We report measurements and modeling of thermal conductivity in periodic three-dimensional dielectric nanostructures, silicon inverse opals. Such structures represent a three-dimensional "phononic crystal" but affect heat flow instead of acoustics. Employing the Stober method, we fabricate high quality silica opal templates that on filling with amorphous silicon, etching and recrystallizing prod...

Thermal conductivity of superconducting MgB 2 was studied in both the superconducting and the normal state region. The latter is almost equally determined by the electronic-and the lattice contribution to the total thermal conductivity. In the superconducting state, however, the lattice contribution is larger. The electronic thermal conductivity below T c was derived from the experimental data ...

The layered Zintl compound SrZnSb2 is investigated using transmission electron microscopy (TEM) to understand the low lattice thermal conductivity. The material displays out-of-phase boundaries with a spacing from 100 down to 2 nm. Density functional theory calculations confirm that the TEM-derived defect structure is energetically reasonable. The impact of these defects on phonon scattering is...

The electronic conductivity of a gold nanoparticle dropcast film was examined by temperature-modulated scanning tunneling spectroscopy (STS). The low-conductance Coulomb blockade was found to shrink with increasing temperature, which at ambient temperature (ca. 290 K) diminished completely. Concomitantly, the potential spacing between adjacent peaks observed in the Coulomb staircase features ex...

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We show evidence of electrical and thermal conductivity percolation in polymer based carbon nanotube (CNT) composites, which follow power law variations with respect to the CNT concentrations in the matrix. The experimentally obtained percolation thresholds, i.e., ~ 0.074 vol % for single walled CNTs and ~ 2.0 vol % for multi-walled CNTs, were found to be aspect ratio dependent and in accordanc...

The thermal conductivity, thermal diffusivity and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan have been measured simultaneously using transient plane source technique. The temperature dependence of thermal transport properties is studied in the temperature range 83-303 K. Different relations for the estimation of thermal conductivity are also tested. T...

in this paper, wavelet collocation method has been used to solve nonlinear fin problem with temperature dependent thermal conductivity and heat transfer coefficient. thermal conductivity of fin materials varies any type so that we consider thermal conductivity as the general function of temperature.  here we consider three particular cases, where we assume that thermal conductivity is constant,...

The increasing worldwide energy consumption calls for the design of more efficient energy systems. Thermoelectrics could be used to convert waste heat back to useful electric energy if only more efficient materials were available. The ideal thermoelectric material combines high electrical conductivity and thermopower with low thermal conductivity. In this regard, the intermetallic type-I clathr...