scholarly journals Magnesium ferrite nanostructures for detection of ethanol vapours - a first-principles study

2017 ◽  
Vol 11 (4) ◽  
pp. 296-303 ◽  
Author(s):  
Veerappan Nagarajan ◽  
Arunachalam Thayumanavan ◽  
Ramanathan Chandiramouli
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
Density Functional ◽  
Mulliken Charge ◽  
Adsorption Behaviour ◽  
Electronic Band ◽  
Ethanol Vapour ◽  
Adsorption Sites ◽  
Ethanol Vapours

The adsorption behaviour and electronic properties of ethanol vapour on MgFe2O4 ceramic nanostructures are studied using density functional theory technique. The structural stability of MgFe2O4 nanostructure is determined with the help of formation energy. The adsorption behaviour of ethanol molecules on MgFe2O4 base material is analysed in terms of average energy gap variation, Mulliken charge transfer, band gap and adsorption energy. The most prominent adsorption sites of ethanol vapours on MgFe2O4 nanostructure are investigated at atomistic level. The density of states spectrum reveals the clear picture about the electronic properties of MgFe2O4 nanostructure. The density of states and electronic band gap confirmed the adsorption of ethanol vapours on MgFe2O4 nanostructure. The changes in the energy band gap and density of states are observed upon adsorption of ethanol vapour molecules on MgFe2O4 nanostructure. The density of states spectrum also confirms the changes in peak maxima due to the transfer of electrons between MgFe2O4 nanostructure and ethanol vapours. The adsorption of oxygen atom from ethanol vapour on iron in MgFe2O4 is found to be more prominent rather than other adsorption sites. The findings show that MgFe2O4 nanostructure can be utilized to sense the presence of ethanol vapour in the atmosphere.

Electronic Properties of Calcium and Zirconium Co-Doped BaTiO3

2020 ◽  
Vol 1010 ◽  
pp. 308-313
Author(s):  
Akeem Adekunle Adewale ◽  
Abdullah Chik ◽  
Ruhiyuddin Mohd Zaki
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
Energy Band ◽  
Density Functional ◽  
Partial Density ◽  
Total Density ◽  
Energy Band Gap ◽  
Wide Energy ◽  
Direct Band

Barium titanate (BaTiO3) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO3 has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A- and B- sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO3 are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba0.875Ca0.125Ti0.875Zr0.125O3 sample at Γ- Γ (2.31 eV) and X- X (2.35 eV) symmetry point.

scholarly journals DFT Study on Structural, Electronic and Optical Properties of Ag-Doped SrTiO3 Perovskite for Optoelectronic Applications

2021 ◽  
Author(s):  
Jalil Rehman ◽  
M.Awais Rehman ◽  
Muhammad Bilal Tahir ◽  
Muhammad Usman ◽  
Faisal Iqbal
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Of States ◽  
Density Functional ◽  
Partial Density ◽  
Electronic Band ◽  
Ag Doping ◽  
Direct Band Gap ◽  
Direct Band ◽  
Optoelectronic Applications

This study addresses the first-principles analysis using generalized gradient approximation (GGA), which is pillared on density functional theory (DFT), to find the effects of silver (Ag) doping on SrTiO3 structurally, electronically and optical properties. As Ag doping into SrTiO3, we see a small decrease in the volume of unit cell. Moreover, Ag-doping adds new states in SrTiO3 at Brillouin zone symmetry points, transferring host material’s indirect band gap to a direct band gap. Ag doping in SrTiO3 results in the transfer density of states to smaller energies and increase in interaction among Ag atom and its surrounding atoms. Moreover, at the conduction band, the partial density of states (PDOS) of SrTiO3 changes generally. As a result, we conclude that Ag doping has an effect on the electronic band structure of SrTiO3. SrTiO3 doping with Ag has improved optical properties and its ability of converting to direct band gap results it in a perfect choice for optoelectronic applications.

scholarly journals Effect of Nitrogen Impurity on Electronic Properties of Boron Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Sandeep Kumar Jain ◽  
Pankaj Srivastava
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Nitrogen Doping ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Functional Theory ◽  
Impurity Atoms ◽  
Nitrogen Impurity ◽  
First Time

For the first time we present electronic band structure and density of states for nitrogen doped hexagonal ultrathin boron nanotubes in the framework of density functional theory. The considered models of nanotubes below 5 Å diameter are armchair (3,3), zigzag (5,0), and chiral (4,2). The impurity chosen for the study is nitrogen and concentration of impurity atoms is limited to two. The study reveals that (3,3) BNT retains its metallic nature after nitrogen doping. However, metallicity gets increased which is attributed by the excess electrons of nitrogen. Further, it also brings out that (5,0) BNT which is originally metal transforms into semiconductor after nitrogen interaction and the band gap at G point increases with the impurity. Moreover, the band gap of (4,2) BNT reduces significantly and turns into semimetal for nitrogen doping. Thus, the nitrogen impurity has the predominant effect on the electronic properties of BNTs and therefore can be regarded as suitable candidates for nanoelectronic and field emission devices.

STRUCTURES AND ELECTRONIC PROPERTIES OF A Co2P CLUSTER DEPOSITED ON THE RUTILE TiO2(110) SURFACE BY FIRST–PRINCIPLES CALCULATIONS

2013 ◽  
Vol 12 (01) ◽  
pp. 1250102 ◽  
Author(s):  
WEI-NA ZHAO ◽  
WEN-KAI CHEN
Keyword(s):  
Electronic Properties ◽  
Molecular Orbital ◽  
First Principles ◽  
Density Functional ◽  
Frontier Molecular Orbital ◽  
Mulliken Charge ◽  
Surface Binding ◽  
Adsorption Sites ◽  
Molecular Orbital Analysis ◽  
Band Gap Narrowing

The structures and electronic properties of different Co2P -supporting configurations on the rutile TiO2 (110) surface have been investigated by first-principles density functional theory (DFT) calculations. A number of possible structural candidates and adsorption sites have been considered, while the calculations are executed on periodic systems using slab model. Our results indicate that the O atoms on TiO2 (110) turn out to be preferable for the cluster to adsorb by Co atoms, with the largest adsorption energy of 211.50 kJ/mol in the most favorable model. According to the Mulliken charge analysis, the Co2P cluster carries a significant positive charge after adsorption, due to the charge transfer occurring from the adsorbate to the substrate. Moreover, the frontier molecular orbital analysis shows that the cluster-surface binding occurs mostly through the interplay of filled Co 3d orbital with unoccupied eigenstates of surface localized on O 2p orbital, which can be also corroborated by the projected density of states investigations, while the lowest unoccupied molecular orbital is mostly contributed by Ti 3d orbital of the surface. In addition, of particular significance is that deposition of Co2P on the rutile TiO2 (110) surface results in a small band gap narrowing vis-à-vis the pure surface, yielding a positive effect on catalytic activity.

First Principles Based Study of Ground State and Electronic Properties of TmPb3 Intermetallic Compound

2016 ◽  
Vol 28 ◽  
pp. 43-46
Author(s):  
Gitanjali Pagare
Keyword(s):  
Intermetallic Compound ◽  
Bulk Modulus ◽  
Electronic Properties ◽  
Density Of States ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Full Potential ◽  
Electronic Band ◽  
Calculated Density

The ground state behavior of rare earth intermetallic compound TmPb3, which crystallize in AuCu3 type structure, has been examined using first principles density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. Very few study on structural and electronic properties of TmPb3 compound has been available in the literature, which motivated us to perform the present study. The spin polarized calculations are carried out within the PBE-GGA and LSDA for the exchange correlation (XC) potential. Our calculated ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B’) are in good agreement with the experimental results. The value of bulk modulus of TmPb3 is found to be 44.32 GPa and 55.01GPa by PBE-GGA and LSDA respectively. The electronic band structure (BS) and density of states (DOS) verify the metallic nature of this compound. The calculated density of states at the fermi level is found to be 0.16 states/eV and 19.50 states/eV for spin-up and spin-down modes respectively. The magnetic moment of TmPb3 is found to be 0.95.

scholarly journals Study of Structural and Electronic Properties of Intercalated Transition Metal Dichalcogenides Compound MTiS2 (M = Cr, Mn, Fe) by Density Functional Theory

2021 ◽  
Keyword(s):  
Transition Metal ◽  
Band Structure ◽  
Electronic Properties ◽  
Density Of States ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Energy Band Structure ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Metal Dichalcogenides

In the present work, we have studied intercalated Transition Metal Dichalcogenides (TMDC) MTiS2 compounds (M = Cr, Mn, Fe) by Density Functional Theory (DFT) with Generalized Gradient Approximation (GGA). We have computed the structural and electronic properties by using first principle method in QUANTUM ESPRESSO computational code with an ultra-soft pseudopotential. A guest 3d transition metal M (viz; Cr, Mn, Fe) can be easily intercalated in pure transition metal dichalcogenides compound like TiS2. In the present work, the structural optimization, electronic properties like the energy band structure, density of states (DoS), partial or projected density of states (PDoS) and total density of states (TDoS) are reported. The energy band structure of MTiS2 compound has been found overlapping energy bands in the Fermi region. We conclude that the TiS2 intercalated compound has a small band gap while the doped compound with guest 3d-atom has metallic behavior as shown form its overlapped band structure.

scholarly journals Hydration Dependent Band Gap Tunability of Self-Assembled Phenylalanine-Tryptophan Nanotubes

2020 ◽  
Author(s):  
Hugo Souza ◽  
Antonio Chaves Neto ◽  
Francisco Sousa ◽  
Rodrigo Amorim ◽  
Alexandre Reily Rocha ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Building Block ◽  
Density Functional ◽  
Tight Binding ◽  
Water Molecules ◽  
Confined Water ◽  
Functional Theory ◽  
Tight Binding Method

In this work, we investigate the effects of building block separation of Phenylalanine-Tryptophan nanotube induced by the confined water molecules on the electronic properties using density-functional theory based tight-binding method. <div><br></div>

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

First-Principles Study of the New Half-Metallic Ferromagnetic Quaternary-Heusler Alloys NaXNO (X=Ca, Sr, Ba)

SPIN ◽  
2020 ◽  
Vol 10 (03) ◽  
pp. 2050022 ◽  
Author(s):  
K. Belkacem ◽  
Y. Zaoui ◽  
S. Amari ◽  
L. Beldi ◽  
B. Bouhafs
Keyword(s):  
Magnetic Properties ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Heusler Alloys ◽  
Exchange Potential ◽  
Energy Calculation ◽  
Full Potential ◽  
Electronic Band ◽  
Half Metallic

The first-principles approach based on density functional theory (DFT) and the full-potential linearized augmented plane-wave method were employed to investigate the structural, elastic, electronic and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. The generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE) and the modified Becke–Johnson exchange potential were used. As far as we know, we present our results which for the first time quantitatively account for the electronic structures and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. From the total energy calculation using three possible atomic configurations ([Formula: see text], [Formula: see text] and [Formula: see text]), it is found that the Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys are more stable in the ferromagnetic [Formula: see text]-phase. From our estimated elastic constants [Formula: see text], it is found that all the considered Heusler alloys are mechanically stable in the [Formula: see text]-phase. We have also investigated the robustness of the half-metallicity with respect to the variation of lattice constants in these alloys. We have found that these alloys are half-metallic ferromagnets (HMFs) with a magnetic moment of 2[Formula: see text][Formula: see text] per formula unit at their equilibrium volumes. The spin-polarized electronic band structure and density of states of these quaternary half-Heusler alloys calculated by GGA (mBJ-GGA) show that the minority spin channels have metallic nature and the majority spin channels have a semiconductor character with half-metallic gaps of 0.49[Formula: see text]eV (2.17[Formula: see text]eV), 0.72[Formula: see text]eV (2.28[Formula: see text]eV) and 0.96[Formula: see text]eV (2.22[Formula: see text]eV) for NaCaNO, NaSrNO and NaBaNO quaternary half-Heusler alloys, respectively. Analysis of the density of states and the spin charge density of these quaternary alloys indicates that their magnetic moments mainly originate from the strong spin-polarization of 2[Formula: see text] states of N atoms and O atoms.

scholarly journals Organically interconnected graphene flakes: A flexible 3-D material with tunable electronic bandgap

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. Klontzas ◽  
E. Tylianakis ◽  
V. Varshney ◽  
A. K. Roy ◽  
G. E. Froudakis
Keyword(s):  
Chemical Composition ◽  
Band Gap ◽  
Electronic Properties ◽  
Flexible Electronics ◽  
Density Functional ◽  
Organic Molecule ◽  
Tight Binding ◽  
Structural And Electronic Properties ◽  
Graphene Flakes ◽  
Band Gap Tuning

Abstract The structural and electronic properties of molecularly pillared graphene sheets were explored by performing Density Functional based Tight Binding calculations. Several different architectures were generated by varying the density of the pillars, the chemical composition of the organic molecule acting as a pillar and the pillar distribution. Our results show that by changing the pillars density and distribution we can tune the band gap transforming graphene from metallic to semiconducting in a continuous way. In addition, the chemical composition of the pillars affects the band gap in a lesser extent by introducing additional states in the valence or the conduction band and can act as a fine band gap tuning. These unique electronic properties controlled by design, makes Mollecular Pillared Graphene an excellent material for flexible electronics.

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