Band gap modulation effect on electronic and optical properties in PbTiO3 under stress: a DFT study

2019 ◽  
Vol 88 (1) ◽  
pp. 10501 ◽  
Author(s):  
Muhammad Rizwan ◽  
Rabia Bibi ◽  
Tariq Mahmood ◽  
Imran Aslam ◽  
Syed Sajid Ali Gillani ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Blue Shift ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Absorption Energy ◽  
Valence States ◽  
External Pressures ◽  
Band Gap Modulation ◽  
Pseudo Potential

First principles calculation was implemented to explore the effect of band gap modulation under stress in cubic PbTiO3 by using generalized gradient approximation (GGA) and ultrasoft pseudo-potential (USP). The band gaps at different external pressures show indirect band nature with significant reduction in band gapes. The density of states indicated that the upper valence states were influenced by O-2p and in the meantime Ti-d states have main contribution in conduction band. The inclusion of external stress not only changes electronic structure but also significantly changes the optical properties such as complex dielectric function, absorption, energy loss function, refractive index and reflectivity. The shifting of absorption edges toward higher energies confirm the presence of blue shift and make this material an appealing candidate for optoelectronic devices.

scholarly journals Structural, Optical, and Magnetic Properties of Gd Doped CdTe Quantum Dots for Magnetic Imaging Applications

2022 ◽  
Author(s):  
Shanmugapriya V ◽  
Bharathi S ◽  
Esakkinaveen D ◽  
Arunpandiyan S ◽  
Selvakumar B ◽  
...  
Keyword(s):  
Optical Properties ◽  
Plane Waves ◽  
Theoretical Data ◽  
Blue Shift ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Magnetic Imaging ◽  
Optical Applications ◽  
Indirect Band Gap ◽  
Pseudo Potential

Abstract The effect of pressure on the electronic and optical properties of SrAl2O4 up to 25 GPa was studied by means of the pseudo-potential plane waves method within the generalized gradient approximation for exchange and correlation. The calculated lattice parameters are consistent with available experimental and theoretical data. By analyzing the electronic and optical properties, the pressure dependences of the electronic structures and optical constants were investigated. The band structures show an indirect band gap for this compound and the calculated band gaps expend with increasing pressure. Meanwhile, the optical properties including the dielectric spectra, absorption coefficient spectra, reflectivity, and the real part of the refractive index spectra in the low energy range have a blue shift. Given this, the optical properties of SrAl2O4 could be tuned by changing pressure to some degree, which is beneficial to the optical applications.

scholarly journals Effect of Yb Concentration on the Structural, Magnetic and Optoelectronic Properties of Yb Doped ZnO: First Principles Calculation

2021 ◽  
Author(s):  
Mohamed Achehboune ◽  
Mohammed Khenfouch ◽  
Issam Boukhoubza ◽  
Issam Derkaoui ◽  
Bakang Moses Mothudi ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Density Functional ◽  
Blue Shift ◽  
First Principles Calculation ◽  
Theoretical Research ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Doped Zno ◽  
Good Agreement

Abstract Density functional theory-based investigation of the electronic, magnetic, and optical characteristics in pure and ytterbium (Yb) doped ZnO has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The calculated lattice parameters and band gap of pure ZnO are in good agreement with the experimental results. The energy band-gap increases with the increase of Yb concentration. The Fermi level moves upward into the conduction band after doping with Yb, which shows the properties of an n-type se miconductor. New defects were created in the band-gap near the conduction band attributed to the Yb-4f states. The magnetic properties of ZnO were found to be affected by Yb doping; ferromagnetic property was observed for 4.17% Yb due to spin polarization of Yb-4f electrons. The calculated optical properties imply that Yb doped causes a blue shift of the absorption peaks, significantly enhances the absorption of the visible light, and the blue shift of the reflectivity spectrum was observed. Besides, a better transmittance of approximately 88% was observed for 4.17% Yb doped ZnO system. The refractive index and the extinction coefficient were observed to decrease as the Yb dopant concentration increased. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.

scholarly journals Effect of Pressure on Electronic and Optical Properties of SrAl2O4

2022 ◽  
Author(s):  
Hua Liang
Keyword(s):  
Optical Properties ◽  
Plane Waves ◽  
Theoretical Data ◽  
Blue Shift ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Effect Of Pressure ◽  
Optical Applications ◽  
Indirect Band Gap ◽  
Pseudo Potential

Abstract The effect of pressure on the electronic and optical properties of SrAl2O4 up to 25 GPa was studied by means of the pseudo-potential plane waves method within the generalized gradient approximation for exchange and correlation. The calculated lattice parameters are consistent with available experimental and theoretical data. By analyzing the electronic and optical properties, the pressure dependences of the electronic structures and optical constants were investigated. The band structures show an indirect band gap for this compound and the calculated band gaps expend with increasing pressure. Meanwhile, the optical properties including the dielectric spectra, absorption coefficient spectra, reflectivity, and the real part of the refractive index spectra in the low energy range have a blue shift. Given this, the optical properties of SrAl2O4 could be tuned by changing pressure to some degree, which is beneficial to the optical applications.

Electronic Structure and Optical Properties of SrTi0.5Zr0.5O3

2013 ◽  
Vol 846-847 ◽  
pp. 1919-1922
Author(s):  
Hong Liang Pan ◽  
Teng Li ◽  
Shi Liang Yang ◽  
Yi Ming Liu
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Energy Band ◽  
Electronic Energy ◽  
Energy Band Structure ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Structure Density ◽  
Pseudo Potential ◽  
Electronic Energy Band

The electronic-energy band structure and optical properties of SrTi0.5Zr0.5O3are calculated by the pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA). The energy band structure, density of states (DOS) are obtained. The optical properties including the dielectric function, reflectivity, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also discussed.

First Principles Calculation of Geometrical and Electronic Structure of Semiconductor Fe1-xMnxSi2

2011 ◽  
Vol 213 ◽  
pp. 483-486
Author(s):  
Fang Gui ◽  
Shi Yun Zhou ◽  
Wan Jun Yan ◽  
Chun Hong Zhang ◽  
Xiao Tian Guo ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
First Principles Calculation ◽  
First Principle ◽  
Substitutional Doping ◽  
Pseudo Potential ◽  
Mn Concentrations

The electronic structure and optical properties of Fe1-xMnxSi2 have been studied using the first principle plane-wave pseudo-potential based on the density function theory. Substitutional doping is considered with Mn concentrations of x=0.0625, 0.125, 0.1875 and 0.25, respectively. The calculated results show that the volume of β-FeSi2 increase and the band gap increase with increasing of Mn.

Optical Properties of NiO Thin Films: A Potential Material for Optoelectronic Devices

2012 ◽  
Vol 488-489 ◽  
pp. 103-108 ◽  
Author(s):  
Manisha Tyagi ◽  
Monika Tomar ◽  
Vinay Gupta
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Substrate Temperature ◽  
Band Gap ◽  
Urbach Energy ◽  
Rf Sputtering ◽  
Blue Shift ◽  
Structural Disorder ◽  
Near Ir

The influence of substrate temperature on the UV-Visible-near-IR optical properties, namely the band gap, the Urbach energy and the refractive index of NiO thin films deposited by RF sputtering has been investigated. The optical band gap of thin films showed the blue-shift in the transmission spectra with increase in the substrate temperature which is related to variation in carrier concentration of the deposited films. Urbach energy (EU) values indicate that the films deposited at 400 oC substrate temperature show least structural disorder. The refractive index of the films is found to decrease continuously with increase in the substrate temperature at all photon energies in the visible and near-IR region, and is attributed to the decreasing packing density of the films. Introduction

Structural Electronic and Optical Properties of MgO, CaO and SrO Binary Compounds: Comparison Study

2016 ◽  
Vol 257 ◽  
pp. 123-126 ◽  
Author(s):  
Salima Labidi ◽  
Jazia Zeroual ◽  
Malika Labidi ◽  
Kalthoum Klaa ◽  
Rachid Bensalem
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Alternative Form ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Optical Dielectric Constant ◽  
Reported Data

First-principles calculations for electronic and optical properties under pressure effect of MgO, SrO and CaO compounds in the cubic structure, using a full relativistic version of the full-potential augmented plane-wave (FP-LAPW) method based on density functional theory, within the local density approximation (LDA) and the generalized gradient approximation (GGA), have been reported. Furthermore, band structure calculations have been investigated by the alternative form of GGA proposed by Engel and Vosko (GGA-EV) and modified by Becke-Johnson exchange correlation potential (MBJ-GGA). All calculated equilibrium lattices, bulk modulus and band gap at zero pressure are find in good agreement with the available reported data. The pressure dependence of band gap and the static optical dielectric constant are also investigated in this work.

scholarly journals Computational Investigation of the Folded and Unfolded Band Structure and Structural and Optical Properties of CsPb(I1−xBrx)3 Perovskites

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 342 ◽  
Author(s):  
Hamid M. Ghaithan ◽  
Zeyad A. Alahmed ◽  
Andreas Lyras ◽  
Saif M. H. Qaid ◽  
Abdullah S. Aldwayyan
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Band Gap ◽  
Spectral Weight ◽  
Band Gap Energy ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Direct Band

The structural, electronic, and optical properties of inorganic CsPb(I1−xBrx)3 compounds were investigated using the full-potential linear augmented-plane wave (FP-LAPW) scheme with a generalized gradient approximation (GGA). Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and modified Becke–Johnson GGA (mBJ-GGA) potentials were used to study the electronic and optical properties. The band gaps calculated using the mBJ-GGA method gave the best agreement with experimentally reported values. CsPb(I1−xBrx)3 compounds were wide and direct band gap semiconductors, with a band gap located at the M point. The spectral weight (SW) approach was used to unfold the band structure. By substituting iodide with bromide, an increase in the band gap energy (Eg) values of 0.30 and 0.55 eV, using PBE-GGA and mBJ-GGA potentials, respectively, was observed, whereas the optical property parameters, which were also investigated, demonstrated the reverse effect. The high absorption spectra in the ultraviolet−visible energy range demonstrated that CsPb(I1−xBrx)3 perovskite could be used in optical and optoelectronic devices by partly replacing iodide with bromide.

First Principles Investigation on the Structural, Electronic and Optical Properties of Amorphous Silica Glass

2017 ◽  
Vol 268 ◽  
pp. 92-96
Author(s):  
R.M. Nor ◽  
S.N.M. Halim ◽  
Mohamad Fariz Mohamad Taib ◽  
M. Kamil Abd-Rahman
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Electronic Properties ◽  
Amorphous Silica ◽  
First Principles ◽  
Glass Structure ◽  
Small Sample ◽  
First Principles Calculation ◽  
Electronic And Optical Properties ◽  
Amorphous Quartz

The structural, electronic, and optical properties of an amorphous SiO2 (a-SiO2) model is investigated by using first-principles calculation. Most research works used beta-cristobalite glass structure as a reference to amorphous silica structure. However, only the electronic properties were been presented without any link towards the optical properties. Here, we demonstrate simultaneous electronic and optical properties, which closely matched to a-SiO2 properties by generating small sample of amorphous quartz glass. Using the Rietveld refinement, amorphous silica structure was generated and optimized using density functional theory in CASTEP computer code. A thorough analysis of the amorphous quartz structure obtained from different thermal treatment was carried out. The structure of amorphous silica was validated with previous theoretical and experimental works. It is shown that small sample of amorphous silica have similar structural, electronic and optical properties with a larger sample. The calculated optical and electronic properties from the a-SiO2 glass match closely to previous theoretical and experimental data from others. The a-SiO2 band gap of 5.853 eV is found to be smaller than the experimental value of ~9 eV. This is due to the underestimation and assumption made in DFT. However, the band gap value is in good agreement with the other theoretical works. Apart from the absorption edge at around 6.5 eV, the refractive index is 1.5 at 0eV. Therefore, this atomic structure can served as a reference model for future research works on amorphous structures.

scholarly journals Optical properties of zinc titanate perovskite prepared by reactive RF sputtering

2017 ◽  
Vol 68 (7) ◽  
pp. 10-16 ◽  
Author(s):  
Jarmila Müllerová ◽  
Pavol Šutta ◽  
Rostislav Medlín ◽  
Marie Netrvalová ◽  
Petr Novák
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Optical Band Gap ◽  
Rf Sputtering ◽  
Blue Shift ◽  
Optical Transmittance ◽  
Titanium Content ◽  
Zinc Titanate ◽  
Band Gap Engineering ◽  
Photocatalytic Applications

AbstractIn this paper we report results from optical transmittance spectroscopy complemented with data on structure from XRD measurements to determine optical properties of a series of ZnTiO3perovskite thin films deposited on glass by reactive magnetron co-sputtering. The members of the series differ by the titanium content that was revealed as an origin of the changes not only in structure but also in dispersive optical properties. Low porosity has been discovered and calculated using the Bruggeman effective medium approximation. An apparent blue-shift of the optical band gap energies with increasing titanium content was observed. The observed band gap engineering is a good prospective foregoptoelectronic and photocatalytic applications of ZnTiO3.

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