Thermal conductivity of Si/Ge nanocomposites with fractal tree-shaped networks by considering the phonon interface scattering

Chen, Yongping; Deng, Zilong; Cheng, Qiuming

doi:10.1016/j.ijheatmasstransfer.2015.04.093

“…Figure 3 d shows the near-linear decrease in the computed thermal conductivity of the three periodic heterostructures as a function of interfacial density, as seen in other semiconducting systems like Si–Ge 22 , 58 . It can be observed that the computed for the third-level fractal falls in line with the trend predicted by the periodic heterostructures.…”

Section: Resultsmentioning

confidence: 65%

“…Alloying modifies thermal transport in materials by affecting one or more of the following material parameters -crystal structure, atomic mass 13 , inter-atomic bonding and anharmonicity 14,15 and is effective in scattering high-frequency phonons 5 . Formation of interfaces and superlattice structures in nanomaterials are very promising for controlling phonon scattering, particularly for low frequency phonons over 1-2 THz [16][17][18][19][20] . Scale-invariant fractal patterning, which results in features of multiple sizes, are widely pursued to affect phonons over a wide range of frequencies and mean free paths 21 .…”

Section: Introductionmentioning

confidence: 99%

Lattice thermal transport in two-dimensional alloys and fractal heterostructures

Krishnamoorthy

¹

,

Baradwaj

²

,

Nakano

³

et al. 2021

Sci Rep

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Engineering thermal transport in two dimensional materials, alloys and heterostructures is critical for the design of next-generation flexible optoelectronic and energy harvesting devices. Direct experimental characterization of lattice thermal conductivity in these ultra-thin systems is challenging and the impact of dopant atoms and hetero-phase interfaces, introduced unintentionally during synthesis or as part of deliberate material design, on thermal transport properties is not understood. Here, we use non-equilibrium molecular dynamics simulations to calculate lattice thermal conductivity of $${\mathrm {(Mo|W)Se_2}}$$ ( Mo | W ) Se 2 monolayer crystals including $${\mathrm {Mo}}_{1-x}{\mathrm {W}}_x{\mathrm {Se_2}}$$ Mo 1 - x W x Se 2 alloys with substitutional point defects, periodic $${\mathrm {MoSe_2}|\mathrm {WSe_2}}$$ MoSe 2 | WSe 2 heterostructures with characteristic length scales and scale-free fractal $${\mathrm {MoSe_2}}|{\mathrm {WSe_2}}$$ MoSe 2 | WSe 2 heterostructures. Each of these features has a distinct effect on phonon propagation in the crystal, which can be used to design fractal and periodic alloy structures with highly tunable thermal conductivities. This control over lattice thermal conductivity will enable applications ranging from thermal barriers to thermoelectrics.

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“…Generally, there are four factors impacting the thermal conductivity of nanocomposites [34][35][36][37] : (1) the intrinsic thermal conductivity of the polymer material, K m ;…”

Section: Resultsmentioning

confidence: 99%

“…Generally, there are four factors impacting the thermal conductivity of nanocomposites [ 34–37 ] : (1) the intrinsic thermal conductivity of the polymer material, K m ; (2) the intrinsic thermal conductivity of the nanofiller, K f ; (3) interfacial thermal resistance between the polymer matrix and the inorganic filler, R 1 ; (4) thermal contact resistance between nanofillers, R 2 . At low‐filling content, the thermal resistance between polymer matrix and inorganic filler is an important factor limiting the improvement of thermal conductivity because the filler cannot be connected to each other to form a thermal conduction path.…”

Section: Resultsmentioning

confidence: 99%

Polymer‐based nanocomposites with ultra‐high in‐plane thermal conductivity via highly oriented boron nitride nanosheets

Gou

¹

,

Xu

²

,

Zhou

³

et al. 2022

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Novel polymer‐based materials with highly thermally conductive and high‐mechanical properties have attracted extensive attention in the field of electronic packaging as thermal interface materials (TIMs), due to the development of electronic equipment to miniaturization and higher power density. However, how to achieve high‐thermal conductivity (exceed 5 W/m·K) with low‐filling content (below 30 vol%) is still the focus of attention. Herein, polymer‐based materials with excellent in‐plane thermal conductivity were prepared by a simple hot‐pressing strategy, and a series of nanocomposites with different orientations were controlled by the hot‐pressing times. As expected, compared with that of randomly dispersed 25 vol% BNNS/P(VDF‐HFP) nanocomposite and pristine P(VDF‐HFP), the in‐plane thermal conductivity of oriented 25 vol% BNNS/P(VDF‐HFP) is promoted by 249% and 3057%, respectively. In contrast to randomly dispersed composites, oriented BNNS/P(VDF‐HFP) at loadings above 10 vol% begin to show an encouraging upward trend. This is because the orientation of BNNS can significantly reduce the percolation threshold and construct an efficient heat conduction network under low‐filling volume. Therefore, this technology can provide new ideas for the development of electronic packaging technology.

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“…The larger the fractal dimension of microcracks, the more disordered the distribution of microcracks on the material surface, which is conducive to the formation of a transfer film on the dual surface of the composite material, and helps to improve wear resistance; the greater the fractal dimension of microcracks, the more disordered the distribution of microcracks on the surface of materials, the tensile fracture of materials gradually changes from ductile fracture to brittle fracture, resulting in the decrease of tensile properties of materials. The effect of fractal dimension and branch number on thermal conductivity of Si/Ge nanocomposites with fractal tree network was studied by the molecular dynamics simulation method, the Si/Ge nanocomposites with fractal tree network had greater length and width, fractal dimension and more branch layers than other Si/Ge nanocomposites; the sub interface scattering is stronger, and the fractal tree network is better than the traditional rectangular core structure in reducing the thermal conductivity of nanocomposites [ 83 ]. The structural stability and properties of the dispersed filled polymer were analyzed by using the macro structure image processing results based on the texture method and multifractal method [ 84 ].…”

Section: Properties and Fractal Of Polymers And Their Composites Imentioning

confidence: 99%

Review about the Application of Fractal Theory in the Research of Packaging Materials

Duan

¹

,

An

²

,

Mao

³

et al. 2021

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The work is intended to summarize the recent progress in the work of fractal theory in packaging material to provide important insights into applied research on fractal in packaging materials. The fractal analysis methods employed for inorganic materials such as metal alloys and ceramics, polymers, and their composites are reviewed from the aspects of fractal feature extraction and fractal dimension calculation methods. Through the fractal dimension of packaging materials and the fractal in their preparation process, the relationship between the fractal characteristic parameters and the properties of packaging materials is discussed. The fractal analysis method can qualitatively and quantitatively characterize the fractal characteristics, microstructure, and properties of a large number of various types of packaging materials. The method of using fractal theory to probe the preparation and properties of packaging materials is universal; the relationship between the properties of packaging materials and fractal dimension will be a critical trend of fractal theory in the research on properties of packaging materials.

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Thermal conductivity of Si/Ge nanocomposites with fractal tree-shaped networks by considering the phonon interface scattering

Cited by 7 publications

References 26 publications

Lattice thermal transport in two-dimensional alloys and fractal heterostructures

Lattice thermal transport in two-dimensional alloys and fractal heterostructures

Polymer‐based nanocomposites with ultra‐high in‐plane thermal conductivity via highly oriented boron nitride nanosheets

Review about the Application of Fractal Theory in the Research of Packaging Materials

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