Fe Au Research Articles

Sustaining Surface Lithiophilicity of Ultrathin Li-Alloy Coating Layers on Current Collector for Zero-Excess Li-Metal Batteries.

Zero-excess Li-metal batteries (ZE-LMBs) have emerged as the ultimate battery platform, offering an exceptionally high energy density. However, the absence of Li-hosting materials results in uncontrolled dendritic Li deposition on the Cu current collector, leading to chronic loss of Li inventory and severe electrolyte decomposition, limiting its full utilization upon cycling. This study presents the application of ultrathin (≈50nm) coatings comprising six metallic layers (Cu, Ag, Au, Pt, W, and Fe) on Cu substrates in order to provide insights into the design of Li-depositing current collectors for stable ZE-LMB operation. In contrast to non-alloy Cu, W, and Fe coatings, Ag, Au, and Pt coatings can enhance surface lithiophilicity, effectively suppressing Li dendrite growth, thereby improving Li reversibility. Considering the distinct Li-alloying behaviors, particularly solid-solution and/or intermetallic phase formation, Pt-coated Cu current collectors maintain surface lithiophilicity over repeated Li plating/stripping cycles by preserving the original coating layer, thereby attaining better cycling performance of ZE-LMBs. This highlights the importance of selecting suitable Li-alloy metals to sustain surface lithiophilicity throughout cycling to regulate dendrite-less Li plating and improve the electrochemical stability of ZE-LMBs.

Morphology and symmetry driven by lattice accommodation in polycrystalline bcc–fcc core–shell metallic nanoparticles

Body-centered-cubic–face-centered-cubic (bcc–fcc) multi-metallic nanoparticles (NPs) associating a single-crystal core (Fe, FeCo alloys, etc.) with a polycrystalline noble metal shell (Au, AuAg alloys, etc.) are perfectly symmetrical or more irregular, even dramatically dissymmetrical, yet presenting a good crystalline organization. Here, a combination of experimental analysis and theoretical symmetry analysis is proposed, in order to provide a unified description of the observed morphologies (Fe–Au and Fe–AuAg systems), whatever their symmetry, and predict some morphology variability in a population of NPs. First, the central role of the crystal lattice accommodation is comprehensively analyzed from the experimental Fe–AuAg system. The two possible bcc–fcc epitaxial relationships generate a core–shell interface in the shape of a truncated rhombic dodecahedron. This results in two different types of grains in the shell, which are elastically accommodated between them by an equal distribution of twins and low-angle grain boundaries, however, at the cost of internal stresses. At the same time, symmetry breaking results from two possible growth variants originating from the Nishiyama–Wasserman epitaxial relationships. The shell grains fit together in a nanopuzzle-like organization, resulting in a large number of possible arrangements distributed in 13 different point groups of symmetry, all of lower order than the core symmetry (highest order of cubic symmetry). If the variants are randomly distributed, the probability for the NP to be asymmetric (group 1) is 80%. The dissymmetrical development of the NPs is then discussed. Extending this approach to other core shapes succeeds in predicting dissymmetrical or dramatically off-centered morphologies experimentally observed in Fe–Au NPs.

Cell-inspired design of cascade catalysis system by 3D spatially separated active sites

Cells possess isolated compartments that spatially confine different enzymes, enabling high-efficiency enzymatic cascade reactions. Herein, we report a cell-inspired design of biomimetic cascade catalysis system by immobilizing Fe single atoms and Au nanoparticles on the inner and outer layers of three-dimensional nanocapsules, respectively. The different metal sites catalyze independently and work synergistically to enable engineered and cascade glucose detection. The biomimetic catalysis system demonstrates ~ 9.8- and 2-fold cascade activity enhancement than conventional mixing and coplanar construction systems, respectively. Furthermore, the biomimetic catalysis system is successfully demonstrated for the colorimetric glucose detection with high catalytic activity and selectivity. Also, the proposed gel-based sensor is integrated with smartphone to enable real-time and visual determination of glucose. More importantly, the gel-based sensor exhibits a high correlation with a commercial glucometer in real samples detection. These findings provide a strategy to design an efficient biomimetic catalysis system for applications in bioassays and nanobiomedicines.

Enhancement of the intrinsic Ni/GDC activity under rSOC operation by means of Fe–Au doping: An electro-kinetic study

The investigation dealt with the effect of Fe and Au wt.% concentrations on the enhanced performance and stability of Ni/GDC under rSOC operation. Moreover, it focused on the comparison of the intrinsic electro-kinetics between the best performing Fe–Au-modified cell and Ni/GDC under SOE operation. The rSOC performance and stability of all cells was examined in the temperature range of 900–800 °C. The electro-kinetic measurements took place at 900 °C by varying the pH2O. All Fe–Au–Ni/GDC electrodes exhibited enhanced activity, compared to the SoA Ni/GDC, with variations in their stability after three rSOC cycles. Specifically, the fuel electrode with the lowest wt.% concentration in Fe and Au (0.5Fe–1Au–Ni/GDC) exhibited the highest activity and stability under rSOC operation. By increasing the wt.% loadings to 2 wt% Fe and 3 wt% Au, there was rapid degradation of the initially high performance, mainly due to increase of the ohmic resistance. SEM analysis showed higher macro-porosity on the reduced state of the modified electrodes, which in the case of the best performing 0.5Fe–1Au–Ni/GDC was the least affected after rSOC operation. Interestingly, the SOE performance of the examined Fe–Au-modified electrodes was not similarly inhibited by the decrease of temperature, compared to Ni/GDC. This was further clarified through electro-kinetic measurements, aiming to verify the effect from the Fe–Au doping on the intrinsic electrochemical activity of Ni/GDC for the H2O electrolysis reaction. Comparison between the SoA and the best performing 0.5Fe–1Au–Ni/GDC showed an enhancing effect on the intrinsic electro-kinetics of the modified electrode. Specifically, the dependence of the polarization resistance on the pH2O was found to be strongly positive, resulting in a higher apparent reaction order, compared to Ni/GDC.

Metallogeny in the Bangong–Nujiang belt, central Tibet, China: A review

The Bangong–Nujiang metallogenic belt consists of scattered Tethyan oceanic blocks, mainly distributed underneath the margins of the Qiangtang and Lhasa terranes in central Tibet. A new world-class metallogenic belt has been reported in this region recently, based on the geological mapping and ore deposit prospecting over the last two decades. It currently comprises inferred resources of 30 Mt Cu and 500 t Au, together with several Cr–Ni, Fe, and W (Mo) resources, forming a significant potential area for future mineral exploration. These metals are mainly hosted in porphyry copper, skarn copper, skarn iron, orogenic gold, quartz-vein tungsten, and ophitic chromite deposits. The mineral deposits in the Bangong–Nujiang metallogenic belt have been widely recognized in different localities, including the southern edge of the southern Qiangtang block, part of the north Lhasa block, and even part of the central Lhasa block, indicating they were formed in variable geological settings, from the initial opening, subduction, and collision to the extension of the Bangong–Nujiang Ocean. Specifically, five major tectonic events contributed to mineralization, including the stage 1 (240–165 Ma) initial opening of the Bangong–Nujiang Ocean, stage 2 (165–145 Ma) oceanic subduction, stage 3 (145–100 Ma) close of the ocean, stage 4 (100–65 Ma) continent–continent collisional orogenesis, and stage 5 (65–0 Ma) post-orogenesis. At stage 1, Cr–Ni deposits were formed during the initial opening of the ocean; porphyry–epithermal Cu (Au), skarn Fe, and minor orogenic Au deposits were formed at stage 2 and stage 3; a younger pulse of a few porphyry–skarn Cu ± Mo and orogenic Au deposits were formed during stage 4; finally, W(Mo) deposits were generated in stage 5. In general, porphyry Cu systems, orogenic Au, and skarn Cu polymetallic deposits that occurred in the subduction and post-collision settings related W(Mo) deposits have the most potential for future exploration. An in-depth investigation of several scientific problems, such as addressing the tectonic setting, magmatism, and metallogeny of this region and genetic linkage of these deposit preservations to plateau uplift, is essential for the future success of exploration in the Bangong–Nujiang metallogenic belt.

From multi-segmented to core/shell nanorods: morphology evolution in Fe–Au nanorods by tuning fabrication conditions

Aiming to obtain hybrid magneto-plasmonic nanostructures, we have developed multisegmented and core/shell structured Fe–Au nanorods using template assisted electrochemical deposition. A facile method of tuning the growth pattern of multisegmented nanorods into core/shell structured is demonstrated. With a precise control of current density and deposition time, a brick-stacked wire like growth led to the formation of hollow nanotubes that could be further tuned to multilayered hollow nanotubes and core/shell structured nanorods. TEM imaging and STEM-EELS technique were used to explore the morphology, microstructure and the distribution of Au and Fe in the nanorods. The easy magnetization direction was found to be perpendicular to the nanorods’ growth direction in the segmented nanorods. On the other hand, core/shell nanorods exhibited isotropic behavior. Our findings provide deeper insights into the fabrication of hybrid nanorods and the opportunity to tune the fabrication method to vary their morphology accordingly. Such studies will benefit design of hybrid nanorods with specific morphologies and physical properties and hence their integration into sensing, spintronics and other potential biomedical and technological applications.

SEQUENTIAL EXTRACTION OF SUBSTANCES WITH KNOWN Au SPECIATION – AN EXPERIMENTAL DATA

A study has been conducted on the features of distriburion of Au among the fractions of a 7-step sequential extraction procedure using model substances that are similar in composition to natural organic matter from the dispersion train of sulfide tailings. Use has been made of model substances with known Au speciations: bulk native gold, nanoscale native gold, Au-containing pyrite, humic acids, and Fe(III) oxides/hydroxides, which served as the basis for preparing mixtures with low-Au filler substances (quartz, limestone, humic acids, Fe(III) oxides/hydroxides). It has been stated that several Au species are leached in one fraction during sequential extraction. Nanoscale Au 0 and gold bound to the organic matter are leached together in easily oxidizable (organic) fraction; gold bound to Fe(III) compounds and Au complexes chemisorbed on the surface of other minerals (sulfides, aluminosilicates) are leached in reducible (hydroxides) fraction; "invisible" gold in sulfides, nanoscale Au 0 and, partially, >1 μm-seized bulk Au 0 are leached in hardly oxidizable (sulfidic) fraction. Bulk native gold is leached predominantly in residual fraction. Mobile species are Au bound to water-soluble organic compounds and complexes of ionic Au desorbed from the surface of minerals.

Microstructures of magnetron sputtered Fe–Au thin films

Abstract Freestanding films of highly pure iron and gold multilayers were fabricated and characterized for their intended use as biodegradable implant materials. These samples were deposited using magnetron sputtering on unheated substrates. This technology allows the combination of various non-compounding materials. After annealing for 2 h at 685 °C and 850 °C, respectively to homogenize the multilayer, the microstructures were investigated using X-ray diffraction, energy dispersive X-ray spectroscopy and scanning transmission electron microscopy. Due to the annealing, the multilayered microstructure converts into a new multiphase system consisting of an iron matrix and two different kinds of gold morphologies: segregations along grain boundaries and nanosized core–shell like precipitates.

Development and Characterization of a One-Pot Synthesized Fe–Au–Pd Surface Alloy Catalyst for Highly Selective Conversion of Castor Oil to Octadecane via Hydrodeoxygenation

Development and Characterization of a One-Pot Synthesized Fe–Au–Pd Surface Alloy Catalyst for Highly Selective Conversion of Castor Oil to Octadecane via Hydrodeoxygenation

Effect of ultra-low amount of gold in oxide-supported bimetallic Au–Fe and Au–Cu catalysts on liquid-phase aerobic glycerol oxidation in water

Low-loaded Au–Fe and Au–Cu supported bimetallic catalysts showed exceptional activity in liquid-phase glycerol oxidation. Strong synergetic effect of Au–Fe (Cu) interaction and Au content tuned the oxidation activity and selectivity of the catalysts.

Room temperature synthesized solid solution AuFe nanoparticles and their transformation into Au/Fe Janus nanocrystals.

Solid solution AuFe nanoparticles were synthesized for the first time under ambient conditions by an adapted method previously established for the Fe3O4-Au core-shell morphology. These AuFe particles preserved the fcc structure of Au incorporated with paramagnetic Fe atoms. The metastable AuFe can be segregated by transformation into Janus Au/Fe particles with bcc Fe and fcc Au upon annealing. The ferromagnetic Fe was epitaxially grown on low index fcc Au planes. This preparation route delivers new perspective materials for magnetoplasmonics and biomedical applications and suggests the reconsideration of existing protocols for magnetite-gold core-shell synthesis.

Mineral Deposit Model of Cu–Fe–Au Skarn System in the Edongnan Region, Eastern China

AbstractCu and Fe skarns are the world's most abundant and largest skarn type deposits, especially in China, and Au‐rich skarn deposits have received much attention in the past two decades and yet there are few papers focused on schematic mineral deposit models of Cu–Fe–Au skarn systems. Three types of Au‐rich deposits are recognized in the Edongnan region, Middle–Lower Yangtze River metallogenic belt: ∼140 Ma Cu–Au and Au–Cu skarn deposits and distal Au–Tl deposits. 137–148 Ma Cu–Fe and 130–133 Ma Fe skarn deposits are recognized in the Edongnan region. The Cu–Fe skarn deposits have a greater contribution of mantle components than the Fe skarn deposits, and the hydrothermal fluids responsible for formation of the Fe skarn deposits involved a greater contribution from evaporitic sedimentary rocks compared to Cu–Fe skarn deposits. The carbonate‐hosted Au–Tl deposits in the Edongnan region are interpreted as distal products of Cu–Au skarn mineralization. A new schematic mineral deposit model of the Cu–Fe–Au skarn system is proposed to illustrate the relationship between the Cu–Fe–Au skarn mineralization, the evaporitic sedimentary rocks, and distal Au–Tl deposits. This model has important implications for the exploration for carbonate–hosted Au–Tl deposits in the more distal parts of Cu–Au skarn systems, and Fe skarn deposits with the occurrence of gypsum‐bearing host sedimentary rocks in the MLYRB, and possibly elsewhere.

Stable C, O, and S Isotope Record of Magmatic-Hydrothermal Interactions Between the Falémé Fe Skarn and the Loulo Au Systems in Western Mali

Abstract The Gara, Yalea, and Gounkoto Au deposits of the >17 Moz Loulo mining district, largely hosted by the Kofi series metasediments, are located several kilometers to the east of the 650-Mt Fe skarn deposits in the adjacent Falémé batholith. The Au deposits are interpreted to have formed through phase separation of an aqueous-carbonic fluid, which locally mixed with a hypersaline brine of metaevaporite origin. Recognition of an intrusive relationship between the Falémé batholith and Kofi series opens the possibility that the Fe skarns and Au deposits are part of the same mineral system. In this paper, we combine new δ13C, δ18O, and δ34S data from the Karakaene Ndi skarn, Au occurrences along the western margin of the Kofi series, and zircons within plutonic rocks of the Falémé batholith. We combine these with existing data from the Loulo Au deposits to model the contribution of magmatic volatiles to Au mineralization. C and O isotope compositions of auriferous carbonate-quartz-sulfide veins from the Loulo Au deposits have wide ranges (δ13C: –21.7 to –4.5‰ and δ18O: 11.8 to 23.2‰), whereas values from carbonate veins in Kofi series Au prospects close to the Falémé batholith and the Karakaene Ndi Fe skarn deposit have more restricted ranges (δ13C: –16.8 to –3.7‰, δ18O: 11.4 to 17.2‰, and δ13C: –3.0 ± 1‰, δ18O: 12.6 ± 1‰, respectively). Kofi series dolostones have generally higher isotopic values (δ13C: –3.1 to 1.3‰ and δ18O: 19.1 to 23.3‰). Pyrite from Kofi series Au prospects adjacent to the Falémé batholith have a wide range of δ34S values (–4.6 to 14.2‰), similar to pyrite from the Karakaene Ndi skarn (2.8 to 11.9‰), whereas δ34S values of pyrite and arsenopyrite from the Loulo deposits are consistently >6‰. Comparison of the C and O isotope data with water-rock reaction models indicates the Loulo Au deposits formed primarily through unmixing of an aqueous carbonic fluid derived from the devolatilization of sedimentary rocks with an organic carbon component. Isotopic data are permissive of the hypersaline brine that enhanced this phase separation including components derived from both Kofi series evaporite horizons interlayered with the dolostones and a magmatic-hydrothermal brine. This magmatic-hydrothermal component is particularly apparent in O, C, and S isotope data from the Gara deposit and Au prospects immediately adjacent to the Falémé batholith.

Equilibrium shape of core(Fe)–shell(Au) nanoparticles as a function of the metals volume ratio

The equilibrium shape of nanoparticles is investigated to elucidate the various core–shell morphologies observed in a bimetallic system associating two immiscible metals, iron and gold, that crystallize in the bcc and fcc lattices, respectively. Fe–Au core–shell nanoparticles present a crystalline Fe core embedded in a polycrystalline Au shell, with core and shell morphologies both depending on the Au/Fe volume ratio. A model is proposed to calculate the energy of these nanoparticles as a function of the Fe volume, Au/Fe volume ratio, and the core and shell shape, using the density functional theory-computed energy densities of the metal surfaces and of the two possible Au/Fe interfaces. Three driving forces leading to equilibrium shapes were identified: the strong adhesion of Au on Fe, the minimization of the Au/Fe interface energy that promotes one of the two possible interface types, and the Au surface energy minimization that promotes a 2D–3D Stranski–Krastanov-like transition of the shell. For a low Au/Fe volume ratio, the wetting is the dominant driving force and leads to the same polyhedral shape for the core and the shell, with an octagonal section. For a large Au/Fe ratio, the surface and interface energy minimizations can act independently to form an almost cube-shaped Fe core surrounded by six Au pyramids. The experimental nanoparticle shapes are well reproduced by the model, for both low and large Au/Fe volume ratios.

Carbonate hosted intermetallic compounds in Paleoproterozoic Salumber Ghatol metallogenic belt, Aravalli Craton, Rajasthan, India

Carbonate hosted intermetallic compound in the Umarvaniyan area is localized within the intensively sheared (mylonitised) dolomite in a NW–SE shear zone (~15 km), belongs to Salumber Ghatol metallogenic belt, in Debari Group of Aravalli Craton, Rajasthan, India. It is characterized by extensive silicification and ferruginisation with hematite, goethite, magnetite and native gold specks. The intermetallic compound within the dolomite is composed of varying proportion of Cu–Zn–Ni–Os–Fe which has been detected by electron probe microanalysis (EPMA) study. The EMPA (WDS) results of the intermetallic compounds also reveal occurrences of intermetallic compounds of Cu–Zn–Ni–Os–Fe and native Au. The occurrence of these non-separable compounds is probably because these metals were formed at very high temperatures and in reducing condition during the evolving shear with low oxygen and low sulfur fugacity. The fast cooling effect thereafter probably made the geochemical environment least conducive for reaction between Cu/Zn/Ni and sulphur or oxygen.

Petrologic Reconstruction of the Tieshan Magma Plumbing System: Implications for the Genesis of Magmatic-Hydrothermal Ore Deposits within Originally Water-Poor Magmatic Systems

Abstract Most genetic models for magmatic-hydrothermal ore deposits are based on the prerequisite that the parental magmas associated with mineralization are enriched in water (> ∼4 wt %). However, it has been recognized that a number of magmatic-hydrothermal ore deposits also formed within tectono-magmatic settings that produce initially water-poor magmas such as Climax-type porphyry deposits. Here, we present a detailed reconstruction of the Tieshan magma plumbing system related to skarn-porphyry Cu–Fe–Au mineralization in the Edong district, in which primitive magmas typically show water-poor features. Applications of multiple thermodynamic calibrations on various magmatic units from the Tieshan and Tonglushan deposits provide a wealth of information regarding the structure and evolution of the transcrustal magmatic system. Petrographic observations and clinopyroxene-liquid thermobarometry calculations indicate that the Tieshan magmatic-hydrothermal system was fed by a deep crustal magma reservoir. An accurate picture of the evolution of H2O within the magma plumbing system is presented using the plagioclase-liquid hygrometer in combination with the amphibole hygrometer. Three critical stages during the evolution of water within the plumbing system have been recognized, associated with H2O contents of 0·8–1·7 wt %, 2·1–2·8 wt % and 3·2–4·6 wt %, respectively. The first enrichment of water in the magmas can be attributed to the separation and transfer of evolved melts from the deep magma reservoir to the shallow crust. Continuous cooling and solidification of the shallow magma body gave rise to the second enrichment of H2O in residual melts, leading to magmas that were fertile for the formation of ore deposits. The detailed chemical evolution of the magma plumbing system was investigated using mineral trace element compositions in combination with the partition coefficients predicted by the lattice strain model. The earliest equilibrium melts are characterized by high Sr contents (the average = 658 ± 64 ppm), suggesting that high Sr/Y signatures were likely derived from their magma sources or fractionation at deeper levels in initially water-poor environments. Variations of some particular geochemical fingerprints in equilibrium melts such as, Dy/Dy* and Eu/Eu*, also provide fundamental information on the evolution of the magma plumbing system. Our study confirms the critical role of a deep crustal magma reservoir on the formation of magmatic-hydrothermal ore deposits. The fertility of magmas with respect to ore deposit formation was enhanced by the extraction and transfer of evolved magmas from the deep reservoir to shallower levels, particularly due to the enrichment of magmatic water contents. In addition, the presence of a deep magma reservoir also sustains the incremental growth of shallow magma chambers, which provide ore-forming fluids.

In-situ trace elements on pyrite and arsenopyrite of the Zhengchong gold deposit, Jiangnan Orogen: Insights for the mineralization mechanism

The Zhengchong gold deposit, with a gold reserve of 19 t, is located in the Liling Goldfield, central Jiangnan Orogen, Southern China. The orebodies are structurally bound by NW- and NNE-NE-trending faults, hosted in the Neoproterozoic slates. The ore styles primarily comprise auriferous pyrite-arsenopyrite-quartz vein, disseminated pyrite-arsenopyrite-sericite-quartz mineralized slate, and intense mineralized slate breccia. The gold-bearing sulfide-quartz veins have average Au grades up to 13.5 g/t, generally higher than that of mineralized rock in all orebodies of 0.6–2.0 g/t and intense mineralized breccia within quartz veins of 2.5–4.0 g/t. Three primary and successive paragenetic sequences are identified: (i) Barren quartz – muscovite; (ii) Quartz – polymetallic sulfides – native gold – muscovite – minor chlorite; (iii) Barren quartz – calcite veins. Native gold has only been observed in the fractures of early barren quartz, pyrite and arsenopyrite in NW-trending auriferous veins. According to textural differences, five types of pyrite and four types of arsenopyrite are recognized from NW- and NNE-NE-trending orebodies.Based on LA-ICPMS spot and imaging analyses of different types of pyrites and arsenopyrites, the refractory, invisible gold in pyrites and arsenopyrites range from < 1 to >500 ppm and was incorporated in these sulfides through substitution of As1− for S2− as the Au and As data plotting below the both gold solubility lines for Carlin and orogenic gold deposits. The invisible gold as the form of Au+ concentrates in sulfides. Besides, minor micro-scale gold with Cu-, Pb-, Sb-, Ag-, and Bi-minerals occur in the pores of pyrite and arsenopyrite. The initial ore-bearing fluid with abundant Si, S, Fe, As and minor Au, Co, Ni, Cu, Zn, Sb, Te, Pb, Bi reacting with Neoproterozoic slates to generate low-grade pyrite (Py-I and Py-III) in both-trending orebodies. For NNE-trending sulfide-quartz veins, cyclic fluid pressure dropping resulted fluid phase separation and destabilization of bisulphide-gold. Due to the small fluid flux in narrow NNE-trending faults, Au+ exhausted after the precipitation of high-grade Py-II, Apy-II and Au-rich rim of Py-I with invisible gold. In NW-trending auriferous quartz veins, hydrofracturing under high fluid pressure in thrust shear-faults, generated massive slate breccias. The sharply pressure decrease in dilations along the ore-controlling faults resulted in significant auriferous fluid phase separation and the solubility reducing of trace elements and gold, which in turn led in the deposition of native gold with chalcopyrite, sphalerite and tetrahedrite in fractures of Py-IV and Apy-III.

Composition and structure of magnetic high-temperature-phase, stable Fe-Au core-shell nanoparticles with zero-valent bcc Fe core.

Advanced quantitative TEM/EDXS methods were used to characterize different ultrastructures of magnetic Fe–Au core–shell nanoparticles formed by laser ablation in liquids. The findings demonstrate the presence of Au-rich alloy shells with varying composition in all structures and elemental bcc Fe cores. The identified structures are metastable phases interpreted by analogy to the bulk phase diagram. Based on this, we propose a formation mechanism of these complex ultrastructures. To show the magnetic response of these magnetic core nanoparticles protected by a noble metal shell, we demonstrate the formation of nanostrands in the presence of an external magnetic field. We find that it is possible to control the lengths of these strands by the iron content within the alloy nanoparticles.

A novel two-step Fe-Au type spin-crossover behavior in a Hofmann-type coordination complex {Fe(4-methylpyrimidine)2[Au(CN)2]2}.

A Hofmann-type two-step spin-crossover (SCO) complex with a pyrimidine derivative ligand, Fe(4-methylpyrimidine)2[Au(CN)2]2, was synthesized, and this complex shows a two-step SCO phenomenon in the intermediate state. Symmetry breaking also occurs in the intermediate state. These results reveal three spin states within the complex for high-spin (HS), HS0.5LS0.5, and low-spin (LS).

Self healing of radiation-induced damage in Fe–Au and Fe–Cu alloys: Combining positron annihilation spectroscopy with TEM and ab initio calculations

Self healing of early stage radiation damage by site selective solute segregation is a promising approach to extend the lifetime of nuclear reactor components. In the present study, the creation and autonomous healing of irradiation-induced damage is investigated in pure Fe and high purity Fe–Au and Fe–Cu model alloys. To create radiation damage samples are irradiated at 550 °C by 120 keV He+ ions with fluences of 5.0 × 1015, 1.0 × 1016 and 5.0 × 1016 ions/cm2. The observed increase in the S and W parameters determined in the variable energy positron annihilation spectroscopy measurements indicates the formation of vacancy-like defects, precipitates and vacancy-solute complexes. The presence of substitutionally dissolved Au is found to reduce the formation of radiation defects more efficiently than solute Cu. Site-specific Au precipitation at defect sites is indicated, which results in damage healing with a reduced swelling, whereas Cu precipitates and radiation damage only show weak interaction. Ab initio calculations show that the binding energies of Au solutes to vacancy clusters (Au-Vn) are significantly larger than those of Cu solutes (Cu-Vn) whereas the binding energies of helium filled vacancy clusters Au-HenVn and Cu-HenVn are comparable.