Synthesis, XRD analysis and electronic structure of InGaTe2 chain semiconductor

2020 ◽  
pp. 2150029
Author(s):  
E. M. Gojayev ◽  
S. S. Osmanova ◽  
S. I. Safarova ◽  
D. M. Gafarova
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Plane Waves ◽  
Density Functional Method ◽  
Xrd Analysis ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Tetragonal Symmetry ◽  
Diagonal Form ◽  
Surface Microrelief

In this work, we developed a technology for growing a single crystal of a ternary compound, using the Atomic Force Microscope (AFM), we studied the surface microrelief in 2D and 3D modes, using X-ray diffraction (XRD) analysis, determined the parameters of the unit cell of this phase and revealed that it crystallizes in tetragonal symmetry with lattice parameters [Formula: see text] Å and [Formula: see text] Å, space group I4/mcm. Using the density functional method, using the ABINIT software package, using the Troiller–Martins pseudopotentials in the basis of plane waves, the band structure was calculated, the origin of the valence and conduction bands was determined. It was revealed that this phase is a direct-gap semiconductor with a bandgap of 0.56 eV. The parameters of the InGaTe2 unit cell were calculated by the pseudopotential and linearized attached plane wave (LAPW) methods, the theoretical and experimental values of the lattice parameters are in good agreement. Based on the band structure, the effective masses of electrons and holes are determined. It is shown that the tensors of the inverse effective mass for both extreme have a diagonal form.

scholarly journals Superconductivity in Diamond-like BC3 Phase

2010 ◽  
Vol 2 (2) ◽  
pp. 203-213 ◽  
Author(s):  
M. M. Ali ◽  
A.K.M. A. Islam ◽  
M. Aftabuzzaman ◽  
F. Parvin
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Density Functional Method ◽  
Metallic Phase ◽  
Tetragonal Symmetry ◽  
Phonon Coupling ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electron Phonon Coupling

Two possible phases of superhard material BC3 originating from the cubic diamond structure are investigated by ab initio pseudopotential density functional method using generalized gradient approximation (GGA). We calculate their elastic constants, electronic band structure, and density of states (DOS). Full phonon frequencies, electron-phonon coupling constant and possible superconducting Tc of the metallic phase with tetragonal symmetry (t-BC3, space group P-42m) have for the first time been investigated at 5 and 10 GPa. The calculated electron-phonon coupling (0.67) and the logarithmically-averaged frequency (862 cm-1) show superconductivity for the undoped t-BC3 with Tc = 20 K at 5 GPa, which decreases to 17.5 K at 10 GPa. Keywords: Superhard BC3; Band structure; Phonon spectra; Superconductivity. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v2i2.2638               J. Sci. Res. 2 (2), 203-213 (2010)     

scholarly journals Intermolecular Interactions in Molecular Organic Crystals upon Relaxation of Lattice Parameters

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 665 ◽  
Author(s):  
Matthias Stein ◽  
Madalen Heimsaat
Keyword(s):  
Structure Prediction ◽  
Density Functional ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Molecular Structures ◽  
Basis Set ◽  
Experimental Unit ◽  
Organic Crystals ◽  
Cell Parameters ◽  
Lattice Energies

Crystal structure prediction is based on the assumption that the most thermodynamically stable structure will crystallize first. The existence of other structures such as polymorphs or from counterenantiomers requires an accurate calculation of the electronic energy. Using atom-centered Gaussian basis functions in periodic Density Functional Theory (DFT) calculations in Turbomole, the performance of two dispersion-corrected functionals, PBE-D3 and B97-D, is assessed for molecular organic crystals of the X23 benchmark set. B97-D shows a MAE (mean absolute error) of 4 kJ/mol, compared to 9 kJ/mol for PBE-D3. A strategy for the convergence of lattice energies towards the basis set limit is outlined. A simultaneous minimization of molecular structures and lattice parameters shows that both methods are able to reproduce experimental unit cell parameters to within 4–5%. Calculated lattice energies, however, deviate slightly more from the experiment, i.e., by 0.4 kJ/mol after unit cell optimization for PBE-D3 and 0.5 kJ/mol for B97-D. The accuracy of the calculated lattice energies compared to the experimental values demonstrates the ability of current DFT methods to assist in the quest for possible polymorphs and enantioselective crystallization processes.

scholarly journals Ab-initio Calculations of Structural Parameters, Band Structure and Density of States of Delafossite CuAlO

2020 ◽  
Author(s):  
A.F. Carlos-Chilo ◽  
F.F.H. Aragon ◽  
L. Villegas-Lelovsky ◽  
D. G. Pacheco-Salazar
Keyword(s):  
Band Structure ◽  
Density Of States ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Structural Parameters ◽  
Lattice Parameters ◽  
High Symmetry ◽  
Delafossite Cualo2 ◽  
Transparent Semiconductor ◽  
P Type

Delafossite CuAlO2 is a p-type transparent semiconductor oxide with space group R-3m (N°166) is a material with extended applications in different fields. Structural parameters, band structure, and density of CuAlO2 have been investigated in the light of the Density Functional Theory (DFT) using PBE pseudopotentials (norm-conserving pseudopotentials). Our calculations are performed with the ABINIT package using cut-off energy of 100 Hartree, showing convergence to cut-off energy up to 30 Hartree. The lattice parameters of CuAlO2 obtained after the relaxation process are a = b = 2.904 Å and c = 17.202 Å; and consequently, volume of V=174.014 Å3 , also the derivate of the bulk modules Bo´=4.1, and bulk modulus Bo=174 Gpa were found. We find that discrepancies between our calculated lattice parameters a, c, and c/a are overestimated about 0.798%, 0.591%, and 0.219% compared to the reference’s theoretical calculations of Qi-Jun Liu et,al respectively. The calculated energy band structure of CuAlO2 and the high-symmetry points of Brillouin Zone show that the delafossite structure has an indirect band gag (~ 1.21 eV) because the top valence and the bottom conduction are found at F point and Г point, respectively. This work aims to study structural parameters, band structure, and density of states of delafossite CuAlO2 and give one application as solar cell.

The Influence Mechanism of Halogen Ion on the Temperature Quenching Performance of Sr2SiO4:Eu Phosphors

2016 ◽  
Vol 16 (4) ◽  
pp. 3990-3993 ◽  
Author(s):  
Lingli Wang ◽  
Haiyong Ni ◽  
Qiuhong Zhang ◽  
Fangming Xiao
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Method ◽  
Luminescent Properties ◽  
Functional Method ◽  
Density Approximation ◽  
Luminescent Intensity ◽  
Temperature Quenching ◽  
Influence Mechanism

The luminescent properties of Sr2SiO4:Eu phosphors synthesized with and without flux have been investigated. With the co-dopation of NH4Cl, the luminescent intensity of Sr2SiO4:Eu is increased and the temperature quenching property is improved. The effect of NH4Cl is analyzed not only from the crystallinity of the Sr2SiO4 crystal but also the band structure of Sr2SiO4 host, which is calculated by density functional method with the local density approximation.

First-Principles Calculations on Structural, Electronic, and Optical Properties of 2H-CuAlO2

2011 ◽  
Vol 197-198 ◽  
pp. 487-490 ◽  
Author(s):  
Li Ping Feng ◽  
Zheng Tang Liu ◽  
Qi Jun Liu
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
Lattice Parameters ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Charge Densities ◽  
Densities Of States

Structural, electronic and optical properties of 2H-CuAlO2 were computed, using the plane-wave ultrasoft pseudopotential technique based on the first-principles density functional theory (DFT). The equilibrium lattice parameters, band structure, densities of states (DOS) and charge densities of 2H-CuAlO2 have been obtained. The equilibrium lattice parameters, band structure and DOS are found to be in good agreement with the available experimental and calculational values. The charge densities and the chemical bonding of 2H-CuAlO2 are analyzed, which show that bonding between Cu and O is mainly covalent due to Cu 3d and O 2p hybridization and that bonding between Al and O is mainly ionic. The complex dielectric function, refractive index and absorption coefficient of 2H-CuAlO2 have been predicted. The calculated static dielectric constant and static refractive index of 2H-CuAlO2 is 7.1 and 2.66, respectively.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

scholarly journals New Quaternary Chalcogenides Tl2MIIMIV3Se8 and Tl2MIIMIVX4

Proceedings ◽  
2020 ◽  
Vol 62 (1) ◽  
pp. 3
Author(s):  
Andrii Selezen ◽  
Yuri Kogut ◽  
Lyudmyla Piskach ◽  
Lubomir Gulay
Keyword(s):  
Crystal Structure ◽  
Ternary Systems ◽  
Lattice Parameters ◽  
Tetragonal Symmetry ◽  
Orthorhombic Symmetry ◽  
Component Ratio

New quaternary thallium-containing chalcogenides Tl2MIIMIV3X8 and Tl2MIIMIVX4 were synthesized, and their crystal structure was determined by XRD. Three Tl2MIIMIV3X8 chalcogenides crystallize in orthorhombic symmetry (S.G. P212121; Tl2CdGe3Se8 lattice parameters a = 0.76023(9), b = 1.2071(2), c = 1.7474(2) nm), eight isostructural Tl2BIIDIVX4 compounds crystallize in tetragonal symmetry, S.G. I-42m. These compounds form in the quasi-ternary systems Tl2X–MIIX–MIVX2 (X–S, Se, Te) at the component ratio 1:1:1 and 1:1:3 at the sections Tl2MIVX3–BIIX and Tl2MIIMIVX4–MIVX2, respectively. The composition of the Tl2CdGe3Se8 compound was additionally confirmed by SEM and EDS.

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