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1.	Al-Zoubi, N., et al. (författare) Assessing the Exact Muffin-Tin Orbitals method for the Bain path of metals 2017 Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 97:15, s. 1243-1264 Tidskriftsartikel (refereegranskat)abstract We scrutinise the muffin-tin approximation and the screening within the framework of the Exact Muffin-Tin Orbitals method in the case of cubic and tetragonal crystal symmetries. Systematic total energy calculations are carried out for the Bain path including the body-centred cubic and face-centred cubic structures for a set of simple and transition metals. The present converged results in terms of potential sphere radius (S) and hard sphere radius (b) are in good agreement with previous theoretical calculations. We demonstrate that for all structures considered here, potential sphere radii around and slightly larger than the average Wigner–Seitz radius (w) yield accurate total energy results whereas S values smaller than w give large errors. It is shown that for converged total energies hard spheres with radii b = 0.7–0.8w should be used for an efficient screening within real space clusters consisting typically of 70–90 lattice sites. The less efficient convergence of the total energy in the case of small hard spheres is ascribed to the delocalisation of the screened spherical waves, which leads to inaccurate interstitial overlap matrix. The above conclusions are not significantly affected by the volume of the system.
2.	Almer, J, et al. (författare) Microstructure and thermal stability of arc-evaporated Cr-C-N coatings 2004 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 84:7, s. 611-630 Tidskriftsartikel (refereegranskat)abstract The role of C incorporation in the microstructure and thermal stability of arc-evaporated Cr-C-N coatings is explored via reactive growth in a mixed C2H4-N2 environment. C is found to react more readily than N at both the Cr cathode and the coating surfaces, so that a C2H4-to-N2 flow ratio of only 1% yields a C-to-N ratio of approximately 10% within the coatings. The as-deposited microstructures consist primarily of the δ-Cr(C, N) phase and possess high compressive residual stresses, which decrease with increasing C content. Post-deposition annealing up to 700°C results in depletion of lattice defects, and concomitant reductions in stress and coating hardness, together with phase transformations which suggest metastable phase formation during growth. Apparent activation energies for this lattice defect are found to be in the range expected for bulk diffusion of N and C (2.4-2.8 eV). The results suggest that inclusion of small amounts of C in this system offers the ability to reduce internal stresses while maintaining defect-related hardness increases, permitting growth of thicker and thus more wear-resistant coatings.
3.	Arwin, Hans, et al. (författare) Chirality-induced polarization effects in the cuticle of scarab beetles: 100 years after Michelson 2012 Ingår i: Philosophical Magazine. - : Taylor and Francis: STM, Behavioural Science and Public Health Titles / Taylor and Francis. - 1478-6435 .- 1478-6443. ; 92:12, s. 1583-1599 Tidskriftsartikel (refereegranskat)abstract One hundred years ago Michelson discovered circular polarization in reflection from beetles. Today a novel Mueller-matrix ellipsometry setup allows unprecedented detailed characterization of the beetles polarization properties. A formalism based on elliptical polarization for description of reflection from scarab beetles is here proposed and examples are given on four beetles of different character: Coptomia laevis - a simple dielectric mirror; Cetonia aurata - a left-hand narrow- band elliptical polarizer; Anoplognathus aureus - a broad-band elliptical polarizer; and Chrysina argenteola - a left-hand polarizer for visible light at small angles, whereas for larger angles, red reflected light is right-handed polarized. We confirm the conclusion of previous studies which showed that a detailed quantification of ellipticity and degree of polarization of cuticle reflection can be performed instead of only determining whether reflections are circularly polarized or not. We additionally investigate reflection as a function of incidence angle. This provides much richer information for understanding the behaviour of beetles and for structural analysis.
4.	Asala, Gbenga, et al. (författare) A study of the dynamic impact behaviour of IN 718 and ATI 718Plus® superalloys 2019 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 99:4, s. 419-437 Tidskriftsartikel (refereegranskat)abstract The dynamic impact response of IN 718 and ATI 718PlusÂ®, in both the solution heat treated and age-hardened conditions, were investigated at different deformation temperatures and strain rates using a direct impact Hopkinson pressure bar. Analyses of the results provide a vital but previously not reported information that the ATI 718PlusÂ® offers a higher resistance to damage during high strain rate ballistic impact deformation compared to the most widely used Iron-nickel based superalloy, Inconel 718. ATI 718PlusÂ® showed higher strain hardening and strain rate sensitivity, in both heat treatment conditions, than IN 718. The difference in the deformation behaviour of both alloys, in the annealed condition, is attributable to the compositional modification in ATI 718PlusÂ® which has been reported to lower its stacking fault energy and increases the tendency for deformation twinning. However, in the age-hardened condition, the difference is believed to be related to the disparity in the operative strengthening mechanism, of the precipitates present in both alloys. Furthermore, a higher susceptibility to strain location and the formation of adiabatic shear band, in aged IN 718, is attributable to the stronger temperature-softening characteristics observed in the alloy and to the limited strain hardening tendency under dynamic impact loading. Â© 2018, Â© 2018 Informa UK Limited, trading as Taylor & Francis Group.
5.	Autieri, Carmine, et al. (författare) Gap opening and large spin–orbit splitting in MX2 (M = Mo,W; X = S,Se,Te) from the interplay between crystal field and hybridisations : insights from ab-initio theory 2017 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 97:35, s. 3381-3395 Tidskriftsartikel (refereegranskat)abstract By means of first-principles density functional calculations, we study the maximally localised Wannier functions for the 2D transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te). We have found that part of the energy gap is opened by the crystal field splitting induced by the X-2-like atoms. The inversion of the band character between the Gamma and the K points of the Brillouin zone is due to the M-M hybridisation. The consequence of this inversion is the closure of the gap in absence of the M-X hybridisation. The M-X hybridisation is the only one that tends to open the gap at every k-point. It is found that the change in the M-X and M-M hybridisation is the main responsible for the difference in the gap between the different dichalcogenide materials. The inversion of the bands gives rise to different spinorbit splitting at Gamma and K point in the valence band. The different character of the gap at Gamma and K point offers the chance to manipulate the semiconducting properties of these compounds. For a bilayer system, the hybridisation between the out-of-plane orbitals and the hybridisation between the in-plane orbitals split the valence band respectively at the Gamma and K point. The splitting in the valence band is opened also without spin-orbit coupling and occurs due to the M-M and X-X hybridisation between the two monolayers. The transition from direct to indirect band gap is governed by the hybridisation between out-of-plane orbitals of different layers and in-plane orbitals of different layers.
6.	Bakaev, A., et al. (författare) Effect of isotropic stress on dislocation bias factor in bcc iron : an atomistic study 2018 Ingår i: Philosophical Magazine. - : Taylor and Francis Ltd.. - 1478-6435 .- 1478-6443. ; 98:1, s. 54-74 Tidskriftsartikel (refereegranskat)abstract The effect of externally applied stress on the dislocation bias factor (BF) in bcc iron has been studied using a combination of atomistic static calculations and finite element integration. Three kinds of dislocations were considered, namely, a0/2〈1 1 1〉{1 1 0} screw, a0/2〈1 1 1〉{1 1 0} edge and a0〈1 0 0〉{0 0 1} edge dislocations. The computations reveal that the isotropic crystal expansion leads to an increasing or constant dislocation bias, depending on the Burgers vector and type of dislocation. On the other hand, compressive stress reduces the dislocation bias for all the dislocations studied. Variation of the dislocation BF depending on dislocation type and Burgers vector is discussed by analysing the modification of the interaction energy landscape and the capture efficiency values for the vacancy and self-interstitial atom.
7.	Bangert, U., et al. (författare) Electron energy loss spectroscopic studies of brown diamonds 2006 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 86:29-31, s. 4757-4779 Tidskriftsartikel (refereegranskat)abstract We investigate both experimentally and theoretically, low-loss electron energy losses in brown type IIa monocrystalline diamonds both before and after high-temperature, high-pressure anneals which remove the brown colouration. We find additional losses within and near the band edge for brown diamond which are significantly reduced after treatment. The additional losses are not associated with dislocations. Graphitic inclusions are detected by EELS as well as TEM studies for some brown diamonds before treatment. These lead to pronounced subgap absorption. However, all brown diamonds exhibit additional losses which are due to point defects lying in the regions between dislocations. First principles theoretical modelling shows that common dislocations are not responsible for the brown colouration but a -bonded vacancy disk lying on {111} planes gives broad bands lying in the diamond band gap, possesses an optical absorption spectrum similar to that of brown diamond, and leads to additional electron energy losses in the band edge region. These and similar defects are suggested to be responsible for the brown colouration. Mechanisms are proposed for their formation and removal.
8.	Bargmann, Swantje, 1980, et al. (författare) Modeling of polycrystals with gradient crystal plasticity: A comparison of strategies 2010 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 90:10, s. 1263-1288 Tidskriftsartikel (refereegranskat)abstract This paper treats the computational modeling of size dependence in microstructure models of metals. Different gradient crystal plasticity strategies are analyzed and compared. For the numerical implementation, a dual-mixed finite element formulation which is suitable for parallelization is suggested. The paper ends with a representative numerical example for polycrystals.
9.	Belonoshko, Anatoly B., et al. (författare) A possible mechanism of copper corrosion in anoxic water 2012 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 92:36, s. 4618-4627 Tidskriftsartikel (refereegranskat)abstract Recent experiments show that solid Cu reacts with anoxic water. The reaction is observed by measuring the hydrogen release. This release is continuous and stable over a period of months. We have since theoretically found that water adsorbs dissociatively at a copper surface. But this adsorption is not enough to explain the amount of hydrogen released in the experiment. This observation calls for the explanation of the removal of the reaction product from the surface to provide a clean Cu surface where the water dissociation takes place. In this paper we investigate, by first-principles calculations, two possible mechanisms for this removal: first the possibility of Cu-O-H nanoparticulate formation, and second the diffusion of the dissociation products into Cu. We show that while the formation of nanoparticulates is energetically unfavorable, the diffusion of OH along grain boundaries can be substantial. The OH being placed in a grain boundary of the Cu sample quickly dissociates and O and H atoms diffuse independently of each other. Such a diffusion is markedly larger than the diffusion in bulk Cu. Thus, grain boundary diffusion is a viable mechanism for providing a clean Cu surface for the dissociation of water at the Cu surface. An order-of-magnitude estimate of the amount of hydrogen released in this case agrees with experiment. But this mechanism is not enough to explain the result of the experiment. We propose the formation of nanocrystals of copper oxide as a second step. A decisive experiment is proposed.
10.	Bjerkén, Christina, et al. (författare) Oriented ordering near line defects in crystals 2017 Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 97:27, s. 2437-2467 Tidskriftsartikel (refereegranskat)abstract General properties of directed ordering near line defects, in particular an edge dislocation, in elastic crystals undergoing phase transition are studied using the two-component time-dependent Ginzburg-Landau equation in two dimensions or 2D-XY model. The associated Landau potential comprises a sixth-order term, cubic anisotropy terms and the field of the dislocation. In thermodynamic equilibrium, the phase diagram for the model is delineated. Upon quenching the system below its transition point, the temporal evolution of the order parameter components in the vicinity of the defect is numerically evaluated. The development of vortices, emanated from the model, is explored and their interaction with the dislocation is examined. The dislocation produced a vortex free circular region whose diameter grew almost linearly with time. The time-dependence of vortex density for various settings of the Landau potential coefficients are evaluated. The vortex density ( in 2D) decreased inversely with time, albeit faster in the absence of dislocation. By computing the two-point correlation function, we established that the dynamic scaling law is satisfied for the considered model if the distance is scaled by L = t(1/2) or by its half-width L-1/2 for a dislocation free crystal. Finally, phase transitions in improper ferroelectrics in the context of the model are discussed.
11.	Bjerkén, Christina, et al. (författare) Phase ordering kinetics of second-phase formation near an edge dislocation 2014 Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 94:6, s. 569-593 Tidskriftsartikel (refereegranskat)abstract The time-dependent Ginzburg-Landau (TDGL) equation for a single component non-conservative structural order parameter is used to study the spatio-temporal evolution of a second phase in the vicinity of an edge dislocation in an elastic crystalline solid. A symmetric Landau potential of sixth-order is employed. Dislocation field and elasticity modify the second-order and fourth-order coefficients of the Landau polynomial, respectively, where the former makes the coefficient singular at the origin. The TDGL equation is solved numerically using a finite volume method, where a wide range of parameter sets is explored. Computations are made for temperatures both above and below the transition temperature of a defect-free crystal Tc0. In both cases, the effects of the elastic properties of the solid and the strength of interaction between the order parameter and the displacement field are examined. If the system is quenched below Tc0, a steady state is first reached on the compressive side of the dislocation. On the tensile side, the growth is held back. The effect of thermal noise term in the TDGL equation is studied. We find that if the dislocation is introduced above Tc0, thermal noise supports the nucleation of the second phase, and a steady state will be attained earlier than if the thermal noise was absent. For a dislocation-free solid, we have compared our numerical computations for a mean-field (spatially averaged) order parameter versus time with the late time growth of the ensemble-averaged order parameter, calculated analytically, and find that both results follow upper asymptotes of sigmoid curves.
12.	Bonny, G., et al. (författare) Density functional theory-based cluster expansion to simulate thermal annealing in FeCrW alloys 2017 Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 97:5, s. 299-317 Tidskriftsartikel (refereegranskat)abstract In this work, we develop a rigid lattice cluster expansion as an ultimate goal to track the micro-structural evolution of Eurofer steel under neutron irradiation. The fact that all (defect) structures are mapped upon a rigid lattice allows a simplified computation and fitting procedure, thus enabling alloys of large chemical complexity to be modelled. As a first step towards the chemical complexity of Eurofer steels, we develop a cluster expansion (CE) for the FeCrW-vacancy system based on density functional theory (DFT) calculations in the dilute alloy limit. The DFT calculations suggest that only CrW clusters containing vacancies are stabilised. The cluster expansion was used to simulate thermal annealing in Fe–20Cr–xW alloys at 773 K. It is found that the addition of W to the alloy results in a non-linear decrease in the precipitation kinetics. The CE was found suitable to describe the energetics of the FeCrW-vacancy system in the Fe-rich limit.
13.	Boschker, J. E., et al. (författare) In-plane structural order of domain engineered La0.7Sr0.3MnO3 thin films 2013 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 93:13, s. 1549-1562 Tidskriftsartikel (refereegranskat)abstract We present a detailed structural study of tensile-strained La0.7Sr0.3MnO3 thin films. We use the substrate miscut to control the number of rhombohedral variants in the films and study the in-plane order and structural distortions. Using high-resolution X-ray diffraction, we demonstrate that step-edge induced lattice modulations occur in 4-variant films, whereas periodic twinning is the dominant in-plane order for 2-variant films. We show that the in-plane twinning angle is almost completely relaxed. However, the relaxation of shear strain by the out-of-plane twinning angle and the monoclinic distortion is only partial. Furthermore, the film thickness dependence of the domain width reveals that domain formation is a universal mechanism for shear strain relaxation. Finally, we show that the structural response to the transition from the paramagnetic to the ferromagnetic phase of La0.7Sr0.3MnO3 at 345K is smaller in 4-variant films compared to 2-variant films.
14.	Carini, Giovanni, et al. (författare) Ultrasonic and hypersonic behaviours of borate glasses 2007 Ingår i: Philosophical Magazine. - 1478-6435 .- 1478-6443. ; 87, s. 697-703 Tidskriftsartikel (refereegranskat)abstract Comparative measurements of Brillouin light scattering and ultrasound in (K2O)0.04(B2O3)0.96 and (Ag2O)0.14(B2O3)0.86 borate glasses as a function of temperature between 1.5 and 300 K reveal that distinct mechanisms regulate the temperature behaviours of the acoustic attenuation. In the MHz range the attenuation and the sound velocity are mainly governed by (i) quantum-mechanical tunnelling below 20 K, (ii) thermally activated relaxations between 20 and 200 K and (iii) vibrational inharmonicity at even higher temperatures. In the GHz range and in the temperature interval between 77 and 300 K, additional contributions besides the relaxation process must be taken into consideration to account for the hypersonic attenuation.
15.	Chen, G., et al. (författare) Protein fluctuations explored by inelastic neutron scattering and dielectric relaxation spectroscopy 2008 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 88:33-35, s. 3877-3883 Konferensbidrag (refereegranskat)abstract Glasses, supercooled liquids and proteins share common properties, in particular the existence of an energy landscape and the presence of two types of fluctuations, alpha and beta. While the effect of alpha fluctuations on proteins has been known for a few years, the effect of beta fluctuations has not been fully understood. By comparing neutron-scattering data on the protein myoglobin with beta fluctuations in the hydration shell measured by dielectric relaxation spectroscopy, we show that the internal protein motions are slaved to these fluctuations. We also show that there is no 'dynamical transition' in proteins near 200 K. The rapid increase in the mean-square displacement with temperature in many neutron-scattering experiments can be quantitatively predicted by beta fluctuations in the hydration shell.
16.	Chernogorova, Olga P., et al. (författare) Indentation behaviour of superelastic hard carbon 2016 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 96:32-34, s. 3451-3460 Tidskriftsartikel (refereegranskat)abstract Superelastic hard carbon particles widely varying in structure andproperties have been studied by instrumented microindentationtechnique. The carbon particles up to 200 μm in size were producedby fullerene collapse upon high-pressure high-temperature treatmentof metal–fullerene powder mixture with simultaneous sintering ofmetal matrix composite materials (CM) reinforced by the particles.The structure and properties of the carbon particles were controlledby changing synthesis parameters and the state (composition andstructure) of the parent fullerite crystals. The specific features of theinstrumented indentation behaviour of the particles were studied asa function of their hardness. Mechanical properties of the particlestested at loads of up to 1970 mN exhibit an indentation size effect,which becomes more pronounced with increasing hardness of thecarbon particles. Upon holding at a constant load, the fullerenederivedcarbon particles undergo unrecoverable deformation, and theindentation creep CIT increases with increasing particle hardness. Anincrease in hardness of the reinforcing carbon particles substantiallyimproves the wear resistance of the CM and decreases their frictioncoefficient.
17.	Dahlberg, Carl F. O., et al. (författare) Hardening and softening mechanisms at decreasing microstructural length scales 2008 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 88:30-32, s. 3513-3525 Tidskriftsartikel (refereegranskat)abstract A laminate structure with varying lamina thicknesses is used as a qualitative model of grain size dependence on yield behaviour in metallic materials. Both strain gradient plasticity and slip between layers are considered. It is shown that an inverse Hall-Petch effect can be generated in this way. For very small thicknesses, corresponding to very small grain sizes, sliding is the dominant mechanism and the strength then decreases with decreasing thickness. For larger thicknesses, strain gradient plasticity is controlling the deformation and the strength is, instead, increasing with decreasing thickness. Numerical examples are presented that demonstrate these mechanisms.
18.	Djurabekova, F., et al. (författare) Kinetics versus thermodynamics in materials modeling : The case of the di-vacancy in iron 2010 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 90:19, s. 2585-2595 Tidskriftsartikel (refereegranskat)abstract Monte Carlo models are widely used for the study of microstructural and microchemical evolution of materials under irradiation. However, they often link explicitly the relevant activation energies to the energy difference between local equilibrium states. We provide a simple example (di-vacancy migration in iron) in which a rigorous activation energy calculation, by means of both empirical interatomic potentials and density functional theory methods, clearly shows that such a link is not granted, revealing a migration mechanism that a thermodynamics-linked activation energy model cannot predict. Such a mechanism is, however, fully consistent with thermodynamics. This example emphasizes the importance of basing Monte Carlo methods on models where the activation energies are rigorously calculated, rather than deduced from widespread heuristic equations.
19.	Dupin, N., et al. (författare) Using first-principles results to calculate finite-temperature thermodynamic properties of the Nb-Ni mu phase in the Bragg-Williams approximation 2006 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 86:12, s. 1631-1641 Tidskriftsartikel (refereegranskat)abstract Results of first-principles (FP) total energy calculations for 32 different configurations of the mu phase in the binary system Nb-Ni are used in the compound energy formalism (CEF) to model finite-temperature thermodynamic properties. A comparison with Cluster Expansion Hamiltonian-Cluster Variation Method (CEH-CVM) calculations indicates that the CEF describes temperature-dependent site occupancies as well as the CEH-CVM within the temperature range of interest for applications. This suggests that the Bragg-Williams-Gorsky approximation (BWGA) used in the CEF is sufficient to describe site occupancies and thermodynamics of the mu phase. A phase diagram is calculated using the mu phase description derived in the present work together with a previous Calphad description for the other phases of this system. The FP-CEF approach significantly improves the description of the thermodynamic properties as a function of composition compared to the Calphad procedure generally used up to now.
20.	Etz, Corina, et al. (författare) ROTMOKE : An assessment of macroscopic models for bcc Ni/Ni(100) 2008 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 88:18-20, s. 2765-2775 Tidskriftsartikel (refereegranskat)abstract Ab-initio Kerr angles for a multilayer system were calculated by means of Luttinger's formalism within the spin-polarized relativistic screened Korringa-Kohn-Rostoker method by including all multiple reflections and optical interferences via the 2 2 matrix technique. Two further macroscopic models are suggested for a multilayer system; i.e., the two-media approach and the three-media approach. The Kerr angles obtained using the two-media approach show that 75 % of the Kerr rotation angles arise from surface contributions when compared to the 2 2 matrix approach. Furthermore, by comparing the three-media approach to the 2 2 matrix technique it is found that almost 25 % of the Kerr rotation angles are due to interfaces between the atomic layers
21.	Forsblom, Mattias, et al. (författare) Vibrational entropy of dislocations in Al 2004 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 84:6, s. 521-532 Tidskriftsartikel (refereegranskat)abstract The region nearest to a lattice defect must be described by an atomistic model, while a continuum model suffices further away from the defect. We study such a separation into two regions for an edge dislocation. In particular we focus on the excess defect energy and vibrational entropy, when the dislocation core is described by a cluster of about 500-100 atoms, embedded in a large discrete and relaxed, but static, lattice. The interaction between the atoms is given by a potential of the embedded-atom model type referring to Al. The dynamic matrix of the vibrations in the cluster is fully diagonalized. The excess entropy DeltaS near the core has positive and negative contributions, depending on the sign of the local strain. Typically, DeltaS/k(B) approximate to 2 per atomic repeat length along the dislocation core in fcc Al. In the elastic continuum region far from the dislocation core the excess entropy shows the same logarithmic divergence as the elastic energy. Although the work refers to a specific material and defect type, the results are of a generic nature.
22.	Hepburn, D. J., et al. (författare) Rescaled potentials for transition metal solutes in α-iron 2009 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 89, s. 3393-3411 Tidskriftsartikel (refereegranskat)abstract We present semi-empirical potentials for dilute transition metal solutes in α-iron. They are in the Finnis–Sinclair form and are therefore suitable for billion atom molecular dynamics simulations. The potentials have been developed using a rescaling technique to provide solute–iron and solute–solute interactions from an existing iron potential. By fitting to first principles calculations, which show clear trends in the properties of transition metal solutes in iron across the series, we find trends in the rescaling parameters, which we model using simple functions of the occupancy of the d-electron band. We comment on the possibility of utilizing such relationships for the fundamental electronic properties of the solute to create multicomponent potentials for transition metal solutes in α-iron.
23.	Hoque, S. Manjura, et al. (författare) Detailed study of ultra-soft magnetic properties of Fe74Cu0.8Nb2.7Si15.5B7 2011 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 91:16, s. 2117-2139 Tidskriftsartikel (refereegranskat)abstract The magnetic properties of nanocrystalline Fe74Cu0.8Nb2.7Si15.5B7 alloy, which were rapidly solidified and then annealed at various temperatures between 475 and 650 degrees C for different holding time, have been studied. Grain size, silicon content and the lattice parameter of alpha-Fe(Si) nanograins at the annealing temperatures were determined. Curie temperature of the amorphous phase was determined from the temperature dependence of permeability. For higher annealing temperatures and times, some Si diffused out of the alpha-Fe(Si) phase and formed an ordered DO3 phase of Fe3Si. This changed the overall magnetostriction and average anisotropy of the matrix, which deteriorated the magnetic softness of the material at higher annealing temperatures. Ultra-soft magnetic properties were achieved by averaging the random anisotropy via exchange interaction. Hysteresis loops for samples in as-cast and annealed conditions have also been studied.
24.	Johansson, Börje, et al. (författare) Itinerant f-electron elements 2009 Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 89:22-24, s. 1793-1799 Tidskriftsartikel (refereegranskat)abstract To obtain a proper understanding of the 5f elements, the actinides, it is useful to compare their behavior with the 4f transition elements, the lanthanides. It is especially rewarding to capitalize on the remarkable similarity between the solid-state properties of compressed Ce and the actinide metals. The intensively studied alpha-gamma transition in Ce is considered to be a Mott transition, namely, the 4f electron changes its behavior from being localized to become delocalized (itinerant/metallic). This change also means that the 4f electron transforms from a non-bonding to a bonding configuration which, in turn, gives rise to a volume collapse. This collapse is isostructural in character, which contributes to the immense interest in this phase transition. An analogous and remarkable change in bonding (cohesive) properties is also found within the actinide series, where the sudden volume increase from Pu to Am (50%) can be viewed as a Mott transition within the 5f shell as a function of atomic number Z. The elements on the metallic side of the 5f Mott transition, i.e. the earlier actinides (Pa-Pu), show low symmetry structures at ambient conditions, while the heavier elements (from Am and beyond) adopt structures typical for the lighter trivalent lanthanide elements with localized 4f electrons. An important consequence of the localized and trivalent behavior in Am is a non-magnetic 5f(6) (J = L + S = 0) configuration for the f electrons. This led to the prediction of superconductivity in americium and subsequently to its experimental verification.
25.	Johari, G.P., et al. (författare) Effects of pressure-temperature protocols on the properties of crystals and ageing effects : an analogy with glasses 2022 Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 102:4, s. 299-320 Tidskriftsartikel (refereegranskat)abstract Properties of a crystal are used to determine the point defects concentration, n, the self diffusion coefficient, D and variation of n and D with tempertaure, T. Also, spontaneous change in the properties of a crystal’s non-equilibrium state is used to determine the decrease in n with time. Both n and D decrease with increase in the pressure, P, until the pressurising-rate dependent, kinetic-freezing pressure for defects disorder, PD-F, is reached. At P > PD-F, a crystal is in a non-equilibrium state. We consider such configurationally-frozen states of a crystal produced by using three unusual P-T protocols: (i) pressurising a crystal to P > PD-F, cooling to a low T and depressurising, (ii) pressurising to P < PD-F, cooling through the defects freezing temperature, TD-F, and depressurising, and (iii) cooling a crystal at 1 bar to T D-F pressurising and maintaining at high P. The non-equilibrium state of the crystal would have defect concentration that kinetically froze at P = PD-F or T = TD-F, but its volume and phonon properties would not correspond to the kinetically-frozen state at P = PD-F or at T = TD-F. On aging, their properties would change differently than those of a non-equilibrium state of a crystal produced by quenching at a fixed P. We relate n, D and the electrical resistivity to thermal conductivity, κ, by the Wiedemann-Franz equation, and discuss how κ would change on aging of a crystal. The above-given effects alter the properties of metallic and non-metallic, metastable materials during their commercial use.

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