scholarly journals Structural, Electronic, and Optical Properties of CsPb(Br1−xClx)3 Perovskite: First-Principles Study with PBE–GGA and mBJ–GGA Methods

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4944
Author(s):  
Hamid M. Ghaithan ◽  
Zeyad. A. Alahmed ◽  
Saif M. H. Qaid ◽  
Abdullah S. Aldwayyan
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
Generalized Gradient ◽  
X Ray ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Average Fraction ◽  
Experimental Values

The effect of halide composition on the structural, electronic, and optical properties of CsPb(Br1−xClx)3 perovskite was investigated in this study. When the chloride (Cl) content of x was increased, the unit cell volume decreased with a linear function. Theoretical X-ray diffraction analyses showed that the peak (at 2θ = 30.4°) shifts to a larger angle (at 2θ = 31.9°) when the average fraction of the incorporated Cl increased. The energy bandgap (Eg) was observed to increase with the increase in Cl concentration. For x = 0.00, 0.25, 0.33, 0.50, 0.66, 0.75, and 1.00, the Eg values calculated using the Perdew–Burke–Ernzerhof potential were between 1.53 and 1.93 eV, while those calculated using the modified Becke−Johnson generalized gradient approximation (mBJ–GGA) potential were between 2.23 and 2.90 eV. The Eg calculated using the mBJ–GGA method best matched the experimental values reported. The effective masses decreased with a concentration increase of Cl to 0.33 and then increased with a further increase in the concentration of Cl. Calculated photoabsorption coefficients show a blue shift of absorption at higher Cl content. The calculations indicate that CsPb(Br1−xClx)3 perovskite could be used in optical and optoelectronic devices by partly replacing bromide with chloride.

First-Principles Study of Structural, Electronic and Optical Properties in BaTi0.5Ni0.5O3

2013 ◽  
Vol 834-836 ◽  
pp. 268-271
Author(s):  
Hong Liang Pan ◽  
Shi Liang Yang ◽  
Teng Li
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
First Principles ◽  
Energy Band Structure ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Structure Density ◽  
Pseudo Potential

The pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA) is applied to study the electronic and optical properties of BaTi0.5Ni0.5O3. 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 calculated and analyzed in detail.

First principles and Debye model study of the thermodynamic, electronic and optical properties of MgO under high-temperature and pressure

2018 ◽  
Vol 32 (05) ◽  
pp. 1850047
Author(s):  
Yurun Miao ◽  
Huayang Li ◽  
Hongjuan Wang ◽  
Kaihua He ◽  
Qingbo Wang
Keyword(s):  
Optical Properties ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Local Density ◽  
Blue Shift ◽  
Debye Model ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Geological Processes

First principles and quasi-harmonic Debye model have been used to study the thermodynamic properties, enthalpies, electronic and optical properties of MgO up to the core–mantle boundary (CMB) condition (137 GPa and 3700 K). Thermodynamic properties calculation includes thermal expansion coefficient and capacity, which have been studied up to the CMB pressure (137 GPa) and temperature (3700 K) by the Debye model with generalized gradient approximation (GGA) and local-density approximation (LDA). First principles with hybrid functional method (PBE0) has been used to calculate the electronic and optical properties under pressure up to 137 GPa and 0 K. Our results show the Debye model with LDA and first principles with PBE0 can provide accurate thermodynamic properties, enthalpies, electronic and optical properties. Calculated enthalpies show that MgO keep NaCl (B1) structure up to 137 GPa. And MgO is a direct bandgap insulator with a 7.23 eV calculated bandgap. The bandgap increased with increasing pressure, which will induce a blue shift of optical properties. We also calculated the density of states (DOS) and discussed the relation between DOS and band, optical properties. Equations were used to fit the relations between pressure and bandgaps, absorption coefficient ([Formula: see text]([Formula: see text])) of MgO. The equations can be used to evaluate pressure after careful calibration. Our calculations can not only be used to identify some geological processes, but also offer a reference to the applications of MgO in the future.

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

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 First principles study of structure, electronic and optical properties of Y3Fe5O12 in cubic and trigonal phases

2015 ◽  
Vol 33 (1) ◽  
pp. 169-174 ◽  
Author(s):  
Shen Tao ◽  
Hu Chao ◽  
Dai Hailong ◽  
Yang Wenlong ◽  
Liu Hongchen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
First Principles ◽  
Structural Parameters ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Experimental Values

AbstractFirst principles calculations have been performed to investigate the structure, electronic and optical properties of Y3Fe5O12. Both the cubic and trigonal phases have been considered in our calculation. The calculated structural parameters are slightly larger than the experimental values. The band structures show that Y3Fe5O12 in cubic and trigonal phases have direct band gaps of 0.65 and 0.17 eV. The calculations of dielectric function, absorption, extinction coefficient, refractive index, energy loss function and reflectivity are presented.

The effect of substitutional doping of Yb2+ on structural, electronic, and optical properties of CsCaX3 (X: Cl, Br, I) phosphors: A first-principles study

2021 ◽  
Author(s):  
Rashid Khan ◽  
Kaleem Ur Rahman ◽  
Qingmin Zhang ◽  
Altaf Ur Rahman ◽  
Sikander Azam ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Dielectric Susceptibility ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Substitutional Doping ◽  
Bandgap Semiconductors ◽  
Magnetic Insulator

Abstract Using first-principles calculations, the effects of Yb$^{2+}$ substitutional doping on structural, electronic, and optical properties of a series of perovskite compounds CsCaX$_3$ (X: Cl, Br, I), have been investigated. We employed generalized gradient approximation (GGA) and HSE hybrid functional to study the electronic and optical properties. A series of pristine CsCaX$_3$(X: Cl, Br, I) is characterized as a non-magnetic insulator with indirect bandgap perovskite materials. These phosphor materials are suitable candidates for doping with lanthanide series elements to tune their electronic bandgaps according to our requirements because of their wide bandgaps. The calculated electronic bandgaps of CsCaX$_3$ (X: Cl, Br, I) are 3.7 eV(GGA) and 4.5 eV (HSE) for CsCaI$_3$, 4.5 eV (GGA) and 5.3 eV (HSE) for CsCaBr$_3$, and 5.4 eV (GGA) and 6.4 eV (HSE) for CsCaCl$_3$. According to formation energies, the Yb$^{2+}$ doped at the Ca-site is thermodynamically more stable as compared to all possible atomic sites. The electronic band structures show that the Yb$^{2+}$ doping induces defective states within the bandgaps of pristine CsCaX$_3$. As a result, the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) become the direct bandgap semiconductors. The defective states above the VBM are produced due to the $f$-orbital of the Yb atom. The impurity states near the CBM are induced due to the major contribution of $d$-orbital of the Yb atom and the minor contribution of $s$-orbital of the Cs atom. The real and imaginary parts of the dielectric function, optical reflectivity, electron energy loss spectrum, extinction coefficient, and refractive index of pristine and Yb$^{2+}$ doped CsCaX$_3$ were studied. The optical dispersion results of dielectric susceptibility closely match their relevant electronic structure and align with previously reported theoretical and experimental data. We conclude that the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) are appealing candidates for optoelectronic devices.

scholarly journals Impact of Lithium Composition on Structural, Electronic and Optical Properties of Lithium Cobaltite Prepared by Solid-state Reaction

2014 ◽  
Vol 6 (2) ◽  
pp. 217-231 ◽  
Author(s):  
F. Khatun ◽  
M. A. Gafur ◽  
M. S. Ali ◽  
M. S. Islam ◽  
M. A. R. Sarker
Keyword(s):  
Optical Properties ◽  
Solid State ◽  
Ionic Conductivity ◽  
Cathode Material ◽  
Solid State Reaction ◽  
Layered Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electronic And Optical Properties ◽  
Lithium Cobaltite

The lithium-cobalt oxide LixCoO2 is a promising candidate as highly active cathode material of lithium ion rechargeable batteries. The crystalline-layered lithium cobaltite has attracted increased attention due to recent discoveries of some extraordinary properties such as unconventional transport and magnetic properties. Due to layered crystal structure, Li contents (x) in LixCoO2 might play an important role on its interesting properties. LiCoO2 crystalline cathode material was prepared by using solid-state reaction synthesis, and then LixCoO2 (x<1) has been synthesized by deintercalation of produced single-phase powders. Structure and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Infrared spectroscopy, Impedance analyzer etc. The influence of lithium composition (x) on structural, electronic and optical properties of lithium cobaltite was studied. Temperature dependent electrical resistivity was measured using four-probe technique. While LixCoO2 with x = 0.9 is a semiconductor, the highly Li-deficient phase (0.75 ? x ? 0.5) exhibits metallic conductivity. The ionic conductivity of LixCoO2 (x = 0.5 – 1.15) was measured using impedance spectroscopy and maximum conductivity of Li0.5CoO2 was found to be 6.5×10-6 S/cm at 273 K. The properties that are important for applications, such as ionic conductivity, charge capacity, and optical absorption are observed to increase with Li deficiency. Keywords: Calcination; Characterization; Inorganic compounds; Solid-State reaction; X-ray diffraction. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v6i2.17900 J. Sci. Res. 6 (2), 217-231 (2014)  

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 Calculations on Cu-Doped TiO2

2015 ◽  
Vol 1101 ◽  
pp. 70-74 ◽  
Author(s):  
Waqas Mahmood
Keyword(s):  
Optical Properties ◽  
Plane Wave ◽  
First Principles ◽  
Geometry Optimization ◽  
Titanium Atom ◽  
Mesh Size ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Cutoff Energy

The electronic and optical properties of tetragonal rutile TiO2 are investigated by first principles calculations using plane-wave pseudopotentials. Generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE) is employed with Vanderbilt’s ultrasoft pseudopotentials (USPs) for the geometry optimization. The cutoff energy 380 eV and Monkhorst-Pack (MP) grid of size 5 x 5 x 8 is used to study the electronic properties of TiO2. Besides, the optical properties of TiO2 are studied using a mesh size of 9 x 9 x 9. A periodic supercell of size 2a x 2b x 2c is created and a single Copper (Cu) atom directly substitutes the titanium atom. The geometry is optimized at cutoff energy 440 eV with MP grid of size 3 x 3 x 8 and a denser k-points mesh of size 6 x 6 x 6 is used for the investigation of optical properties.

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