Al掺杂TiO_2基晶体材料电子结构及光学性质的理论研究
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摘要
采用密度泛函理论计算分析的方法系统研究了Al掺杂TiO_2基晶体材料的电子结构和光学性质.结果表明,本征Ti02材料具有直接带隙型能带,其带隙宽度为2.438 eV,Al掺杂TiO_2材料同样具有直接带隙型能带,其带隙宽度降低至2.329 eV.本征TiO_2与Al掺杂的TiO_2材料均含有五个子能带,但是Al掺杂TiO_2材料子能带位置发生改变.Al掺杂在Ti02材料价带中引入大量新的能级,降低了费米能级上的态密度,Al掺杂为n型掺杂.对于Al掺杂TiO_2材料来说,s态电子和p态电子主要在Al掺杂TiO_2材料的带内跃迁过程起较大的作用.Al掺杂的TiO_2材料最强的介电吸收峰在320 nm附近,Al掺杂拓展了TiO_2材料的光吸收范围,其介电吸收能量范围向长波方向移动.本征TiO_2及Al掺杂TiO_2材料在1000 nm以下波长的折射率曲线相似.Al掺杂TiO_2材料在500 nm以下的折射率较本征TiO_2材料降低,而500 nm以上折射率较本征TiO_2材料增大.
The electronic structure and optical properties of the Al-doped TiO_2 crystalline material is investigated by density functional theory calculation method. The results show that the intrinsic TiO_2 has direct energy gap of 2.438 eV, the Al-doped TiO_2 has decreased direct energy gap of 2.329 eV. The intrinsic TiO_2 and the Al-doped TiO_2 both have five sub-bands, but the regions that the sub-band location has changed for the Al-doped TiO_2. The Al has introduced many new bands within the valance bands; the density of states at Fermi level has been also decreased. The Al-doping is n type doping for the TiO_2 material. The s and p electrons contribute to the mobility of carriers within the bands. The dielectric absorption peak of Al-doped TiO_2 locates at 320 nm, the absorption region is widened by Al-doping and the absorption region has moved to long wave light area. Both systems have the similar refractive index curves under 1000 nm. The refractive index of Al-doped TiO_2 is decreased under 500 nm, and it is increased above500 nm comparing with the intrinsic TiO_2.
The electronic structure and optical properties of the Al-doped TiO_2 crystalline material is investigated by density functional theory calculation method. The results show that the intrinsic TiO_2 has direct energy gap of 2.438 eV, the Al-doped TiO_2 has decreased direct energy gap of 2.329 eV. The intrinsic TiO_2 and the Al-doped TiO_2 both have five sub-bands, but the regions that the sub-band location has changed for the Al-doped TiO_2. The Al has introduced many new bands within the valance bands; the density of states at Fermi level has been also decreased. The Al-doping is n type doping for the TiO_2 material. The s and p electrons contribute to the mobility of carriers within the bands. The dielectric absorption peak of Al-doped TiO_2 locates at 320 nm, the absorption region is widened by Al-doping and the absorption region has moved to long wave light area. Both systems have the similar refractive index curves under 1000 nm. The refractive index of Al-doped TiO_2 is decreased under 500 nm, and it is increased above500 nm comparing with the intrinsic TiO_2.
引文
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[2] Roca R A, Guerrero F, Eiras J A, et al. Structural and electrical properties of Li-doped TiO_2 rutile ceramics[J].Ceramics International, 2015, 41:6281-6285.
[3] Anh L T, Rai A K, Thi T V, et al. Improving the electrochemical performance of anatase titanium dioxide by vanadium doping as an anode material for lithium-ion batteries[J].Journal of Power Sources, 2013, 243:891-898.
[4] Meng R J, Hou H Y, Liu X X, et al. Reassessment of the roles of Ag in TiO_2 nanotubes anode material for lithium ion battery[J]. Ceramics International, 2015, 41:9988-9994.
[5] McManamon C, Connell J, Delaney P, et al. A facile route to synthesis of S-doped TiO_2 nanoparticles for photocatalytic activity[J]. Journal of Molecular Catalysis A:Chemical, 2015, 406:51-57.
[6] Li Y, Wang Y, Kong J, et al. Synthesis and characterization of carbon modified TiO_2 nanotube and photocatalytic activity on methylene blue under sunlight[J].Applied Surface Science, 2015, 344:176-180.
[7] Gong Y, Chu R, Xu Z, et al. Electrical propertiesof Ta_2O_5-doped TiO_2 varistor ceramics sintered at lowtemperature[J]. Ceramics International, 2015, 41:9183-9187.
[8] Jiang P, Xiang W, Kuang J, et al. Effect of cobalt doping on the electronic, optical and photocatalytic properties of TiO_2[J]. Solid State Science, 2015, 46:27-32.
[9] Zhao D, Yu Y, Cao C, et al. The existing states of doped B~(3+)ions on the B doped TiO_2[J]. Applied Surface Science, 2015, 345:67-71.
[10] Su D Z, Xu J M, Shao L Y, et al. A study of the calculation of optical constants for SiO_2 by means of Kramers-Kronig relation[J]. Chinese Journal of Infrared Research(红外研究),1986, 5:175-180(in Chinese).
[11] Harada Y, Hoshina K, Inagaki H, et al. Influence of synthesis conditions on crystal formation and electrochemical properties of TiO_2(B)particles as anode materials for lithium-ion batteries[J]. Electrochimica Acta, 2013, 112:310-317.
[12] Payne M C, Teter M P, Allan D C, et al. Iterative minimization techniques for abinitio total-energy calculationsmolecular-dynamics and conjugate gradients[J]. Review of Modern Physics,1992, 64:1045.
[13] Jiang P, Xiao W, Kuang J, Liu W, Cao W, Effect of cobalt doping on the electronic, optical and photocatalytic properties of TiO_2[J].Solid State Sciences, 2015, 46:27-32.