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Phonon transport in nanocomposites
Author(s) -
Singh Mahi R.,
Guo Jiaohan,
Gumbs Godfrey
Publication year - 2017
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700142
Subject(s) - phonon , thermal conductivity , materials science , nanocomposite , condensed matter physics , refractive index , surface phonon , phonon scattering , relaxation (psychology) , nanoparticle , dielectric , scattering , composite material , nanotechnology , optics , optoelectronics , physics , psychology , social psychology
The transport properties of phonons in a nanocomposite have been investigated in this paper. In our model, the nanocomposite consists of nanoparticles embedded in a host dielectric material. The phonon dispersion relation of the nanocomposite is characterized in terms of a defined phonon refractive index and a filling factor parameter. This phonon refractive index depends on its velocity whereas the filling factor is determined by the diameter of the nanoparticles. Consequently, at zero filling, only the host material is present. Our model calculations also include point defects such as impurities, vacancies and the mass and size variations of nanoparticles. The phonon conductivity is determined by employing the Kubo formulism. We also report our calculated results for the phonon relaxation rates due to point defects and boundaries scattering where the latter is due to phonons interacting with the surface boundaries of nanoparticles and the host material. The thermal conductivity, dispersion relation, velocity, density‐of‐states and relaxation rates of phonons are determined by the filling factor and phonon refractive indices of the nanoparticles. There is a good agreement between our numerical results and the data obtained experimentally for the conductivity of AlN‐polyimide nanocomposite. Our results also demonstrate that as the filling factor is increased the phonon conductivity also increases. Possible applications are new types of nanocomposites with variable thermal conductivity by adjusting the filling factor and refractive indices of the nanoparticle and host material. These nanocomposites may be important components in the fabrication of thermal nanodevices used for heating and cooling.