镧和氧空位掺杂钙钛矿相SrFeO_3的结构分析

Structure Characteristics of La and Oxygen Vacancy Doped Perovskite Phase SrFeO_3

运用第一性原理赝势方法计算纯SrFeO_3,La和氧空位单掺及共掺后SrFeO_3的几何结构和形成能等并进行分析.计算结果表明:只有含本征空位缺陷的LaFeO_3发生了晶胞畸变,La单掺以及La和氧空位 V_O共掺体系只对能量有一定的影响,并且共掺的能量最高,也预示着其具有更高的晶体不稳定性.形成能结果表明含本征空位缺陷 V_O的SrFeO_3最容易形成.能带结构图谱表明费米能级穿过导带呈现n型半导体特征,禁带宽度几乎为0,掺杂后杂质能级显著增多,说明具有大量自由电子,掺杂后的晶体已经非常接近于金属化.

The geometric structure and the formation energy of pure SrFeO3, VO and La atoms doped SrFeO3 system was described by the first-principles method based on the density functional theory. The results show that only the LaFeO3 with intrinsic vacancy defects VO has cell distortion, other doping has only a certain effect on the energy,and the energy of the co-doping is the highest, which also indicates that it has higher crystal instability. The formation energy results show that the intrinsic vacancy defect VO is the easiest to form. The energy band structure diagram shows that Fermi level passes through the conduction band to present n-type semiconductor characteristics,the forbidden band width is almost zero, and the impurity level after doping is obviously increased, the description is provided with a large number of free electronics, and the doped crystal is very close to metallization.