Optoelectronic and Magnetic Properties of Eu2Si5N8: An Ab-initio Study

2015 ◽  
Vol 70 (11) ◽  
pp. 897-904
Author(s):  
Sikander Azam ◽  
Saleem Ayaz Khan ◽  
R. Khenata ◽  
G. Murtaza ◽  
S. Bin Omran ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
Loss Function ◽  
Density Functional ◽  
Energy Gap ◽  
Optical Memory ◽  
Inorganic Materials ◽  
Coulomb Energy ◽  
Energy Loss Function

AbstractEu2Si5N8 is considered the most important compound in the development of inorganic materials with high potential and performance. Therefore, the electronic, magnetic and optical properties of Eu2Si5N8 are investigated here using density functional theory. The electronic interactions are described within the generalised gradient approximation, GGA+U (where U is the Hubbard Coulomb energy term). The calculated energy gap was 3.5 eV for the investigated compound, resulting in a direct band gap semiconductor. The optical constants, including the dielectric function, refractive index, absorption coefficient, reflectivity, and energy loss function were calculated for radiation up to 14 eV. The optical properties demonstrate that the main differences in absorption, reflectivity, energy-loss function and refractive index occur in the infrared and visible regions for the spin-up and spin-down states, which makes this material an excellent candidate for optical memory devices.

DFT study of pressure effects in molecular crystal 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo-[5.5.0.05,903,11]-dodecane

2014 ◽  
Vol 92 (7) ◽  
pp. 616-624 ◽  
Author(s):  
Zhichao Liu ◽  
Qiong Wu ◽  
Weihua Zhu ◽  
Heming Xiao
Keyword(s):  
High Pressure ◽  
Energy Loss ◽  
Loss Function ◽  
Density Functional ◽  
Pressure Range ◽  
Blue Shift ◽  
Pressure Effects ◽  
Ambient Conditions ◽  
Energy Loss Function ◽  
Electron Transitions

Density functional theory was used to study the structural, electronic, and optical properties of crystalline 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo-[5.5.0.05,903,11]-dodecane (TEX) under hydrostatic pressure. The results indicate that there is a displacive transition in TEX under compression that has never been found in experiments. As the pressure increases, the band gap gradually decreases but presents an abnormal increase at 61 GPa, called the structural transition; moreover, the gap reduction is more pronounced in the low-pressure range compared with the high-pressure range. An analysis of density of states shows that the electronic delocalization in TEX is enhanced gradually under the influence of pressure. The peaks of the imaginary parts of the dielectric functions, energy-loss function, and reflectivity may come mainly from the electron transitions between the oxygen 2p and nitrogen 2p states. The electron energy-loss function presents a blue shift under compression. TEX has relatively higher optical activity at high pressure than at ambient conditions.

First-principle studies of the optoelectronic properties of ASnF3 (A = Na, K, Rb and Cs)

2017 ◽  
Vol 31 (21) ◽  
pp. 1750148 ◽  
Author(s):  
Imad Khan ◽  
Nasir Shehzad ◽  
Iftikhar Ahmad ◽  
Zahid Ali ◽  
S. Jalali-Asadabadi
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
Ab Initio Calculations ◽  
Loss Function ◽  
Electron Transition ◽  
First Principle ◽  
Electronic Band ◽  
New Type ◽  
Electronic Band Structures

In this paper, we communicate a new type of Auger-free luminescence (AFL) compounds, alkali tin fluorides ASnF3 (A = Na, K, Rb and Cs). The luminescence in these compounds originates due to the electron transition from the top valence band (VB) of tin-[Formula: see text] orbital to the outermost core levels of halogen, i.e., halogen-[Formula: see text] orbital ([Formula: see text]-[Formula: see text] transitions). The AFL of these compounds is expected to be of L-type. Furthermore, the electronic band structures and optical properties such as dielectric functions, refractive index and energy loss function are also investigated using ab initio calculations.

scholarly journals Energy-loss Function for Lead

2017 ◽  
Vol 27 (1) ◽  
pp. 65
Author(s):  
Hieu T. Nguyen-Truong ◽  
Tan-Tien Pham ◽  
Nam H. Vu ◽  
Dang H. Ngo ◽  
Hung M. Le
Keyword(s):  
Energy Loss ◽  
Loss Function ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Functional Theory ◽  
Energy Loss Function ◽  
Zero Momentum ◽  
Electron Energy Loss ◽  
Linearized Augmented Plane Wave

We study the energy-loss function for lead in the framework of the time-dependent density functional theory, using the full-potential linearized augmented plane-wave plus local orbitals method. The ab initio calculations are performed in the adiabatic local density approximation. The comparison between the obtained energy-loss function for zero momentum transfer with those from reflection electron energy loss spectroscopy measurements and from first-principles calculations shows good agreement.

scholarly journals Structure, electronic and optical properties of chalcopyrite-type nano-clusters XFeY2 (X=Cu, Ag, Au; Y=S, Se, Te): a density functional theory study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Prabhat Ranjan ◽  
Praveen K. Surolia ◽  
Tanmoy Chakraborty
Keyword(s):  
Density Functional Theory ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Solar Cells ◽  
Density Functional ◽  
Energy Gap ◽  
Lumo Energy ◽  
Functional Theory ◽  
Homo Lumo

Abstract Iron-based chalcopyrite materials have diverse applications in solar cells, spintronic, thermoelectric devices, LEDs and medical sciences. In this report we have studied structure, electronic and optical properties of chalcopyrite-type nano-cluster XFeY2 (X=Cu, Ag, Au; Y=S, Se, Te) systematically by using Density Functional Theory (DFT). Our computed HOMO-LUMO energy gap of XFeY2 is in the range of 1.568–3.982 eV, which endorses its potential application in optoelectronic devices and solar cells. The result shows that chalcopyrite-type material AuFeS2 having a star-type structure with point group C2v and sextet spin multiplicity, is the most stable cluster with HOMO-LUMO energy gap of 3.982 eV. The optical properties viz. optical electronegativity, refractive index, dielectric constant, IR and Raman activity of these nano-clusters are also investigated. The result exhibits that HOMO-LUMO energy gap of XFeY2 along with optical electronegativity and vibrational frequency decreases from S to Se to Te, whereas refractive index and dielectric constant increases in the reverse order.

An ab-initio study of electronic and optical properties of RhXO3 (X = Ga, Ag) perovskites

2022 ◽  
Author(s):  
Syed Awais Rouf ◽  
Muhammad Iqbal Hussain ◽  
Umair Mumtaz ◽  
Hafiz Tariq Masood ◽  
Hind Albalawi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Energy Loss ◽  
Ab Initio ◽  
Loss Function ◽  
Extinction Coefficient ◽  
Ab Initio Study ◽  
Band Formation ◽  
Optical Behavior

Abstract The ab-initio computations were performed to study the electronic and optoelectronic properties of RhXO3 (X = Ga, Ag) using WIEN2k code. The RhGaO3 has band gap of 2.29 eV, and the behavior of RhAgO3 metallic. The sub-TDOS of the studied materials revealed that rhodium and oxygen atoms have significant contributions in the valence band and conduction band formation of both materials. The silver cation is responsible for the reasonable peaks appearing at the Fermi level of RhAgO3, which demonstrated the conducting nature of RhAgO3. The dielectric functions, optical conductivity, energy loss function, absorption coefficient, refractive index, extinction coefficient, and reflectivity are computed for these materials to understand the optical behavior of the studied materials. The analysis of optical properties ensure the RhGaO3 is a promising material for optoelectronics while RhAgO3 has metallic nature.

Characterization of the Electronic Structure and Optical Properties of Al2O3, ZrO2 and SrTiO3 from Analysis of Reflection Electron Energy Loss Spectroscopy in the Valence Region

2003 ◽  
Vol 786 ◽  
Author(s):  
G. L. Tan ◽  
L. K. Denoyer ◽  
R. H. French ◽  
A. Ramos ◽  
M. Gautier-Soyer ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Loss Function ◽  
Electron Energy Loss Spectroscopy ◽  
Oxide Materials ◽  
Energy Loss Function ◽  
Electron Energy Loss

ABSTRACTCharacterization of thin surficial films of oxides has become the focus of increased interest due to their applications in microelectronics. The ability to experimentally determine the electronic structure and optical properties of oxide materials permits the direct study of the interband transitions from the valence to the conduction band states. In the past years there has been much progress in the quantitative analysis of transmission electron energy loss spectroscopy (TEELS) in the electron microscopeHere we employed reflection electron energy loss function (REELS) as well as vacuum ultraviolet (VUV) spectroscopy to determine the dielectric functions of oxide materials, i.e. Al2O3, ZrO2 and SrTiO3. The two main steps in the analysis are the removal of the effects of multiple scattering from the REELS spectra followed by application of the Kramers-Kronig dispersion transforms to the single scattering energy loss function to determine the conjugate optical variable and then the complex dielectric function. The surface and bulk plasma resonance spectra for these oxide materials have been determined from VUV and REELS, along with the influence of primary electron energy on the REELS results. The relative contribution of surface and bulk plasmon oscillation in REELS has been investigated. Comparison with VUV results and existing TEELS results indicate that Kramers-Kronig analysis can also be applied to REELS spectra and the corresponding conjugate optical properties can be obtained. Quantitative studies of the electronic structure and optical properties of thin surficial films using VUV and REELS or TEELS, represent a new avenue to determine the properties of these increasingly important films.

Investigations of the Optical Properties of LaNi5 and LaNi4.5Sn0.5

2013 ◽  
Vol 321-324 ◽  
pp. 495-498 ◽  
Author(s):  
Dong Chen ◽  
Chao Xu
Keyword(s):  
Experimental Data ◽  
Refractive Index ◽  
Optical Properties ◽  
Density Functional ◽  
Low Frequency ◽  
Potential Method ◽  
Frequency Region ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Pseudo Potential

The reflectivity, loss function, refractive index, extinction coefficient and dielectric function of the LaNi5and LaNi4.5Sn0.5intermetallic compounds are investigated through the plane-wave pseudo-potential method based on the density functional theory. The effects of Sn impurity are discussed and some interesting features are found in the low frequency region. Some important optical properties such as static dielectric constant and static refractive index are obtained. The equation [n (0)]2=ε1(0)is satisfied according to our calculation, which indicates that our results are correct and reasonable. Nevertheless, the calculated results need to be testified in the future due to the lack of experimental data.

Theoretical investigation on tautomerism and NLO properties of Salicylideneaniline derivatives

2021 ◽  
Author(s):  
N. Daho ◽  
N. Benhalima ◽  
F. KHELFAOUI ◽  
O. SADOUKI ◽  
M. Elkeurti ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Intramolecular Proton Transfer ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Visible Absorption ◽  
Charge Delocalization ◽  
Intramolecular Hydrogen

In this work, a comprehensive investigation of the salicylideneaniline derivatives is carried out using density functional theory to determine their linear and non-linear optical properties. Geometry optimizations, for gas and solvent phases, of the tautomers (enol and keto forms) are calculated using B3LYP levels with 6–31G (d,p) basis set . An intramolecular proton transfer, for 1SA-E and 2SA-E, is performed by a PES scan process at the B3LYP/6-31G (d,p) level. The optical properties are determined and show that they have extremely high nonlinear optical properties. In addition, the RDG analysis, MEP, and gap energy are calculated. The low energy gap value indicates the possibility of intramolecular charge transfer. The frontier molecular orbital calculations clearly show the inverse relationship of HOMO–LUMO gap with the first-order hyperpolarizability (β = 59.6471 × 10-30 esu), confirming that the salicylideneaniline derivatives can be used as attractive future NLO materials. Therefore, the reactive sites are predicted using MEP and the visible absorption maxima are analyzed using a theoretical UV–Vis spectrum. Natural bond orbitals are used to investigate the stability, charge delocalization, and intramolecular hydrogen bond.

scholarly journals Optical properties of AlN layers obtained by magnetron sputtering

2018 ◽  
Vol 36 (4) ◽  
pp. 717-721
Author(s):  
Piotr Potera ◽  
Grzegorz Wisz ◽  
Łukasz Szyller
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Magnetron Sputtering ◽  
Energy Gap ◽  
Optical Measurements ◽  
Transmission Spectra ◽  
Glass Substrates ◽  
Different Content

AbstractThe growth of AlN layers on glass substrates using magnetron sputtering method was performed and the grown layers were subjected to optical measurements. Transmission spectra of the layers grown at different content of N2 in the atmosphere were obtained. The transmission spectra as well as energy gap depended on N2 content. The annealing of the layers in air led to transmission changes and influenced energy gap and refractive index values.

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