Calculation And Study Of Nano-doping AgSnO₂ Electrical Contact Materials

China has forbidden using AgCdO contact material on the household appliances because of the poisonous element Cd which exists in it. And as the subsititute of AgCdO contact material, AgSnO2 contact material has much more strongpoints, for example, excellent electic arc resistant, stand wear and tear, and well fusion welding resistant and so on. It is replacing the AgCdO material to become the main force in the contact material. But there are also some defects in it, for example, large contact resistance, high temperature rise, difficult to be machined. The main causation is that SnO2 is a kind of wide gap and almost insulated semiconductor, and it makes the resistance of contact increase and then makes the temperature rise higher. So the improvement of the tin oxide's electric conductivity is too impatient to wait. And it has been proved that doping was an effective method to the problems.First of all, we carry out the first principle calculation to the Bi, Cu, Ni, Co, and Ti doping SnO2 respectively. Then combine the semiconductor theory to make the important conclusion abstractly by analyzing the geometric optimization result and the band structure, density of state, electron density difference of the doping system. The conclusion is that all of these doping elements can improve the specific conductance of SnO2, and the best doping ratio is 5% and the best doping element is Bi, the others are Ti, Cu, Ni, Co in turn.According to the calculation result, we adopt the Sol-Gel method to prepare five elements nanometer doping AgSnO2 contacts. The result of test indicates that all of the dopants didn't change the crystal structure of SnO2, and the doping elements can be entered into the crystal lattice. The diameter of the powder is nanometer and the conductivity of SnO2 is improved. The most improvement in conductivity of the doping systems is SnO2-Bi, the others are SnO2-Cu, SnO2-Ti, SnO2-Ni, SnO2-Co in turn, and the most important is that the result of the test is basically inosculate.We prepared five nanometer doping AgSnO2 contacts by powder metallurgic process and test their density, rigidity, strength of compress. Then we compare the performance of AgSnO2 contacts that we prepared to Guo Biao. The result indicated that the performance of our contacts is much better than Guo Biao.