Ce-C共掺SnO2导电性能和力学性质的第一性原理研究

AgSnO2触头材料由于优异的性能成为代替AgCdO的电接触材料之一，但由于SnO2导电性能较差以及硬度大，会使材料变脆，容易形成裂纹，降低了AgSnO2触头的使用寿命。本文采用基于密度泛函理论的第一性原理方法，研究了稀土元素Ce和C单掺杂以及共掺杂SnO2的导电性能和力学性质的理论计算。通过超晶胞结构优化后的能量计算，得到了超晶胞的晶格常数、掺杂形成能、能带结构、态密度、弹性常数和德拜温度。结果表明：通过掺杂后的带隙值减小，增加了杂化轨道，能够提高SnO2的导电性能以及改善SnO2的脆韧性，从而改善AgSnO2触头的成型和使用寿命。相对于Ce、C单掺杂，Ce-C共掺杂时的电子有效质量减小，并且带隙宽度变窄，Ce-C共掺杂SnO2的导电性能更好，硬度的改善更大。

First-principles study on the electrical and mechanical properties of Ce-C co-doped SnO2

AgSnO2 contact material has become one of the electrical contact materials to replace AgCdO because of its excellent performance. However, because of the poor electrical conductivity and high hardness of SnO2, the material will become brittle and easy to form cracks, which reduces service life of AgSnO2 contacts. In this paper, the first-principles method based on density functional theory is used to study the theoretical calculations of the electrical conductivity and mechanical properties of the rare earth elements Ce and C single-doped and co-doped SnO2. Through the energy calculation after the supercell structure is optimized, the lattice constant, doping formation energy, band structure, density of state, elastic constant and Debye temperature of the supercell are obtained. The results show that by reducing the band gap value after doping and increasing the hybrid orbit, the conductivity of SnO2 and the brittleness and toughness of SnO2 can be improved, thereby improving the forming and service life of AgSnO2 contacts. Compared with Ce and C single doping, the effective electronic mass of Ce-C co-doping is reduced, and the band gap width is narrowed. Ce-C co-doping SnO2 has better conductivity and greater improvement in hardness.