Determination of the Electronic Structure and UV鈥揤is Absorption Properties of (Na2鈥?i>xCux)Ta4O11 from First-Principle Calculations

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• 作者：Moussab Harb ; Dilshad Masih ; Samy Ould-Chikh ; Philippe Sautet ; Jean-Marie Basset ; Kazuhiro Takanabe
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：August 29, 2013
• 年：2013
• 卷：117
• 期：34
• 页码：17477-17484
• 全文大小：492K
• 年卷期：v.117,no.34(August 29, 2013)
• ISSN：1932-7455

文摘

Density functional theory (DFT) and density functional perturbation theory (DFPT) were applied to study the structural, electronic, and optical properties of a (Na_2鈥?i>xCu_x)Ta₄O₁₁ solid solution to accurately calculate the band gap and to predict the optical transitions in these materials using the screened coulomb hybrid (HSE06) exchange-correlation formalism. The calculated density of states showed excellent agreement with UV鈥搗is diffuse reflectance spectra predicting a significant red-shift of the band gap from 4.58 eV (calculated 4.94 eV) to 2.76 eV (calculated 2.60 eV) as copper content increased from 0 to 83.3%. The band gap narrowing in these materials, compared to Na₂Ta₄O₁₁, results from the incorporation of new occupied electronic states, which are strongly localized on the Cu 3d orbitals, and is located within 2.16鈥?.34 eV just above the valence band of Na₂Ta₄O₁₁. These new occupied states, however, possess an electronic character localized on Cu, which makes hole mobility limited in the semiconductor.