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Numrering	Referens	Omslagsbild	Hitta
1.	Ahuja, R., et al. (författare) High-pressure structural phase transitions in RuO2 and its geophysical implications 2001 Ingår i: Journal of Physics and Chemistry of Solids. - 0022-3697 .- 1879-2553. ; 62:11, s. 2035-2037 Tidskriftsartikel (refereegranskat)
2.	Alm, Ove, et al. (författare) Thermal conductivity of KCl up to 19 kbar 1974 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 35:3, s. 421-424 Tidskriftsartikel (refereegranskat)abstract The pressure dependency of the thermal conductivity of KCl has been measured at room temperature up to 19 kbar. The high pressure tool was of the “belt” type and a solid medium was used. The specimen was cylindrical and was heated along its axis. The conductivity was found to increase linearly at a rate of (3·3 ± 0·3) per cent/kbar.
3.	Andersson, Ove, et al. (författare) Thermal conductivity of normal and deuterated tetrahydrofuran clathrate hydrates 1996 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 57:1, s. 125-132 Tidskriftsartikel (refereegranskat)abstract The thermal conductivity λ of normal and deuterated tetrahydrofuran (THF) clathrate hydrates has been measured at temperatures in the range 55-250 K and at pressures up to 0.16 GPa. The normal and deuterated samples exhibited the same values of λ to within 5%. At isobaric heating, the transition from the proton ordered low temperature (LT) phase to the proton disordered high temperature (HT) phase was detected as a discontinuous decrease of λ by about 15% for both the normal and the deuterated samples. The magnitude is nearly the same as that found previously for the related transition phase XI → phase Ih of ice and might be due to a change in the lattice anharmonicity. The thermal conductivity of the LT and HT phases increased slightly with increasing temperature and, hence, these crystalline phases exhibited both a glass-like λ(T). These results can be described using the resonance scattering model in which the phonons are scattered against THF vibrations. The LT phase of both samples exhibited a slight increase of λ with increasing pressure whereas that of the HT phases was roughly independent of pressure, showing that λ does not depend on density.
4.	Andersson, Per (författare) Thermal conductivity and heat capacity of cyclohexane under pressure 1978 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 39:1, s. 65-68 Tidskriftsartikel (refereegranskat)abstract The transient hot-wire technique was used to determine the thermal conductivity, λ, and the specific heat capacity per unit volume, ρcp, of cyclohexane up to 1.5 GPa in the range 120–340 K. The measurements were carried out in a piston-cylinder apparatus, 45 mm in internal diameter, cooled by liquid nitrogen. There is only a small (6%) increase in λ on freezing, while there is an increase by a factor of two corresponding to the plastic→ normal crystal transition. The variation of λ with temperature (T) at P = 0.03 GPa is d(lnλ)/dT = −2.2×10−3K−1 for the liquid and d(ln λ)/dT = −0.9×10−3K−1 for the plastic crystalline phase. In the normal crystal phase an approximate T−1 dependence is observed. Within each of the phases λ increases linearly with pressure, and the slope of λ (P) is smallest in the plastic crystal phase. The existence of a recently reported new high pressure phase is evident from conductivity data. Qualitative ρcp -results are reported.
5.	Buga, Sergei G., et al. (författare) DSC study of annealing and phase transformations of C60 and C70 polymerized under pressures in the range 9.5 - 13 GPa. 2002 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 63:2, s. 331-343 Tidskriftsartikel (refereegranskat)abstract C60 and C70 fullerenes polymerized under pressures between 9.5 and 13 GPa and temperatures between 670 and 1850 K were investigated by differential scanning calorimetry (DSC) in the range 240–640 K. Endothermal heat effects were observed with a peak maximum just below 540 K, a temperature characteristic for breakdown of (2+2) intermolecular links in dimers, 1D and 2D polymers. Exothermal effects, starting from 380 K, were observed for the first time in polymeric fullerenes. These effects are attributed to relaxation processes and to breakdown of other types of intermolecular bonds such as common four-sided rings and (3+3) interlinks.
6.	Edman, Ludvig, et al. (författare) Sodium-sodium halide co-intercalated graphite: chemistry, structure and electrical transport 1999 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 60:4, s. 475-482 Tidskriftsartikel (refereegranskat)abstract This study deals with the second to fourth stage compounds resulting from the co-intercalation of sodium and sodium halides into graphite. The charge transfer was determined through chemical analyses and X-ray diffraction and the results are compatible with Raman spectroscopy data. We present detailed results on c axis conduction between 4.2 K and 295 K and for hydrostatic pressures as high as 1.6 GPa. Possible mechanisms explaining the c axis conduction are discussed.
7.	Håkansson, Björn, et al. (författare) Thermal conductivity and heat capacity of solid NaCl and NaI under pressure 1986 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 47:4, s. 355-362 Tidskriftsartikel (refereegranskat)abstract We measured the thermal conductivity and heat capacity per unit volume for solid NaCl and NaI using the transient hot-wire technique. Measurements were performed in the temperature range 100–400 K and at pressures up to 2 GPa. Analysis of the thermal conductivity data showed that the Leibfried-Schlömann formula is a better description for NaCl than for NaI. For both NaCl and NaI the effect of optic phonons on thermal conductivity cannot be ignored. However, taking only acoustic phonons into account is a better approximation for NaI than for NaCl, due to the larger ionic mass ratio for NaI. The specific heat capacities, obtained at room temperature, were approximately independent of pressure.
8.	Jacobsson, Per, et al. (författare) Pressure dependence of the thermal and electrical conductivities of the intermetallic compounds AuCu and AuCu3 1988 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 49:4, s. 441-450 Tidskriftsartikel (refereegranskat)abstract The thermal diffusivity, a, electrical resistivity, ρ, and Seebeck coefficient, S, of ordered and disordered AuCu3 and AuCu have been measured as functions of T and P in the range 100–300 K and 0–2 GPa, and the thermal conductivity, λ, has been calculated from the data for a. The experimental data for ρ agree well with literature data. The ρ dependence of ρ and λ differs significantly between ordered and disordered specimens, but apart from the effect of impurity scattering the disordered materials behave much like the noble metals. For the temperature-dependent part of p (and λ) the P dependence differs by a factor of 2–3 between ordered and disordered states. This is shown to result from the difference in electron band structure, as reflected also in the thermoelectric parameter ξ. The P dependence of the relatively large lattice thermal conductivity of these materials causes the Lorenz ratio L = λρ/T to increase with ρ in all cases.
9.	Jansson, Roger, et al. (författare) Optical and microstructural characterization of thin films of photochromic fulgides 2001 Ingår i: Journal of Physics and Chemistry of Solids. - 0022-3697 .- 1879-2553. ; 62:7, s. 1219-1228 Tidskriftsartikel (refereegranskat)abstract Variable angle spectroscopic ellipsometry has been used for determining the optical properties, in terms of the complex dielectric function in the near UV-VIS-near IR spectral range, and the thicknesses of thin fulgide films of type E-a-(2,5-dimethyl-3-furyl)-ethylidene(adamantylidene)succinic anhydride and (E)-2-[a-(2,5-dimethyl-3-thienyl)ethylidene]-3-isopropylidenesuccinic anhydride. The films had thicknesses in the range 28-40 nm and were spin coated onto silicon substrates. To simultaneously extract film thicknesses and optical properties of the films, several methods of analysis were employed in order to decrease correlation between the fitting parameters in the optical model of the structure. In agreement with previous absorbance measurements done by others on similar materials in liquid or solid form, it was found that the fulgides studied have several resonances in the wavelength region below 400 nm and that new resonances appear in the middle of the visible region upon UV exposure. The ellipsometric analysis, as well as atomic force microscopy studies, showed that the films were very smooth with a root mean square surface roughness <0.4 nm and that a small thickness change of the film takes place upon UV exposure. Furthermore, AFM studies revealed that large phase changes take place when the samples are stored in darkness for several days, indicating that the materials are not stable in thin film form. © 2001 Elsevier Science Ltd.
10.	Persson, Per-Axel, et al. (författare) The physical properties of high-pressure polymerized C60 1997 Ingår i: Journal of Physics and Chemistry of Solids, volume 58, issue 11. - : Elsevier B.V.. ; 58:11, s. 1881-1885 Konferensbidrag (refereegranskat)abstract We have studied the structural, thermophysical, and spectroscopic properties of polymeric C60 obtained by high pressure treatment at pressures and temperatures near 1 GPa and 600 K. We present here a brief overview of our results for the structural and thermophysical properties and a more detailed report on recent results obtained by Raman spectroscopy on both thin films, polycrystalline, and single crystal material. The results presented include a comparison between Raman results for photopolymerized and pressure polymerized thin films and a preliminary estimate of the binding energy of polymeric C60.
11.	Ross, Russell G. (författare) Predicting the equation of state of condensed materials through use of low-pressure expansion and room-temperature compression data 1992 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 53:7, s. 857-864 Tidskriftsartikel (refereegranskat)abstract Empirical prediction of the equation of state (EOS) over an area in pressure-temperature (p-T) space was attempted using primary data for low-pressure (p0) expansion and room-temperature (T0) compression together with various ansatz to effectively restrict the functional form which the EOS could have. Tests against experimental data for the EOS of a variety of substances at p-T co-ordinates which were not on the p0 isobar or T0 isotherm showed that some ansatz could successfully predict the EOS at a general p-T co-ordinate which was within the ranges of the primary data. However, success rate in prediction was only at about the 50% level and furthermore no systematics were detected which would enable prior selection of the appropriate ansatz to be applied to a specific substance. Theoretical models for the EOS which include a general assumption of one of the ansatz under consideration were therefore shown to be lacking in empirical justification. It was concluded that at present reliable knowledge of the EOS over an area in p-T space can only be obtained through direct experimental determination.
12.	Soldatov, Alexander, et al. (författare) Molecular rotation in C70 at high pressures: a thermal conductivity study 1996 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier Science Ltd. - 0022-3697 .- 1879-2553. ; 57:9, s. 1371-1375 Tidskriftsartikel (refereegranskat)abstract We have measured the thermal conductivity ε and the heat capacity per unit volume varrhocp of highly pure C70 in the temperature interval 100–450 K under pressures up to 1 GPa. Anomalies indicating freezing of uniaxial molecular rotation were observed in λ and varrhocp upon both cooling and increasing pressure. The phase boundary for this transition has an approximate slope dT/dp = 70 K Gpa−1. The temperature and pressure dependence of λ indicate a substantial amount of structural defects in the sample and strong metastability effects.
13.	Sundqvist, Bertil, et al. (författare) Thermal conductivity of gold and silver at high pressures 1978 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 39:10, s. 1133-1137 Tidskriftsartikel (refereegranskat)abstract The thermal diffusivities of gold and silver have been measured under pressure up to 2.5 GPa at room temperature. From the measured data the pressure dependence of the thermal conductivity, λ, has been calculated. The values found for the pressure coefficient λ−1 δλ/δP were 3.9 × 10−2GPa−1 for gold and 4.0 × 10−2 GP silver at atmospheric pressure. The results are compared to theoretical predictions of the pressure dependence and also to previous experimental results for copper and aluminium. For the noble metals, small angle or “vertical” scattering of electrons is shown to have a stronger volume dependence than “horizontal” scattering.
14.	Wågberg, Thomas, et al. (författare) Structural evolution of low-pressure polymerised C60 with polymerisation conditions 1999 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 60:12, s. 1989-1994 Tidskriftsartikel (refereegranskat)abstract We show in this paper that characteristic features in the Raman spectra, especially the frequency of the pentagonal pinch mode, can give information about the polymeric structure of pressure polymerised C60. High-pressure treatment at 1 GPa below 510 K for 3 h results in the formation of a low fraction of dimers only, while treatment at the same pressure and time above 540 K affords a fully polymerised material. In the latter case, different relative fractions of dimers and polymer chains are obtained depending on whether the final reaction conditions were reached by isobaric or isothermal path. We suggest that this difference results from different reaction dynamics in the two cases. The polymerisation rate depends on T and p and on the rotational and orientational states of the molecules. At 1 GPa no polymerisation is observed in sc C60, while in “hexagon” oriented sc C60 at 1.7 GPa dimers are already formed 175 K below the fcc–sc transition and a fully polymerised material is obtained just below the transition to the fcc phase.
15.	Aryasetiawan, F., et al. (författare) Modern theory of orbital magnetic moment in solids 2019 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 128, s. 87-108 Tidskriftsartikel (refereegranskat)abstract The magnetic moment in a solid is usually associated with the electron spins but there is an additional contribution due to the orbital motion of the electrons. For a finite system such as an atom or molecule the orbital moment can be readily calculated. However, for a periodic system the formula used for finite systems becomes ill-defined due to the presence of the position operator. In the last decade a modern theory of orbital magnetization that allows for a rigorous calculation of the magnetic moment of periodic crystals has been developed. This article provides a survey of the theoretical development of this new topic as well as recent, albeit a few, applications of the new formula to real materials. Although the original theory was worked out for non-interacting systems, there has been recent progress in the theory of orbital magnetic moment of interacting electrons in solids. To include the effects of electron-electron interactions two approaches have been proposed, one based on current spin density functional theory and another on the many-body Green's function method. The two approaches are very different but both methods provide convenient yet rigorous means of including the effects of exchange and correlations beyond the commonly used local density approximation of density functional theory.
16.	Bayat, Nazlin, et al. (författare) In-Situ Study of Phase Transformations during Homogenization of 6060 and 6063 Al Alloys 2019 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 130, s. 165-171 Tidskriftsartikel (refereegranskat)
17.	Belonoshko, Anatoly B., et al. (författare) High-pressure crystal structure studies of Fe, Ru and Os 2004 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 65:09-aug, s. 1565-1571 Tidskriftsartikel (refereegranskat)abstract In order to reveal structural trends with increasing pressure in d transition metals, we performed full potential linear muffin-tin orbital calculations for Fe, Ru, and Os in the hexagonal close packed structure. The calculations cover a wide volume range and demonstrate that all these hexagonal close-packed metals have non-ideal c/a at low pressures which, however, increases with pressure and asymptotically approaches the ideal value at very high compressions. These results are in accordance with most recent experiment for Ru and Os. The experimental data for iron is not conclusive, but it is believed that the c/a ratio decreases weakly with increasing pressure at moderate compression. Since, the experimental and calculated equations of state for iron are in increasingly good agreement with increasing pressure, it is possible that either the negative c/a trend is valid only for a restricted pressure range, or related to the experimental difficulties (e.g. non-hydrostaticity).
18.	Benyahia, K, et al. (författare) Ab-initio calculations of the optical and magnetic properties of erbium silicide ErSi2 2009 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 70:10, s. 1378-1384 Tidskriftsartikel (refereegranskat)abstract We present a computational method for the ab-initio study of the optical and magnetic properties using the augmented plane wave plus local orbitals (APW+lo) method. The calculations are presented within the local density (LDA) approximation. Erbium silicide (ErSi2) is representative of the whole trivalent heavy-rare-earth disilicides family, and its study will provide information valid for all of them. Thus, the study of its optical and magnetic properties is very important, especially for the calculation of magneto-optical quantities. In this paper the optical and magnetic properties are well described. Up to now no theoretical study on optical and magnetic properties of ErSi2 is available in the literature. We report theoretical calculations of the reel and imaginary parts of the dielectric function (DF), the refractive index and the extinction coefficient, the spectra of the reflectivity, the absorption coefficient, the energy-loss function (ELF), and the magnetic moments. (C) 2009 Elsevier Ltd. All rights reserved.
19.	Blanter, M. S., et al. (författare) Interstitial-interstitial interactions in bcc VB group metals : Ab initio calculations 2013 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 74:5, s. 716-722 Tidskriftsartikel (refereegranskat)abstract Chemical and strain-induced interactions of oxygen and nitrogen interstitials in bcc V and Ta have been obtained for the first 12 coordination shells in the supercell first-principles calculations by the Viena ab initio simulation package (VASP). It is shown that the chemical interactions are dominating at the first several coordination shells while the strain-induced interactions become important at more distant coordination shells. The latter are in reasonable agreement with the earlier results of a microscopic phenomenological Krivoglaz-Kanzaki-Khachaturyan model (KKKM). The obtained interstitial-interstitial interactions have been used in calculations of the concentration dependence of the oxygen Snoek peak, which is in good agreement with the existing experimental data.
20.	Blanter, M. S., et al. (författare) Strain-induced interaction of interstitials in IVA group hcp metals 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:10, s. 1416-1420 Tidskriftsartikel (refereegranskat)abstract Strain-induced (elastic) interactions of oxygen, nitrogen and carbon atoms in IVA group metals, alpha-Ti, Zr, and -Hf, are calculated in the framework of the microscopic Krivoglaz-Kanzaki-Khachaturyan theory. The experimental elastic constants, lattice spacing of the host metal, and concentration expansion coefficients are used as the input numerical parameters. The resulting interactions are stronger in a-Ti than in alpha-Zr and alpha-Hf. A comparative analysis of interactions in the hcp IVA group metals with those in bcc and fcc solid solutions reveals the crystal structure effect. In general, the strain-induced interactions of O, N, and C in hcp IVA group metals are weaker than in bcc solid solutions and are stronger than in fcc solid solutions.
21.	Danoix, F., et al. (författare) Grain size effect on interfacial segregation in nanomaterials 2022 Ingår i: Journal of Physics and Chemistry of Solids. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0022-3697 .- 1879-2553. ; 164 Tidskriftsartikel (refereegranskat)abstract Segregation of impurities to grain boundaries in materials impact their structural, mechanical, electrical or functional properties. In the present paper, a theoretical study of the influence of grain size on grain boundaries segregation in a binary system by coupling the McLean theory, the concept of excess number with the grain boundaries fraction, is presented. The obtained results show that both grain boundary and bulk solute content decrease with reducing the grain size. However, it is shown the equilibrium segregation rate to grain boundaries increases. This effect is enhanced when the grain size is lower than 10 mu m and thus should be amplified in nanomaterials. This size dependence is larger at low temperatures, where segregation becomes more pronounced.
22.	De Sarkar, Abir, et al. (författare) Electronic charge transport through ZnO nanoribbons 2014 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 75:11, s. 1223-1228 Tidskriftsartikel (refereegranskat)abstract I-V characteristics of ZnO nanoribbons (NRs) have been investigated using density functional theory coupled to non-equilibrium Green's Function. The current through the NRs drops with the increasing NR width, leveling off to 1.66 and 0.42 mu A in zig-zag and arm-chair NRs respectively for widths similar to 20 angstrom at 3 V of electrical bias. The transconductance as well as the current flowing through the arm-chair NRs decays exponentially with NR width for both odd and even number of dimer lines traversed. The current through the zig-zag NRs falls off exponentially with NR width, being insensitive to the odd or even numbers of zig-zag lines appearing along the normal to the charge transport direction.
23.	Dmitriev, V. V., et al. (författare) Ab initio based investigation of interstitial interactions and Snoek relaxation in Nb-O 2012 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 73:2, s. 182-187 Tidskriftsartikel (refereegranskat)abstract Chemical and strain-induced effective pair interactions of interstitial oxygen atoms in bcc Nb have been determined in supercell first-principles calculations using Vienna ab initio simulation package (VASP). The strain-induced interactions are in reasonable agreement with those obtained earlier within a phenomenological microscopic Krivoglaz-Kanzaki-Khachaturyan model (KKKM). At the same time, the chemical interactions, which have been considered to be small in earlier theoretical considerations, turned out to be dominating at the first several coordination shells. The obtained interactions have been used in calculations of the concentration- and temperature-dependence of the internal friction Snoek peak. The theoretical results are found to be in good agreement with the existing experimental data.
24.	Fries, S. G., et al. (författare) Development of multicomponent thermodynamic databases for use in process modelling and simulations 2005 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 66:04-feb, s. 226-230 Tidskriftsartikel (refereegranskat)abstract Thermodynamic databases describe the Gibbs energy of each phase in a given system, as a function of temperature, pressure and its constitution taking into account various properties like crystal structure, solubility of different element on different types of sites, magnetism, etc. The energetics from first principles calculations, crystallographic information and atomistic modelling results can be incorporated into the parametric Gibbs energies models in order to construct thermodynamic databases, being, however, experimental data obtained, e.g. from calorimetry, emf, thermal analyse, metallography, etc. which provides enthalpies, chemical potentials, phase boundary, etc. the basic type of information used. These thermodynamic databases can be an intermediate level between atomistic and macroscopic modelling, bridging scales and theoretical and empirical modelling. Thermodynamic databases provide consistent and accurate information for understanding the macroscopic behaviour of processes and transformations in real materials. This is essential to make realistic modelling and simulations for improving the production as well as teaching of phenomena which are too complex to be modelled directly from a pure theoretical approach. The majority of the phases present in materials for technical applications are solution phases, being its modelling the most complex part of the development of databases. In this paper, we show some features of the making of these databases, as well as the feedback obtained from their different applications and how that results in improvements.
25.	Ghosh, Sukanya, et al. (författare) Rashba-induced spin texture and spin-layer-locking effects in the antiferromagnetic CrI3 bilayer 2023 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 173 Tidskriftsartikel (refereegranskat)abstract The antiferromagnetic (AFM) CrI3 bilayer is a particularly interesting representative of van der Waals 2D semiconductors, which are currently being studied for their magnetism and for their potential in spintronics. Using ab initio density-functional theory calculations, we investigate the spin texture in momentum space of the states of the (doubly degenerate) highest valence band of the AFM CrI3 bilayer with Cr-spin moments perpendicular to the layers. We find the existence, in the main central part of the Brillouin zone, of a Rashba in-plane spin texture of opposite signs on the two layers, resulting from the intrinsic local electric fields acting on each layer. To study the layer segregation of the wavefunctions, we apply a small electric field that splits the degenerate states according to their layer occupancy. We find that the wavefunctions of the highest valence band are layer-segregated, belonging to only one of the two layers with opposite in-plane spin textures, and the segregation occurs over nearly the whole Brillouin zone. The corresponding layer locking of the in-plane -canted spin is related to the separation in energy of the highest AFM band from the rest of the valence bands. We explain how the band interactions destroy the layer locking at the K, K ', and Gamma points. Furthermore, we compare the layer locking of the in-plane-canted spin in our AFM bilayer system with the hidden spin polarization in centrosymmetric nonmagnetic materials, pointing out the differences in segregation mechanisms and their consequences for the layer locking. We note that a similar Rashba effect with layer locking of in -plane-canted spin could occur in other van der Waals AFM bilayers with strong spin-orbit coupling and an isolated energy band.
26.	Huang, L., et al. (författare) Anomalous temperature dependence of elastic constant c(44) in V, Nb, Ta, Pd, and Pt 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:8, s. 1065-1068 Tidskriftsartikel (refereegranskat)abstract The anomalous temperature dependence of elastic constant c(44) for elements V. Nb, Ta, Pd, and Pt, has been calculated using first-principles theory. It is shown that the variation of elastic constant for simple elements can be approximated as the sum of thermal expansion and electronic components. The thermal expansion contributes the normal linearly decreasing effect to the elastic constant with temperature, while electronic contribution is determined by the unique character of electronic structure of elements and leads to the anomalous effect to the elastic constant with temperature.
27.	Ju, Zhiping, et al. (författare) First-principles prediction on Ag3SbS4 as a photovoltaic absorber 2023 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 183 Tidskriftsartikel (refereegranskat)abstract Generally, tetrahedrally coordinated Ag-based chalcogenides have wider band gaps than their Cu-based counterparts. Recent studies have suggested Cu3SbS4 as the absorber in low-cost and low-toxicity photovoltaic (PV), however its band gap is ∼0.5 eV smaller than the ideal value of ∼1.3 eV. In this work, we investigate Ag3SbS4 by first-principles means, since one can anticipate improved optical properties for this compound. The results indeed demonstrate that enargite Ag3SbS4 is a direct-gap semiconductor with a band gap of 1.38 eV, thus optimal for single-junction solar cells. Furthermore, its carrier effective masses, optical coefficients and spectroscopic limited maximum efficiency are comparable to well-established PV compounds. The compound exhibits also thermodynamical and dynamical stability. Hence, based on the present theoretical study we predict that Ag3SbS4 could be a candidate for absorber in high-efficient thin-film PVs.
28.	Kall, M., et al. (författare) Resonance Raman scattering as a probe of oxygen dynamics in YBa2Cu3Ox 1998 Ingår i: Journal of Physics and Chemistry of Solids. - 0022-3697 .- 1879-2553. ; 59, s. 1988-1990 Tidskriftsartikel (refereegranskat)abstract We report on the metastable photo-bleaching of the 2.15 eV yellow Raman resonance in oxygen deficient YBa2Cu3Ox (x = 6.35-6.87), extending investigations by Wake ct al. (Phys. Rev. Lett., 1991,67, 3728) for x approximate to 7. Polarization, x dependence and phonon spectra indicate that the resonance is localized at oxygen vacancies in long CuO-chains. The resonance is thermally reactivated from the metastable bleached state with a relaxation time tau similar to exp[Delta/k(B)T] with Delta approximate to 1 eV. The resulting temperature dependent equilibrium resonance intensity essentially miners the oxygen superstructure disordering around T* approximate to 100 degrees C observed in the same crystals by hard X-ray diffraction, thus offering a new effective probe of chain-oxygen dynamics in YBa2Cu3Ox. (C) 1998 Elsevier Science Ltd. All rights reserved.
29.	Kim, D. Y., et al. (författare) Ab initio study of the pressure effects on R2Mo2O7 2008 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 69:9, s. 2245-2247 Tidskriftsartikel (refereegranskat)abstract Structural parameters and Mo 4d bands in geometrically frustrated pyrochlore R2Mo2O7 (R: Nd, Sm, Gd, Tb, Dy) have been studied using ab initio methods. Both of chemical pressure and external pressure give linear behaviors of structural parameters. The chemical pressure affects more strongly on Mo-O-Mo bond angle, oxygen coordinate and lattice constant, whereas one electron bandwidth varies more rapidly with external pressure in good agreement with experimental results.
30.	Kumar, Vipin, et al. (författare) First-principles calculations to investigate the dielectric and optical anisotropy in two-dimensional monolayer calcium and magnesium difluorides in the vacuum ultraviolet 2023 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 181 Tidskriftsartikel (refereegranskat)abstract Anisotropic dielectric and optical properties of two-dimensional (2D) calcium and magnesium difluorides were investigated in the vacuum ultraviolet (VUV) region of the electromagnetic spectrum (EM) using the first principles density functional theory (DFT). The anisotropy between the in-plane and out-of-plane directions shows that these materials are uniaxial, exhibiting optical and dielectric anisotropy. The optical functions of these anisotropic materials-optical absorption, photoconductivity, refractive index, reflection and extinction coefficients, and electron energy loss (EEL) spectra-are calculated in the framework of DFT. The low refractive index values and relatively small extinction coefficient make these materials alternative low-index 2D materials for the long wavelengths in the VUV region of the EM spectrum. The reflection and transmission spectra indicate the antireflective property of these materials. The calculated EEL function shows less energy loss of fast-traveling electrons in the material's medium. The maxima in the EEL spectrum are the main feature of plasma oscillations. The dissipation in the incident light radiation energy propagating through the dielectric medium is estimated with the dielectric loss tangent (tan & delta;). The magnesium difluoride is identified as a less dielectric loss medium than calcium difluoride in the VUV region. The present results suggest that these 2D materials are promising in low refractive index, high reflective, and antireflective coating materials in optoelectronic device applications. Also, electronic studies revealed that these are excellent materials for gate insulators in field-effect transistors based on 2D electronic materials.
31.	Landa, A., et al. (författare) Ab initio calculations of elastic constants of the bcc V-Nb system at high pressures 2006 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 67:10-sep, s. 2056-2064 Tidskriftsartikel (refereegranskat)abstract First-principles total energy calculation based on the exact muffin-tin orbital and full-potential linear muffin-tin orbital methods were used to calculate the equation of state and shear elastic constants of bcc V, Nb, and the V95Nb05 disordered alloy as a function of pressure up to 6 Mbar. We found a mechanical instability in C-44 and a corresponding softening in C at pressures similar to 2 Mbar for V. Both shear elastic constants show softening at pressures similar to 0.5 Mbar for Nb. Substitution of 5 at% of V with Nb removes the instability of V with respect to trigonal distortions in the vicinity of 2 Mbar pressure, but still leaves the softening of C-44 in this pressure region. We argue that the pressure-induced shear instability (softening) of V (Nb) originates from the electronic system and can be explained by a combination of the Fermi surface nesting, electronic topological transition, and band Jahn-Teller effect.
32.	Larsson, Per-Lennart, et al. (författare) A numerical study of the mechanical behavior at contact between particles of dissimilar elastic-ideally plastic materials 2015 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 77, s. 92-100 Tidskriftsartikel (refereegranskat)abstract In the present study contact between elastic-ideally plastic dissimilar spheres are investigated in detail. The investigation is based on numerical methods and in particular the finite element method. The numerical results presented are discussed with respect to correlation of global contact properties as well as the behavior of local field variables such as contact pressure distribution and the evolution of the effective plastic strain. Large deformation effects are accounted for and discussed in detail. The constitutive behavior is described by classical Mises plasticity. It is shown that correlation of the dissimilar contact problem can be accurately achieved based on the Johnson contact parameter with the representative stress chosen as the yield stress of the softer material.
33.	Lenarciak, A., et al. (författare) Thermal, electrical, and magnetic properties of Fe2O3-PbO-SiO2 glass prepared by traditional melt-quenching and twin roller fast-cooling methods 2019 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 135 Tidskriftsartikel (refereegranskat)abstract In this study, Fe-Pb-Si oxide glasses containing between 12.5 and 17.5 mol% Fe2O3 were prepared using two different methods comprising traditional melt-quenching and twin roller fast-cooling techniques. The topography and structure of the materials obtained were characterized by X-ray powder diffraction and scanning electron microscopy. All of the materials were found to be amorphous. The topography of most of the glasses comprised random or evenly distributed nanostructures, where the size and amount were dependent on the iron content and preparation technique. The thermal properties of the glasses were analyzed by differential scanning calorimetry, which showed that the glass transition temperatures varied between 529 degrees C and 552 degrees C. The electric conductivity and magnetic susceptibility of the glasses were analyzed by impedance spectroscopy and with an alternating current magnetic properties measurement system, respectively. The measurements of the electrical properties indicated a relatively low activation energy for direct current conductivity (similar to 0.5-0.68 eV), which is typical of the polaron hopping mechanism. All of the materials exhibited magnetic hysteresis loops and they were ferromagnetic.
34.	Li, Sa, et al. (författare) Dehydrogenation associated with Ti catalyst in sodium alanate 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:8, s. 1073-1076 Tidskriftsartikel (refereegranskat)abstract Addition of small amount of Ti precursors to sodium alanate has recently been found to substantially improve the kinetics and thermodynamics of hydrogen sorption in sodium alanate. In spite of several attempts, a fundamental understanding of how the catalyst works has remained unattainable. Using first principles methods we have investigated the mechanisms for hydrogen desorption in this material. We conclude that Ti substituted at Al site is energetically most favorable. The small amount of Ti substitution does not introduce large lattice distortion. The Ti atom serves as a magnet that continues to attract nearby H atoms as the nearest ones are successively desorbed. The number of Al atoms near to the Ti site remains at four upon hydrogen desorption when Ti is substituted at the Al site. These results provide important new insight into the design of future catalysts for hydrogen storage materials.
35.	Lousada, Claudio M., et al. (författare) Segregation of P and S to frequently occurring grain boundaries of Cu: Single atoms and cooperative effects 2024 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 193 Tidskriftsartikel (refereegranskat)abstract Materials design and performance prediction relies on detailed knowledge of the distribution of solutes that can affect the materials properties. Here we report a study on the distribution and mechanisms of interaction of S and P atoms at four relevant grain boundaries (GBs) of fcc Cu: Σ3, Σ5, Σ9 and Σ11. Segregation site preference was investigated for single atoms and compared to the case where impurities segregate as pairs. Both the driving force for segregation—local minima—and the interactions between impurities at the GBs—global minima—have been investigated. An analysis of geometric and electronic structure effects in segregation was performed. Single S-atoms bind more strongly to GB sites than single P-atoms. For all GBs the driving force for segregation decays fast with distance from the planes and reaches the bulk values already at ≈ 4 Å. In the near vicinity of the GBs, with increased concentration, the interactions between S-atoms are mostly attractive, while for the same sites the interactions between P-atoms are mostly repulsive. S-atoms are capable of displacing P-atoms and the accumulation of P is not favorable at the GB planes, while the accumulation of S is favorable. We also performed geometric and electronic structure analyses using symmetry quantifying indicators and developed a descriptor of electronic structure effects called “impurity projected density of states (DOS)” for analyzing the bonding between the impurities and the Cu matrix. Overall, segregation is favored by an increase in the asymmetry of the segregation sites. S binds more asymmetrically to those sites preferring an off-center position while P-atoms bind more symmetrically adopting a central position. At GBs with the same excess volume, S-atoms bind stronger than P-atoms and fitting functions that describe these trends were obtained. The balance between bonding states, antibonding states, and the covalent contributions to the bonding between the impurities and the copper matrix are at the origin of the observed preferences.
36.	Lousada, Claudio M., et al. (författare) Single vacancies at ∑5, ∑9 and ∑11 grain boundaries of copper and the geometrical factors that affect their site preference 2022 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 169, s. 110833- Tidskriftsartikel (refereegranskat)abstract The occurrence and distribution of vacancies has implications in many technologically relevant properties of materials. Despite their importance there is no detailed account of vacancy preference at atomic sites of frequently occurring grain boundaries (GBs) of fcc Cu. Here we present a computational investigation of single vacancy site preference at three high angle low index symmetric tilt GBs of fcc Cu: Σ5(310) [100], 36.9°; Σ9(2 2‾1‾) [110], 38.9°; and Σ11(1 1‾ 3) [110], 129.5°; performed with density functional theory (DFT). Using Voronoi tessellation data we developed a symmetry quantifying parameter (σ) based on the difference in surface area between the Voronoi polyhedron and the Wigner-Seitz sphere of the corresponding atomic site. We show that this parameter accurately quantifies changes in symmetry at each atomic site relative to the symmetry at the bulk fcc lattice. Subsequently, we performed a geometrical analysis that shows that the correlation between the values of σ with the coordination number (Cn) and with the volume expansion (Vx) are different for the three GBs, and that their dependencies on the distance from the GB planes are also different. We show that for most atomic sites, a reduction in symmetry is associated with changes in Vx and this is GB dependent. The GB that has the largest distortions relative to the bulk is the Σ5, closely followed by the Σ9, while the Σ11 has a decrease in symmetry which is only ¼ of the other two. At Σ5, changes in site Cn imply changes in the site symmetry to extents that do not occur for the other two GBs.For 100% of the sites at Σ5 and 50% of the sites at Σ9 and Σ11, the formation of vacancies is more favorable than in the bulk. However, the vacancy formation energies show that Σ11 has little ability to stabilize vacancies, which means that vacancies will occur at this GB with a similar frequency as in the bulk. These results show that the transferability of vacancy formation energies and vacancy distribution data between different GBs is nontrivial.
37.	Luo, Wei, et al. (författare) Electronic structure of a thermoelectric material : CsBi4Te6 2008 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 69:9, s. 2274-2276 Tidskriftsartikel (refereegranskat)abstract We have calculated the electronic structure of CsBi4Te6 by means of first-principles self-consistent total-energy calculations within the local-density approximation using the full-potential linear-muffin-tin-orbital method. From our calculated electronic structure we have calculated the frequency dependent dielectric function. Our calculations shows that CsBi4Te6 a semiconductor with a band gap of 0.3 eV. The calculated dielectric function is very anisotropic. Our calculated density of state support the recent experiment of Chung et al. [Science 287 (2000) 10241 that CsBi4Te6 is a high performance thermoelectric material for low temperature applications. (C) 2008 Elsevier Ltd. All rights reserved.
38.	Massih, Ali R, et al. (författare) Phase ordering under quenching : a case of Zr-alloy 2004 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 65:6, s. 1193-1198 Tidskriftsartikel (refereegranskat)abstract The Lifshitz–Cahn–Allen kinetic theory of second-order phase transition has been successfully applied to the case of microstructure development of Zr alloy subjected to different cooling rates under the allotropic β→α transformation. In particular, the dependence of α-Zr lamella width on quenching rate observed in the Widmanstätten structure of the material is captured. The effect of the interstitial element oxygen, acting as a driving conveyor for transformation, is considered as an external field within the Ginzburg-Landau free energy framework.
39.	Mogulkoc, Y., et al. (författare) First principle and tight-binding study of strained SnC 2017 Ingår i: Journal of Physics and Chemistry of Solids. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0022-3697 .- 1879-2553. ; 111, s. 458-463 Tidskriftsartikel (refereegranskat)abstract We study the electronic and optical properties of strained single-layer SnC in the density functional theory (DFT) and tight-binding models. We extract the hopping parameters tight-binding Hamiltonian for monolayer SnC by considering the DFT results as a reference point. We also examine the phonon spectra in the scheme of DFT, and analyze the bonding character by using Mulliken bond population. Moreover, we show that the band gap modulation and transition from indirect to direct band gap in the compressive strained SnC. The applied tensile strain reduces the band gap and eventually the semiconductor to semimetal transition occurs for 7.5% of tensile strain. In the framework of tight-binding model, the effect of spin-orbit coupling on energy spectrum are also discussed. We indicate that while tensile strain closes the band gap, spin-orbit gap is still present which is order of similar to 40 meV at the Gamma point. The substrate effect is modeled through a staggered sub -lattice potential in the tight-binding approximation. The optical properties of pristine and strained SnC are also examined in the DFT scheme. We present the modulation of real and imaginary parts of dielectric function under applied strain.
40.	Noor, Saroaut, et al. (författare) Magnetic behavior of Cd2+ substituted cobalt ferrites 2012 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 73:2, s. 227-231 Tidskriftsartikel (refereegranskat)abstract The effect of Cd-substitution on the variation of saturation magnetization M,, Curie temperature T-c, and magnetic moments n(B) of Co1-xCdxFe2O4 (x=0.0-1.0 in steps of 0.1) ferrites have been investigated using SQUID magnetometer and impedance analyzer. The samples were prepared by conventional double sintering ceramic technique and found to be single-phase cubic spinel structure by X-ray diffraction. Saturation magnetization M-s, is found to increase with increase of Cd substitution attaining a maximum value at x=0.4 and decreases thereafter. Curie temperature decreases almost linearly with increasing x content up to x=0.7. Samples having x >= 0.8 display complex magnetic behavior with competing antiferromagnetic and ferromagnetic interactions with the manifestation of large hysteresis at low temperature and no sign of saturation. Samples with x > 0.8 show paramagnetic characteristic at T=5 K with no spontaneous magnetization revealed through Arrot-Belov-Kouvel (ABK) plots.
41.	Pluengphon, Prayoonsak, et al. (författare) Thermodynamic and dynamic stability of NaLiC4 : Exploring superconductivity in a layered hexagonal compound through first-principles calculations 2024 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 189 Tidskriftsartikel (refereegranskat)abstract The layered hexagonal compound NaLiC4 has been thoroughly investigated to assess its thermodynamic and dynamic stability in comparison to its parent compounds NaC2 and LiC2. Utilizing first -principles calculations and phonon analyzes, NaLiC4 has demonstrated remarkable stability within a pressure range of 10 to 100 GPa, surpassing the thermodynamic stability of NaC2 and LiC2. It exhibits metallic behavior with distinctive electronic bands along high symmetry paths, suggesting a conducive environment for superconductivity. The superconducting transition temperature (Tc) of NaLiC4 under different pressures was estimated using the Allen- Dynes equation, with a maximum Tc of 79 K observed at 10 GPa. However, as pressure increases, Tc gradually decreases, indicating the significant impact of external pressure conditions on the superconducting properties. Notably, the in-plane E2g phonon mode originating from the layered hexagonal structure of carbon atoms plays a crucial role in facilitating electron-phonon coupling and influencing the superconducting behavior and Tc of NaLiC4. These findings highlight the thermodynamic and dynamic stability of NaLiC4 as a promising candidate for exploring superconductivity, offering insights into its electronic properties, pressure -dependent Tc behavior, and the influence of specific phonon modes. Further theoretical investigations and experimental studies are necessary to fully unlock the potential of NaLiC4 and its contribution to the development of high-performance superconductors.
42.	Qiu, Liqin, et al. (författare) Electrochemical deposition of Bi2Te3-based thin films 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:8, s. 1131-1136 Tidskriftsartikel (refereegranskat)abstract The electrochemical reduction processes on stainless-steel substrates from an aqueous electrolyte composed of nitric acid, Bi3+, HTeO2+, SbO+ and H2SeO3 systems were investigated using cyclic voltammetry. The thin films with a stoichiometry of Bi2Te3, Bi0.5Sb1.5Te3 and Bi2Te2.7Se0.3 have been prepared by electrochemical deposition at selected potentials. The structure, composition, and morphology of the films were studied by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM) and electron microprobe analysis (EMPA). The results showed that the films were single phase with the rhombohedral Bi2Te3 structure. The morphology and growth orientation of the films were dependent on the deposition potentials.
43.	Ramzan, Muhammad, et al. (författare) High pressure and temperature study of hydrogen storage material BH3NH3 from ab initio calculations 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:8, s. 1137-1139 Tidskriftsartikel (refereegranskat)abstract We report on BH3NH3, which is material considered promising to use as hydrogen storage, using density functional theory with generalized gradient approximation (GGA). We study the phase transition of BH3NH3 at high pressure and temperature. Our observed phase transition of BH3NH3 from body-centered tetragonal to orthorhombic at 220 K supports the recent and earlier studies. We observe the phase transformation of BH3NH3 at approximate to 11.5 GPa, which is in good agreement with experimental value. Specifically, we predict the phase transition at 11.5 GPa to be orthorhombic to body-centered tetragonal on the basis of our first principles calculations.
44.	Sa, Baisheng, et al. (författare) Phase stability and electronic structure of Si2Sb2Te5 phase-change material 2010 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 71:8, s. 1165-1167 Tidskriftsartikel (refereegranskat)abstract On the basis of an ab initio computational study, the present work provide a full understanding on the atomic arrangements, phase stability as well as electronic structure of Si2Sb2Te5, a newly synthesized phase-change material. The results show that Si2Sb2Te5 tends to decompose into Si1Sb2Te4 or Si1Sb4Te7 or Sb2Te3, therefore, a nano-composite containing Si1Sb2Te4, Si1Sb4Te7 and Sb2Te3 may be self-generated from Si2Sb2Te5. Hence Si2Sb2Te5 based nano-composite is the real structure when Si2Sb2Te5 is used in electronic memory applications. The present results agree well with the recent experimental work.
45.	Shahid, Robina, et al. (författare) Synthesis, COSMO-RS analysis and optical properties of surface modified ZnS quantum dots using ionic liquids 2015 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 85, s. 34-38 Tidskriftsartikel (refereegranskat)abstract Zinc sulfide (ZnS) quantum dots (QDs) were synthesized using the microwave assisted ionic liquid (MAIL) route. Three ionic liquids (ILs), namely, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), trihexyl(tetradecyl) phosphonium bis(trifluoromethanesulfonyl) amide ([P-6,P-6,P-6,P-14][TSFA]) and trihexyl (tetradecyl) phosphonium chloride ([P-6,P-6,P-6,P-14][Cl]) were used in this study. The size and structure of the QDs were characterized by high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern, respectively. The synthesized QDs were of wurtzite crystalline structure with size less than 5 nm. The QDs were more uniformly distributed while using the phosponium based ILs as a reaction medium during synthesis. The optical properties were investigated by UV-vis absorption and photoluminescence (PL) emission spectroscopy. The optical properties of QDs showed the quantum confinement effect in their absorption and the effect of cation and anion structural moiety was observed on their bandedge emission. The QDs emission intensity was measured higher for [P-6,P-6,P-6,P-14][Cl] due to their better dispersion as well as high charge density of Cl anion. The capability of the ILs in stabilizing the QDs was interpreted by density functional theory (DFT) computations. The obtained results are in good agreement with the theoretical prediction.
46.	Shiryaev, A.A., et al. (författare) Isotopic heterogeneity in synthetic and natural silicon carbide 2008 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 69:10, s. 2492-2498 Tidskriftsartikel (refereegranskat)abstract The distribution of both carbon and silicon isotopes in synthetic sublimation growth SiC wafers and in natural SiC grains was studied using secondary ion mass-spectrometry (SIMS). Significant variations in both isotopic ratios were observed which were broadly correlated with the crystalline perfection as documented by Raman microspectroscopy. Domains consisting of 15R (or with its admixture) are, on average, enriched in 12C isotope relative to 6H domains, and they also show larger scatter in their observed silicon isotope ratios. We ascribe such heterogeneity to fluctuations of Si/C ratio in the growth medium and it is possible to model the spatial extent of such fluctuations. For the natural SiC grains the isotopic data suggest that they grew under relatively stable conditions, although some of them show significant isotopic zoning.
47.	Simak, Sergey, 1967-, et al. (författare) The role of orthorhombic distortions in gallium under high hydrostatic pressure 2006 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 67:10-sep, s. 2132-2135 Tidskriftsartikel (refereegranskat)abstract We have performed a detailed analysis ofthedouble-well feature ofthetotal energy fortheGa-III phase as a function of tetragonal andorthorhombicdistortionsoftheface-centered cubic (fcc) lattice. We demonstrate that inthelow-pressureregion this double-well feature disappears and only one minimum exists. In order to reveal this result,thepossibility oforthorhombicdistortionshas to be taken into account. At elevatedpressurebetween 58 and 84 GPa,thesecond minimum becomes pronounced, but never develops into a separate local minimum up tothetransformation intothefcc phase.
48.	Sousa, O. M., et al. (författare) Pressure effect on the structural, electronic, and magnetic properties of the battery cathode material LiMn2O4 : An ab-initio study 2023 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 175 Tidskriftsartikel (refereegranskat)abstract LiMn2O4 is a battery cathode material with desirable properties such as low cost, low toxicity, high natural abundance of Mn, and environmental compatibility. By means of first-principles calculations, we study the structural, magnetic, and electronic properties of LiMn2O4 under ambient conditions and high hydrostatic pressures (until 20 GPa). We obtain two oxidation states for Mn, even using a cubic structure, which differ in all analyzed properties: structural, electronic, and magnetic. At P > 0, such properties were found to display a standard behavior decreasing smoothly and linearly with pressure. Furthermore, the enthalpy of cubic and orthorhombic structures under low and high-pressure conditions were examined, showing that no cubic to orthorhombic phase transition exists in all the investigated pressure range, nor is a magnetic cubic to a non-magnetic cubic phase transition possible.
49.	Sundqvist, Bertil (författare) Resistivity saturation in crystalline metals : Semi-classical theory versus experiment 2022 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 165 Tidskriftsartikel (refereegranskat)abstract The electrical resistivities of metals and alloys tend to saturate at some value in the range 150–250 μΩcm, corresponding to semi-classical mean free paths near a few interatomic distances. The origin of this effect is still under debate and no accepted theory exists. However, the saturation behavior can often be described quite accurately by algebraic functions derived from simple theory. Such functions may be used for analyzing resistivity data in experimental and applied physics. In this work, several functions recently proposed have been fitted to 184 sets of resistivity data from the literature, measured on 149 elements, alloys, and intermetallic compounds. The results have been evaluated in terms of both accuracy of fit and of the validity of fitted parameter values. Different functions give the best fit to data for different materials, suggesting that there is no universal functional dependence and thus probably no universal mechanism behind the saturation phenomenon.
50.	Sundqvist, Bertil, et al. (författare) Saturation and pressure effects on the resistivity of titanium and two Ti-Al alloys 2018 Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 122, s. 41-50 Tidskriftsartikel (refereegranskat)abstract The electrical resistivities of a phase titanium and two Ti-Al alloys have been measured as functions of temperature, T, between 4 and 700 K and, in the range 175 to 700 K, as a function of pressure up to 1.2 GPa. All materials showed resistivity saturation effects at the highest temperatures. A “parallel resistivity” saturation model could be fitted to all data with excellent results if Mott-Fermi smearing, expected for a transition metal, was included by adding a term in T3 to the phonon-induced resistivity. However, in the standard saturation model the fitted resistivity parameters were not always realistic. A modified saturation model which partially retained Matthiessen’s rule could be fitted equally well and gave numerically acceptable results for both residual, electron-phonon and saturation resistivities. This new model also fitted the T dependence of the pressure coefficients with a single set of coefficients, each valid for all three materials. Although simple free-electron and Debye models could apparently explain the observed pressure dependence of the impurity and electron-phonon resistivities, a model taking band structure changes with pressure into account showed that the electron-phonon interaction factor of titanium is practically independent of pressure while the plasma frequency has a strong pressure dependence. This model gave reasonable numerical results for the pressure dependence of both the residual, electron-phonon and saturation resistivities and also agreed with experimental data for the superconducting critical temperature Tc under pressure for a titanium.

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