Thermal Conductivity Reduction in a Nanophononic Metamaterial versus a Nanophononic Crystal: A Review and Comparative Analysis

Hussein, Mahmoud I.; Tsai, Churng-Jou; Honarvar, Hossein

doi:10.1002/adfm.201906718

Cited by 52 publications

(53 citation statements)

References 118 publications

(183 reference statements)

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“…Both screw dislocations and surface resonant structures reduce the TC of NWs by roughly the same amount for every size. However, it is worth noting that the magnitude of TC reduction can be tuned by Burgers vector length [23,24], resonator dimension and number density [8,12,48,49]. As an illustration, we constructed resonant NWs with different pillar heights L h and the corresponding TCs at 300 K are calculated.…”

Section: Resultsmentioning

confidence: 99%

Synergistic impeding of phonon transport through resonances and screw dislocations

et al. 2021

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Improving the control of heat flow at the nanoscale is essential for promoting its applications in many fields, such as energy conversion, thermal informatics, and communication technologies. Here we perform a systematic study on the synergistic effect of screw dislocations and surface resonators on thermal transport of Si nanowires and the corresponding mechanisms based on molecular dynamics simulations. We uncover that screw dislocations reduce the thermal conductivity by enhancing the anharmonicity of nanowires due to the non-homogeneous stress field. For resonant structures, we demonstrate that the suppression of relaxation time is the main mechanism for thermal conductivity reduction. The suppression of relaxation time by more than two orders of magnitude below 4 THz dramatically reduces the resonant structure thermal conductivity, while the previously proposed group velocity reduction mechanism can only impede phonon transport beyond 4 THz slightly. By comparing the mechanisms produced by dislocations and resonators, we find that the resonators have a stronger effect over screw dislocations in impeding the phonon transport at low-frequencies while it becomes opposite at high-frequencies. As a result, they can be combined together to manipulate phonon transport synergistically at all frequencies. Our findings not only provide new insights on the mechanisms of thermal conductivity engineering by screw dislocations and surface resonators, but also illustrate a new paradigm for ultralow thermal conductivity design through the tailoring of the entire frequency range of phonon transport.

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Section: Resultsmentioning

confidence: 99%

Synergistic impeding of phonon transport through resonances and screw dislocations

et al. 2021

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“…1(a). Previous studies 29,30 found that pillars on the surface of a membrane act as local resonators and their predominant resonance frequency is expectedly decreasing with the pillar height 31,32 . To achieve frequency difference between the resonators, we thus consider two types of pillars with different heights, i.e.…”

Section: Methodsmentioning

confidence: 96%

Thermal self-synchronization of nano-objects

Zhang

Guo

Bescond

et al. 2021

Journal of Applied Physics

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Self-synchronization is a ubiquitous phenomenon in nature, in which oscillators are collectively locked in frequency and phase through mutual interactions. While self-synchronization requires the forced excitation of at least one of the oscillators, we demonstrate that this mechanism spontaneously appears due to the activation from thermal fluctuations. By performing molecular dynamics simulations, we demonstrate selfsynchronization in a platform supporting doped silicon resonator nanopillars having different eigenfrequencies. We find that pillar's vibrations are spontaneously converging to the same frequency and phase. In addition, the dependencies on intrinsic frequency difference and coupling strength agree well with the Kuramoto model predictions. More interestingly, we find that a balance between energy dissipation resulting from phononphonon scattering and potential energy between oscillators is reached to maintain synchronization. The balance could be suppressed by increasing the membrane size. While microscopic stochastic motions are known to follow random probability distributions, we finally prove that they also can yield coherent collective motions via self-synchronization.

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“…Nonlinearity in such non-Fourier models can simply be incorporated by temperature-dependent quantities like specific heat capacity, thermal conductivity or relaxation times, or by introducing extra nonlinear terms through extended irreversible thermodynamics [280], phonon hydrodynamics [281], and other filed effects [282]. Another aspect of tuning the wave nature is focusing on the ballistic transport of low-frequency phonons [283][284][285], especially at low temperatures. In this way, heat conduction is sometimes essentially no different from elastic waves and can be modulated by phononic crystals [247,286,287].…”

Section: Summary and Perspectivesmentioning

confidence: 99%

Designing nonlinear thermal devices and metamaterials under the Fourier law: A route to nonlinear thermotics

Dai

2021

Front. Phys.

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Nonlinear heat transfer can be exploited to reveal novel transport phenomena and thus enhance people's ability to manipulate heat flux at will. However, there hasn't been a mature discipline called nonlinear thermotics like its counterpart in optics or acoustics to make a systematic summary of relevant researches. In the current review, we focus on recent progress in an important part of nonlinear heat transfer, i.e., tailoring nonlinear thermal devices and metamaterials under the Fourier's law, especially with temperature-dependent thermal conductivities. We will present the basic designing techniques including solving the equation directly and the transformation theory. Tuning nonlinearity coming from multi-physical effects, and how to calculate effective properties of nonlinear conductive composites using the effective medium theory are also included. Based on these theories, researchers have successfully designed various functional materials and devices such as the thermal diodes, thermal transistors, thermal memory elements, energy-free thermostats, and intelligent thermal materials, and some of them have also been realized in experiments. Further, these phenomenological works can provide a feasible route for the development of nonlinear thermotics.

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Thermal Conductivity Reduction in a Nanophononic Metamaterial versus a Nanophononic Crystal: A Review and Comparative Analysis

Cited by 52 publications

References 118 publications

Synergistic impeding of phonon transport through resonances and screw dislocations

Synergistic impeding of phonon transport through resonances and screw dislocations

Thermal self-synchronization of nano-objects

Designing nonlinear thermal devices and metamaterials under the Fourier law: A route to nonlinear thermotics

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