H掺杂α-Fe2O3的第一性原理研究  

First-principles calculation for hydrogen-doped hematite

作　　者：石瑜[1] 白洋[1] 莫丽玢[1] 向青云[1] 黄亚丽[1] 曹江利[1] 

机构地区：[1]北京科技大学,新材料技术研究院,北京100083

出　　处：《物理学报》2015年第11期324-329,共6页Acta Physica Sinica

基　　金：中央高校基本科研经费专项资金(批准号:FRF-SD-12-027A,FRF-TP-13-047);新世纪优秀人才支持计划(批准号:NCET-12-0778);科技部创新方法工作专项项目(批准号:2012IM030500)资助的课题~~

摘　　要：α-Fe2O3是一种重要的磁性半导体材料,在电子器件中应用广泛,具有重要的研究意义.本文基于密度泛函理论,采用GGA+U方法,应用第一性原理对间隙H掺杂前后的六方相α-Fe2O3的晶格常数、态密度、Bader电荷分布进行了计算分析.研究了U值对结果的影响,发现U=6 eV时,体相α-Fe2O3的晶胞平衡体积、Fe原子磁矩、带隙值与实验值最符合.在选取合适U值后,第一性原理计算结果表明,H掺杂后,间隙H部分被氧化,其最近邻的Fe和O部分被还原,H和O有一定程度的成键.在费米面附近,出现了新的杂化能级,杂化能级扩展了价带顶的宽度,同时导带底下移,引起带隙减小,表明H掺杂是一种有效的能带结构调控方法.Hexagonal α-Fe2O3 is one of the most common functional material used as magnetic semiconductor, and plays an important part in various applications, such as electronic devices etc. Based on the density functional theory, the lattice parameters, density of states and Bader charge analysis ofα-Fe2O3 have been calculated using the first-principles calculation with GGA＋U method. As Fe is a transition metal element, the value of U can be more accurate by considering the influence of the strong on-site Coulomb interaction between 3d electrons. First, the crystal equilibrium volume, the magnetic moment of Fe atom, and the band gap value ofα-Fe2O3 are synthetically researched and compared with those with different U. Results indicate that the calculation model of α-Fe2O3 are in good agreement with the experimental model when the value of U is 6 eV. These parameters can also be adapted to the following doping calculaton. The α-Fe2O3 unit cell has both tetrahedral and octahedral interstitial sites. The calculation of doping formation energy shows that theα-Fe2O3 system is most stable when the doped hydrogen atom is in the tetrahedral interstitial site. The density of states show that the valence band and conduction band compositions are similar for the bulk and hydrogen-dopedα-Fe2O3. That is, the valence bands are dominated mainly by both O 2p and Fe 3d orbitals with the O 2p orbitals playing a leading role, while the conduction band is dominated by Fe 3d orbitals. The band gap of α-Fe2O3 decreases from 2.2 to 1.63 eV after hydrogen doping. Also, a strong hybrid peak occurs near the Fermi level after hydrogen doping, which is chiefly composed of Fe 3d orbital, and the O 2p orbital also has a small contribution. The H 1s orbital is mainly in the lower level below the top valence band. Results of the Bader charge analysis and the density of states calculation for partial correlated atoms suggest that the new hybrid peak is chiefly caused by Fe atom which is closest to the hydrogen atom in the crystal cell. In this

关 键 词：第一性原理 Α-FE2O3 间隙H掺杂 态密度 

分 类 号：O469[理学—凝聚态物理] O483[理学—电子物理学]