Search

A novel mechanism of NiO electrochromic response is proposed, suggesting the tuning of the electronic structure upon reduction as responsible for color change.

High temperature properties of ceria surfaces are important for many applications. Here we report the temperature dependences of surface energy for the (111) and (110) CeO2 obtained in the framework of the extended two-stage upsampled thermodynamic integration using Langevin dynamics (TU-TILD). The method was used together with machinelearning potentials called moment tensor potentials (MTPs), which were fitted to the results of the ab initio MD calculations for (111) and (110) CeO2 at different temperatures. The parameters of MTPs training and fitting were tested and the optimal algorithm for the ceria systems was proposed. We found that the temperature increases from 0 K to 2100 K led to the decrease of the Helmholtz free energy of (111) CeO2 from 0.78 J/m2 to 0.64 J/m2. The energy of (110) CeO2 dropped from 1.19 J/m2 at 0 K to 0.92 J/m2 at 1800 K. We show that it is important to take anharmonicity into account as simple consideration of volume expansion gives wrong temperature dependences of the surface energies., 8 pages, 4 figures

Generation and diffusion of innovation are two distinct processes that are interlinked in several ways. First, innovation efforts of firms are stimulated by the diffusion of innovation ideas. Secon ...

Using the Exact Muffin-Tin Orbitals method within the Perdew-Burke-Ernzerhof exchange-correlation approximation for solids and solid surfaces (PBEsol), we study the single crystal elastic constants of 4d transition metals (atomic number Z between 39 and 47) and their binary alloys in the body centered cubic (bcc) and face centered cubic (fcc) structures. Alloys between the first neighbors Z(Z + 1) and between the second neighbors Z(Z + 2) are considered. The lattice constants, bulk moduli and elastic constants are found in good agreement with the available experimental and theoretical data. It is shown that the correlation between the relative tetragonal shear elastic constant C′fcc-2C′bcc and the structural energy difference between the fcc and bcc lattices Δ E is superior to the previously considered models. For a given crystal structure, the equiatomic Z(Z + 2) alloys turn out to have similar structural and elastic properties as the pure elements with atomic number (Z + 1). Furthermore, alloys with composition Z1−x(Z + 2)x possess similar properties as Z1−2x(Z + 1)2x. The present theoretical data on the structural and the elastic properties of 4d transition metal alloys provides consistent input for coarse scale modeling of material properties.

Due to its unique physical and chemical properties, graphene is being considered as a promising material for energy conversion and storage applications. Introduction of functional groups and dopant ...

Production theory has remained substantially unchanged since the publication of the theory of production by Frisch (Theory of production, D. Reidel, Dordrecht, 1928; Nord 613 Tidskr Tek Okon 1:12–27, 1935). The theory is based on the idea of a firm deciding on the possible input and output combinations of a single unit of production. His theory was substantially copied in contributions by Carlson (A study on the pure theory of production, University of Chicago, Chicago, 1939) and Schneider (Einfuhrung in die Wirtschaftstheorie. 4 Bande, Mohr, Tubingen, 1947), and later by practically all textbooks in microeconomics. The idea is to model the firm as a “black box” in which a finite number of externally purchased inputs are transformed into a finite number of outputs to be sold in the market(s). Most of the time, the prices are externally determined. Often, the production process is summarized by some simplified production function as, for example, in the form of a CES function. Another and conceptually richer approach is the formulation of an activity analysis model. In the latter case, simple internal interdependencies can be included. In this paper, we indicate how internal interdependencies can also be modeled within a special CES framework. In recent decades, there has been a remarkable growth in the number of production units of firms such as IKEA, Walmart and Apple to name a few such global networking firms. Most of the analysis of these network firms has been modeled by logistics and other operations-research analysts (Simchi-Levi et al. 2008) and to a limited extent by researchers in business administration schools. Very little has been done in economics. We propose a modeling approach consistent with the microeconomic theory.

We investigated surface properties of metals by performing first-principles calculations. A systematic database was established for the surface relaxation, surface energy (γ), and surface stress (τ) for metallic elements in the periodic table. The surfaces were modeled by multi-layered slab structures along the direction of low-index surfaces. The surface energy γ of simple metals decreases as the atomic number increases in a given group, while the surface stress τ has its minimum in the middle. The transition metal series show parabolic trends for both γ and τ with a dip in the middle. The dip occurs at half-band filling due to a long-range Friedel oscillation of the surface charge density, which induces a strong stability to the Peierls-like transition. In addition, due to magnetic effects, the dips in the 3d metal series are shallower and deeper for γ and τ, respectively, than those of the 4d and 5d metals. The surface stress of the transition metals is typically positive, only Cr and Mn have a negative τ for the (100) surface facet, indicating that they are under compression. The light actinides have an increasing γ trend according to the atomic number. The present work provides a useful and consistent database for the theoretical modelling of surface phenomena.

New electrode materials for alkaline-ion batteries are a timely topic. Among many promising candidates, V2O5 is one of the most interesting cathode materials. While having very high theoretical capacity, in practice, its performance is hindered by low stability and poor conductivity. As regards theoretical descriptions of V2O5, common DFT-GGA calculations fail to reproduce both the electronic and crystal structure. While the band gap is underestimated, the interlayer spacing is overestimated as weak dispersion interactions are not properly described within GGA. Here we show that the combination of the DFT+U method and semi-empirical D2 correction can compensate for the drawbacks of the GGA approximation when it comes to the modelling of V2O5. When compared to common PBE calculations, with a modest increase of the computational cost, PBE+U+D2 fully reproduced the experimental band gap of V2O5, while the errors in the lattice parameters are only a few percent. Using the proposed PBE+U+D2 methodology we studied V2O5 doped with 3d elements (from Sc to Zn). We show that both the structural and electronic parameters are affected by doping. Most importantly, a significant increase of conductivity is expected upon doping, which is of great importance for the application of V2O5 in metal-ion batteries., 20 pages, 8 figures, 2 tables, 56 references, Supplementary Information included, submitted to Physical Chemistry Chemical Physics

Development of novel materials may often require a rational use of high price components, like noble metals, in combination with the possibility to tune their properties in a desirable way. Here we present a theoretical DFT study of Au and Pd single atoms supported by doped MgO(001). By introducing B, C and N impurities into the MgO(001) surface, the interaction between the surface and the supported metal adatoms can be adjusted. Impurity atoms act as strong binding sites for Au and Pd adatoms and can help to produce highly dispersed metal particles. The reactivity of metal atoms supported by doped MgO(001), as probed by CO, is altered compared to their counterparts on pristine MgO(001). We find that Pd atoms on doped MgO(001) are less reactive than on perfect MgO(001). In contrast, Au adatoms bind CO much stronger when placed on doped MgO(001). In the case of Au on N-doped MgO(001) we find that charge redistribution between the metal atom and impurity takes place even when not in direct contact, which enhances the interaction of Au with CO. The presented results suggest possible ways for optimizing the reactivity of oxide supported metal catalysts through impurity engineering., 26 pages, 8 figures, 4 tables, 65 references, submitted to Physical Chemistry Chemical Physics

Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation − an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.

We have developed an improved Finnis-Sinclair (IFS) potential for vanadium-rich V–Ti–Cr random alloys with body-centred cubic structure. An extra exponential term is added to the original FS potential to enhance the repulsive interaction. The IFS potential is fitted to experimental crystal structure, cohesive energy and elastic constants of pure metals (V, Ti and Cr) and theoretical data of binary alloys (V 15 Ti, V 15 Cr and Ti 8 Cr 8 ). The good agreement of the predicted formation energies of mono-vacancy and self-interstitial of octahedral interstitial site, tetrahedral interstitial site, -dumbbell, -dumbbell, and -dumbbell with available experimental and theoretical data confirms the validity of our IFS potential in pure V. Furthermore, the agreement of elastic properties and defect properties of typical alloy (V–4Ti–4Cr) with experimental or DFT data also support the applicability of the IFS potential in V-rich ternary V–Ti–Cr alloys. Finally, this work also provides a reference to develop empirical potentials for other ternary alloys.

Introduction - interdependencies of spatial development, Ake E. Andersson, William P. Anderson, Borje Johansson disappearing distance in city systems, Makoto Okumura, Kiyoshi Kobayashi spatial equilibrium with cities and rural areas, Wei-Bin Zhang hierarchical fields of influence of spatial exchange, Michael Sonis, Geoffrey J.D. Hewings, Nuzal Achjar estimating sources of regional manufacturing productivity using shift-share extensions, Kingsley E. Haynes, Mustafa Dinc, Jean H.P. Paelinck "place" as "network" - applications of network theory to local communities, Roger E. Bolton the spatial structure of the city - a North American perspective on trends, prospects and research directions, William P. Anderson behavioural adaptations to traffic congestion, Robert E. Skinner, Jr a simultaneous model of long-term regional job and population changes, Ingvar Holmberg, Borje Johansson, Ulf Stromquist economic development and health patterns, David E. Andersson growth and development policy under economic globalization, Ake E. Andersson on the processes generating impacts from transportation improvements - the impacts of air transportation on recreation tourism, William L. Garrison, David Gillen, Christopher R. Williges transportation and energy policy - retrospect and prospect, David L. Greene plan evaluation methodologies - some aspects of decision requirements and analytical response, Wilbur A. Steger, T.R. Lakshmanan.

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 en ...

This chapter examines in which ways social and economic networks can be a part of social capital, and to what extent social capital can be understood as a resource for organizing economic networks. It is recognized that social capital is a spatial public good with geographic extension. This suggests that social capital is intangible and benefits certain groups of actors who are associated with spatial areas for which the social capital is present. The extension of social capital can be identified on a scale ranging from community culture to system-wide institutions. A major part of the analysis focuses on how economic and social networks differ in nature and motivation, observing that economic links often lack a public-good nature, for example by excluding competitors. There is also a comparison between the concepts of social capital and social infrastructure. The analysis suggests that future research should consider the following three areas: (1) social and societal capital; (2) exclusion, interaction and sharing; and (3) accessibility and agglomeration economies.

This paper introduces a model framework which identifies the economic activity of each local economy (location) and observes the time distance between each pair of locations. Time distance for interaction inside local economies is taken as reference. Two models of location patterns are formulated on the basis of principles adhering to new economic geography (NEG). The first model describes how business service firms (classified into three levels of knowledge intensity) select locations with a favorable demand potential, depicting a location’s access to customer demand. The second model takes the location of business-service supply as given and describes how other firms select locations with a favorable supply potential, depicting the access to business-service supply. In order to calculate each location’s demand and supply potentials we need distance-decay parameters for interaction outside the local economy. When estimating the two models we develop an approach where the distance-decay (time sensitivity) parameters are determined endogenously as an integral part of estimating location choice parameters. The exercise can be appreciated as a test of NEG principles.

Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates.

A density-functional theory investigation of the (100) and (110) surfaces of the body-centered cubic (bcc) Fe1-xbCrxb binary alloys, x(b)

For carbon-based materials, in contrast to metal surfaces, the relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to +/-5%) on the structure, electronic properties and the reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodium-ion battery electrodes are discussed., Comment: Manuscript: 22 pages, 11 figures; supplementary information: 1 page, 1 figure and 1 table

In 2017, we discovered quaternary i-MAX phases atomically layered solids, where M is an early transition metal, A is an A group element, and X is C-with a ((M2/3M1/32)-M-1)(2)AC chemistry, where the M-1 and M-2 atoms are in-plane ordered. Herein, we report the discovery of a class of magnetic i-MAX phases in which bilayers of a quasi-2D magnetic frustrated triangular lattice overlay a Mo honeycomb arrangement and an Al Kagome lattice. The chemistry of this family is (Mo2/3RE1/3)(2)AlC, and the rare-earth, RE, elements are Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. The magnetic properties were characterized and found to display a plethora of ground states, resulting from an interplay of competing magnetic interactions in the presence of magnetocrystalline anisotropy. Funding Agencies|Knut and Alice Wallenberg (KAW) Foundation [KAW 2015.0043]; Swedish Research Council [642-2013-8020, 2015-00607, 621-2014-4890]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; DFG [SA 3095/2-1]; IAEC Pazy Foundation Grant; NSF [DMR-1740795]

This paper focuses on the concept of knowledge and examines models depicting and explaining the role of knowledge in regional development and provides an assessment of empirical studies of how knowledge affects growth and development in functional regions. For this paper it is crucial to understand those factors that make knowledge spatially sticky and knowledge-production capacity trapped. It is equally important to explain the conditions for knowledge flows and diffusion. The presentation also widens the view by extending the analysis of knowledge creation to include aspects of creativity. Since location advantages and especially the knowledge-based advantages have the feature of moving in slowly path-dependent processes the regional policy needs to focus on structural adjustments of tangible and non-tangible infrastructure to succeed.

We investigate the generalized stacking fault energy ( [GRAPHICS] -surface) of paramagnetic [GRAPHICS] -Fe as a function of temperature. At static condition, the face-centred cubic (fcc) lattice is thermodynamically unstable with respect to the hexagonal close-packed lattice, resulting in a negative intrinsic stacking fault energy (ISF). However, the unstable stacking fault energy (USF), representing the energy barrier along the [GRAPHICS] -surface connecting the ideal fcc and the intrinsic stacking fault positions, is large and positive. The ISF is calculated to have a strong positive temperature coefficient, while the USF decreases monotonously with temperature. According to the recent plasticity theory, the overall effect of temperature is to move paramagnetic fcc Fe from the stacking fault formation regime ( [GRAPHICS] K) towards maximum twinning ( [GRAPHICS] K) and finally to a dominating full-slip regime ( [GRAPHICS] K). Our predictions are discussed in connection with the available experimental observations.

Oxide materials offer a wide range of interesting physical and chemical properties. Even more versatile behavior of oxides is seen at the nanoscale, qualifying these materials for a number of applications. In this study we used DFT calculations to investigate the physical and chemical properties of small hexagonal MgO nanotubes of different length. We analyzed the effect of Li, B, C, N, and F doping on the properties of the nanotubes. We find that all dopants favor the edge positions when, incorporated into the nanotubes. Doping results in the net magnetization whose value depends on the type of the impurity. Using the CO molecule as a probe, we studied the adsorption properties of pristine and doped MgO nanotubes. Our results show that the dopant sites are also the centers of significantly altered chemical reactivity. While pristine MgO nanotubes adsorb CO weakly, very strong adsorption at the dopant sites (B-, C-, and N-doped nanotubes) or neighboring edge atoms (F- and Li-doped nanotubes) is observed. Our results suggest that impurity engineering in oxide materials can be a promising strategy for the development of novel materials with possible use as selective adsorbents or catalysts., 23 pages, 8 figures, 3 tables, 45 references, included Supplementary Information (8 pages, 2 figures, 12 tables); submitted to Applied Surface Science

Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation of carbon materials in advanced technologies. We report the results of a systematic DFT study of atomic adsorption on graphene with a single vacancy for the elements of rows 1 to 6 of the Periodic Table of Elements (PTE), excluding lanthanides. The calculations have been performed using PBE, long-range dispersion interaction-corrected PBE (PBE+D2 and PBE+D3) and non-local vdW-DF2 functional. We find that most elements strongly bind to the vacancy, except for the elements of groups 11 and 12, and noble gases, for which the contribution of dispersion interaction to bonding is most significant. The strength of the interaction with the vacancy correlates with the cohesive energy of the elements in their stable phases: the higher the cohesive energy is the stronger bonding to the vacancy can be expected. As most atoms can be trapped at the SV site we have calculated the potentials of dissolution and found that in most cases the metals adsorbed at the vacancy are more "noble" than they are in their corresponding stable phases., Comment: 22 pages, 10 figures, Supplementary Information included, Submitted to Physical Chemistry Chemical Physics

The understanding of atomic adsorption on graphene is of high importance for many advanced technologies. Here we present a complete database of the atomic adsorption energies for the elements of the Periodic Table up to the atomic number 86 (excluding lanthanides) on pristine graphene. The energies have been calculated using the projector augmented wave (PAW) method with PBE, long-range dispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local vdW-DF2 approach. The inclusion of dispersion interactions leads to an exothermic adsorption for all the investigated elements. Dispersion interactions are found to be of particular importance for the adsorption of low atomic weight earth alkaline metals, coinage and s-metals (11th and 12th groups), high atomic weight p-elements and noble gases. We discuss the observed adsorption trends along the groups and rows of the Periodic Table as well some computational aspects of modelling atomic adsorption on graphene., 27 pages, 7 figures, submitted to Applied Surface Science

In this paper we analyze how firms’ knowledge absorption capacity – given the knowledge environment – affects the development, adoption and introduction of new export products among Swedish manufacturing firms. Our model formulation builds on theoretical arguments which imply that firms can influence the usefulness of their knowledge environment by establishing formal and informal networks with input suppliers (especially suppliers of knowledge-intensive business services) and by exploiting their absorptive capacity. The model suggests that the higher the knowledge absorption in firms, the higher the introduction frequency of new export products. In particular, it is the conjunction of a high absorptive capacity and a high external knowledge potential that makes certain firms successful introducers of new export products.

This introduction to the special issue of EINT surveys a collection of eight papers that study innovation and productivity at the firm level and the industry level for a number of European countrie ...

We examine the combined effect of exports, innovation and external knowledge on total factor productivity growth among manufacturing firms. This paper distinguishes between frequent and temporary exporters as well as between frequent and temporary innovators. Applying a dynamic approach on an unbalanced panel consisting of 8516 Swedish firms observed over a 12-year period, the results show that among firms with permanent presence in export markets, persistent innovators have 0.5% point higher annual productivity growth than non-innovative exporters and 0.4% higher growth compared to firms that switch between being innovative or not. A similar pattern is found for the group of companies that alternates between exporting and non-exporting; however, the differences in growth rates are not statistically significant. We also show that only persistently innovative exporters and exporters with a large fraction of exports in their sales benefit from their presence in the local milieu with high knowledge intensity.

Iron-chromium is the base material for most of the stainless steel grades. Recently, new insights into the origins of fundamental physical and chemical characteristics of Fe-Cr based alloys have be ...

The activation of plastic deformation mechanisms determines the mechanical behavior of crystalline materials. However, the complexity of plastic deformation and the lack of a unified theory of plasticity have seriously limited the exploration of the full capacity of metals. Current efforts to design high-strength structural materials in terms of stacking fault energy have not significantly reduced the laborious trial and error works on basic deformation properties. To remedy this situation, here we put forward a comprehensive and transparent theory for plastic deformation of face-centered cubic metals. This is based on a microscopic analysis that, without ambiguity, reveals the various deformation phenomena and elucidates the physical fundaments of the currently used phenomenological correlations. We identify an easily accessible single parameter derived from the intrinsic energy barriers, which fully specifies the potential diversity of metals. Based entirely on this parameter, a simple deformation mode diagram is shown to delineate a series of convenient design criteria, which clarifies a wide area of material functionality by texture control.

This paper explores the capacity to produce new knowledge proxied by patents granted in 18 industries in 11 European economies. For each industry in each country, the number of granted U.S. Patent and Trademark Office patents is recorded over the 1991–2005 period. Controlling for research and development, industry composition, and institutional setting, the paper shows that systematic differences in patent intensity exist between the studied countries, such that almost all industries are affected by country-specific conditions, suggesting that the countries’ innovation systems differ in efficiency. The countries with the highest R&D efficiency are Sweden and Finland, followed by the Netherlands and Germany.

Firms in local industries maintain their capability to generate new export varieties by simultaneously exploiting internal and external knowledge resources. The paper introduces the notion ‘variety triplet’ to distinguish individual export varieties, where a triplet is a unique combination of a firm, a product code and a destination country. For each date, the set of variety triplets in each local industry records all remaining export varieties introduced in the past. In view of this, the paper examines how internal and external knowledge of local industries influence the industry's scope and value of export varieties. First, the paper contributes by considering a local industry's internal and external knowledge, as well as the conjunction of its internal and external knowledge sources. Second, the knowledge sources are shown to influence both the stock and the dynamics of a local industry's variety triplets, using firm-level data from Sweden.

Reduced activation ferritic/martensitic (RAFM) steels are considered as the primary candidate for the blanket module in International Thermonuclear Experimental Reactor (ITER), and the basic composition of RAFM steels is Fe–Cr–W alloy. Using the exact muffin-tin orbitals method (EMTO) combined with coherent potential approximation (CPA), we investigated composition dependence of elastic properties for Fe–Cr–W random alloys in the composition range of 7.8–10.0 wt.% of Cr and 1.0–2.0 wt.% of W. Bulk modulus, shear modulus, Young’s modulus, B/G ratio, and Poisson ratio are discussed as functions of ternary composition. The elastic moduli of Fe–Cr–W alloys increase with chromium content in the studied range of alloy compositions, the effect of tungsten is slight.

Temperature dependence of intrinsic stacking-fault energies (SFE) and anti-phase boundary energies (APBE) of Al Sc is investigated in first-principles calculations using the axial Ising model and supercell approach. The temperature effect has been taken into consideration by including the one-electron thermal excitations in the electronic structure calculations, and vibrational free energy in the harmonic approximation as well as by using temperature dependent lattice constant. The latter has been determined within the Debye–Gruneisen model, which reproduces well the experimental data. The APBE and SFE are found to be reduced by about 10% in the temperature interval from 0 to 1000 K. It is shown that the inclusion of the free energy of lattice vibrations in the harmonic approximation increases the SFE further by about 4%. We also find a substantial contribution from local lattice relaxations in the case of APBE for the (1 1 1) plane and SFE leading to their reduction by about 30%.

This paper explores three under-researched questions in the literature on multinational enterprises (MNEs), clustering, and innovation. First, to what extent does multinationality lead to higher rates of innovation activity and performance? Second, what, if any, is the link between MNE cluster location and innovation inputs and outputs? Third, are there any significant differences between enterprises belonging to domestic and overseas MNEs in these regards? Evidence is based primarily on 11,775 firms derived from the UK Community Innovation Survey 2007. Diversity in the regional economy exerts the most consistent positive influence, followed by the scale of employment in the enterprise’s own industry. Enterprises belonging to domestic MNEs appear to exert higher levels of innovation effort. However, evidence regarding their superiority in innovation outputs was weaker. Contrary to Michael Porter’s work, it appears that enterprises belonging to overseas firms benefit more than domestic firms.

Aluminum addition to ferritic stainless steels was found to effectively suppress the deleterious 475 degrees C embrittlement resulting from the phase decomposition in concentrated Fe-Cr alloys. Wit ...

We systematically investigate elastic anharmonic behavior in ferromagnetic body-centered cubic (bcc) Fe and ${\mathrm{Fe}}_{1\ensuremath{-}x}{M}_{x}$ ($M=\mathrm{Al}$, V, Cr, Co, or Ni) random alloys by means of density-functional simulations. To benchmark computational accuracy, three ab initio codes are used to obtain the complete set of second- and third-order elastic constants (TOECs) for bcc Fe. The TOECs of ${\mathrm{Fe}}_{1\ensuremath{-}x}{M}_{x}$ alloys are studied employing the first-principles alloy theory formulated within the exact muffin-tin orbital method in combination with the coherent-potential approximation. It is found that the alloying effects on ${C}_{111},\phantom{\rule{0.28em}{0ex}}{C}_{112}$, and ${C}_{123}$, which are governed by normal strains only, are more pronounced than those on ${C}_{144},\phantom{\rule{0.28em}{0ex}}{C}_{166}$, and ${C}_{456}$, which involve shear strains. Remarkably, the magnitudes of all TOECs but ${C}_{123}$ decrease upon alloying with Al, V, Cr, Co, or Ni. Using the computed TOECs, we study compositional effects on the pressure derivatives of the effective elastic constants ($d{B}_{ij}/dP$), bulk ($dK/dP$), and shear moduli ($dG/dP$) and derive longitudinal acoustic nonlinearity parameters ($\ensuremath{\beta}$). Our predictions show that the pressure derivatives of $K$ and $G$ decrease with $x$ for all solute elements and reveal a strong correlation between the compositional trends on $dK/dP$ and $dG/dP$ arising from the fact that alloying predominantly alters $d{B}_{11}/dP$. The sensitivity of $d{B}_{11}/dP$ to composition is attributed to intrinsic alloying effects as opposed to lattice parameter changes accompanying solute addition. For Fe and the considered Fe-based alloys, $\ensuremath{\beta}$ along high-symmetry directions orders as $\ensuremath{\beta}[111]g\ensuremath{\beta}[100]g\ensuremath{\beta}[110]$, and alloying increases the directional anisotropy of $\ensuremath{\beta}$ but reduces its magnitude.

The composition-dependent crystal structure, volume, elastic constants, and electronic structure of $\ensuremath{\delta}\text{\ensuremath{-}}{\mathrm{Pu}}_{1\ensuremath{-}x}{M}_{x}$ $(M=\text{Ga and Al},0\ensuremath{\le}x\ensuremath{\le}0.1)$ alloys are systematically studied by using first-principles EMTO-CPA calculations. It is shown that the fcc and $L{1}_{2}$ structures co-exist in the alloys with $x\ensuremath{\le}0.04$ whereas for $xg0.04$, the $L{1}_{2}$ structure is more and more preferable and around $x=0.1$, it tends to be stabilized alone. The evaluated $V\ensuremath{\sim}x$ of the $L{1}_{2}$ structure, being negative deviation from Vegard's law, turns out to be in good agreement with the experimental result. For $x\ensuremath{\le}0.04$, the estimated $E$, $G$, $\ensuremath{\nu}$, and $\mathrm{\ensuremath{\Theta}}$ of both the fcc and $L{1}_{2}$ structures are in line with the measured data, whereas when $xg0.04$, only those of the $L{1}_{2}$ structure are close to the experimental results. The electronic hybridization between Pu and $M$ atoms is dominated by Pu for the $s,d$, and $f$ states but $M$ for the $p$ state. The strong interactions between Pu and $M$ atoms in the same site of the $L{1}_{2}$ structure should be responsible for its relative stability in the alloys with $xg0.04$. The electron-phonon coupling further decreases the phase stability of $\ensuremath{\delta}\text{\ensuremath{-}}{\mathrm{Pu}}_{1\ensuremath{-}x}{M}_{x}$ with increasing $x$.

The strained Fe-Co alloy in body-centered tetragonal (bct) structure has raised considerable interest due to its giant uniaxial magnetocrystalline anisotropy energy. On the basis of the classical H ...

This study addresses an important neglected question: To what extent do geographic clusters promote outward foreign direct investment (ODI)? We find evidence that clusters do promote ODI and so support Porter’s argument that advantages gained in clusters can be the foundations of successful internationalisation. Digging deeper, we find that certain cluster incumbents promote more ODI than others, with more experienced firms and firms with stronger resource bases accounting for more ODI. We also find that firms located in clusters within major global nodes/cities engage in more ODI. Finally, we find that both localisation and urbanisation economies promote ODI. However, the former, within-industry effects, are more important. Overall, this study echoes Dunning’s call for more focus on the ‘L’ component of the OLI paradigm and particularly on the advantages that reside in clusters that make them not only attractive destinations for FDI but also fertile environments from which FDI can spring.

Materials with excellent mechanical properties, such as light mass combined with remarkable hardness and toughness, are technologically important not least for automotive and other transport applications. Solid solution strengthening, due to dislocation pinning by impurities, is an effective route to enhance the intrinsic hardness of alloys. In the present work, we use advanced quantum theory to reveal the mechanical characteristics of iron alloys within and beyond their thermodynamic stability fields. Among the considered alloying elements, magnesium strongly reduces the density of the host alloys and significantly enhances the hardness. Our findings suggest that stainless steel grades containing a few percent of magnesium are promising engineering materials for high-strength and light-weight designs.

Vacancy–solute interactions play a crucial role in diffusion-controlled processes, such as ordering or decomposition, which occur in alloys under heat treatment or under irradiation. Detailed knowledge of these interactions is important for predicting long-term behavior of nuclear materials (such as reactor steels and nuclear-waste containers) as well as for advancing our general understanding of kinetic processes in alloys. Using first-principles calculations based on the density functional theory and employing the locally self-consistent Green’s function technique, we develop a database of vacancy–solute interactions in dilute alloys of bcc Fe with 3p (Al, Si, P, S), 3d (Sc–Cu), and 4d (Y–Ag) elements. Unrelaxed interactions within the first three coordination shells have been computed in the ferromagnetic state as well as in the paramagnetic (disordered local moment) state of the iron matrix. Magnetism is found to have a strong effect on the vacancy–solute interactions. Implications of the obtained results for interpreting the effects of vacancy trapping and enhanced impurity diffusion are discussed.

In this paper, the five-layer modulated (5M) martensitic structures of Ni(2)Mn(Al(x)Ga(1-x)), with x = 0, 0.1 and 0.2, are investigated by the use of the exact muffin-tin orbital method in combination with the coherent potential approximation. The 5M martensite is modeled by varying c/a (shear) and wave-like displacements of the atoms on (1 1 0) plane (shuffle) scaled by eta according to Martynov and Kokorin (J. Phys. III 2, 739 (1992)). For Ni(2)MnGa, we obtain 5M martensite with equilibrium c/a of 0.92 and eta of 0.08, in reasonable agreement with the experiment results (0.94 and 0.06, respectively). c/a and eta are linearly coupled to each other. Al-doping increases c/a and decreases eta, but the linear c/a similar to eta coupling remains. Comparing the total energies of the 5M martensite and L2(1) austenite, we find that the martensite is more stable than the austenite. Al-doping increases the relative stability of the austenite and finally becomes energetically degenerated with the 5M martensite at an Al atomic fraction (x) of about 0.26. The relative phase stability is analyzed based on the calculated density of states. The calculated total magnetic moments mu(0) as a function of c/a exhibit a maximum around the equilibrium c/a. Al-doping reduces mu(0) (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

By means of ab-initio calculations, we perform an analysis of the configurational thermodynamics, effects of disorder, and structural energy differences in Fe-Ni alloys at the pressure and temperature conditions of the Earths core. We show from ab-initio calculations that the ordering energies of fcc and hcp-structured Fe-Ni solid solutions at these conditions depend sensitively on the alloy configuration, i.e., on the degree of chemical disorder, and are on a scale comparable with the structural energy differences. From configurational thermodynamic simulations we find that a distribution of Fe and Ni atoms in the solutions should be very close to completely disordered at these conditions. Using this model of the Fe-Ni system, we have calculated the fcc-hcp structural free energy difference in a wide pressure-temperature range of 120-360 GPa and 1000-6600K. Our calculations show that alloying of Fe with Ni below 3000 K favours stabilisation of the fcc phase over the hcp, in agreement with experiments. However, above 3000 K the effect is reversed, and at conditions corresponding to those of the Earths inner core, Ni acts as an agent to stabilise the hcp phase. Original Publication: Marcus Ekholm, Arkady Mikhaylushkin, Sergey Simak, B Johansson and Igor Abrikosov, Configurational thermodynamics of Fe-Ni alloys at Earths core conditions, 2011, Earth and Planetary Science Letters, (308), 1-2, 90-96. http://dx.doi.org/10.1016/j.epsl.2011.05.035 Copyright: Elsevier http://www.elsevier.com/

V-(4-5) wt.% Cr-(4-5) wt.% Ti alloys are important candidate structural materials for the first-wall and blanket in future fusion reactor. Thus it is necessary to study the fundamental mechanical properties and the irradiation effects of the V-based alloys. Within a random solid solution model, the elastic constants and ideal strength of the V-4Cr-4Ti and the V-5Cr-5Ti alloys were calculated and compared with those of pure V solid. According to the theoretical Cauchy pressure and the ratio of bulk modulus and shear modulus, both alloys exhibit good ductility. Within the 250-atom supercell, inclusion of one vacancy defect or one interstitial H (He) atom will further enhance the ductility of these alloys.