Thermal conductivity of argon-SiO2 cryocrystal nanocomposite

Abstract

The effective thermal conductivity of samples of cryocrystal nanocomposite obtained from argon and SiO 2 nanopowder was determined in the temperature interval 2-35 K using the steady-state method. The thermal conductivity of crystalline argon with nanoparticles of amorphous silica oxide embedded in its structure shows a weak dependence on particle linear dimension in the interval 5-42 nm. The temperature dependence of the thermal conductivity of the nanocomposites can be well approximated by taking into account only the two mechanisms of heat carrier scattering: phonon-phonon interaction in U-processes and scattering of phonons by dislocations. PACS: 65.60 +a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.; 66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves; 63.20.-e Phonons in crystal lattices.

Thermal conductivity of systems with a gap in the phonon spectrum

“…For the thermal conductivity, we use the standard expression [29] κ(T ) = β 2 k B dωg ph (ω)ω 2 D(T, ω)cosh(β ω/2)/4, (8) where β = h/k B T and k B is the Boltzmann constant. To analyze the effect of the gap in the phonon spectrum, we take into account, one after another, additional contributions to the diffusion coefficient D(T, ω), assuming…”

“…In recent years, considerable attention of researchers has been attracted to new complex systems which, though not being amorphous materials, exhibit glass-like thermal properties (the so-called glassy crystals). [1] Such materials include solid alcohols, [2,3] clathrates, [4,5] ferroelectric relaxors (single crystals and ceramics), [6,7] cryocrystal nanocomposite, [8,9] and thermoelectrcs. [10][11][12] Manifestation of glass-like thermal properties in systems of different nature calls for new theoretical models able to explain both their similarities and differences in a unified approach.…”