First-Principles Study on Electronic and Optical Properties in Pr-Doped Anatase TiO2

The crystal structures, band structures, density of states, charge density, overlap population and optical properties of pure anatase TiO2 and Pr-doped anatase TiO2 were studied by using the plane-wave pseudopotential method based on the first-principles. After Pr doping, the valence band and the conduction band moved down and became dense, energy gap became narrow and a impurity band which consists of Pr 4f states appeared. And the dipole moment got improved, which is good for the separate of the electron-hole pairs. These effectively overcome two huge shortcomings of TiO2. Besides, Pr-doped anatase TiO2 produced more carriers which have good transport properties and the absorption spectra of Pr-O bond appear in the region that the wavelength is longer. The calculation results of optical properties show that the absorption edge occured red shift, which means the photocatalytic activity of anatase TiO2 got remarkable improved during visible-light region. This conforms to the previous analysis. So the photocatalytic activity of anatase TiO2 got remarkable improved after Pr doping.

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Investigation of Electronic Structures of F-Doped TiO2 by First-Principles Calculation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.620-622.647 ◽

2009 ◽

Vol 620-622 ◽

pp. 647-650 ◽

Cited By ~ 3

Author(s):

Ying Cui ◽

Hao Du ◽

Li Shi Wen

Keyword(s):

Photocatalytic Activity ◽

First Principles ◽

Electronic Structures ◽

Lower Energy ◽

Anatase Tio2 ◽

First Principles Calculation ◽

Visible Light Region ◽

Doped Tio2 ◽

Light Region ◽

Calculation Results

F-doped TiO2 has exhibited superior photocatalytic activity. However, its electronic structures and photocatalysis mechanism are still unclear. In the present work, the structural optimization and electronic structure of F-doped anatase TiO2 have been investigated by means of the first-principles pseudopotential total energy method. It has been demonstrated that F doping would modify the valence band at the lower energy direction in the F-doped TiO2. Calculation results confirm that doping of fluorine would not shift the absorption edge into the visible light region. Instead, we attributed its photocatalytic activity to the enhancement of the oxidative power of F-doped TiO2.

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Regulating the electronic and optical properties of GaN/InN core/shell nanowires: A first-principles study

International Journal of Modern Physics B ◽

10.1142/s0217979220502148 ◽

2020 ◽

Vol 34 (25) ◽

pp. 2050214 ◽

Cited By ~ 1

Author(s):

Chang Liu ◽

Enling Li ◽

Tuo Peng ◽

Kaifei Bai ◽

Yanpeng Zheng ◽

...

Keyword(s):

Optical Properties ◽

First Principles ◽

Core Shell ◽

First Principles Calculations ◽

Electronic And Optical Properties ◽

Gan Nanowires ◽

The Core ◽

Light Region ◽

Calculation Results ◽

Shell Nanowires

In this paper, electronic and optical properties of GaN/InN core/shell nanowires (CSNWs) have been theoretically investigated through the first principles calculations. The binding energy of In and N atoms on surface of six crystal planes along the [Formula: see text]-axis of GaN nanowires are all negative, which indicate that In and N atoms can be effectively deposited on the surface of GaN nanowires and preparing GaN/InN CSNWs is feasible theoretically. Calculation results of electronic properties indicate that the core/shell ratio and diameter of GaN/InN CSNWs have significant effect on the band structure, bandgap can be effectively adjusted when keeping the number of GaN layers unchanged and changing the number of InN layers. Moreover, with the increase in the number of InN layers, the absorption spectrum of GaN/InN CSNW has significant redshift and few weak absorption peaks appear in the visible light region.

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The Effect of Chromium on the Optical Properties and Photoactivity of Nano-Particulate Rutile

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.554-556.502 ◽

2012 ◽

Vol 554-556 ◽

pp. 502-506 ◽

Cited By ~ 1

Author(s):

Li Wei Wang ◽

Terry A. Egerton

Keyword(s):

Optical Properties ◽

Photocatalytic Activity ◽

Reflectance Spectroscopy ◽

Electron Trapping ◽

Electron Hole ◽

High Chromium ◽

Chromium Doping ◽

Chromium Addition ◽

Co Precipitation ◽

Hole Recombination

Chromium doped rutile TiO2was synthesized by either co-precipitation or impregnation (surface-doping) and characterized by XRD and reflectance spectroscopy. Chromium addition did not change the TiO2structure nor did the structure of the co-precipitated products differ from that of the impregnated samples. However, chromium doping moved the absorption of both sets of products into the visible and significantly affected the TiO2photocatalytic activity for isopropanol (IPA) oxidation. At high chromium concentrations the photoactivity of the co-precipitated samples was reduced by a larger amount than that of the impregnated samples; this was attributed to a higher concentration of Cr3+ions in the rutile lattice. Unexpectedly, increased photoactivity was measured for low Cr levels of surface-doped rutile. This may be caused by increased electron-trapping, at surface Cr6+ions, and correspondingly reduced, electron-hole recombination.

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Effect of thickness on optical properties of pure Epoxy Resin plates

Baghdad Science Journal ◽

10.21123/bsj.11.2.554-559 ◽

2014 ◽

Vol 11 (2) ◽

pp. 554-559

Author(s):

Baghdad Science Journal

Keyword(s):

Optical Properties ◽

Epoxy Resin ◽

Energy Gap ◽

Visible Region ◽

Refraction Index ◽

Ultraviolet Region ◽

Intensity Increase ◽

Absorption Intensity ◽

Light Region ◽

Different Thickness

In this study, Epoxy Resin plates was prepared by mixing epoxy(A) and hardner(B)with ratio(A:B) (3:1) with different thickness (0.3-0.96)cm. The effect of thickness on optical properties have been studied (absorption ,transmission ,reflectance) also the optical constant were found like (absorption coefficient, extenuation coefficient and refraction index) for all of the prepared plates. The results have shown that by increasing the thickness of plates., the absorption intensity increase in which at plates thickness (0.3-0.96)cm the absorption intensity were(1.54-1.43) respectively, and since absorption peak for epoxy occur in ultraviolet region and exactly at wavelength(368)nm and energy gap(Eg=3.05 eV) thus their good transmittance in the visible light region The plates have transmittance of about (60-83.4)% in visible region ,the refraction index for Elda epoxy is (n= 1.53 ) and its reflectance is (R=4 )% at wavelength (368 nm).

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Unraveling the quantum dynamics origin of high photocatalytic activity in nitrogen-doped anatase TiO2: time-domain ab initio analysis

Journal of Materials Chemistry A ◽

10.1039/d0ta08712b ◽

2020 ◽

Vol 8 (47) ◽

pp. 25235-25244

Author(s):

Yating Yang ◽

Zhaosheng Zhang ◽

Wei-Hai Fang ◽

Sebastian Fernandez-Alberti ◽

Run Long

Keyword(s):

Photocatalytic Activity ◽

Ab Initio ◽

Time Domain ◽

Quantum Dynamics ◽

High Photocatalytic Activity ◽

Anatase Tio2 ◽

Electron Hole ◽

Nitrogen Doped ◽

Hole Recombination

TiO2 doping with nitrogen greatly suppresses nonradiative electron-hole recombination and enhances photocatalytic activity.

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Theoretical investigation on the interaction between groups in LAP crystal and its linear optical properties

International Journal of Modern Physics B ◽

10.1142/s021797921950156x ◽

2019 ◽

Vol 33 (15) ◽

pp. 1950156

Author(s):

Lei Wang ◽

Meixia Xiao ◽

Bingtian Tu

Keyword(s):

Optical Properties ◽

First Principles ◽

Energy Gap ◽

Electronic Transitions ◽

Electronic Interaction ◽

First Principles Calculations ◽

Nonlinear Optical Material ◽

Kdp Crystal ◽

Intergroup Interactions ◽

Linear Optical Properties

LAP crystal is an excellent nonlinear optical material and it has some unexplained specificities, which makes the interaction between groups in molecule received much attention. In this paper, the first-principles calculations are performed to investigate the intergroup interactions by the electronic structure and optical properties of LAP crystal. The energy gap of LAP crystal is 5.02 eV, indicating that the electronic transition is easier than KDP crystal. The strong electronic interaction between the carboxyl, phosphate and guanidine groups is found. In addition, since the LAP molecule has the greatest dipole in [010] direction and the electronic transitions are most likely to occur between the carboxyl group, phosphate and guanidine groups located on both ends of the molecule along [010] direction, the LAP crystal shows specific optical properties in this direction. The results reveal the correlations between the optical properties and the intergroup interactions of LAP crystal.

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Electronic and Optical Properties of Si/SiO2 Superlattices from First Principles: Role of Interfaces.

MRS Proceedings ◽

10.1557/proc-677-aa4.10 ◽

2001 ◽

Vol 677 ◽

Cited By ~ 4

Author(s):

Pierre Carrier ◽

Gilles Abramovici ◽

Laurent J. Lewis ◽

M. W. C. Dharma-wardana

Keyword(s):

Optical Properties ◽

First Principles ◽

Energy Gap ◽

Local Density ◽

Interband Transition ◽

Theoretical Research ◽

Slab Thickness ◽

Full Potential ◽

Wave Method

ABSTRACTThe observation of intense luminescence in Si/SiO2 superlattices (SLs) has lead to new theoretical research on silicon-based materials. We have performed first-principles calculations using three Si/SiO2 SL models in order to examine the role of interfaces on the electronic structure and optical properties. The first two models are derived directly from crystalline structures and have simple interfaces. These models have been studied using the full-potential, linearized-augmented-plane-wave method, in the local-density-approximation (LDA). The optical absorption within the interband transition theory (excluding excitonic effects) have been deduced. The Si(001)-SiO2 interface structure is shown to affect the optical behaviour. Following these observations, we have considered a more realistic, fully-relaxed model. The projector-augmented-wave method under the LDA is used to perform the structural relaxation as well as band structure and optical calculations. The role of confinement on the energy gap is studied by inserting additional silicon slabs into the supercell. Direct energy gaps are observed and the energy gap is found to decrease with increasing silicon slab thickness, as observed experimentally. The role of the interface has been considered in more details by studying the contribution to the energy gap of Si atoms having different oxidation patterns; partially oxidized Si atoms at the interface, as well as Si atoms inside the Si layer, are shown to contribute to the transitions at the energy gap.

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