applications. In this work, we have simultaneously optimized the electrical conductivity and Seebeck coefficient of GZO thin films using the combination of oxygen defects and sandwich structure (GZO-ZnO-GZO). Benefiting from energy filtering effect at the interface between GZO and ZnO layers and high oxygen vacancy concentration, the density of states (DOS) effective mass has been increased together with a relatively high carrier concentration. As a result, an improved power factor value of 434 μW m −1 K −2 at 623 K has been achieved, which is comparable to the best values reported for ZnO-based films. This method of combining defect engineering and sandwich structure design shows great potential in enhancing the thermoelectric performance of ZnO-based thin films or other oxide materials. K E Y W O R D S defect engineering, electrical conductivity, energy filtering effects, GZO thin film, sandwich structure design How to cite this article: Zhou Z, Xu Y, Zou M, et al. A sandwich structure assisted by defect engineering for higher thermoelectric performance in ZnO-based films.

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Phonon-glass electron-crystals in ZnO-multiwalled carbon nanotube nanocomposites

Cited by 16 publications

References 52 publications

Strategies for Manipulating Phonon Transport in Solids

Strategies for Manipulating Phonon Transport in Solids

Gigantic Phonon-Scattering Cross Section To Enhance Thermoelectric Performance in Bulk Crystals

A sandwich structure assisted by defect engineering for higher thermoelectric performance in ZnO‐based films

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