3d过渡金属掺杂锐钛矿相TiO_2的第一性原理研究

First-principles study of 3d transition metal-doped anatase

采用基于密度泛函理论的平面波超软赝势方法研究了纯锐钛矿相TiO2及掺杂3d过渡金属TiO2的几何、电子结构及光学性质.计算结果表明掺杂能级的形成主要是掺杂过渡金属3d轨道的贡献,掺杂能级在禁带中的位置是决定TiO2吸收带边能否出现红移的重要因素.Cr,Mn,Fe,Ni,Co,Cu掺杂使TiO2的吸收带边产生红移,并在可见光区有一定的吸收系数;Sc,Zn掺杂使TiO2的吸收带边产生蓝移,但在可见光区有较大的吸收系数;掺V不但使TiO2的吸收带边产生红移,增强了在紫外光区的光吸收,而且在可见光区有非常大的吸收系数.

The geometry,electronic structure and optical properties of pure and 3d transition metals-doped anatase-phase TiO2 were studied by using the plane-wave ultrasoft pseudopotential method based on the density functional theory.The calculations show that the formation of impurity energy level is mainly contributed by 3d orbital of the transition metal doped in TiO2,and the position of impurity energy levels in the band gap is the dominating factor that decides whether the absorption threshold wavelength has a red-shift or not.The doping of Cr,Mn,Fe,Ni,Co and Cu causes the absorption wavelength to red-shift,and the absorption coefficient in the visible light region is increased;whereas the doping of Sc,Zn causes the absorption wavelength to blue-shift,but leads to higher absorption coefficients in the visible region.The doping of V not only causes the absorption wavelength to red-shift and strengthens the absorption in the ultraviolet light region,but also gives rise to extremely big absorption coefficient in the visible region.