Related papers: Three-dimensional phonon population anisotropy in …
We develop a computational framework, based on the Boltzmann transport equation, with the ability to compute the thermal transport in nanostructured materials of any geometry using as the only input the bulk thermal conductivity…
Materials with very low thermal conductivity are of high interest for both thermoelectric and optical phase-change applications. Synthetic nanostructuring is most promising to suppress thermal conductivity by scattering phonons, but…
We study the effect of confinement on the phonon properties of ultra-narrow silicon nanowires of side sizes of 1-10nm . We use the modified valence force field method to compute the phononic dispersion, and extract the density of states,…
Vibrations in materials and nanostructures at sufficiently high temperatures result in anharmonic atomic displacements, which leads to new phenomena such as thermal expansion and multiphonon scattering processes, with a profound impact on…
The interaction between light and acoustic phonons is strongly modified in sub-wavelength confinement, and has led to the demonstration and control of Brillouin scattering in photonic structures such as nano-scale optical waveguides and…
There is still a gap in understanding phonons scattering by geometrical defects at the nanoscale, and it remains a significant challenge for heat transfer management in nanoscale devices and systems. In this study, we aim to explore the…
This computational research study analyzes the increase of the specific charge capacity that comes with the reduction of the anisotropic volume expansion during lithium ion insertion within silicon nanowires. This research paper is a…
Porous materials provide a large surface to volume ratio, thereby providing a knob to alter fundamental properties in unprecedented ways. In thermal transport, porous nanomaterials can reduce thermal conductivity by not only enhancing…
We calculate low-frequency Raman scattering from the confined acoustic phonon modes of CdS1-xSex nanoparticles embedded in borosilicate glass. The calculation of the Raman scattering by acoustic phonons in nanoparticles has been performed…
The nanocrystallite have the finite number of the oscillation modes. Their number increases proportionally to a cube of the characteristic size. Thus the oscillation spectrum of nanocrystal becomes discrete, and the separate modes of…
Nanostructuring on length scales corresponding to phonon mean free paths provides control over heat flow in semiconductors and makes it possible to engineer their thermal properties. However, the influence of boundaries limits the validity…
Because of high surface-to-volume ratio, the most prominent size effect limiting thermal transport originates from phonon-surface scattering in nanostructures. Herein we propose the mechanism of phonon scattering by the bond strength…
Nanoporous materials are of broad interest for various applications, in particular advanced thermoelectric materials. The introduction of nanoscale porosity, even at modest levels, has been known to drastically reduce a materials thermal…
Metamaterials are structures engineered at a small scale with respect to the wavelength of the excitations they interact with. These structures behave as artificial materials whose properties can be chosen by design, mocking and even…
We study the relaxation of coherent acoustic phonon modes with frequencies up to 500 GHz in ultra-thin free-standing silicon membranes. Using an ultrafast pump-probe technique of asynchronous optical sampling, we observe that the decay time…
The thermal conductivity of nanostructures needs to be as small as possible so that it will have a greater efficiency for solid-state electricity generation/refrigeration by thermoelectrics. We studied how the period length and the mass…
We have observed a softening of phonons and a structural phase transition in a superconducting Ba0.59K0.41BiO3 (Tc = 31 K) single crystal using elastic and inelastic neutron scattering measurements. The soft phonon occurs for the [111]…
We present atomistic valence force field calculations of thermal transport in Si nanowires of diameters from 12nm down to 1nm. We show that as the diameter is reduced, the phonon density-of-states and transmission function acquire a finite…
This study presents a comprehensive computational investigation of magnetite nanoparticles, systematically evaluating a range of force fields against experimental results. We analyze the influence of particle size, temperature, and…
A study of the transverse acoustic phonons on nano-structured AlN films has been carried out by using high-resolution micro-Brillouin spectroscopy. Dense films have been deposited by radio frequency (r.f.) magnetron sputtering under ultra…