scholarly journals Structural Features of Y2O2SO4 via DFT Calculations of Electronic and Vibrational Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3246
Author(s):  
Aleksandr S. Oreshonkov ◽  
Yuriy G. Denisenko
Keyword(s):  
Density Functional ◽  
Dielectric Material ◽  
Electronic Band Structure ◽  
Density Functional Theory Calculations ◽  
Structural Features ◽  
Spectral Lines ◽  
Partial Density ◽  
X Ray Diffraction ◽  
Electronic Band ◽  
The Difference

The traditional way for determination of molecular groups structure in crystals is the X-Ray diffraction analysis and it is based on an estimation of the interatomic distances. Here, we report the analysis of structural units in Y2O2SO4 using density functional theory calculations of electronic properties, lattice dynamics and experimental vibrational spectroscopy. The Y2O2SO4 powder was successfully synthesized by decomposition of Y2(SO4)3 at high temperature. According to the electronic band structure calculations, yttrium oxysulfate is a dielectric material. The difference between the oxygen–sulfur and oxygen–yttrium bond nature in Y2O2OS4 was shown based on partial density of states calculations. Vibrational modes of sulfur ions and [Y2O22+] chains were obtained theoretically and corresponding spectral lines observed in experimental Infrared and Raman spectra.

scholarly journals Structural, Electronic and Vibrational Properties of YAl3(BO3)4

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 545 ◽  
Author(s):  
Aleksandr S. Oreshonkov ◽  
Evgenii M. Roginskii ◽  
Nikolai P. Shestakov ◽  
Irina A. Gudim ◽  
Vladislav L. Temerov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dielectric Material ◽  
Electronic Band Structure ◽  
Vibrational Properties ◽  
Electronic Band ◽  
Functional Theory ◽  
Dynamical Properties ◽  
Indirect Band Gap

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrared spectrum is observed in both trigonal and hypothetical monoclinic structures of YAl3(BO3)4. The electronic band structure is studied theoretically, and the value of the band gap is obtained. It was found that the YAl3(BO3)4 is an indirect band gap dielectric material.

Synthesis, Structure, and Visible Phosphorescence Emission of Novel CuI Coordination Polymers Based on 4,4′-Bis(3-pyridyl)-2,2′-bis(hydroxylmethyl) Biphenyl

2015 ◽  
Vol 68 (2) ◽  
pp. 307 ◽  
Author(s):  
Guo-Xia Jin ◽  
Jian-Ping Ma ◽  
Chuan-Zhi Sun ◽  
Yu-Bin Dong
Keyword(s):  
Coordination Polymers ◽  
Density Functional ◽  
Room Temperature ◽  
Emission Spectra ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Ligand Charge Transfer ◽  
Yellow Orange ◽  
The Difference ◽  
1D Chains

Four new CuI coordination polymers, [(CuCl)L]n (1), {[(CuCl)2L2]·(H2O)}n (2), [(CuBr)L]n (3), and {[(CuBr)2L2]·(H2O)}n (4), were obtained from a new ligand 4,4′-bis(3-pyridyl)-2,2′-bis(hydroxylmethyl) biphenyl (L) and characterized by single-crystal X-ray diffraction. In 1 and 3, the rhombic [Cu2(μ-X)2] units are connected to each other by the bidentate linkers to form an infinite 1D double chain (X = Cl, Br). Such 1D chains are arranged into a 2D sheet through inter-chain π···π interactions. In 2 and 4, there are similar 1D double chains, but different inter-chain arrangement. Such 1D chains are connected into a 2D layer and further arranged in an ABAB fashion through O–H···X hydrogen bonds. The emission spectra and lifetimes in the microsecond range were measured at room temperature and at 77 K. Complexes 1 and 3 exhibit strong orange and yellow–orange emission in the solid state at room temperature, and were assigned to X-and M-to-ligand charge transfer excited states based on density functional theory calculations. The emission property of 2 and 4 was distinctly different from that of 1 and 3, probably due to the difference in coordination environments of the CuI centres as well as the dissimilar intermolecular arrangement.

scholarly journals Intriguing electronic, optical and photocatalytic performance of BSe, M2CO2 monolayers and BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures

RSC Advances ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 42-52
Author(s):  
M. Munawar ◽  
M. Idrees ◽  
Iftikhar Ahmad ◽  
H. U. Din ◽  
B. Amin
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Density Functional ◽  
Photocatalytic Performance ◽  
Electronic Band Structure ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Van Der Waals Heterostructures ◽  
Electronic Band ◽  
Functional Theory

Using density functional theory calculations, we have investigated the electronic band structure, optical and photocatalytic response of BSe, M2CO2 (M = Ti, Zr, Hf) monolayers and their corresponding BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures.

Electronic Structure and Ground State Properties of A4[Ag4O4] (A=Na, K and Rb): A First-Principles Study

2013 ◽  
Vol 665 ◽  
pp. 43-48
Author(s):  
Rajagopalan Umamaheswari ◽  
M. Yogeswari ◽  
G. Kalpana
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
First Principles Calculation ◽  
Partial Density ◽  
Electronic Band ◽  
Ground State Properties

The first-principles calculation within density functional theory is used to study in detail the electronic structure and ground state properties of alkali-metal oxoargenates A4[Ag4O4] (A= Na, K and Rb). The total energies calculated within the atomic sphere approximation (ASA) were used to determine the ground state properties such as equilibrium lattice parameter, c/a ratio, bulk modulus and cohesive energy. The theoretically calculated equilibrium lattice constants values are in well agreement with the available experimental values. The electronic band structures, total and partial density of states are calculated. The result of electronic band structure shows that the KAgO and RbAgO are direct band gap semiconductors with their gap lying between the Γ-Γ points, whereas NaAgO is found to be an indirect band gap semiconductor with its gap lying between Z-Γ points.

The Structural, Electronic, Optical and Thermo-Electric Properties of Oxynitride Perovskite CaTaO2N

SPIN ◽  
2020 ◽  
Vol 10 (01) ◽  
pp. 2050007
Author(s):  
K. Hocine ◽  
O. Cheref ◽  
K. Bettine ◽  
D. Rached ◽  
S. Benalia ◽  
...  
Keyword(s):  
Band Structure ◽  
Figure Of Merit ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Electric Properties ◽  
Partial Density ◽  
Full Potential ◽  
Thermo Electric ◽  
Electronic Band

In this study, we carried out ab-initio calculations of structural, electronic, optical and thermo-electric properties of CaTaO2N compound in Pnma orthorhombic structure, using the full-potential linearized augmented plane wave method (FP-LAPW), within the framework of density functional theory (DFT). The calculated structural parameters are found to be in good agreement with the experimental results. Moreover, we have studied the electronic band structure, total and partial density of states in order to explain the origin of band gaps and the nitrogen anion contribution in the valence and the conduction bands. The CaTaO2N band structure has shown a direct band gap in the direction [Formula: see text] (with the value 2.32[Formula: see text]eV). The optical properties represented by the dielectric functions for CaTaO2N compound have revealed that the Pnma structure absorbs the light at a large window in the edge UV-Vis regions. In order to explain the thermo-electric properties, we have calculated Seebeck coefficient, electrical conductivity, thermal conductivity and the factor figure of merit in this temperature range 100–1000 K. The factor figure of mérit (ZT) of CaTaO2N takes a maximum value of 0.775 at [Formula: see text][Formula: see text]K.

Improving the photocatalytic activity of s-triazine based graphitic carbon nitride through metal decoration: an ab initio investigation

2016 ◽  
Vol 18 (38) ◽  
pp. 26466-26474 ◽  
Author(s):  
K. Srinivasu ◽  
Brindaban Modak ◽  
Swapan K. Ghosh
Keyword(s):  
Photocatalytic Activity ◽  
Density Functional ◽  
Carbon Nitride ◽  
Electronic Band Structure ◽  
Density Functional Theory Calculations ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Electronic Band ◽  
Solar Water Splitting ◽  
Metal Decoration

Through density functional theory calculations, we attempted to tune the electronic band structure of poly s-triazine based graphitic carbon nitride by decorating it with different metal atoms and clusters for improving its photocatalytic activity towards solar water splitting.

Firs-Principles Investigation of the Electronic and Optical Properties of B-Doped ZnO under Pressure

2019 ◽  
Vol 807 ◽  
pp. 115-120
Author(s):  
Ling Ping Xiao ◽  
Yun Qin Liu
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Pressure Effects ◽  
Partial Density ◽  
Electronic Band ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Doped Zno

Based on the density functional theory (DFT), the first-principles approach is used to study the electronic band structure of B-doped wuritzite ZnO with different pressure. The pressure effects on the lattice parameters, electronic band structures, and partial density of states (PDOS) of crystalline B-doped ZnO are calculated up to 8 GPa. Moreover, the evolution of the dielectric function, absorption coefficient (), reflectivity (), and the real part of the refractive index () at high pressure are also presented. Keywords: high pressure; density functional theory; B-doped ZnO.

scholarly journals Visualizing band structure hybridization and superlattice effects in twisted MoS2/WS2 heterobilayers

2D Materials ◽  
2021 ◽  
Author(s):  
Alfred J. H. Jones ◽  
Ryan Muzzio ◽  
Sahar Pakdel ◽  
Deepnarayanan Biswas ◽  
Davide Curcio ◽  
...  
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Twist Angle ◽  
Electronic States ◽  
Single Layer ◽  
Density Functional Theory Calculations ◽  
Layer Transition ◽  
Electronic Band ◽  
Wide Range

Abstract A mismatch of atomic registries between single-layer transition metal dichalcogenides (TMDs) in a two dimensional van der Waals heterostructure produces a moiré superlattice with a periodic potential, which can be fine-tuned by introducing a twist angle between the materials. This approach is promising both for controlling the interactions between the TMDs and for engineering their electronic band structures, yet direct observation of the changes to the electronic structure introduced with varying twist angle has so far been missing. Here, we probe heterobilayers comprised of single-layer MoS2 and WS2 with twist angles ranging from 2° to 20° and determine the twist angle-dependent evolution of the electronic band structure using micro-focused angle-resolved photoemission spectroscopy. We find strong interlayer hybridization between MoS2 and WS2 electronic states at the Γ-point of the Brillouin zone, leading to a shift of the valence band maximum in the heterostructure. Replicas of the hybridized states are observed at the centre of twist angle-dependent moiré mini Brillouin zones. We confirm that these replica features arise from the inherent moiré potential by comparing our experimental observations with density functional theory calculations of the superlattice dispersion. Our direct visualization of these features underscores the potential of using twisted heterobilayer semiconductors to engineer hybrid electronic states and superlattices that alter the electronic and optical properties of 2D heterostructures for a wide range of twist angles.

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.

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