First-principles Study On Thermal Conductivity Of AgSnO₂ Contact Materials By Metal Doping

The electrical contacts of the switching appliance assume the task of making and breaking the circuit.In order to improve the electrical conductivity of contact materials,many scholars usually adopt the method of doping rare earth elements on SnO₂powder to study the effect of doping.It is found that the band gap of the material decreases,and the energy required for the carriers to be excited from the valence band to the conduction band is reduced,which greatly improves the conductivity of SnO₂.And on this basis,doping SnO₂materials by single-doping and co-doping rare earth elements,then the cell structure was optimized,and the influence of doping on the thermal conductivity of AgSnO₂contact material was compared and analyzed,so as to obtain the crystal with good thermal conductivity in theory and guide the experimental research.Firstly,the first-principles calculation is carried out for the undoped（0%）and single-doped La（12.5%,16.7%,25%,and 50%）elements and the two co-doped La-W（16.7%,25%）SnO₂system.Through the optimization of structure and energy calculation,the related thermal parameters were obtained.The results show that the single-doped La concentration of 25%and the co-doped concentration of 16.7%La-W doped SnO₂crystal structure is more stable and the thermal conductivity is better.Secondly,seven kinds of SnO₂ crystal powders were prepared by sol-gel method and the powders were subjected to XRD test.It was verified that the doped atoms could successfully enter the SnO₂unit cell to form a solid solution,that is,the doping would not change the structure of the SnO₂ crystal.Finally,the AgSnO₂ contact material were prepared by mixing powdered gel SnO₂with Ag powder by powder metallurgy.The thermal conductivity and arcing performance of the AgSnO₂contact material were tested,and the accuracy of simulation calculation results is verified by experimental results.