Thermal Conductivity of VO2 Nanowires at Metal-Insulator Transition Temperature

Vanadium dioxide (VO2) nanowires endowed with a dramatic metal−insulator transition have attracted enormous attention. Here, the thermal conductance of VO2 nanowires with different sizes, measured using the thermal bridge method, is reported. A size-dependent thermal conductivity was observed where the thicker nanowire showed a higher thermal conductivity. Meanwhile, the thermal conductivity jump at metal−insulator transition temperature was measured to be much higher in the thicker samples. The dominant heat carriers were phonons both at the metallic and the insulating regimes in the measured samples, which may result from the coexistence of metal and insulator phases at high temperature. Our results provide a window into exploring the mechanism of the metal−insulator transition of VO2 nanowires.

Synthesis and Antioxidant Behavior of Carbon-Coated Copper Nanoparticles

We use plasma method syntheisized Carbon coated copper nanoparticles The structure , size distribution and phase composition of the particles were analysised by TEM , XRD and DSC. Meanwhile, The conductivity of carbon-coated copper nanoparticles were measured. Results show that Carbon coated copper nanoparticles were core-shell structure for the copper core inside, the multi carbon layer outside, around the copper core is graphite-like carbon and far away from the copper core is amorphous carbon. While carbon-coated copper nanoparticles at room temperature and high temperatures have shown good oxidation resistance; The conductivity of carbon-coated copper nanoparticles with metal content increases and when the copper content is 80% the conductivity jump.