| 1. |
- Adell, Johan, 1980, et al.
(författare)
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Electron spectroscopic studies of nanowires formed by (GaMn)As growth on GaAs(111)B
- 2011
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 151:11, s. 850-854
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Tidskriftsartikel (refereegranskat)abstract
- Valence band photoemission with photon energies around the Mn2p excitation threshold has been used to study the development of nanowires catalyzed by MnAs particles. A gradual change in the spectra with increasing nanowire length is observed, such that the resonant photoemission eventually dominates over the Auger decay channel. The change is ascribed to dilution of Mn, showing that Mn is transferred from the MnAs particles into the nanowires. (C) 2011 Elsevier Ltd. All rights reserved.
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| 2. |
- Araujo, Rafael B., et al.
(författare)
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Lithium transport investigation in LixFeSiO4 : A promising cathode material
- 2013
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 173, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we investigate lithium mobility in both Li 2FeSiO4 and its half-lithiated state LiFeSiO4 considering an orthorhombic crystal structure. We find that the calculated activation energy of Li+ ions hopping between adjacent equilibrium sites predicts two least hindered diffusion pathways in both materials. One of them is along the [100] direction characterizing an ionic diffusion in a straight line and the other follows a zig-zag way between the Fe-Si-O layers. We also show that diffusion of Li+ ions in the half-lithiated structure follows the same behavior as in the lithiated structure. As a whole, the activation energies for the investigated compounds present a greater value compared with the activation energies in currently used materials such as LiFePO4. The results were calculated in the framework of density functional theory in conjunction with the climbing image nudged elastic band method. The Hubbard term was added to the Kohn-Sham Hamiltonian to overcome the delocalization problem of d electrons. Furthermore, the diffusion coefficients were calculated for both structures considering temperatures ranging from 300 to 700 K.
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| 3. |
- Barannikova, S A, et al.
(författare)
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Significant correlation between macroscopic and microscopic parameters for the description of localized plastic flow auto-waves in deforming alloys
- 2012
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Ingår i: Solid State Communications. - : Elsevier. - 0038-1098 .- 1879-2766. ; 152:9, s. 784-787
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Tidskriftsartikel (refereegranskat)abstract
- Understanding of mechanical properties of materials and a possibility to predicting them from ab initio calculations have fundamental importance for solid state theory. In this work we establish a significant correlation between the product of the macroscopic parameters of localized plastic flow auto-waves in deforming alloys, their length and propagation rate and the product of the microscopic (lattice) parameters of these materials, the spacing between close-packed planes of the lattice and the rate of transverse elastic waves. Thus, these products can be regard as invariants of plastic and elastic deformation processes, respectively. Moreover, the established regularity suggests that the elastic and the plastic processes simultaneously involved in the deformation are closely related. Our work also demonstrates that ab initio simulations can be used for the prediction of parameters of localized plastic flow auto-waves in deforming alloys.
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| 4. |
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| 5. |
- Bouibes, A., et al.
(författare)
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Promising optical characteristics of zinc peroxide from first-principles investigation
- 2017
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 263, s. 6-9
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Tidskriftsartikel (refereegranskat)abstract
- The structural, electronic and optical properties of zinc peroxide have been investigated using first principle pseudopotential method within generalized gradient approximation (GGA) proposed by Perdew-Burke-Ernzerhof (PBE) and also within Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional for the exchangecorrelation. An underestimated band gap (1.77 eV) along with the higher density of states and expanded energy bands around the Fermi level is obtained. The HSE06 approach corrects the band gap and allows a proper description of defects with energy levels close to the conduction band. According to the HSE06 calculations, the obtained band gap is 3.2 eV. This value is very close to semiconductors band gap such as TiO2 (3.1 eV). The dielectric constants are identified with respect to electronic band structure and are utilized to derive the other optical properties such as retractive index, energy loss function, reflectivity and absorption. This mainly shows that zinc peroxide is a poor absorber of visible light.
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| 6. |
- Haldar, Soumyajyoti, et al.
(författare)
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Functionalization of edge reconstructed graphene nanoribbons by H and Fe : A density functional study
- 2012
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 152:18, s. 1719-1724
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we have studied functionalization of 5-7 edge-reconstructed graphene nanoribbons by ab initio density functional calculations. Our studies show that hydrogenation at the reconstructed edges is favorable in contrast to the case of unreconstructed 6-6 zigzag edges, in agreement with previous theoretical results. Thermodynamical calculations reveal the relative stability of single and dihydro-genated edges under different temperatures and chemical potential of hydrogen gas. From phonon calculations, we find that the lowest optical phonon modes are hardened due to 5-7 edge reconstruction compared to the 6-6 unreconstructed hydrogenated edges. Finally, edge functionalization by Fe atoms reveals a dimerized Fe chain structure along the edges. The magnetic exchange coupling across the edges varies between ferromagnetic and antiferromagnetic ones with the variation of the width of the nanoribbons.
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| 7. |
- Huang, L. M., et al.
(författare)
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Defect-induced strong ferromagnetism in Cr-doped In2O3 from first-principles theory
- 2010
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 150:13-14, s. 663-665
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate by means of first-principles calculations that the high Curie temperature observed in Cr-doped In2O3 is mediated by intrinsic p-type defects, namely In vacancies or O interstitials. Charge transfer from Cr 3d states to the hole states formed by these defects makes Cr ions in the mixed valence state, giving rise to a strong ferromagnetic coupling. Calculated formation energies of various defects also show that doping Cr in In2O3 could greatly lower the formation energies of p-type intrinsic defects even in oxygen-deficient growth conditions. These results advance our understanding of the underlying physics of diluted magnetic oxides.
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| 8. |
- Kadas, Krisztina, et al.
(författare)
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Thermo-physical properties of body-centered cubic iron-magnesium alloys under extreme conditions
- 2011
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 151:3, s. 203-207
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Tidskriftsartikel (refereegranskat)abstract
- Using density functional theory formulated within the framework of the exact muffin-tin orbitals method, we investigate the thermo-physical properties of body-centered cubic (bcc) iron-magnesium alloys, containing 5 and 10 atomic % Mg, under extreme conditions, at high pressure and high temperature. The temperature effect is taken into account via the Fermi-Dirac distribution of the electrons. We find that at high pressures pure bcc iron is dynamically unstable at any temperature, having a negative tetragonal shear modulus (C'). Magnesium alloying significantly increases C' of Fe, and bcc Fe-Mg alloys become dynamically stable at high temperature. The electronic structure origin of the stabilization effect of Mg is discussed in detail. We show that the thermo-physical properties of a bcc Fe-Mg alloy with 5% Mg agree well with those of the Earth's inner core as provided by seismic observations. (C) 2010 Elsevier Ltd. All rights reserved.
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| 9. |
- Li, Chun-Xia, et al.
(författare)
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Lattice parameters and relative stability of alpha '' phase in binary titanium alloys from first-principles calculations
- 2013
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 159, s. 70-75
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Tidskriftsartikel (refereegranskat)abstract
- The crystallographic structure and stability of the alpha" phase relative to the alpha and beta phases in Ti-x M (M=Ta, Nb, V, Mo) alloys are investigated by using the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation. We show that, with increasing concentration of the alloying elements, the structure of the orthorhombic-alpha'' phase evolutes from the hcp-alpha to the bcc-beta phase, i.e., the lattice parameters b/a and c/a as well as the basal shuffle y decreases from those corresponding to the alpha phase to those of the beta phase. The compositional alpha/alpha" and alpha"/beta phase boundaries are determined by comparing the total energies of the phases. The predicted alpha/alpha" phase boundaries are about 10.2, 10.5, 11.5, 4.5 at% for Ti-V, Ti-Nb, Ti-Ta, and Ti-Mo, respectively, in reasonable agreement with experiments. The alpha"/beta phase boundaries are higher than the experimental values, possibly due to the absence of temperature effect in the first-principles calculations. Analyzing the electronic density of states, we propose that the stability of the alpha" phase is controlled by the compromise between the strength of the covalent and metallic bonds.
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| 10. |
- Li, Yunguo, et al.
(författare)
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Hydrogen storage in polylithiated BC3 monolayer sheet
- 2013
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Ingår i: Solid State Communications. - Uppsala : Elsevier BV. - 0038-1098 .- 1879-2766. ; 170, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- We perform a detailed study on the stability, electronic structure and hydrogen storage capacity of polylithiated (CLi3 functionalized) boron carbide (BC3) monolayer sheet using first-principles calculations. The binding of the CLi3 radical to the boron carbide (BC3) monolayer sheet is found to be large enough to ensure its uniform distribution without any clustering. The structural stability has been confirmed by molecular dynamics. Each lithium atom is able to accommodate 4 H2 molecules with an average binding energy of 0.21 eV, which is suitable for reversible H2 adsorption/desorption at ambient temperatures. The uptake of H2 is found to reach up to 9.83 wt% in polylithiated BC3 monolayer sheet.
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