Calculation of the thermal conductivity of zirconium and tungsten

Thermal conductivity measures the efficiency for solid to conduct heat. This property is important when a material is used in a high temperature environment, for instance in a plane engine or in a nuclear reactor. From a fundamental point of view the mechanisms of heat conduction are understood: heat is transported by vibrations in insulators while in metals electrons contribute too. Nevertheless many things remain to be clarified especially for what concerns the variation of thermal conductivity with temperature in metals. Indeed simple models predict that thermal conductivity should be constant or slightly decreasing at high temperature. However some metals exhibit an increase of thermal conductivity with temperature, the origin of which remains unknown. The goal of this internship is to calculate with atomic scale calculations the thermal conductivity of two transition metals : zirconium and tungsten. These two materials have direct applications in the nuclear industry. Indeed zirconium is a coating material for the fuel of usual fission reactors, while tungsten is contemplated as a plasma facing material in fusion reactor. Though chemically rather close, these two metals behave differently regarding thermal conductivity. It slightly decreases in tungsten while it strongly rises in zirconium. The intern will have to calculate the thermal conductivities as a function of temperature of these two metals with a combination of molecular dynamics and electronic structure calculations. One should reproduce the experimental values and from a detailed analysis of the calculated electronic structure explain the difference in behaviour between the two materials. This is therefore a numerical and theoretical internship. An strong background in materials science or solid state physics is required ; some knowledge of computer use (basic practice of linux) would be appreciated. The intership is paid, the exact salary depends on the master and initial diplomas. It will possible to continue as a PhD student in the laboratory Contact : Jean-Paul Crocombette, CEA Saclay, DEN/DMN/SRMP [email protected], http://crocombette.free.fr