(1. 河北大学 电子信息工程学院,保定 071002;
2. 河北大学 计算材料研究中心,保定 071002)
摘 要: 利用基于密度泛函理论的第一性原理超软赝势平面波方法对不同浓度P替位Ti掺杂锐钛矿相TiO2的晶格参数、P电荷布居、能带结构、态密度和吸收光谱进行计算。计算结果表明:随着P掺杂浓度的增加,锐钛矿相TiO2的晶胞体积逐渐减小,但掺杂P原子的电荷布居数基本没有变化;同时禁带宽度逐渐增大,并在价带顶附近引入了掺杂能级,费米能级进入导带,使TiO2呈现半金属特性。随着掺杂浓度的增大,掺杂TiO2在可见光区域吸收逐渐增强,同时吸收带边蓝移程度逐渐增大。本研究中P掺杂锐钛矿相TiO2禁带宽度的计算结果与实验获得的随P掺杂浓度的提高TiO2禁带宽度增大相一致。
关键字: 锐钛矿相TiO2;P掺杂;第一性原理;电子结构
(1. College of Electronic and Informational Engineering, Hebei University, Baoding 071002, China;
2. Research Center for Computational Materials,Hebei University, Baoding 071002, China)
Abstract:The lattice parameters, P charge populations, energy band structures, density of states and absorption spectra of anatase TiO2 doped with different concentrations of P substituting at Ti sites were calculated using the first-principles plane-wave ultra-soft pseudo-potential method based on the density functional theory. The calculated results show that with the increase of P doping concentration, the cell volume of the anatase TiO2 decreases, while the electronic populations of P keep almost unchanged. At the same time, the width of forbidden band gradually becomes larger, impurity levels are introduced near the valence band maximum,and the Fermi level goes into the conduction band, which makes that the TiO2 presents a half metal property. The absorption ability of TiO2 is gradually enhanced in the visible light region and the degree of the absorption edge blue shift becomes larger. The calculated forbidden band widths of the P-doped anatase TiO2 are consistent with the experimental results that, with the increase of P doping concentration, the forbidden band widths are enlarged.
Key words: anatase TiO2; P doping; first-principles; electronic structure