Influence of amorphous layers on the thermal conductivity of phononic crystals

Verdier, Maxime; Lacroix, David; Didenko, S. A.; Robillard, J.F.; Lampin, E.; Bah, Thierno-Moussa; Termentzidis, Konstantinos

doi:10.1103/physrevb.97.115435

Cited by 15 publications

(11 citation statements)

References 54 publications

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“…But for the same diameter, MD predicts larger thermal conductivity than MC. This could be related to the surface specularity, which is high in MD simulations [32], and zero with MC because of the diffuse boundary condition. In order to compare the results obtained with the two numerical methods for different diameters, we normalized the thermal conductivity.…”

Section: Resultsmentioning

confidence: 99%

Radial dependence of thermal transport in silicon nanowires

et al. 2018

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A radial decomposition of the heat flux in a silicon crystalline nanowire is studied with molecular dynamics (MD) and Monte Carlo (MC) simulations. Less heat flux is carried in the external layer of nanowires than in the center. The difference between the center and the surface is of the order of 50% and 30% with MD and MC simulations, respectively. As a result, a heat flux close to the surface is 30% and 15% lower than the total axial heat flux in the structure. The physical mechanism behind is analyzed from partial contribution of each atom in each phonon mode calculated from lattice dynamics. The reduction of the flux close to the surface is related to back-scattering, the amorphouslike DOS of the external layer and flattened dispersion curves, thus lower phonon group velocities. Our study points to the need for cautions analysis of experimental determination of the thermal conductivity involving contact measurements, such as scanning thermal microscopy.

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Section: Resultsmentioning

confidence: 99%

Radial dependence of thermal transport in silicon nanowires

et al. 2018

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“…This can be achieved through the thermoelectric conversion, whose efficiency depends on the capability of materials of keeping a temperature gradient constant, and thus on their good thermal insulation. As such, the development of means for controlling heat transfer, its propagation direction and efficiency, is at the heart of the current research in thermal science as well as microtechnology [2,3,4,5,6,7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

“…The propagative contribution can be reduced through the presence of interfaces, which scatter phonons. This concept has indeed been largely exploited for efficiently manipulating long-wavelength acoustic phonons, which assure sound propagation at low frequency, through the introduction in materials of periodic interfaces on a macroscopic scale (phononic crystal) [10,16,17,18]. Depending on the actual design and the contrast of properties between the materials on the two sides of the interface, acoustic filters or guides have successfully been built [6,19,20,21,22].…”

Section: Introductionmentioning

confidence: 99%

Thermal Transport in a 2D Nanophononic Solid: Role of bi-Phasic Materials Properties on Acoustic Attenuation and Thermal Diffusivity

et al. 2019

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Nanophononic materials have recently arisen as a promising way for controlling heat transport, mirroring the results in macroscopic phononic materials for sound transmission, filtering and attenuation applications. Here we present a Finite Element numerical simulation of the transient propagation of an acoustic Wave-Packet in a 2D nanophononic material, which allows to identify the effect of the nanostructuration on the acoustic attenuation length and thus on the transport regime for the vibrational energy. Assuming elastic behavior in the matrix and in the inclusions, we find that the rigidity contrast between them not only tunes the apparent attenuation length of the wave packet along its main trajectory, but gives rise to different behaviours, from weak to strong scattering, and waves pinning. As a consequence, different energy transport regimes can be identified in the three-parameter space of the excitation frequency, inclusions size and rigidity contrast, leading to the identification of a combination of parameters allowing for the shortest attenuation distance. These results could have applications both in the field of acoustic insulation, and for the control of heat transfer.

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“…In nanowires parallel to the direction of interest, if scattering is fully diffuse, there is only 50% chance for each scattered phonon to go back (backscattering); while at the crossings with the perpendicular nanowires, which do not contribute to heat transport in the direction of measurement, phonons colliding with the walls are necessarily scattered backward. Moreover, it has been shown that free surfaces modeled in Molecular Dynamics have a great specularity, even at room temperature [28]. In 3 the case of fully specular walls, nanowires parallel to the heat flux are supposed not to be resistive at all, while perpendicular nanowires would lead to 100% of backscattering.…”

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confidence: 99%

Thermal transport in two- and three-dimensional nanowire networks

2018

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We report on thermal transport properties in 2 and 3 dimensions interconnected nanowire networks (strings and nodes). The thermal conductivity of these nanostructures decreases in increasing the distance of the nodes, reaching ultra-low values. This effect is much more pronounced in 3D networks due to increased porosity, surface to volume ratio and the enhanced backscattering at 3D nodes compared to 2D nodes. We propose a model to estimate the thermal resistance related to the 2D and 3D interconnections in order to provide an analytic description of thermal conductivity of such nanowire networks; the latter is in good agreement with Molecular Dynamic results.New innovating and hightly sophisticated architectured nanostructures are now feasible with the rapid evolution of the elaboration methods [1][2][3][4]. Among them 2D and 3D networks of nanowires are a new class of nanostructured materials with interesting mechanical, optical, electronic and thermal properties. 2D networks are proposed as optoelectronic or biological devices and sensors due to their mechanical strength and flexibility [4]. Furthermore, 2D or 3D ordered or disordered networks could be useful for complex integrated nanoelectronic circuits [5]. Independently of their application, their main characteristics are the extremely low mass density, the high surface to volume ratio as well as high porosity and their remarkable mechanical properties. In the literature, 3D networks have been elaborated during the last decade at the nanoscale with several different materials (silver [6], manganese dioxide [7] or silicon [8,9]).There are three main fields of applications for silicon nanowire (NW) networks and nanomeshes. (i) Thermoelectricity (TE): The huge porosity and surface-tovolume ratio of such nanostructures reduce strongly their lattice thermal conductivity (TC), making Si NW networks promising candidate for TE applications [10][11][12][13].(ii) Transistors: These systems can be easily integrated in nanoelectronic devices (Si compatible) and could be the next generation of transistors thanks to their high density of nanowire interconnections [14][15][16]. (iii) Catalysis: Nanowire networks are interesting for catalysis applications because of their large surface-to-volume ratio that allows improved efficiency of chemical reactions. Furthermore, their strong mechanical robustness as compared to isolated nanowires or nanoparticles make them interesting candidates to practically achieved all these innovative applications [1,17].Concerning the thermal properties of nanostructures, they have attracted high attention for various applications in the fields of microelectronics, optoelectronics and energy harvesting. Nanoscale heat transfer is known to diverge from classical physics [18], especially in semi- * Konstantinos.Termentzidis@insa-lyon.fr conductors where heat is mostly carried by lattice vibrations (phonons). Interestingly, nano-structuration usually reduces the TC due to boundary scattering while the electrical properties could be preserved [19]....

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Influence of amorphous layers on the thermal conductivity of phononic crystals

Cited by 15 publications

References 54 publications

Radial dependence of thermal transport in silicon nanowires

Radial dependence of thermal transport in silicon nanowires

Thermal Transport in a 2D Nanophononic Solid: Role of bi-Phasic Materials Properties on Acoustic Attenuation and Thermal Diffusivity

Thermal transport in two- and three-dimensional nanowire networks

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