Abstract:We present the concept of a locally resonant nanophononic metamaterial for thermoelectric energy conversion. Our configuration, which is based on a silicon thin film with a periodic array of pillars erected on one or two of the free surfaces, qualitatively alters the base thin-film phonon spectrum due to a hybridization mechanism between the pillar local resonances and the underlying atomic lattice dispersion. Using an experimentally fitted lattice-dynamics-based model, we conservatively predict the metamateri… Show more
“…The pioneering works mainly studied how local resonances flatten phonon dispersion and open phononic bandgaps, which can suppress propagation of phonons at gigahertz frequencies. In the past few years, this idea expanded beyond the phononic bandgaps and researchers began dreaming about the suppression of phonons in the terahertz frequency range thus reducing the thermal conductivity of materials [30,32,33,55]. However, the Brillouin light scattering experiments could confirm changes in phonon dispersion only up to a few tens of gigahertz [31,48], which affects only a negligible part of the thermal phonon spectrum at room temperature.…”
Section: Discussionmentioning
confidence: 99%
“…The data show that the pillar height ( t ) has no significant impact, at least for the pillars taller than several angstroms, Recently, Honarvar and Hussein [34] studied the height dependence in more details. They showed that even nanopillars of a few angstroms in height already reduce the thermal conductivity by more than 50%, but as nanopillars become taller this reduction gradually saturates.10.1080/14686996.2018.1542524-F0004Figure 4.Example of a molecular dynamics model of a pillar-based PnC and the dependence of the thermal conductivity normalized by that of a membrane on the pillar height ( t ) found in Refs [33,34,55,58].
…”
Section: Simulations Of Heat Conductionmentioning
confidence: 95%
“…In 2014, Davis and Hussein [55] proposed to use pillar-based PnCs to suppress heat conduction for thermoelectric applications. Using the lattice dynamics simulations, they demonstrated a 50% reduction in thermal conductivity of silicon membranes by adding periodic nanopillars of a few nanometers in size on the surface.…”
Section: Simulations Of Heat Conductionmentioning
confidence: 99%
“…Example of a molecular dynamics model of a pillar-based PnC and the dependence of the thermal conductivity normalized by that of a membrane on the pillar height ( t ) found in Refs [33,34,55,58]. …”
Section: Simulations Of Heat Conductionmentioning
confidence: 99%
“…Usually, researchers tentatively attribute the thermal conductivity reduction to the impact of local resonances on the phonon dispersion [32–34,55,57,58]. Indeed, the occurrence of the local resonances was demonstrated by different simulation techniques [30,38,55,58], and since the local resonances flatten the dispersion branches (Figure 1), the average group velocity becomes lower [32,33,57]. Hence, this effect can be linked to the thermal conductivity reduction.…”
Phononic crystals have been studied for the past decades as a tool to control the propagation of acoustic and mechanical waves. Recently, researchers proposed that nanosized phononic crystals can also control heat conduction and improve the thermoelectric efficiency of silicon by phonon dispersion engineering. In this review, we focus on recent theoretical and experimental advances in phonon and thermal transport engineering using pillar-based phononic crystals. First, we explain the principles of the phonon dispersion engineering and summarize early proof-of-concept experiments. Next, we review recent simulations of thermal transport in pillar-based phononic crystals and seek to uncover the origin of the observed reduction in the thermal conductivity. Finally, we discuss first experimental attempts to observe the predicted thermal conductivity reduction and suggest the directions for future research.
“…The pioneering works mainly studied how local resonances flatten phonon dispersion and open phononic bandgaps, which can suppress propagation of phonons at gigahertz frequencies. In the past few years, this idea expanded beyond the phononic bandgaps and researchers began dreaming about the suppression of phonons in the terahertz frequency range thus reducing the thermal conductivity of materials [30,32,33,55]. However, the Brillouin light scattering experiments could confirm changes in phonon dispersion only up to a few tens of gigahertz [31,48], which affects only a negligible part of the thermal phonon spectrum at room temperature.…”
Section: Discussionmentioning
confidence: 99%
“…The data show that the pillar height ( t ) has no significant impact, at least for the pillars taller than several angstroms, Recently, Honarvar and Hussein [34] studied the height dependence in more details. They showed that even nanopillars of a few angstroms in height already reduce the thermal conductivity by more than 50%, but as nanopillars become taller this reduction gradually saturates.10.1080/14686996.2018.1542524-F0004Figure 4.Example of a molecular dynamics model of a pillar-based PnC and the dependence of the thermal conductivity normalized by that of a membrane on the pillar height ( t ) found in Refs [33,34,55,58].
…”
Section: Simulations Of Heat Conductionmentioning
confidence: 95%
“…In 2014, Davis and Hussein [55] proposed to use pillar-based PnCs to suppress heat conduction for thermoelectric applications. Using the lattice dynamics simulations, they demonstrated a 50% reduction in thermal conductivity of silicon membranes by adding periodic nanopillars of a few nanometers in size on the surface.…”
Section: Simulations Of Heat Conductionmentioning
confidence: 99%
“…Example of a molecular dynamics model of a pillar-based PnC and the dependence of the thermal conductivity normalized by that of a membrane on the pillar height ( t ) found in Refs [33,34,55,58]. …”
Section: Simulations Of Heat Conductionmentioning
confidence: 99%
“…Usually, researchers tentatively attribute the thermal conductivity reduction to the impact of local resonances on the phonon dispersion [32–34,55,57,58]. Indeed, the occurrence of the local resonances was demonstrated by different simulation techniques [30,38,55,58], and since the local resonances flatten the dispersion branches (Figure 1), the average group velocity becomes lower [32,33,57]. Hence, this effect can be linked to the thermal conductivity reduction.…”
Phononic crystals have been studied for the past decades as a tool to control the propagation of acoustic and mechanical waves. Recently, researchers proposed that nanosized phononic crystals can also control heat conduction and improve the thermoelectric efficiency of silicon by phonon dispersion engineering. In this review, we focus on recent theoretical and experimental advances in phonon and thermal transport engineering using pillar-based phononic crystals. First, we explain the principles of the phonon dispersion engineering and summarize early proof-of-concept experiments. Next, we review recent simulations of thermal transport in pillar-based phononic crystals and seek to uncover the origin of the observed reduction in the thermal conductivity. Finally, we discuss first experimental attempts to observe the predicted thermal conductivity reduction and suggest the directions for future research.
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