First-Principles Calculations and Experimental Study of H+-Irradiated Zr/Nb Nanoscale Multilayer System

Nanoscale multilayer coating (NMC) based on Zr/Nb layers (100/100 nm) before and after H+ irradiation was investigated by combining experimental techniques with first-principles calculations. Detailed studies of structural and phase state and defect structure of Zr/Nb NMC were performed using methods of transmission electron microscopy, X-ray structural analysis, glow discharge optical emission spectrometry, and the Doppler broadening spectroscopy using variable energy positron beam. The first-principles calculations of binding energies for hydrogen in metal Zr/Nb layers was carried out by the pseudopotential method within the density functional theory framework. First-principles calculations and experimental data indicate the presence of macro- and microstrains predominantly in the zirconium layers of Zr/Nb NMC. The main feature of the studied Zr/Nb NMC is the predominant hydrogen localization in Zr layers near the interfaces. The annihilation of positrons is shown to occur mainly in the Zr layers in the vicinity of the interface.

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Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

10.26434/chemrxiv.8052218.v3 ◽

2019 ◽

Author(s):

Henrik Pedersen ◽

Björn Alling ◽

Hans Högberg ◽

Annop Ektarawong

Keyword(s):

Thin Films ◽

Thermodynamic Stability ◽

First Principles ◽

Thermal Equilibrium ◽

Density Functional ◽

Van Der Waals ◽

Chemical Vapor ◽

First Principles Calculations ◽

Functional Theory ◽

The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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Effect of wood biomass components on self-heating

Bioresources and Bioprocessing ◽

10.1186/s40643-021-00373-7 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Nozomi Miyawaki ◽

Takashi Fukushima ◽

Takafumi Mizuno ◽

Miyao Inoue ◽

Kenji Takisawa

Keyword(s):

Moisture Content ◽

Inductively Coupled Plasma ◽

Optical Emission ◽

Chemical Oxidation ◽

Spontaneous Ignition ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Self Heating ◽

Inorganic Substances ◽

Before And After

AbstractBiomass may ignite due to biological oxidation and chemical oxidation. If this phenomenon (spontaneous ignition) is controlled, it would be possible to produce biochar at a lower cost without the need for an external heat resource. We investigated if self-heating could be controlled by using sawdust and bark chips. When sawdust and bark chips were used under controlled conditions, the bark chips temperature increased to the torrefaction temperature. The ash content of bark chips was ~ 2%d.b. higher than that of sawdust; consequently, the inorganic substances contained in the bark chips might affect the self-heating. Self-heating was suppressed when inorganic substances were removed by washing with water. Therefore, the inorganic substances in the biomass might have affected self-heating. The inorganic element contents of the bark chips were measured by inductively coupled plasma optical emission spectrometry before and after washing. The potassium content of the bark chips was reduced remarkably by washing, and there was a possible influence of potassium on self-heating. Finally, the effect of moisture content on self-heating was investigated to obtain stable reactivity. Thus, at a moisture content of 40%w.b., a steady self-heating behavior may be realized.

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Hydrogenation and oxidation enhances the thermoelectric performance of Si2BN monolayer

New Journal of Chemistry ◽

10.1039/d0nj06000c ◽

2021 ◽

Author(s):

H. R. Mahida ◽

Deobrat Singh ◽

Yogesh Sonvane ◽

Sanjeev K. Gupta ◽

P. B. Thakor ◽

...

Keyword(s):

Density Functional Theory ◽

Charge Transport ◽

Transport Properties ◽

First Principles ◽

Density Functional ◽

Thermoelectric Performance ◽

First Principles Calculations ◽

Functional Theory

In the present study, we have investigated the structural, electronic, and charge transport properties of pristine, hydrogenated, and oxidized Si2BN monolayers via first-principles calculations based on density functional theory (DFT).

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Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

Modern Physics Letters B ◽

10.1142/s0217984916504145 ◽

2016 ◽

Vol 30 (35) ◽

pp. 1650414 ◽

Cited By ~ 6

Author(s):

Mingliang Wang ◽

Zhe Chen ◽

Dong Chen ◽

Cunjuan Xia ◽

Yi Wu

Keyword(s):

Thermodynamic Properties ◽

Debye Temperature ◽

First Principles ◽

Density Functional ◽

Coefficient Of Thermal Expansion ◽

Local Density ◽

Debye Model ◽

First Principles Calculations ◽

Generalized Gradient ◽

Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

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Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

Physical Chemistry Chemical Physics ◽

10.1039/c6cp06785a ◽

2017 ◽

Vol 19 (5) ◽

pp. 3679-3687 ◽

Cited By ~ 10

Author(s):

Tao Yang ◽

Masahiro Ehara

Keyword(s):

Density Functional Theory ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Density Functional Theory Calculations ◽

First Principles Calculations ◽

Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

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Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

Canadian Journal of Physics ◽

10.1139/p06-008 ◽

2006 ◽

Vol 84 (2) ◽

pp. 115-120 ◽

Cited By ~ 3

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

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Mono- and Bi-Molecular Adsorption of SF6 Decomposition Products on Pt Doped Graphene: A First-Principles Investigation

Applied Sciences ◽

10.3390/app8102010 ◽

2018 ◽

Vol 8 (10) ◽

pp. 2010 ◽

Cited By ~ 2

Author(s):

Yongqian Wu ◽

Shaojian Song ◽

Dachang Chen ◽

Xiaoxing Zhang

Keyword(s):

Single Molecule ◽

First Principles ◽

Density Functional ◽

Energy Gap ◽

Adsorption Parameters ◽

Functional Theory ◽

Decomposition Products ◽

Before And After ◽

Doped Graphene ◽

Sf6 Decomposition

Based on the first-principles of density functional theory, the SF6 decomposition products including single molecule (SO2F2, SOF2, SO2), double homogenous molecules (2SO2F2, 2SOF2, 2SO2) and double hetero molecules (SO2 and SOF2, SO2 and SO2F2, SOF2 and SO2F2) adsorbed on Pt doped graphene were discussed. The adsorption parameters, electron transfer, electronic properties and energy gap was investigated. The adsorption of SO2, SOF2 and SO2F2 on the surface of Pt-doped graphene was a strong chemisorption process. The intensity of chemical interactions between the molecule and the Pt-graphene for the above three molecules was SO2F2 > SOF2 > SO2. The change of energy gap was also studied and according to the value of energy gap, the conductivity of Pt-graphene before and after adsorbing different gas molecules can be evaluated.

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Computational investigation of NH3 adsorption and dehydrogenation on a W-modified Fe(111) surface

Physical Chemistry Chemical Physics ◽

10.1039/c5cp05983f ◽

2015 ◽

Vol 17 (45) ◽

pp. 30598-30605 ◽

Cited By ~ 3

Author(s):

Ming-Kai Hsiao ◽

Chia-Hao Su ◽

Ching-Yang Liu ◽

Hui-Lung Chen

Keyword(s):

Density Functional Theory ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Computational Investigation ◽

Functional Theory ◽

Nh3 Adsorption ◽

Tungsten Metal

We employed monolayer tungsten metal to modify the Fe(111) surface, denoted as W@Fe(111), and calculated the adsorption and dehydrogenation behaviors of NH3 on W@Fe(111) surface via first-principles calculations based on density functional theory (DFT).

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FIRST PRINCIPLES DENSITY FUNCTIONAL INVESTIGATION OF SUPPORTED TUNGSTEN CLUSTER (Wn; n = 1 TO 6) ON ANCHORED GRAPHITE (0001) SURFACE

International Journal of Computational Materials Science and Engineering ◽

10.1142/s2047684113500152 ◽

2013 ◽

Vol 02 (03n04) ◽

pp. 1350015

Author(s):

SONALI BARMAN ◽

G. P. DAS ◽

Y. KAWAZOE

Keyword(s):

First Principles ◽

Density Functional ◽

Metal Clusters ◽

Theoretical Study ◽

First Principles Calculations ◽

Novel Technique ◽

Defect Site ◽

Positive Ions ◽

Spin Polarized ◽

Functional Investigation

Size-selected Wn clusters can be deposited firmly on a graphite (0001) surface using a novel technique, where the positive ions (of the same metal atom species) embedded on the graphite surface by ion implantation, act as anchors. The size selected metal clusters can then soft land on this anchored surface m [Hayakawa et al., 2009]. We have carried out a systematic theoretical study of the adsorption of Wn (n = 1-6) clusters on anchored graphite (0001) surface, using state-of-art spin-polarized density functional approach. In our first-principles calculations, the graphite (0001) surface has been suitably modeled as a slab separated by large vacuum layers. Wn clusters bond on clean graphite (0001) surface with a rather weak Van-der-Waals interaction. However, on the anchored graphite (0001) surface, the Wn clusters get absorbed at the defect site with a much larger adsorption energy. We report here the results of our first-principles investigation of this supported Wn cluster system, along with their reactivity trend as a function of the cluster size (n).

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Magnetism and Half-Metallicity in (100) Surface of Inverse Heusler Mn2CoSb

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.377 ◽

2014 ◽

Vol 1015 ◽

pp. 377-380

Author(s):

Tao Chen ◽

Ying Chen ◽

Yin Zhou ◽

Hong Chen

Keyword(s):

Density Functional Theory ◽

Magnetic Properties ◽

First Principles ◽

Heusler Alloy ◽

Density Functional ◽

Magnetic Moments ◽

Surface States ◽

First Principles Calculations ◽

Half Metallicity ◽

Functional Theory

Using the first-principles calculations within density functional theory (DFT), we investigated the electronic and magnetic properties of (100) surface of inverse Heusler alloy Mn2CoSb with five different terminations. Our work reveals that the surface Mn atom moves to vacuum while surface Co atom moves to slab. Moreover, duo to the reason that the surface atom lost half of the nearest atoms with respect to the bulk phase, resulting in the decrease of hybridization, the atom-resolved spin magnetic moments of surface atoms are enhanced. Further investigation on DOS and PDOS showed that half-metallicity was preserved only in SbSb-termination while was destroyed in MnCo-, MnSb-, MnMn-, and CoCo-termination due to the appearance of surface states.

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