Research On Electron-phonon Coupling In The Thermal Conductivity Of Nanoparticle Composites

With the rapid development of nanoscience and technology,various kinds of new materials have emerged.Compared with traditional materials,nano-particle composites not only have improved strength but also retain good toughness and plasticity,and also own specific heat transfer performance.These excellent properties are attributed to the addition of nanoparticles,which results in a finer structure of the material and a reduction in self-defects.However,the size of the nanoparticles is smaller than or comparable to the mean free path of the carriers(electron,phonon,photon),so the properties of nano-particle composites are quite different from those of the conventional materials.Therefore,it's our key research direction to study and master the thermal conductivity of new materials.In order to understand better the influence of electron-phonon coupling on the effective thermal conductivity of nanoparticle composites,the two-temperature model of heat conduction is improved.we take 1)the composite material composed by nonmetal nano-particle and metal matrix,and 2)pure nanocrystalline Cu as examples respectively.The effective thermal conductivity of SiC/Al composites(SiC particles are dispersed in aluminum matrix),and nanocrystalline Cu materials(which are considered to be composites composed of grains and grain boundary regions),was studied based on the two-temperature model of heat conduction.The heat transfer process of nanoparticle composites was explored from a new perspective.The effects of interactions between different heat carriers,as well as the effects of interfacial thermal resistance,particle volume fraction and particle size on the effective thermal conductivity were discussed.It is not only essential to reveal the heat transfer mechanism of nano-scale composites and but also provide a way of controlling the thermal conductivity of nano-particle composites.In this paper,the results show that the effect of electron-phonon coupling leads to a reduction of the thermal conductivity,which is compared with the value without considering the electron-phonon coupling.In addition,the grain size effect on thermal conductivity of SiC/Al composites was not obvious,which decreases slightly with the decreasing of particle size.However,the thermal conductivity was influenced strongly by the volume fraction of the particle.When the particle size is in the range of 0-150 nm,the effective thermal conductivity decreases significantly as the particle size increases.The results also show that when the interface thermal resistance is large enough,the effective thermal conductivity of the composite can be lower than the thermal conductivity of the dispersed phase and the matrix We conclude that the thermal transport process of nanoparticle composites is not only affected by the interface thermal resistance but also by the electron-phonon coupling.