Structural and electronic properties of Cu4O3 (paramelaconite): the role of native impurities

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Aleksandar Živković ◽  
Jacobina Sheehama ◽  
Michael E. A. Warwick ◽  
Daniel R. Jones ◽  
Claire Mitchel ◽  
...  
Keyword(s):  
Density Functional ◽  
Mixed Valence ◽  
Stability Range ◽  
Electronic Band ◽  
Oxide Compound ◽  
Type Conductivity ◽  
Narrow Region ◽  
Electronic Band Gap ◽  
The Stability ◽  
Experimental Findings

Abstract Hybrid density functional theory has been used to study the phase stability and formation of native point defects in Cu4O3. This intermediate copper oxide compound, also known as paramelaconite, was observed to be difficult to synthesize due to stabilization issues between mixed-valence Cu1+ and Cu2+ ions. The stability range of Cu4O3 was investigated and shown to be realized in an extremely narrow region of phase space, with Cu2O and CuO forming readily as competing impurity phases. The origin of p-type conductivity is confirmed to arise from specific intrinsic copper vacancies occurring on the 1+ site. Away from the outlined stability region, the dominant charge carriers become oxygen interstitials, impairing the conductivity by creating deep acceptor states in the electronic band gap region and driving the formation of alternative phases. This study further demonstrates the inadequacy of native defects as a source of n-type conductivity and complements existing experimental findings.

SPIN-POLARIZATION-DEPENDENT TRANSPORT IN GRAPHENE NANORIBBON WITH A VACANCY

2011 ◽  
Vol 10 (03) ◽  
pp. 533-538 ◽  
Author(s):  
CHUN-MEI LIU ◽  
NIAN-HUA LIU ◽  
ZHENG-FANG LIU ◽  
LI-PING AN
Keyword(s):  
Spin Polarization ◽  
Electronic Transport ◽  
First Principles ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Electronic Band ◽  
Functional Theory ◽  
Electronic Band Gap ◽  
The Stability ◽  
Dependent Transport

By using the first-principles density functional theory combining with the nonequilibrium Green’s function techniques, we investigate the electronic structure and the spin-polarization-dependent electronic transport of zigzag graphene nanoribbons (ZGNR) with a defect of vacancy. The total energy of the graphene ribbons corresponding to different vacancy locations is calculated to analyze the stability of the structures. It is found that the existence of a vacancy causes a significant change in the electronic band gap. The electronic band and the transport become spin-polarization-dependent. The calculated I–V characteristic shows that the spin-polarization-dependent effect can be enhanced under a finite bias voltage.

Systematic first principles calculations of the effects of stacking faults defects on the 4H-SiC band structure

2010 ◽  
Vol 1246 ◽  
Author(s):  
Massimo Camarda ◽  
pietro delugas ◽  
Andrea Canino ◽  
Andrea Severino ◽  
nicolo piluso ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Faults ◽  
Perfect Crystal ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Functional Theory ◽  
Experimental Findings ◽  
Electronic Band Structures ◽  
Formation Energies

AbstractShockley-type Stacking faults (SSF) in hexagonal Silicon Carbide polytypes have received considerable attention in recent years since it has been found that these defects are responsible for the degradation of forward I-V characteristics in p-i-n diodes. In order to extend the knowledge on these kind of defects and theoretically support experimental findings (specifically, photoluminescence spectral analysis), we have determined the Kohn-Sham electronic band structures, along the closed path Γ-M-K-Γ, using density functional theory. We have also determined the energies of the SSFs with respect to the perfect crystal finding that the (35) and (44) SSFs have unexpectedly low formation energies, for this reason we could expect these two defects to be easily generated/expanded either during the growth or post-growth process steps.

scholarly journals Relative Stability of Small Silver, Platinum, and Palladium Doped Gold Cluster Cations

2019 ◽  
Vol 9 (8) ◽  
pp. 1666 ◽  
Author(s):  
Piero Ferrari ◽  
Ewald Janssens
Keyword(s):  
Density Functional ◽  
Gold Cluster ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Local Maxima ◽  
Dissociation Energies ◽  
Valence Electrons ◽  
Pd Doping ◽  
The Stability ◽  
Experimental Findings

The stability patterns of single silver, platinum, and palladium atom doped gold cluster cations, MAuN−1+ (M = Ag, Pt, Pd; N = 3–6), are investigated by a combination of photofragmentation experiments and density functional theory calculations. The mass spectra of the photofragmented clusters reveal an odd-even pattern in the abundances of AgAuN−1+, with local maxima for clusters containing an even number of valence electrons, similarly to pure AuN+. The odd-even pattern, however, disappears upon Pt and Pd doping. Computed dissociation energies agree well with the experimental findings for the different doped clusters. The effect of Ag, Pt, and Pd doping is discussed on the basis of an analysis of the density of states of the N = 3–5 clusters. Whereas Ag delocalizes its 5s valence electron in all sizes, this process is size-specific for Pt and Pd.

Computational Prediction of New Series of Topological Ternary Compounds LaXS (X = Si, Ge, Sn) from First-Principles

J ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 577-588
Author(s):  
Jack Howard ◽  
Joshua Steier ◽  
Neel Haldolaarachchige ◽  
Kalani Hettiarachchilage
Keyword(s):  
Density Functional ◽  
Mechanical Stability ◽  
Computational Prediction ◽  
Orbit Coupling ◽  
Energy Calculation ◽  
Type I ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electronic Band ◽  
The Stability

Dirac materials and their advanced physical properties are one of the most active fields of topological matter. In this paper, we present an ab initio study of electronics properties of newly designed LaXS (X = Si, Ge, Sn) tetragonal structured ternaries, with the absence and presence of spin–orbit coupling. We design the LaXS tetragonal non-symophic p4/nmm space group (no. 129) structures and identify their optimization lattice parameters. The electronic band structures display several Dirac crossings with the coexistence of both type I and type II Dirac points identified by considering the effect of spin–orbit coupling toward the linear crossing. Additionally, we perform the formation energy calculation through the density functional theory (DFT) to predict the stability of the structures and the elastic constants calculations to verify the Born mechanical stability criteria of the compounds.

scholarly journals Doping Induced Structural Stability and Electronic Properties of GaN Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Anurag Srivastava ◽  
Mohammad Irfan Khan ◽  
Neha Tyagi ◽  
Purnima Swaroop Khare
Keyword(s):  
Density Functional Theory ◽  
Structural Stability ◽  
Ground State ◽  
Density Functional ◽  
Formation Energy ◽  
Electronic Band ◽  
Functional Theory ◽  
Mn Doping ◽  
Manganese Doping ◽  
Electronic Band Gap

The present paper discusses the effect of manganese doping on the structural stability and electronic band gap of chiral (2, 1), armchair (3, 3), and zigzag ((6, 0) and (10, 0)) single walled GaN nanotube by using density functional theory based Atomistix Toolkit (ATK) Virtual NanoLab (VNL). The structural stability has been analyzed in terms of minimum ground state total energy, binding, and formation energy. As an effect of Mn doping (1–4 atoms), all the GaN nanotubes taken into consideration show semiconducting to metallic transition first and after certain level of Mn doping changes its trend.

A BN analog of two-dimensional triphenylene-graphdiyne: stability and properties

Nanoscale ◽  
2019 ◽  
Vol 11 (18) ◽  
pp. 9000-9007 ◽  
Author(s):  
Imran Muhammad ◽  
Huanhuan Xie ◽  
Umer Younis ◽  
Yu Qie ◽  
Waseem Aftab ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Two Dimensional ◽  
Electronic Band ◽  
Functional Theory ◽  
The Stability ◽  
First Time ◽  
Recent Synthesis

Motivated by the feasibility of hybridizing C- and BN-units as well as the recent synthesis of a triphenylene-graphdiyne (TpG) monolayer, for the first time we explore the stability and electronic band structure of a Tp-BNyne monolayer composed of C-chains and the BN analog of triphenylene (Tp-BNyne) by using density functional theory.

scholarly journals Synthesis, structural characterization and comparison of experimental and theoretical results by DFT level of molecular structures of 1,2,3-triazoles derived from 5-chloroisatin

2017 ◽  
Vol 5 (2) ◽  
pp. 91
Author(s):  
Zineb Tribak ◽  
Mohammed Skalli ◽  
Omar Senhaji ◽  
Youssef Kandri Rodi
Keyword(s):  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Molecular Structures ◽  
Basis Set ◽  
Dipolar Cycloaddition ◽  
Nmr Characterization ◽  
The Stability ◽  
Experimental Findings ◽  
Good Agreement

This work deals about the synthesis, NMR characterization and the density functional method (B3LYP) with the 6-31G basis set of 1, 3-dipolar cycloaddition reactions between the two azides as dipoles and propargylchloroisatin as dipolarophile. Furthermore, DFT calculations were used to study the nucleophile–electrophile interactions of the azides and dipolarophile and also the stability between the regioisomers comparing their energy. Our calculations are in a good agreement with the experimental findings.

scholarly journals Structural, Electronic and Optical Properties of InAs Phases: By GGA-PBG and GGA-EV Approximations

2017 ◽  
Vol 41 (3) ◽  
pp. 172-182
Author(s):  
Leila Sohrabi ◽  
Arash Boochani ◽  
S. Ali Sebt ◽  
S. Mohammad Elahi
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Photonic Devices ◽  
Optical Parameters ◽  
Full Potential ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Direct Band ◽  
Electronic Band Gap

Structural, electronic and optical properties of InAs are investigated in the zinc-blende (ZB), rock-salt (RS) and wurtzite (WZ) phases using the full potential linearised augmented plane wave method in the framework of density functional theory (DFT). The electronic band gap of the ZB and WZ phases are improved and in good agreement with experiments by GGA-EV approximation. This compound has a direct band gap in the ZB and WZ phases in point at the centre Brillouin zone and in the RS phase the conduction band crosses towards the valence band and has metallic behaviour. Also, the optical parameters such as the real and imaginary parts of epsilon, energy loss, and the refraction and reflection indices of all the phases are calculated and compared. The calculated optical properties of InAs have promising applications such as the design of optoelectronic and photonic devices.

scholarly journals Topotactic Oxidation of Perovskites to Novel SrMo1-xMxO4−δ (M = Fe and Cr) Deficient Scheelite-Type Oxides

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4441
Author(s):  
V. Cascos ◽  
R. Martínez-Coronado ◽  
M. T. Fernández-Díaz ◽  
J. A. Alonso
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Powder Diffraction ◽  
Perovskite Phase ◽  
Mixed Valence ◽  
Surface Oxidation ◽  
Oxygen Stoichiometry ◽  
Stability Range ◽  
X Ray ◽  
The Stability ◽  
Xps Study

New polycrystalline SrMo1−xMxO4−δ (M = Fe and Cr) scheelite oxides have been prepared by topotactical oxidation, by annealing in air at 500 °C, from precursor perovskites with the stoichiometry SrMo1−xMxO3−δ (M = Fe and Cr). An excellent reversibility between the oxidized Sr(Mo,M)O4−δ scheelite and the reduced Sr(Mo,M)O3−δ perovskite phase accounts for the excellent behavior of the latter as anode material in solid-oxide fuel cells. A characterization by X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) has been carried out to determine the crystal structure features. The scheelite oxides are tetragonal, space group I41/a (No. 88). The Rietveld-refinement from NPD data at room temperature shows evidence of oxygen vacancies in the structure, due to the introduction of Fe3+/Cr4+ cations in the tetrahedrally-coordinated B sublattice, where Mo is hexavalent. A thermal analysis of the reduced perovskite (SrMo1−xMxO3−δ) in oxidizing conditions confirms the oxygen stoichiometry obtained by NPD data; the stability range of the doped oxides, below 400–450 °C, is lower than that for the parent SrMoO3 oxide. The presence of a Mo4+/Mo5+ mixed valence in the reduced SrMo1−xMxO3−δ perovskite oxides confers greater instability against oxidation compared with the parent oxide. Finally, an XPS study confirms the surface oxidation states of Mo, Fe, and Cr in the oxidized samples SrMo0.9Fe0.1O4-δ and SrMo0.8Cr0.2O4-δ.

The Electronic Properties of Al-, P-Doped and Al, P Co-Doped Boron Nitride Nanotubes

2011 ◽  
Vol 399-401 ◽  
pp. 2215-2221 ◽  
Author(s):  
Miao Sun ◽  
Gong Lian Wu ◽  
Ting Ye ◽  
Hui Zhang ◽  
Zhao Di Yang ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Boron Nitride Nanotubes ◽  
Electronic Band ◽  
First Principle Calculation ◽  
Impurity Atoms ◽  
Impurity Doped ◽  
The Stability ◽  
Co Doped

The electronic properties of Al-, P-doped, and Al, P co-doped in a (6, 6) BN nanotubes were obtained using the first principle calculation based on the density functional theory. For the doped BNNTs, the structures are with ignorable deformation observed around the doping atoms. The analysis of the formation energies shows that aluminum replacement to be favorable, particularly in the case of the low concentration, and the stability of nanotubes has nothing to do with the doping position. The electronic band structure and DOS for the systems of Al-, and P-doped BNNTs all behave as impurity-doped widegap semiconductor. And as to the P-doped BNNTs, the conductivity becomes stronger with the higher concentration. Whereas, the results of the system of Al, P co-doped BNNTs illustrate that the electronic properties of nanotubes have nothing to do with the doping positions of impurity atoms.

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