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We investigate how the magnetic state influences the interaction of Cr substitutional impurities with ½⟨111⟩ screw dislocations in bcc Fe via density functional theory (DFT). We compare the paramagnetic state, modeled with a non-collinear disordered local moment (DLM) model, with the ferromagnetic state. In a previous work [Casillas-Trujillo et al., Phys. Rev. B 102, 094420 (2020)], we have shown that the magnetic moment and atomic volume landscape around screw dislocations in the paramagnetic state of iron are substantially different from that in the ferromagnetic state. Such a difference can have an impact in the formation energies of substitutional impurities, in particular, magnetic solutes. We investigate the formation energies of Cr solutes as a function of position with respect to the screw dislocation core, the interaction of Cr atoms along the dislocation line, and the segregation profile of Cr with respect to the dislocation in paramagnetic and ferromagnetic bcc iron. Our results suggest that with increasing temperature and connected entropic effects, Cr atoms gradually increase their occupation of dislocation sites, close to twice the amount of Cr in the DLM case than in the ferromagnetic case, with possible relevance to understand mechanical properties at elevated temperatures in low-Cr ferritic steels in use as structural materials in nuclear energy applications. [ABSTRACT FROM AUTHOR]

10.1063/5.0085292 85 R. Knepper, S. Rupper, S. DeJong, M. P. Marquez, D. E. Kittell, R. L. Schmitt, and A. S. Tappan, "Investigating growth to detonation in vapor-deposited hexanitrostilbene and pentaerythritol tetranitrate films using high-throughput methods", J. Appl. Phys. Such investigations can be applied to a wide range of materials such as pure metals,[[23], [25], [27]] steels,[29] other metallic alloys[[15], [30], [32]] including additively manufactured alloys,[[34]] ceramics,[36] polymers,[37] energetic materials,[38] or nanoporous materials.[[39]] B. Equation of state and phase transitions under shock compression I In situ i x-ray diffraction (XRD) has been used to investigate the occurrence and nature of phase transitions upon shock compression at large laser facilities, synchrotron, and x-ray free electron lasers. 10.1063/5.0076869 52 P. E. Specht, W. Reinhart, and C. Scott Alexander, "Measurement of the Hugoniot and shock-induced phase transition stress in wrought 17-4 PH H1025 stainless steel", J. Appl. Phys. R. Armstrong, H. B. Radousky, R. A. Austin, O. Tschauner, S. Brown, A. E. Gleason, N. Goldman, E. Granados, P. Grivickas, N. Holtgrewe, M. P. Kroonblawd, H. J. Lee, S. Lobanov, B. Nagler, I. Nam, V. Prakapenka, C. Prescher, E. J. Reed, E. Stavrou, P. Walter, A. F. Goncharov, and J. L. Belof, "Highly ordered graphite (HOPG) to hexagonal diamond (lonsdaleite) phase transition observed on picosecond time scales using ultrafast x-ray diffraction", J. Appl. Phys. [Extracted from the article]

This paper is devoted to an experimental and 3D atomistic study of the influence of loading rate on fracture toughness in dilute Fe–Si alloys and in bcc iron. We analyze new and previous experimental results from fracture tests performed at room temperature on bcc iron–silicon single crystals with edge cracks (1 ¯ 10) [110] (crack plane/crack front). The specimens of single edge notch-type were loaded in tension mode I under different loading rates. The ductile–brittle behavior at the crack front was monitored online via optical microscopy together with external force and prolongation of the specimens. About 30% decrease in fracture toughness was monitored in the new experiment under the highest loading rate. The nanoscopic processes produced by the crack itself were studied at room temperature via 3D molecular dynamics (MD) simulations in bcc iron under equivalent boundary conditions as in experiments to reveal (explain) the sensitivity of the crack to loading rate. For this purpose, this MD study utilizes the self-similar character of linear fracture mechanics. The results show that the emission of blunting dislocations from the crack is the most difficult under the highest loading rate, which leads to the reduced fracture toughness of the atomistic sample. This is in a qualitative agreement with the experimental (macro) results. Moreover, MD indicates that there may be some synergetic (resonant) effect between the loading rate and thermal activation that promotes dislocation emission. [ABSTRACT FROM AUTHOR]

In this work, in order to develop new Fe-based amorphous alloys with room-temperature magnetocaloric effect and good magnetocaloric performance, high iron content Fe-based amorphous alloys were designed, and their Curie temperatures were adjusted to room temperature through the addition of Mo. As a result, a new Fe83Mo6Si1B7P2C1 amorphous alloy with room-temperature magnetocaloric effect was successfully prepared by melt-spinning technique, and it has the Curie temperature of 300 K, the maximum isothermal magnetic entropy change of 2.74 J kg−1 K−1 and the refrigerant capacity of 485.2 J kg−1 under an applied magnetic field of 5 T. Combining with the advantages of excellent magnetocaloric properties, negligible hysteresis loss, and low material cost, the present Fe83Mo6Si1B7P2C1 amorphous alloy should be a promising candidate as room-temperature magnetic refrigerants. [ABSTRACT FROM AUTHOR]

The melting temperatures of Fe–Ni alloys and their densities in the liquid state at relevant pressure–temperature (P–T) conditions present in the core are of great importance for understanding the composition and thermal structure of the Earth's core. We measured shock temperatures of the Fe–11Ni–18Cr (wt. %) alloy up to ∼304 GPa using a special target configuration, a quasi-spectral pyrometer, and velocimeter diagnostics in a two-stage light-gas gun. The present results show that Fe–11Ni–18Cr starts to melt at the pressure of 210 (8) GPa and 4700 (300) K and completes at the pressure of 280 (10) GPa and 5250 (350) K under shock loading, which is ∼1000 K lower than some previous shock temperature measurements. The melting temperatures of the Fe–11Ni–18Cr alloy are 4100 (250) K and 5500 (450) K at the pressures present at the core-mantle boundary (∼136 GPa) and inner-core boundary (∼330 GPa), respectively, which are slightly lower than that of pure iron. Combined with the previous results of the pressure–density measurements at Hugoniot states, our results indicate that the presence of limited amounts of Ni and Cr into Fe has a minor effect on its melting curve and density in the liquid state, suggesting that sufficient light elements are required in the outer core to satisfy both the core density deficit and the reduced melting temperature. [ABSTRACT FROM AUTHOR]

Diamondlike carbon (DLC) coatings provide interesting properties for industrial applications. However, the low adhesion of DLC coatings on any type of ferrous alloy compromises technological applications. One possible solution to this issue is the application of adhesion interlayers. The aim of this study is to investigate the adhesion of DLC films on low-alloy steel through the use of silicon-containing interlayers at different deposition times using tetramethylsilane. The role of time on the physical-chemical, microstructural, and tribological properties of the material system was evaluated. The interlayer thickness linearly increased and greater contributions of silicon bonds were measured as a function of the interlayer deposition time. Nevertheless, longer deposition times increased the roughness and defect ratio in DLC coatings. Although good enough adhesion for decorative applications was acquired, no drastic variation in the average critical load (∼4.2 N) for delamination was observed at different deposition times for the samples that achieved adhesion. [ABSTRACT FROM AUTHOR]

Chemical pressure from the isovalent substitution of Se by a larger Te atom in the epitaxial film of iron chalcogenide FeSe can effectively tune its superconducting, topological, and magnetic properties. However, such substitution during epitaxial growth inherently leads to defects and structural inhomogeneity, making the determination of alloy composition and atomic sites for the substitutional Te atoms challenging. Here, we utilize machine learning to distinguish between Se and Te atoms in scanning tunneling microscopy images of single-layer FeSe1−xTex on SrTiO3(001) substrates. Defect locations are first identified by analyzing spatial-dependent dI/dV tunneling spectra using the K-means clustering method. After excluding the defect regions, the remaining dI/dV spectra are further analyzed using the singular value decomposition method to determine the Se/Te ratio. Our findings demonstrate an effective and reliable approach for determining alloy composition and atomic-scale electronic inhomogeneity in superconducting single-layer iron chalcogenide films. [ABSTRACT FROM AUTHOR]

An outstanding challenge in developing a complete equation of state for materials at elevated pressure and temperature is a robust method of determining the bulk temperature state under dynamic conditions. In metals, the determination of bulk temperature states by optical pyrometry is complicated by the small optical depth and thermal conduction effects. These effects lead to observed temperatures differing by 20% or more from the bulk temperature state. In this work, we show the presence of thermal conduction effects in temperature measurements of tin and iron coatings during dynamic compression experiments. We demonstrate that tin, in contrast to iron, coatings can fail to converge to a bulk temperature source over the time scale of the experiment, requiring the experimenter to modify assumptions, design, or analysis. This work bounds thermal transport at shocked conditions. [ABSTRACT FROM AUTHOR]

The Fe4+/3+ donor level is experimentally determined to be 0.70 eV (±0.05 eV) above the valence band maximum in β-Ga2O3. Electron paramagnetic resonance (EPR) is used to monitor Fe3+ ions that are unintentionally present in an Mg-doped β-Ga2O3 crystal (with a low Fermi level). For temperatures near 255 K, exposure to 325 nm laser light converts a portion of the Fe3+ ions to Fe4+ and Fe2+ ions and, at the same time, forms neutral magnesium acceptors (Mg Ga 0) and neutral Ir donors (Ir3+). After removing the light, the intensity of the Fe3+ EPR spectrum has a significant additional decrease as holes thermally released to the valence band from rapidly decaying neutral Mg acceptors are trapped at Fe3+ ions and form even more Fe4+ ions. This demonstrates that the Mg0/− acceptor level, near 0.65 eV, is closer to the valence band than the Fe4+/3+ level. Following the fast initial post-light decrease, the Fe3+ spectrum then slowly recovers as Fe4+ ions are destroyed by electrons thermally excited from the valence band. An activation energy for the thermal decay of the Fe4+ donors, and thus a value for the Fe4+/3+ level, is obtained from the analysis of five Fe3+ isothermal recovery curves taken from the Mg-doped crystal between 250 and 270 K. A first-order kinetics model is used, as minimal retrapping is observed. In separate experiments, EPR shows that Fe4+ ions are also produced in an Fe-doped β-Ga2O3 crystal (without Mg acceptors) during exposures to laser light at temperatures near 255 K. [ABSTRACT FROM AUTHOR]

To enhance the rate of argon–oxygen refining of ferroalloys, this article is based on the physical and chemical reactions of the smelting process as well as the actual smelting data. A mechanistic model of the rate of change of oxygen supply and carbon content in the smelting process and the temperature of the reaction fluid in the furnace is established. An expert internal model control framework with furnace temperature and carbon content as output and oxygen supply rate as input is constructed. An adaptive parameter adjustment mechanism is added to the control framework by combining data on the maximum gas supply rate and temperature threshold of the stage in the actual production process. The method improves smelting speed and smelting accuracy compared to the general method. It is also able to adjust the furnace temperature according to the actual smelting situation. The actual smelting was carried out according to this method, the improved method reduced the smelting time by 12.79% compared to the general method, and the furnace temperature was controlled below 1950 K. [ABSTRACT FROM AUTHOR]

Fe-Co alloys are promising materials for high power density motors, since they have higher Bs than Fe-Si steels which are most commonly used as the motor cores. It is known, however, that the Fe-Co alloys generally have poor workability due to an existence of the brittle phase, ordered B2. In this study, effects of Co content and Si/Al addition with the Fe-Co alloys on the workability and magnetic properties were investigated. The neutron diffraction measurements of the Fe-Co alloys with different Co contents of 5, 18, 27, and 49 mass% were first conducted to know the existence of the ordered B2 phase. The result showed that the B2 phase was observed in the Fe-Co alloys with Co contents of 27 and 49 mass%, while the alloys with 5 and 18 mass% did not contain it, which suggests the latter two alloys have the better workability. Then, we checked the effect of Si/Al addition on the magnetic properties of the 82Fe-18Co alloy, and found that the co-addition of Si/Al reduce the coercivity, Hc to about 60 A/m and iron loss to less than 170 W/kg while maintaining a high B value at 30 000 A/m above 2.2 T. [ABSTRACT FROM AUTHOR]

We report here a systematic study of the magnon-drag induced thermoelectric properties of Fe-rich, Fe-Co body-centered-cubic alloys. The sign of the low temperature behavior of thermopower is explained well by the hydrodynamic theory for magnon-drag, informed by density functional theory calculations of the ground state of Fe-Co alloys. The high-temperature thermopower of some of the alloys, and indeed that of elemental iron, changes the sign, as previously observed. We propose a mechanism to elucidate this hitherto unexplained observation. Further, the power factor of Fe72Co28 peaks around 35 μV/cm K2 at 500 K, comparable to the standard thermoelectric material Bi2Te3. Because of their high thermoelectric power factor, Fe-Co alloys are potential candidate thermoelectric metals for active cooling of electronic devices. [ABSTRACT FROM AUTHOR]

Hyperfine parameters of iron nuclei such as isomer shift, quadrupole splitting, and asymmetry parameter are calculated for β -FeSi 2 with and without vacancies, using density functional theory. They are applied, in combination with parameters of α -FeSi 2 obtained earlier, for analyzing Mössbauer and X-ray diffraction experiments on the mechanical alloying of silicon with iron in the range of 1–33 at. % of Fe. Such an approach allows more detailed and precise information to be obtained on the structure of Fe–Si samples. In particular, the fraction of vacancies in α - and β -FeSi 2 is estimated, and the mechanism of formation of these phases and their transformation into each other is discussed. A new model is developed for analyzing experiments on hyperfine interaction, such as Mössbauer spectroscopy, time-differential perturbed-angular correlation, and the like, for Fe–Si systems with a high Si content. [ABSTRACT FROM AUTHOR]

The interaction of plasticity and martensitic transformation in iron bicrystals under shock has been investigated via nonequilibrium molecular-dynamic simulations with our modified analytic embedded-atom model potential. Our results show that grain boundaries (GBs) can change the kinetics of α → ɛ martensitic transformations. The condition that GBs trigger strain induced transformation (SIT) is revealed, that is, the local structure of GBs can be converted to a hexagonal close packing (HCP) lattice with a lower potential barrier than the BCC → HCP transformation (stress assist transformation, SAT) because the driving energy of transition can be partly provided by the energy of GBs. It can explain why the threshold of the phase transition can be greatly reduced in samples containing some types of GBs. The threshold of SIT is lower than that of SAT, which agrees well with experimental results. Then, the nucleation kinetics of phase transition induced by dislocations are described. The propagation of dislocation provides the driving force for the nucleation of the phase transition. The dislocations can be directly emitted from the GBs under shock, which provides a new view that the phase transition is not always preceded by dislocations near GBs. In addition, dislocations can be induced by pre-existing dislocations under shock, which makes it understandable that GBs can emit dislocations. Our findings have an important significance for experimental studies and macroscopic and mesoscopic scale simulations regarding iron martensitic transformation. [ABSTRACT FROM AUTHOR]

From the Ising model and the Lennard-Jones fluid to water and the iron-carbon system, phase diagrams are an indispensable tool to understand phase equilibria. Despite the effort of the simulation community, the calculation of a large portion of a phase diagram using computer simulation is still today a significant challenge. Here, we propose a method to calculate phase diagrams involving liquid and solid phases by the reversible transformation of the liquid and the solid. To this end, we introduce an order parameter that breaks the rotational symmetry and we leverage our recently introduced method to sample the multithermal-multibaric ensemble. In this way, in a single molecular dynamics simulation, we are able to compute the liquid-solid coexistence line for entire regions of the temperature and pressure phase diagram. We apply our approach to the bcc-liquid phase diagram of sodium and the fcc-bcc-liquid phase diagram of aluminum. [ABSTRACT FROM AUTHOR]

The adsorption-based functionalities of porous metal-organic framework (MOF) materials that lead to applications such as catalysis and gas separation rely on specific host–guest interactions often involving the framework metal sites. These interactions are difficult to probe on the molecular level and consequently poorly understood. Conventional X-ray absorption spectroscopy (XAS) methods can provide molecular-level insights but, as the sole method of characterization, often lack the ligand sensitivity required to probe the relevant local metal coordination changes associated with MOF adsorption processes. Here, we investigate a series of trinuclear iron μ3-oxo-based MOFs under different metal-coordinating guest environments (water, pyridine, propylene, and guest-free) using a multipronged spectroscopy approach, including valence-to-core X-ray emission spectroscopy (vtc-XES) along with conventional XAS and vibrational spectroscopy, in an effort to characterize their local metal site coordination environments, including ligand identity. Closely related iron μ3-oxo reference complexes with known coordination are characterized as well for comparison to evaluate the ligand diagnostic nature of the combined spectroscopy approach. Density functional theory calculations aid the vtc-XES band assignments and provide insights into the molecular orbital parentage of the vtc transitions. This series of MOFs and complexes illustrates the advantages and limitations of using this combination of complementary techniques for distinguishing subtle differences in framework metal node coordination environments. [ABSTRACT FROM AUTHOR]

The electronic thermal conductivity of iron at the Earth's core conditions is an extremely important physical property in the geophysics field. However, the exact value of electronic thermal conductivity of iron under extreme pressure and temperature still remains poorly known both experimentally and theoretically. A few recent experimental studies measured the value of the electronic thermal conductivity directly and some theoretical works have predicted the electronic thermal conductivity of iron at the Earth's core conditions based on the Kubo-Greenwood method. However, these results differ largely with each other. A very recent research has confirmed that for iron at the Earth's core conditions, the strength of electron-electron scattering could be comparable to that for electron-phonon scattering, meaning that the electron-electron scattering should also be considered when evaluating the electronic thermal conductivity in the Earth's core situations. Here, by utilizing a newly developed methodology based on direct non-equilibrium ab initio molecular dynamics simulation coupled with the concept of electrostatic potential oscillation, we predict the electronic thermal conductivity of iron in h.c.p. phase. Our methodology inherently includes the electron-phonon and electron-electron interactions under extreme conditions. Our results are comparable to the previous theoretical and experimental studies. More importantly, our methodology provides a new physical picture to describe the heat transfer process in ϵ -iron at the Earth's core conditions from the electrostatic potential oscillation point of view and offers a new approach to study the thermal transport property of pure metals in the planet's cores with different temperature and pressure. [ABSTRACT FROM AUTHOR]

Fe83Ga17 (at. %) coatings with a thickness of 270-500 μm were prepared on 316L stainless steel by high velocity oxy-fuel spraying technology. The coatings exhibited a lamellar structure, and the magnetostriction reached 34.5 ppm. The magnetostrictive coatings were applied to electromagnetic acoustic transducers (EMATs), where the different bias magnetic fields and coating thicknesses were considered to examine the ultrasonic guided wave sensing capability and the detection sensitivity. The 180-kHz ultrasonic guided waves were captured from artificial defects and the pipe end under different bias magnetic fields. Among them, the EMATs exhibited the best sensing performance under a bias magnetic field of 255.7 Oe. Meanwhile, magnetostrictive stress induced the decrease of the magnetic permeability and the rearranged magnetic moment, resulting in a large strain sensitivity (dλ/dH). Because of the relatively good field sensitivities in magnetization and magnetostriction, the EMATs using Fe83Ga17 coating with a thickness of 500 μm exhibited better detection sensitivity than that of 300 μm. This work provides a good prospect of Fe-Ga alloy coatings applied in non-destructive testing. [ABSTRACT FROM AUTHOR]

Mixed metal oxides of earth-abundant 3d transition metals are an interesting class of materials that show interesting magnetic properties and a significant synergistic effect as catalysts for electrochemical oxygen evolution compared to simple unary oxides. However, the exact atomic-scale nature of such mixed oxide phases and the link to their interesting physico-chemical properties are poorly understood. Here, a combination of scanning tunneling microscopy and x-ray photoemission spectroscopy reveals that Fe species embed in a facile way into CoO bilayers on Au(111) resulting in an Fe doped oxide. Density functional theory and the spectroscopic fingerprint from x-ray photoemission spectroscopy reveal that the Fe dopants in the cobalt oxide matrix assume a higher oxidation state than in the structurally corresponding unary bilayer oxide. Furthermore, the substituted Fe is structurally displaced further away from the Au than the metal in either of the corresponding pure unary oxides. Both O and to a smaller extent Co in the nearest coordination shell are also structurally and electronically perturbed. The interesting effects observed in the bilayer binary oxides may enable a better fundamental understanding of the nature of doping of metal oxides, in general, and promotion effects in catalytic applications. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) are promising candidates for alternate energy conversion devices owing to their various advantages including high efficiency, reliability, and environmental friendliness. The performance of PEMFCs is fundamentally limited by the sluggish kinetics of the oxygen reduction reaction (ORR) at the cathode. Various studies have addressed myriads of Pt-based alloys as potential catalysts for ORR. However, most of these studies only focus on the cubic-structured Pt-based alloys which require further improvements especially in terms of stability and required loading. In this work, we perform first-principle density functional theory calculations to explore Fe and Co alloys of Pt in a different face centered tetragonal (L10) geometry as potential catalysts for ORR. The work focuses on understanding the reaction mechanism of ORR by both dissociative and associative mechanisms on L10–FePt/Pt(111) and L10–CoPt/Pt(111) surfaces. The binding pattern of each reaction intermediate is studied along with the complete reaction free energy landscape as a function of Pt overlayers. The L10–FePt/Pt(111) and L10–CoPt/Pt(111) surfaces show higher calculated surface activity for ORR as compared to the native fcc Pt(111) surface. The decrease in the required overpotential (η) for the alloys with respect to the unstrained Pt(111) surface is found to be in the range (0.04 V–0.25 V) assuming the dissociative mechanism and (0.02 V–0.10 V) assuming the associative mechanism, where the variation depends on the thickness of Pt overlayers. We further correlate the binding behavior of the reaction intermediates to the applied biaxial strain on the Pt(111) surface with the help of a mechanical eigenforce model. The eigenforce model gives a (semi-) quantitative prediction of the binding energies of the ORR intermediates under applied biaxial strain. The numerical values of the limiting potential (UL) obtained from the eigenforce model are found to be very close to ones obtained from electronic structure calculations (less than 0.1 V difference). The eigenforce model is further used to predict the ideal equi-biaxial strain range required on Pt(111) surfaces for optimum ORR activity. [ABSTRACT FROM AUTHOR]

The effects of stress relief on the magnetic characteristics of Fe-based metallic glass (MG) ribbons are investigated under external stress through various annealing treatments. We found that long-time annealing treatments benefit for making softer magnetic MGs under applied bending stress. We show that the irreversible domain wall movement region and the irreversible domain wall rotation region in the M-H curve represent the stress relief, which can be well reflected by the demagnified magnetic anisotropy. The magnetic coercivity and effective permeability variations in the lower frequency regime also represent the stress relief state. These observations have implications for understanding the relationship between the stress relief, microstructure change, and magnetic softness in magnetic MGs and might be helpful for the performance improvement of the ferromagnetic glassy materials. [ABSTRACT FROM AUTHOR]

The effect of the divacancy defect on magnetic properties of Fe94V6 alloys was investigated using the first-principles calculations based on density functional theory. The model of Fe28V2 super-lattice for a divacancy in Fe94V6 alloy was established, in comparison with the perfect Fe30V2 super-lattice. For the first time, the effect of the on-site Coulomb repulsion term was considered to correct the underestimation for the bandgap. The magnetism of the Fe, V atoms, and the super-lattice were analyzed by the electron hybridization of the atoms, and the interactions between V and four different neighboring Fe atoms were also investigated. The results show that both Fe28V2 and Fe30V2 super-lattices are ferromagnetic, which is determined mainly by the strong ferromagnetism of Fe 3d electrons, and the hybridizations between Fe 3d electrons and Fe 2p and V 3d electrons account for the weak anti-ferromagnetism. When the Fe divacancy exists, the average magnetic moments of the Fe28V2 super-lattice and Fe atoms inside increase, while that of V atoms decreases due to the change of the Fe-V charges. The variation of the magnetic moments of different neighboring Fe atoms with respect to V atoms depends on the charge transfer and the Fe-V interaction. [ABSTRACT FROM AUTHOR]

Phthalocyanine (Pc) and its metal complexes (MPcs) have been used industrially since their discovery in the early 20th century. The phthalonitrile (PN) method is a well-known synthesis method in which Pc or MPc can be afforded by heating a mixture of PN and metal powders over 280 °C with only moderate yield. However, the formation mechanism of the phthalocyanines and the intermediate stages of this seemingly simple reaction have yet to be fully understood. To study this mechanism computationally, we carried out quantum chemical molecular dynamics (MD) simulations based on the density-functional tight-binding (DFTB) method, applying the replica-exchange umbrella sampling (REUS) method, starting from four PN molecules and one iron atom. The DFTB-REUS-MD simulations successfully yielded FePc, and a metastable structure very similar to FePc but with a reactive nitrene unit was also identified that might explain the incomplete conversion of the reactants into FePc. Analysis of the MD trajectories reveals a three-step FePc formation mechanism for the PN method. [ABSTRACT FROM AUTHOR]

Knowledge of the dynamic magnetic susceptibility of patterned films is of great importance for exploring future data-storage applications and microwave devices. Since ferromagnetic resonance frequency is a function of the geometric parameters of a certain magnetic system, in this work, we investigate by micromagnetic simulations a set of stripe-patterned FeGa films, which have an identical thickness of 10 nm but a varying width in the range of 30–80 nm and a varying length in the range of 200–1000 nm. Fast-Fourier transform analysis of the simulation results for ferromagnetic resonance calculation identifies two distinct resonance peaks, which are assigned to a “bulk” mode and an “edge” mode. The presence of stress-induced anisotropy significantly affects both the two resonant modes. The occupation area of the spreading magnetization near the stripe ends is controllable by a tensile or compressive stress applied along the strip width. Consequently, the dynamic susceptibility of FeGa can be adjusted by an applied stress. [ABSTRACT FROM AUTHOR]

The properties of iron and steel are of considerable interest scientifically to the dynamic materials properties' community, as well as to a broader audience, for many applications. This is true in part because of the existence of a solid-solid phase (α–ε) transition at relatively modest stress (13 GPa). Because of this, there is a significant amount of data on iron and steel alloy shock compression properties at stresses above 13 GPa, but much less fundamental data under stress conditions lower than that, where the metals are in the α-phase. New data have been obtained under relatively low stress (below 10 GPa) conditions in which samples are subjected to low-velocity symmetric impact on the order of 0.2 to 0.4 km/s. We used well-developed flyer plate impact methods combined with velocity interferometry to measure wave speeds and strength properties in compression and tension. The shock α-phase Hugoniot data reported here are compared with literature values. A comparison of spall strength and Hugoniot elastic limit is made between different types of steel studied and for pure iron. [ABSTRACT FROM AUTHOR]

Epitaxial thin films of Fe doped SrTiO3 have been studied by the use of resonant photoemission. This technique allowed us to identify contributions of the Fe and Ti originating electronic states to the valence band. Two valence states of iron Fe2+ and Fe3+, detected on the base of x-ray absorption studies spectra, appeared to form quite different contributions to the valence band of SrTiO3. The electronic states within the in-gap region can be attributed to Fe and Ti ions. The Fe2+ originating states which can be connected to the presence of oxygen vacancies form a broad band reaching binding energies of about 0.5 eV below the conduction band, while Fe3+ states form in the gap a sharp feature localized just above the top of the valence band. These structures were also confirmed by calculations performed with the use of the FP-LAPW/APW+lo method including Coulomb correlations within the d shell. It has been shown that Fe doping induced Ti originating states in the energy gap which can be related to the hybridization of Ti and Fe 3d orbitals. [ABSTRACT FROM AUTHOR]

We have investigated the anomalous Ettingshausen effect (AEE) in iron–carbon alloys, i.e., cast irons and steel, using the lock-in thermography. All the alloys exhibit the clear AEE-induced temperature modulation, and their anomalous Ettingshausen coefficient is an order of magnitude greater than that of the pure iron at room temperature. The dimensionless figure of merit for AEE in the ductile cast iron is 55 times greater than that in the pure iron owing to the significant increase in the anomalous Ettingshausen coefficient. Our result reveals a potential of iron–carbon alloys as transverse thermoelectric materials, although the composition and microstructures optimizations are necessary. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are conducted to study the effects of alloying elements on the primary damage behaviors in three Fe-based ferritic alloy systems: (1) a Fe-Cr system in which the heat of mixing changes its sign with the Cr concentration; (2) a Fe-Cu system that has a positive heat of mixing; and (3) an ideal but artificial Fe-Cr system that has a zero heat of mixing, which is used as a reference system to investigate solute interstitial formation based on probability. It is found that in these alloys, the solute type and concentration do not have a significant effect on the total number of surviving Frenkel pairs. However, the fraction of solute interstitials has distinct behaviors. In Fe-Cr, the Cr interstitial fraction is much higher than the Cr solute concentration and the Cr interstitial production efficiency decreases with the increasing Cr concentration. By contrast, in Fe-Cu, Cu interstitials are barely produced. In the ideal alloy, the solute interstitial fraction is close to the solute concentration. The defect formation energies in both dilute and concentrated alloys, interstitial binding energies, liquid diffusivities of Fe and solute atoms, and heat of mixing have been calculated for both Fe-Cr and Fe-Cu alloys. Among them, we find that the relative thermodynamic stability between Fe self-interstitials and solute interstitials plays the most important role in the solute interstitial production behaviors. The decrease of Cr interstitial production efficiency with increasing Cr concentration can be explained by the probability distribution functions of solute interstitial formation energy in concentrated alloys. [ABSTRACT FROM AUTHOR]