Electronic structure of gadolinium-doped ceria system: A DFT study

2019 ◽  
Vol 33 (08) ◽  
pp. 1950095
Author(s):  
Jianfeng Wang
Keyword(s):  
Thin Film ◽  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Conductivity ◽  
Film Structure ◽  
Dft Study ◽  
Doped Ceria ◽  
Generalized Gradient ◽  
Gadolinium Doped Ceria

We have performed a density functional theory (DFT) study of the electronic structure in ceria [Formula: see text] and gadolinium-doped ceria (GDC) system using VASP code in the generalized gradient approximation (GGA) with DFT[Formula: see text]+[Formula: see text]U. The band structures in GDC and thin film GDC are calculated and compared to that of bulk ceria. Doping of gadolinium significantly decreases the band gap of ceria, while the thin film structure of GDC raises the band gap greatly. The results help explain the electronic conductivity behavior of GDC and suggest that thin film-structured GDC could be used as a possible way to overcome the current leakage disadvantage of GDC.

Carrier and Transition Metals (M = Nb, Cr and Fe) Doping Effects on Structure and Electronic Structure in Spinel Li4Ti5O12 Compounds

2020 ◽  
Vol 310 ◽  
pp. 88-95
Author(s):  
Lkhagvajav Sarantuya ◽  
Namsrai Tsogbadrakh ◽  
Galsan Sevjidsuren ◽  
Pagvajav Altantsog
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Electronic Conductivity ◽  
Generalized Gradient ◽  
Promising Candidate ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Doping Effects ◽  
Li Ion ◽  
Projector Augmented Wave

Spinel Li4Ti5O12 (LTO) is one of the most promising candidate anode material for Li-ion battery (LIB) known, as zero strain material, it has poor intrinsic electronic properties. In order to enhance it, we have investigated effect of doping on electronic conductivity of spinel LTO phase structure. We consider the carrier and transition metal doping effect on structure and electronic structure of spinel LTO. It is shown that the doping can improve the electronic conduction of spinel LTO. Our calculations were based on the projector augmented wave (PAW) method with the generalized gradient approximation (GGA+U+J0) including the Hubbard U parameter for exchange correlation functional within the framework of density functional theory (DFT).

scholarly journals DFT Study of the Electronic Structure of Cubic-SiC Nanopores with a C-Terminated Surface

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Calvino ◽  
A. Trejo ◽  
M. I. Iturrios ◽  
M. C. Crisóstomo ◽  
Eliel Carvajal ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Surface Passivation ◽  
Phase Changes ◽  
Surface Relaxation ◽  
Oh Radicals ◽  
Functional Theory ◽  
Band Gap Engineering ◽  
Chemical Surface

A study of the dependence of the electronic structure and energetic stability on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using density functional theory (DFT) and the supercell technique. The pores were modeled by removing atoms in the [001] direction to produce a surface chemistry composed of only carbon atoms (C-phase). Changes in the electronic states of the porous structures were studied by using different passivation schemes: one with hydrogen (H) atoms and the others gradually replacing pairs of H atoms with oxygen (O) atoms, fluorine (F) atoms, and hydroxide (OH) radicals. The results indicate that the band gap behavior of the C-phase pSiC depends on the number of passivation agents (other than H) per supercell. The band gap decreased with an increasing number of F, O, or OH radical groups. Furthermore, the influence of the passivation of the pSiC on its surface relaxation and the differences in such parameters as bond lengths, bond angles, and cell volume are compared between all surfaces. The results indicate the possibility of nanostructure band gap engineering based on SiC via surface passivation agents.

Electronic Structure Of (AgSb)xPbn-2xTen

2003 ◽  
Vol 793 ◽  
Author(s):  
Daniel I Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Two Component System ◽  
Functional Theory ◽  
Covalent Interaction ◽  
Salt Structure ◽  
Linearized Augmented Plane Wave

ABSTRACTComplex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems form in the rock-salt structure similar to the well known two component system PbTe (x=0). In these systems Ag and Sb occupy Pb sites randomly although there is some evidence of short-range order. To gain insights into the electronic structure of these compounds, we have performed electronic structure calculations in AgSbTe2 (x=n/2). These calculations were carried out within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spinorbit interaction (SOI) was incorporated using a second variational procedure. Since it is difficult to treat disorder in ab initio calculations, we have used several ordered structures for AgSbTe2. All these structures show semimetallic behavior with a pseudogap near the Fermi energy. Te and Sb p orbitals, which are close in energy, hybridize rather strongly indicating a covalent interaction between Te and Sb atoms.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

scholarly journals Oxygen vacancy and doping atom effect on electronic structure and optical properties of Cd2SnO4

RSC Advances ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 640-646 ◽  
Author(s):  
Mei Tang ◽  
JiaXiang Shang ◽  
Yue Zhang
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Oxygen Vacancy ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
La Doped ◽  
Doping Atom ◽  
Atom Effect

The electronic structure and optical properties of oxygen vacancy and La-doped Cd2SnO4 were calculated using the plane-wave-based pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA).

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.

Electronic Structure and Ferromagnetic Properties of Doped Calcium Sulfide Ca1−xTMxS (TM = V, Cr and Co)

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050013 ◽  
Author(s):  
Amina Aiche ◽  
Abdelkader Tadjer ◽  
Hadj Moulay Ahmed Mazouz ◽  
Bendouma Doumi ◽  
Houari Khachai
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Double Exchange ◽  
Ferromagnetic State ◽  
Spin Splitting ◽  
Full Potential ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic

The electronic structure and magnetic properties of diluted Ca[Formula: see text]TMxS (TM[Formula: see text][Formula: see text][Formula: see text]V, Cr and Co) in the rocksalt structure at concentrations [Formula: see text], 0.125 and 0.25 were studied using the full-potential linearized augmented plane wave approximation of the density functional theory with the Wu-Cohen generalized gradient approximation (WC-GGA) and the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential. Features such as lattice constant, bulk modulus, spin-polarized band structures, total and local densities of states and magnetic properties have been computed. The electronic structure show that Ca[Formula: see text](V, Cr)xS at all the studied concentrations and the diluted Ca[Formula: see text]CoxS with [Formula: see text] compounds are half-metallic ferromagnets with spin polarization of 100%. The calculated total magnetic moments for Ca[Formula: see text]VxS and Ca[Formula: see text]CoxS show the same integer value of 3[Formula: see text][Formula: see text] per formula unit and Ca[Formula: see text]CrxS exhibit a total magnetic moment of 4[Formula: see text][Formula: see text], which confirm the half-metallic behavior of these compounds. We also calculated the values of the band edge spin splitting of the valence and conduction bands and the exchange constants. We have found that the ferromagnetic state is stable by the p-d exchange associated with the double-exchange mechanism. The diluted Ca[Formula: see text](V,Cr,Co)xS are found to be new promising candidates for spintronic applications.

scholarly journals Carbon-Based Band Gap Engineering in the h-BN Analytical Modeling

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1026
Author(s):  
Mohammad Taghi Ahmadi ◽  
Ahmad Razmdideh ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Tight Binding ◽  
Band Gap Energy ◽  
Specific Structure ◽  
Partial Substitution ◽  
Generalized Gradient ◽  
Complete Replacement

The absence of a band gap in graphene is a hindrance to its application in electronic devices. Alternately, the complete replacement of carbon atoms with B and N atoms in graphene structures led to the formation of hexagonal boron nitride (h-BN) and caused the opening of its gap. Now, an exciting possibility is a partial substitution of C atoms with B and N atoms in the graphene structure, which caused the formation of a boron nitride composite with specified stoichiometry. BC2N nanotubes are more stable than other triple compounds due to the existence of a maximum number of B–N and C–C bonds. This paper focused on the nearest neighbor’s tight-binding method to explore the dispersion relation of BC2N, which has no chemical bond between its carbon atoms. More specifically, the band dispersion of this specific structure and the effects of energy hopping in boron–carbon and nitrogen–carbon atoms on the band gap are studied. Besides, the band structure is achieved from density functional theory (DFT) using the generalized gradient approximations (GGA) approximation method. This calculation shows that this specific structure is semimetal, and the band gap energy is 0.167 ev.

scholarly journals Effect of Vacancy Defects on the Electronic Structure and Optical Properties of GaN

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Lili Cai ◽  
Cuiju Feng
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Lower Energy ◽  
Density Functional ◽  
Nitrogen Vacancy ◽  
Main Peak ◽  
Generalized Gradient ◽  
Vacancy Defects ◽  
Gallium Vacancy ◽  
Defect Levels

The effect of gallium vacancy (VGa) and nitrogen vacancy (VN) defects on the electronic structure and optical properties of GaN using the generalized gradient approximation method within the density functional theory were investigated. The results show that the band gap increases in GaN with vacancy defects. Crystal parameters decrease in GaN with nitrogen vacancy (GaN:VN) and increase in GaN with gallium vacancy (GaN:VGa). The Ga vacancy introduces defect levels at the top of the valence band, and the defect levels are contributed by N2p electron states. In addition, the energy band shifts to lower energy in GaN:VNand moves to higher energy in GaN:VGa. The level splitting is observed in the N2p states of GaN:VNand Ga3d states of GaN:VGa. New peaks appear in lower energy region of imaginary dielectric function in GaN:VNand GaN:VGa. The main peak moves to higher energy slightly and the intensity decreases.

Compare Study of Electronic Structure, Chemical Bonding and Elastic Properties of Ti3AC2 (A=Al, Si, Sn) by First-Principles

2012 ◽  
Vol 624 ◽  
pp. 117-121 ◽  
Author(s):  
Fan Jun Zeng ◽  
Qing Lin Xia
Keyword(s):  
Electronic Structure ◽  
Elastic Properties ◽  
Chemical Bonding ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Hexagonal Phase ◽  
Partial Density ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Compare Study

The electronic structure, chemical bonding and elastic properties of Ti3AC2 (A=Al, Si, Sn) were investigated by generalized gradient approximation (GGA) based on density functional theory (DFT). The calculated lattice parameters and equilibrium volumes are in good agreement with the available experimental data. The density of state (DOS) and partial density of states (PDOS) show that the DOS at the Fermi level (EF) is located at the bottom of a valley and originate mainly from the Ti-3d electrons. Population analyses suggest that there are strong covalent bonding in Ti1-C and Ti2-C atoms in Ti3AC2 (A=Al, Si, Sn). Single-crystal elasticity constants were calculated and the polycrystalline elastic modules were estimated according to Voigt, Reuss and Hill’s approximations (VRH). The Young’s modulus Y, Poisson’s ratio ν and BH/GH are also predicted. Results conclude that the hexagonal phase Ti3AC2 (A=Al, Si, Sn) are mechanical stable and behaves in a brittle manner. Polycrystalline elastic anisotropy coefficients AB and AG are also derived from polycrystalline bulk modulus B and shear modulus G.

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