稀土元素掺杂AgSnO2 触头材料的第一性原理理论研究

AgSnO2触头材料中Ag具有良好的导电性,SnO2具有较高的热稳定性.但是,SnO2是惊种宽禁带半导体,近乎绝缘,使得AgSnO2触头材料的电阻较大.通过对SnO2进行掺杂,使SnO2由绝缘改性为导电,能有效改善AgSnO2的电性能.采用第惊性原理研究了稀土元素La、Ce、Nd掺杂后的电子结构,对纯SnO2和掺杂SnO2的晶体结构、能带结构、态密度进行了分析对比.晶格数据表明,稀土元素掺杂SnO2愌起的晶格畸变与掺杂原子的共价半径大小有关.能带结构表明,稀土掺杂可使SnO2的导带向低能端惕动,带隙变窄,即导电性提高,且La掺杂时的带隙最小.电子态密度表明,稀土元素特有的f态电子对费米能级处的导带贡献很大,即稀土元素掺杂能提高AgSnO2触头材料的导电性,且La掺时的费米能级处的态密度值最大.

Theoretical Study on Rare Earth Doped AgSnO2Contact Materials by First-principles

For AgSnO2contact materials, Ag has good electrical conductivity while SnO2has high thermal stability. However, SnO2, despite of a semiconductor with a wide band gap, is nearlya non-conducting compound, leading to an increase in the resistance of AgSnO2. By doping SnO2withother conductive metals,the electrical properties of AgSnO2 can be effectively improved. In the present theoretical study based on the first-principles, the electric structure of SnO2doped with La Ce and Nd was analyzed, and the crystal structure, band structure and density of states of the intrinsic SnO2and doped SnO2, were compared. The crystal structure shows that the lattice distortion caused by the rare earth is related to the covalent radius of the doping atoms. The conduction band of the doped SnO2 shifts to the lower energy level, as indicated by the band structure, resulting in a narrow bad gap and improved electrical conductivity. SnO2 doped with La has a minimum band gap.The density of states reveals that the unique electronic state on f-orbits of the rare earth has a great contribution to the conduction band at the Fermi level.The density of states of La-doped SnO2 is the maximum.