scholarly journals Newly synthesized MAX phase Zr2SeC: DFT insights into physical properties towards possible applications

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 16892-16905
Author(s):  
M. A. Ali ◽  
Muhammad Waqas Qureshi
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Dft Calculations ◽  
Elastic Anisotropy ◽  
Max Phase ◽  
Electronic Charge ◽  
Time Study ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
First Time

This is the first time study of the mechanical properties including Vickers hardness and elastic anisotropy, electronic charge density distribution, thermodynamic and optical properties of the synthesized MAX phase Zr2SeC via DFT calculations.

scholarly journals Direct Correlations among the Grain Size, Texture, and Indentation Behavior of Nanocrystalline Nickel Coatings

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 188 ◽  
Author(s):  
Lu Feng ◽  
Yong-Yue Ren ◽  
Yan-heng Zhang ◽  
Shibin Wang ◽  
Linan Li
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Elastic Anisotropy ◽  
Texture Coefficient ◽  
Process Conditions ◽  
Nickel Coatings ◽  
Fundamental Relationship ◽  
Underlying Mechanisms ◽  
First Time

By using nc-Ni coatings as a model system, systematic experiments were designed to evaluate the interaction between the microstructural and mechanical properties tailored by electrodeposition conditions. A direct correlation between grain size and texture was established for the first time. The grain size of the (111) crystalline plane decreases with the texture coefficient (RTC) regardless of the process conditions, and that of the (220) plane has different trends. Then, a peculiar phenomenon is revealed that the dependence of hardness on grain size is accurately described by the Hall-Petch relationship when changing the temperature or pH, but with different slopes, while it deviates from such a relationship with changing current density, denoting more underlying mechanisms related to texture. Finally, a surprising degree of influence of texture on hardness and elastic modulus is also presented, with the overall trend of hardness increasing with texture; and when the RTC of (111) exceeds 40%, the elastic modulus increases with texture, implying a fundamental relationship between modulus and texture. Texture predominates over the other factors on the elastic modulus, revealing the importance of elastic anisotropy. Significantly, the present work suggests a useful tailoring routine to fabricate high quality nc-Ni coatings with the desired structure and mechanical properties.

scholarly journals New MAX Phase Superconductor Ti2GeC: A First-principles Study

2013 ◽  
Vol 6 (1) ◽  
pp. 11-27 ◽  
Author(s):  
M. A. Hadi ◽  
M. Roknuzzaman ◽  
F. Parvin ◽  
S. H. Naqib ◽  
A. K. M. A. Islam ◽  
...  
Keyword(s):  
Optical Properties ◽  
Thermodynamic Properties ◽  
Fermi Surface ◽  
Vickers Hardness ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Debye Model ◽  
First Principles Calculation ◽  
Max Phase ◽  
Specific Heats

This is the first DFT-based first-principles prediction of the detailed optical and thermodynamic properties, including Vickers hardness and Fermi surface of 211 MAX phase Ti2GeC for which superconductivity (Tc~ 9.5 K) was reported very recently. The calculated structural properties are in excellent agreement with experiments. Our results on elastic parameters indicate a slight elastic anisotropy and brittleness of the compound. The chemical bonding is seen to be a combination of covalent, ionic and metallic nature. The rather stronger covalent bonding is responsible for its high Vickers hardness of 11.6 GPa. The investigated Fermi surface is formed mainly by the low-dispersive bands, which should be responsible for the presence of superconductivity in Ti2GeC. All the optical properties are evaluated and analyzed for two different polarization directions of incident photon. The temperature and pressure dependence of primitive cell volume, thermal expansion coefficient, specific heats, bulk modulus, and Debye temperature of Ti2GeC are derived from the quasi-harmonic Debye model with phononic effect and the various implications are discussed in details.  Keywords: First-principles calculation; Vickers hardness; Optical properties; Thermodynamic properties. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i1.16604 J. Sci. Res. 6 (1), 11-27 (2014)

scholarly journals Electronic Structure, Electronic Charge Density, and Optical Properties Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jisha Annie Abraham ◽  
Gitanjali Pagare ◽  
Sankar P. Sanyal
Keyword(s):  
Optical Properties ◽  
Charge Density ◽  
Density Of States ◽  
Density Functional ◽  
Electronic Charge ◽  
Ambient Conditions ◽  
Electronic Charge Density ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Calculated Density

The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N(EF) shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail.

The study on charge-density distribution in TiAl by quantitative electron crystallography method

1995 ◽  
Vol 10 (8) ◽  
pp. 1913-1916 ◽  
Author(s):  
Yu Miao ◽  
Jing Zhu ◽  
X.W. Lin ◽  
W.J. Jiang
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Interatomic Bond ◽  
Electronic Charge ◽  
Electron Crystallography ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Density Distributions ◽  
Structure Factors ◽  
Equiaxed Grain

Structure factors of μ-TiAl equiaxed grain in TiAl duplex intermetallic compound before and after V-alloying were measured by the quantitative electron crystallography method. Then the structure factors were transferred into charge-density distributions of real space. Comparing the charge-density distributions in γ-TiAl with those in V-alloyed γ-TiAl, it was found that V-alloying with the optimum amount decreases the electronic charge density in the Ti-Ti interatomic bond, and increases the electronic charge density in the Al-Al interatomic bond and Ti-Al interatomic bond. Thus, the anisotropy of charge-density distribution in γ-TiAl equiaxed grain is reduced.

Microcrystalline β-RbNd(MoO4)2: spin polarizing DFT+U

RSC Advances ◽  
2015 ◽  
Vol 5 (56) ◽  
pp. 44960-44968 ◽  
Author(s):  
A. H. Reshak
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Electronic Band ◽  
Functional Theory ◽  
Hubbard Hamiltonian ◽  
The Density Functional Theory ◽  
Structure Density

Using the density functional theory plus Hubbard Hamiltonian we have investigated the spin up/down electronic band structure, density of states, electronic charge density distribution and the dispersion of the optical properties of microcrystalline β-RbNd(MoO4)2.

Charge Density Study of 2-Pyridone

1998 ◽  
Vol 54 (6) ◽  
pp. 912-920 ◽  
Author(s):  
H. W. Yang ◽  
B. M. Craven
Keyword(s):  
Charge Density ◽  
Critical Points ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Molecular Dipole ◽  
X Ray ◽  
Density Study

The crystal structure of 2-pyridone has been redetermined from high-resolution X-ray data collected at 123 K. The molecule is in the lactam form. Bond lengths (corrected for rigid-body libration) and angles have been determined with s.u.'s of 0.001 Å and 0.1°, respectively. The hydrogen-bonded cyclic dimers which occur in the vapor and in solution are absent in the crystal where molecules are linked by N—H...O hydrogen bonds to form puckered chains. There also appears to be a weaker C—H...O interaction (H...O, 2.57 Å) and weak C—H...π or van der Waals interactions occurring on both sides of the pyridone ring. Following a refinement of the structure assuming Stewart's rigid pseudo-atom model, the electronic charge density distribution in the crystal and its Laplacian have been calculated for atoms at rest. The total electrostatic potential has been mapped for an isolated molecule and the molecular dipole moment has been determined [8.8 (19)  D; 1D ≃ 3.33564 × 10−30 C m]. Critical points in the electron density have been located for the bonds within the molecule and for the molecular interactions cited above. For the C—H...π interactions, only the spherical components of the valence density for the pyridone ring atoms contribute effectively at the critical points. Hence, these may be better described as van der Waals interactions.

scholarly journals CO2 Electrochemical Reduction by Exohedral N-Pyridine Decorated Metal-Free Carbon Nanotubes

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2703 ◽  
Author(s):  
Giulia Tuci ◽  
Jonathan Filippi ◽  
Andrea Rossin ◽  
Lapo Luconi ◽  
Cuong Pham-Huu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Density Distribution ◽  
Charge Density ◽  
Carbon Nanomaterials ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Faradaic Efficiency ◽  
Metal Free ◽  
Electrochemical Co2 Reduction

Electrochemical CO2 reduction reaction (CO2RR) to fuels and chemicals represents nowadays one of the most challenging solutions for renewable energy storage and utilization. Among the possible reaction pathways, CO2-to-CO conversion is the first (2e−) reduction step towards the production of a key-feedstock that holds great relevance for chemical industry. In this report we describe the electrocatalytic CO2-to-CO reduction by a series of tailored N-decorated carbon nanotubes to be employed as chemoselective metal-free electrocatalysts. The choice of an exohedral functionalization tool for the introduction of defined N-groups at the outer surface of carbon nanomaterials warrants a unique control on N-configuration and electronic charge density distribution at the dangling heterocycles. A comparative electrochemical screening of variably N-substituted carbon nanomaterials in CO2RR together with an analysis of the electronic charge density distribution at each heterocycle have suggested the existence of a coherent descriptor for the catalyst’s CO faradaic efficiency (FECO). Evidence allows to infer that N-configuration (N-pyridinic vs. N-pyrrolic) of exohedral dopants and electronic charge density distribution at the N-neighboring carbon atoms of each heterocycle are directly engaged in the activation and stabilization of CO2 and its reduction intermediates.

The influence of replacing Se by Te on electronic structure and optical properties of Tl4PbX3(X = Se or Te): experimental and theoretical investigations

RSC Advances ◽  
2015 ◽  
Vol 5 (124) ◽  
pp. 102173-102181 ◽  
Author(s):  
A. H. Reshak ◽  
Z. A. Alahmed ◽  
I. E. Barchij ◽  
M. Yu. Sabov ◽  
K. J. Plucinski ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Structure ◽  
Charge Density ◽  
Single Crystals ◽  
Energy Band ◽  
Energy Band Structure ◽  
Electronic Charge ◽  
Electronic Charge Density ◽  
Theoretical Investigations

The energy band structure, electronic charge density and optical features of Tl4PbSe3and Tl4PbTe3single crystals were studied within a framework of the recently modified Becke–Johnson potential (mBJ).

Sign in / Sign up

Export Citation Format

Share Document