第一性原理研究InFeO3和In2FeCrO6的电子结构和光吸收性质

First-principles Study on the Electronic Structure and Optical Absorption Properties of In FeO3 and In2FeCrO6

采用基于第一性原理的密度泛函理论和Hubbard修正方法(DFT+U)计算了多铁材料InFeO3和In2FeCrO6的电子结构和光吸收性质。计算结果表明,Cr掺杂InFeO3的形成能比BiFeO3要低,相对容易完成掺杂,In2FeCrO6带隙宽度相对本征InFeO3没有明显的变化,但能带的色散变小,促进了可见光吸收。通过态密度分析可知,In2FeCrO6中CBM的Fe-3d能级比InFeO3的CBM的Fe-3d能级占据数变小,局域化程度降低,能带变得比较平缓。在InFeO3和In2FeCrO6体系中,Fe和Cr的化合价约为1.7+,Fe-O和Cr-O之间的库伦作用和成键程度差异性不大,导致两者的带隙变化不明显。光吸收谱分析表明,在入射光能量2.1~2.75 eV范围内,Cr的掺入改善了InFeO3的可见光的吸收性能。

The electronic structure and optical absorption properties of InFeO3 and In2FeCrO6 multiferroic materials were calculated by density functional theory based on first principles and Hubbard modification(DFT+U).The calculated results show that the formation energy of Cr doped InFeO3 is lower than that of BiFeO3,and it is relatively easy to be formed.The band gap value of In2FeCrO6 has no obvious change compared with the InFeO3,while the dispersion of energy band decreases,which could lead to promote the absorption of visible light.Through state density analysis,it can be seen that Fe-3d energy level near CBM in In2FeCrO6 become fewer and less localized than the case of InFeO3.In InFeO3 and In2FeCrO6 systems,the valence of Fe and Cr is about 1.7+,which indicate that the coulomb effect and bonding degree between Fe-O and Cr-O is not changed significantly.This could make the band gap values between the InFeO3 and In2FeCrO6 similar.Cr doped InFeO3 can improve the absorption performance of visible light within the range of incident light energy 2.1-2.75 eV by analysis of optical absorption spectrum.