锐钛矿相和金红石相TiO_2:Nb的光电性能研究
Electronic and optical properties of anatase and rutile TiO_2:Nb
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摘要: 采用基于密度泛函理论的第一性原理计算了锐钛矿相和金红石相TiO_2:Nb的晶体结构、电子结构和光学性质.结果表明,在相等的摩尔掺杂浓度下(6.25%),锐钛矿相TiO_2:Nb的导带底电子有效质量小于金红石相TiO_2:Nb,且前者室温载流子浓度是后者的两倍左右,即具有更大的施主杂质电离率,从而解释了锐钛矿相TiO_2:Nb比金红石相TiO_2:Nb具有更优异电学性能的实验现象.光学计算也表明锐钛矿相在可见光区有更大的透过率,从而在理论上解释了锐铁矿相TiO_2:Nb比金红石相'riO_2:Nb更适于做透明导电材料的原因.计算结果与实验数据能较好符合.Abstract: First-principles calculations based on the density functional theory are used to study the crystal structure,electronic and optical properties of Nb doped anatase and rutile TiO_2.The calculated results reveal that anatase TiO_2:Nb has a smaller effective mass and carriers nearly twice lager than those of rutile TiO_2:Nb under the same doping concentration.And anatase TiO_2:Nb also exhibits a greater room-temperature ionization of donors.Besides,the calculated optical properties indicate that anatase TiO_2:Nb has a more excellent transparency than rutile TiO_2:Nb.All the results suggest that anatase TiO_2:Nb is more applicable to transparent conductive oxides.The calculated results consist well with the available experimental results.
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