CoSi_2合金电子结构和光学性质的理论研究  

The theoretical study of electronic structure and optical properties for CoSi_2 alloy

作　　者：张富春[1] 崔红卫[1] 杨延宁[1] 张威虎[1] 

机构地区：[1]延安大学物理与电子信息学院,陕西延安716000

出　　处：《功能材料》2015年第14期14043-14047,共5页Journal of Functional Materials

基　　金：陕西省自然科学基金资助项目(2014JM2-5058);陕西省教育厅自然科学基金资助项目(2013JK0917);延安市科技攻关资助项目(2013-KG03);榆林市产学研资助项目(036);延安大学科研引导资助项目(YDY2014-02)

摘　　要：采用基于密度泛函理论框架的第一性原理计算方法,利用LSDA+U方法计算了CoSi2合金材料的电子结构和光学性质。计算结果表明,CoSi2合金能带结构的导带和价带在费米能级附近存在明显的交叠,表现出半金属特性。随着U值的增加,费米能级处的能级逐渐分裂,导带部分和价带部分分别向高能和低能方向移动,当U=8时,CoSi2合金出现自旋劈裂现象。电荷密度计算结果显示Co—Si键是一种以共价键为主且含有部分离子键成分的混合价合金材料,载流子具有明显的由Si原子向Co原子的电荷转移特性。光学吸收谱分析表明,随着U值的增大,CoSi2材料的吸收峰发生蓝移现象,吸收峰强度逐渐减弱。这些结果表明,CoSi2合金材料是一种很好的具有一定发光性能的热电材料。The electronic structure and optical properties of CoSi2 alloy materials,were calculated by using the first-principles based on the framework of density functional theory(DFT).The calculated results revealed that there was an obvious overlap between the conduction bands and valence bands,which showed the half-metal characteristics.With increase of the U values,the energy levels near the Fermi level were gradually split apart,the conduction and valence band shifted to the high and low energy,respectively.When U value was equal to8.0eV,CoSi2 alloy appeared spin-splitting phenomenon.The calculated results of charge density showed that the Co-Si bonds were mainly composed of covalent bond and part of ionic bond,which was a kind of mixed valence alloy material.Moreover,the most notable character in the CoSi2 alloy was the charge transmission from Si atoms to Co.The optical absorption spectra showed that the absorption peaks have a blue-shift,and the intensity of absorption spectra weakened with the increases of the Hubbard U values.These results indicated that CoSi2 alloy was a good thermoelectric material with certain luminescence properties.

关 键 词：CoSi2合金 HubbardU 电子结构 光学性质 

分 类 号：TB01[一般工业技术]