The Yablonovite Structure as a Three-Dimensional Phononic Crystal

2019 ◽  
Vol 11 (3) ◽  
pp. 198-203 ◽  
Author(s):  
A. Konstantopoulou ◽  
N. Aravantinos-Zafiris ◽  
M.M. Sigalas
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional

Thermal Design of Highly-Efficient Thermoelectric Materials With Atomic-Scale Three-Dimensional Phononic Crystals

2007 ◽  
Author(s):  
Jean-Numa Gillet ◽  
Yann Chalopin ◽  
Sebastian Volz
Keyword(s):  
Thermal Conductivity ◽  
Bulk Material ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Mean Free Path ◽  
Dispersion Curves ◽  
Phononic Crystals ◽  
Thermal Design ◽  
Atomic Scale ◽  
Thermal Insulating

Owing to their thermal insulating properties, superlattices have been extensively studied. A breakthrough in the performance of thermoelectric devices was achieved by using superlattice materials. The problem of those nanostructured materials is that they mainly affect heat transfer in only one direction. In this paper, the concept of canceling heat conduction in the three spatial directions by using atomic-scale three-dimensional (3D) phononic crystals is explored. A period of our atomic-scale 3D phononic crystal is made up of a large number of diamond-like cells of silicon atoms, which form a square supercell. At the center of each supercell, we substitute a smaller number of Si diamond-like cells by other diamond-like cells, which are composed of germanium atoms. This elementary heterostructure is periodically repeated to form a Si/Ge 3D nanostructure. To obtain different atomic configurations of the phononic crystal, the number of Ge diamond-like cells at the center of each supercell can be varied by substitution of Si diamond-like cells. The dispersion curves of those atomic configurations can be computed by lattice dynamics. With a general equation, the thermal conductivity of our atomic-scale 3D phononic crystal can be derived from the dispersion curves. The thermal conductivity can be reduced by at least one order of magnitude in an atomic-scale 3D phononic crystal compared to a bulk material. This reduction is due to the decrease of the phonon group velocities without taking into account that of the phonon average mean free path.

scholarly journals Three-dimensional phononic crystal with ultra-wide bandgap at megahertz frequencies

2021 ◽  
Vol 118 (6) ◽  
pp. 063507
Author(s):  
Julio Andrés Iglesias Martínez ◽  
Johnny Moughames ◽  
Gwenn Ulliac ◽  
Muamer Kadic ◽  
Vincent Laude
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Wide Bandgap

Three-Dimensional Silicon Phononic Crystal

2013 ◽  
Vol 50 (6) ◽  
pp. 51-54
Author(s):  
Y.-K. Lin ◽  
H.-W. Ting ◽  
L.-J. Chou ◽  
L.-J. Chen
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional

Atomic-Scale Three-Dimensional Phononic Crystals With a Large Thermoelectric Figure of Merit

2008 ◽  
Author(s):  
Jean-Numa Gillet ◽  
Sebastian Volz
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Phononic Crystals ◽  
Atomic Scale ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Low Thermal Conductivity ◽  
Cmos Compatible

The design of thermoelectric materials led to extensive research on superlattices with a low thermal conductivity. Indeed, the thermoelectric figure of merit ZT varies with the inverse of the thermal conductivity but is directly proportional to the power factor. Unfortunately, as nanowires, superlattices cancel heat conduction in only one main direction. Moreover they often show dislocations owing to lattice mismatches, which reduces their electrical conductivity and avoids a ZT larger than unity. Self-assembly is a major epitaxial technology to design ultradense arrays of germanium quantum dots (QDs) in silicon for many promising electronic and photonic applications as quantum computing. Accurate positioning of the self-assembled QD can now be achieved with few dislocations. We theoretically demonstrate that high-density three-dimensional (3-D) arrays of self-assembled Ge QDs, with a size of only some nanometers, in a Si matrix can also show an ultra-low thermal conductivity in the three spatial directions. This property can be considered to design new CMOS-compatible thermoelectric devices. To obtain a realistic and computationally-manageable model of these nanomaterials, we simulate their thermal behavior with atomic-scale 3-D phononic crystals. A phononic-crystal period (supercell) consists of diamond-like Si cells. At each supercell center, we substitute Si atoms by Ge atoms to form a box-like nanoparticle. Since this phononic crystal is periodic, we compute its phonon dispersion curves by classical lattice dynamics. Non-periodicities can be introduced with statistical distributions. From the flat dispersion curves, we obtain very small group velocities; this reduces the thermal conductivity in our phononic crystal compared to bulk Si. However, owing to the wave-particle duality at very small scales in quantum mechanics, another reduction arises from multiple scattering of the particle-like phonons in nanoparticle clusters. At room temperature, the thermal conductivity in an example phononic crystal can be reduced by a factor of at least 165 compared to bulk Si or below 0.95 W/mK. This value, which is lower than the classical Einstein limit of single crystalline Si, is an upper limit of the thermal conductivity since we use an incoherent-scattering approach for the nanoparticles. Because of its very low thermal conductivity, we hope to obtain a much larger ZT than unity in our atomic-scale 3-D phononic crystal. Indeed, this silicon-based nanomaterial is crystalline with a power factor that can be optimized by doping using CMOS-compatible processes. Future research on the phononic-crystal electrical conductivity has to be performed in order to compute the full ZT with a good accuracy.

scholarly journals Synthetic Weyl Points of the Shear Horizontal Guided Waves in One-Dimensional Phononic Crystal Plates

2021 ◽  
Vol 12 (1) ◽  
pp. 167
Author(s):  
Hongbo Zhang ◽  
Shaobo Zhang ◽  
Jiang Liu ◽  
Bilong Liu
Keyword(s):  
Guided Waves ◽  
Dimensional Space ◽  
Phononic Crystal ◽  
Phase Interface ◽  
Three Dimensional ◽  
Interface States ◽  
Geometrical Parameters ◽  
One Dimensional ◽  
Higher Dimensional ◽  
Shear Horizontal

Weyl physics in acoustic and elastic systems has drawn extensive attention. In this paper, Weyl points of shear horizontal guided waves are realized by one-dimensional phononic crystal plates, in which one physical dimension plus two geometrical parameters constitute a synthetic three-dimensional space. Based on the finite element method, we have not only observed the synthetic Weyl points but also explored the Weyl interface states and the reflection phase vortices, which have further proved the topological phase interface states. As the first realization of three-dimensional topological phases through one-dimensional phononic crystal plates in the synthetic dimension, this research demonstrates the great potential of applicable one-dimensional plate structural systems in detecting higher-dimensional topological phenomena.

scholarly journals Study on a Large-Scale Three-Dimensional Ultrasonic Plastic Welding Vibration System Based on a Quasi-Periodic Phononic Crystal Structure

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 21 ◽  
Author(s):  
Jiyan Lin ◽  
Shuyu Lin
Keyword(s):  
Crystal Structure ◽  
Large Scale ◽  
Design Method ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Amplitude Distribution ◽  
Vibration System ◽  
Output Amplitude ◽  
Welding Surface ◽  
Plastic Welding

The uniformity of amplitude distribution and amplitude gain are two main factors affecting the performance of ultrasonic welding vibration system. In order to improve the uniformity of amplitude distribution and amplitude gain of welding surface to enhance the performance of the vibration system, a new design method of a large-scale three-dimensional ultrasonic plastic welding vibration system based on a quasi-periodic phononic crystal structure is proposed. In this method, the composite horn combined with a conical section and a cylindrical section can effectively improve the output amplitude gain of the welding surface. In addition, the method forms a quasi-periodic phononic crystal structure by slotting in a large-scale three-dimensional tool head, and utilizes the band gap property of the structure to effectively suppress lateral vibration of the tool head and improve the amplitude distribution uniformity of the tool head’s welding surface. However, when the size of the tool head is relatively large, the quasi-periodic phononic crystal structure cannot suppress the lateral vibration very well. Therefore, the paper processes fan-shaped slopes on the output surface of the tool head which can further improve the uniformity of the amplitude distribution and amplitude gain. Finally, the simulation analysis and experiments show that the design method can optimize the large-scale three-dimensional ultrasonic plastic welding system, improve the uniformity of the vibration distribution and increase the output amplitude gain of the welding surface.

The low-frequency bandgap characteristics of a new three-dimensional multihole phononic crystal

2021 ◽  
Vol 127 (11) ◽  
Author(s):  
Gang-Gang Xu ◽  
Xiao-Wei Sun ◽  
Ren-Sheng Li ◽  
Zheng-Rong Zhang ◽  
Ting Song ◽  
...  
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Low Frequency

A Heuristic Model for Estimating the Lowest Gap of Locally Resonant Phononic Crystals

2005 ◽  
Author(s):  
Yaozong Liu ◽  
Lihui Shao ◽  
Gang Wang ◽  
Dianlong Yu
Keyword(s):  
Multiple Scattering ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Phononic Crystals ◽  
Scattering Method ◽  
Heuristic Model ◽  
Material Parameters ◽  
Resonance Modes ◽  
Simple Mass ◽  
Multiple Scattering Method

The influences of the constituent material parameters of the three-dimensional locally resonant phononic crystal on the lower and upper edge frequencies of its lowest gap are investigated with the Multiple-scattering theory. It is found that the frequency dependence on those parameters can be well reproduced by a simple mass-spring model, which manifests the physical essence of the resonance modes determining the edge frequencies of the gap. Since the equivalent mass and stiffness of the model can be determined from the material parameters and structure size in one unit cell, the lower and upper edge frequencies of the lowest gap of locally resonant phononic crystals can be estimated from this model analytically. Comparison between the analytical estimations and the numerical results calculating with multiple scattering method shows very good agreement. The proposed heuristic model lends itself to understand the locally resonant mechanism more clearly. The frequency estimating formulas induced from the model allow one to predict the edge frequencies of the lowest gap, which simplifies the design process of locally resonant phononic crystals.

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