Bulk Composition Research Articles

The Influence of Architecture on the Tensile and Flexural Properties of Single-Polymer Composites

This study investigates the tensile and flexural properties of self-reinforced polylactic acid (SrPLA) and poly(ethylene terephthalate) (SrPET) for prosthetic socket applications. These self-reinforced polymer (srP) composites utilize both a matrix and reinforcement made from the same material, resulting in an optimal matrix–interface bond that significantly enhances mechanical properties compared to traditional bulk polymers and composites. Prosthetic sockets serve as a critical interface between an amputee’s residuum and the prosthetic components, such as pylons and feet. Conventional socket materials, including monolithic high-density polyethylene and polypropylene, as well as advanced fillers reinforced with thermoset resins, often fall short in strength or affordability, particularly for amputees in low- to middle-income countries. In this study, we employed srP composites with various architectural stitch densities, aiming to achieve superior material properties. The results demonstrate that these materials exhibit higher strength and strain capabilities than many existing prosthetic materials. Notably, the low-density srPET composites achieved a tensile strength of 85.11 MPa and a strain of 19.7%, while high-density srPLA exhibited a failure strength of 36.65 MPa and a strain of 1.4%. Additionally, our findings reveal that the stiffness of both srPLA and srPET increases as the density of the reinforcement decreases. Overall, this study suggests that srP composites represent a viable and sustainable alternative for the manufacturing of prosthetic sockets, offering both enhanced performance and cost-effectiveness.

Development of supported intermetallic compounds: advancing the Frontiers of heterogeneous catalysis.

Intermetallic compound (IMC) catalysts have garnered significant attention due to their unique surface and electronic properties, which can lead to enhanced catalytic performance compared to traditional monometallic catalysts. However, developing IMC materials as high-performance catalysts has been hindered by the inherent complexity of synthesizing nanoparticles with well-defined bulk and surface compositions. Achieving precise control over the composition of supported bimetallic IMC catalysts, especially those with high surface area and stability, has proven challenging. This review provides a comprehensive overview of the recent progress in developing supported IMC catalysts. We first examine the various synthetic approaches that have been explored to prepare supported IMC nanoparticles with phase-pure bulk structures and tailored surface compositions. Key factors influencing the formation kinetics and compositional control of these materials are discussed in detail. Then the strategies for manipulating the surface composition of supported IMCs are delved into. Applications of high-performance supported IMCs in important reactions such as selective hydrogenation, reforming, dehydrogenation, and deoxygenation are comprehensively reviewed, showcasing the unique advantages offered by these materials. Finally, the prevailing research challenges associated with supported IMCs are identified, including the need for a better understanding of the composition-property relationships and the development of scalable synthesis methods. The prospects for the practical implementation of these versatile catalysts in industrial processes are also highlighted, underscoring the importance of continued research in this field.

Mineralization Characteristics of the Hokuryu Epithermal Au‐Ag Deposit, Hokkaido, Japan

ABSTRACTVeins intersected by a ~600‐m‐long drill core into the Hokuryu epithermal Au‐Ag deposit in the northeastern part of Hokkaido, Japan, were investigated including mineralogy, texture, quartz composition, and fluid inclusion characteristics, with relation to elevation. Host rocks of these veins are flow‐banded rhyolite, pyroclastic breccia, and andesite and are mainly altered by illite and chlorite. The veins display crustiform and massive macroscopic textures. The crustiform veins generally located at higher elevations, contain Ag‐rich and Au‐Ag‐rich bands. The massive veins are mainly present at lower elevations, and they are generally barren of precious metals. The Ag‐rich bands in the crustiform veins contain mineral assemblage of hessite + sphalerite + pyrite + galena. These minerals, together with anhedral to rhombic adularia, exist within the interstices of quartz that display microspherical texture. The Au‐Ag‐rich bands contain mineral assemblage of electrum ± naumannite‐aguilarite associated with quartz with colloform, ghost‐sphere, and ghost‐bladed textures. Bulk compositions of the veins reflect the ore mineralogy observed in which Ag is strongly correlated with Pb, Te, Zn, Cd, and Bi. The barren massive veins are mainly composed of granular quartz. Textural and mineralogical characteristics of Au‐ and Ag‐bearing bands in the crustiform veins indicate amorphous silica and calcite precursors. Together with the coexistence of adularia, these suggest liquid boiling during vein formation. Quartz associated with Au‐ and Ag‐bearing minerals exhibits blue cathodoluminescence (ca. 400 nm wavelength) triggered by high Al impurity probably due to pH and pressure fluctuations or impurity redistribution during recrystallization from metastable amorphous silica. Fluid inclusions hosted in quartz and adularia, which contain negligible amounts of CO2, show a modal homogenization temperature range of 260°C–290°C and a salinity range of 1.2–6.9 wt% NaCl equivalent. The homogenization temperatures follow a boiling point curve and indicate an erosion of up to ~340 m for the deposit. The variable salinities in relation to elevation suggest extreme vapor loss during boiling at depth, episodic influx of high salinity fluids from deeper source, or mixing with high salinity fluids along anastomosing fractures at relatively shallower depths.

PDS 70b Shows Stellar-like Carbon-to-oxygen Ratio

Abstract The ~5 Myr PDS 70 is the only known system with protoplanets residing in the cavity of the circumstellar disk from which they formed, ideal for studying exoplanet formation and evolution within its natal environment. Here, we report the first spin constraint and C/O measurement of PDS 70b from Keck/KPIC high-resolution spectroscopy. We detected CO (3.8σ) and H2O (3.5σ) molecules in the PDS 70b atmosphere via cross correlation, with a combined CO and H2O template detection significance of 4.2σ. Our forward-model fits, using BT-Settl model grids, provide an upper limit for the spin rate of PDS 70b (<29 km s−1). The atmospheric retrievals constrain the PDS 70b C/O ratio to 0.28 − 0.12 + 0.20 (<0.63 under 95% confidence level) and a metallicity [C/H] of − 0.2 − 0.5 + 0.8 dex, consistent with that of its host star. The following scenarios can explain our measured C/O of PDS 70b in contrast with that of the gas-rich outer disk (for which C/O ≳ 1). First, the bulk composition of PDS 70b might be dominated by dust+ice aggregates rather than disk gas. Another possible explanation is that the disk became carbon enriched after PDS 70b was formed, as predicted in models of disk chemical evolution and as observed in both very low-mass stars and older disk systems with JWST/MIRI. Because PDS 70b continues to accrete and its chemical evolution is not yet complete, more sophisticated modeling of the planet and the disk, and higher-quality observations of PDS 70b (and possibly PDS 70c), are necessary to validate these scenarios.

Siloxane–Ethylene Oxide–Urethane Block Copolymers: Synthesis and Properties

Siloxane–ethylene oxide–urethane block copolymers were synthesized by the interaction of oligosiloxane organodiols of the general formula HO(CH2)2OCH2Me2SiO–[SiR2O]n–SiMe2CH2O(CH2)2OH (R = Me, Et) and oligo(ethylene oxide) (OEO) (–CH2CH2O–)m with 4,4'-diphenylmethane diisocyanate. The copolymers obtained were studied by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The effect of the bulk composition on the composition and structure of the surface was established.

Heterogeneous Cu Doping Facilitates Excellent Thermoelectric and Mechanical Performance in n-Type SnSe Composites.

SnSe materials have attracted extensive attention in thermoelectrics due to their low thermal conductivity. Nevertheless, the thermoelectric properties of n-type polycrystalline SnSe are still low, and metallic Sn distributed in the SnSe1-x materials would affect the repeatability of thermoelectric performance. Herein, the thermoelectric properties of n-type polycrystalline SnSe0.95-based composites are highly enhanced by heterogeneous Cu doping. The carrier concentration of the SnSe0.95 material was optimized by SnCl2 doping. The strategy of heterogeneous Cu doping is employed in further improving the thermoelectric performance of the SnCl2-doped SnSe0.95 materials. In addition, partial Cu+ doping tunes the electron concentration to enhance the Seebeck coefficient. Moreover, metallic Sn distributed along the grain boundaries can be stabilized by forming Cu6Sn5 alloys, which improve the thermal stability of bulk composites. Excessive Cu particles and SnCl2 precipitates strengthen phonon scattering for lowering the lattice thermal conductivity. Ultimately, a peak ZT of 1.55 is yielded at 773 K in the SnSe0.95-1 wt % SnCl2-1 wt % Cu bulk composite, whose mechanical hardness is also increased. Hence, these results promote a feasible approach to simultaneously enhance the thermoelectric and mechanical properties of n-type SnSe-based composites, which might be worth exploring in other thermoelectric materials.

Generalized <i>Р—Т</i> path and fluid regime of exhumation of metapelites of the central zone of the Limpopo complex, south Africa

The P–T paths of exhumation of Precambrian granulite complexes at the craton boundaries usually include two stages: sub-isothermal decompression and a decompression–cooling stage with a more gentle P–T path. Our goal is to understand the possible causes of the change in the slope of the P–T path of exhumation of the Central Zone (CZ) of the Limpopo granulite complex (South Africa), located between the Kaapvaal and Zimbabwe cratons. For this purpose, rocks (mainly, metapelites) from various structural positions within the Central Zone, i.e. dome structures, regional crossfolds, local and regional shear-zones, were studied. Metapelites are gneisses of similar bulk composition. Relics of leucosomes composed of quartz-feldspar aggregates with garnet and biotite are variously manifested in rocks, and melanocratic areas enriched in cordierite usually mark micro-shear-zones that envelope and/or break garnet porphyroblasts. Study of polymineral (crystallized melt and fluid) inclusions in garnet, its zoning with respect to the major (Mg, Fe, Ca) and some trace (P, Cr, Sc) elements, fluid inclusions in quartz, as well as phase equilibria modeling (PERPLE_X) showed that rocks coexisted with granite melts and aqueous-carbonic-salt fluids (aH2O = 0.74–0.58) at the peak of metamorphism at 800–850°C and 10–11 kbar. Partial melting initiated sub-isothermal exhumation of rocks to 7.5–8 kbar during diapirism of granitic magmas in the Neoarchean (2.65–2.62 Ga). This is reflected in the specific zoning of garnet grains in terms of the grossular content. A change in the rheology of rocks as a result of partial removal and crystallization of the melt activated shear-zones during further exhumation to 6–5.5 kbar along the P–T decompression–cooling path of 95–100°/kbar, reflecting a slower uplift of rocks in the middle crust. This process was resumed due to thermal effects and interaction of rocks with aqueous fluids (aH2O 0.85) in the Paleoproterozoic (~2.01 Ga). Such a scenario of metamorphic evolution implies that the Limpopo granulite complex, in general, and its Central Zone, in particular, are the result of the evolution of an ultra-hot orogen, where vertical tectonic movements associated with diapirism were conjugate with horizontal tectonic processes caused by the convergence of continental blocks.

Magmatic evolution and magma chamber conditions of the Alpehué tephra from Sollipulli Volcano, Andean Southern Volcanic Zone, Chile/Argentina

The trachydacitic Alpehué tephra from Sollipulli volcano (Andean Southern Volcanic Zone), consists of ignimbrite and fallout from a Plinian eruption about 3000 years ago. It is mainly composed of (1) crystal-rich pumice and ash but also contains (2) chilled knobbly basaltic lava clasts and (3) mostly highly inflated glomerocrystic fragments with high crystal-glass ratios interpreted to represent a crystal mush zoned from basaltic to dacitic bulk compositions. Knobbly lava clasts are of three types: (a) a very phenocryst-poor basalt, (b) a basalt with large, unzoned olivine and plagioclase phenocrysts and glomerocrysts, and (c) mixtures of microcrystalline basalt with various fragments, glomerocrysts and crystals derived from a crystal mush. Clast type (4) in the tephra is banded pumices in which the three magmatic components occur variably mingled. Thermobarometry and petrographic observations, particularly presence or absence of amphibole, constrain an upper-crustal succession of a lower basaltic reservoir, a zoned basaltic to dacitic crystal mush reservoir, and a separate trachydacite magma chamber on top. All Alpehué magmatic components form a coherent liquid line of descent which supports the interpretation that the crystal mush reservoir is a gradually solidifying magma chamber, not the result of large-scale crystal-liquid segregation. The trachydacite magma may originally have formed as melt escaping from the crystal-mush reservoir but subsequently underwent a long and complex evolution recorded in large strongly zoned plagioclase phenocrysts including resorption horizons. The ascending mafic magmas collected samples from the crystal mush body and intruded the trachydacite reservoir. The phenocryst-poor basalt (a) arrived first and entrained and partially resorbed plagioclase from the host magma. The phyric basalt (b) arrived later and did not resorb entrained plagioclase before eruption. Estimated cooling times, plagioclase resorption times and ascent rates avoiding amphibole breakdown limit the duration of these pre-eruptive processes to not more than a few days.

Convective Mixing in Gas Giant Planets with Primordial Composition Gradients

Linking atmospheric measurements to the bulk planetary composition and ultimately the planetary origin is a key objective in planetary science. In this work, we identify the cases in which the atmospheric composition represents the bulk composition. We simulate the evolution of giant planets considering a wide range of planetary masses (0.3–2 M J), initial entropies ( 8-11kBmu−1 ), and primordial heavy-element profiles. We find that convective mixing is most efficient at early times (ages ≲107 yr) and that primordial composition gradients can be eroded. In several cases, however, the atmospheric composition can differ widely from the planetary bulk composition, with the exact outcome depending on the details. We show that the efficiency of convection is primarily controlled by the underlying entropy profile: For low primordial entropies of 8-9kBmu−1 , convective mixing can be inhibited and composition gradients can persist over billions of years. The scaling of mixing efficiency with mass is governed by the primordial entropy. For the same primordial entropy, low-mass planets mix more efficiently than high-mass planets. If the primordial internal entropy would increase with mass, however, this trend could reverse. We also present a new analytical model that predicts convective mixing under the existence of composition (and entropy) gradients. Our results emphasize the complexity in the interpretation of atmospheric abundance measurements and show the great need to better understand the planetary formation process as it plays a key role in determining the planetary evolution and final structure.

Dissolution and solubility of the calcium-nickel carbonate solid solutions [(Ca1−xNix)CO3] at 25 °C

A series of the calcium-nickel carbonate solid solutions [(Ca1−xNix)CO3] were synthesized and their dissolution in N2-degassed water (NDW) and CO2-saturated water (CSW) at 25 °C was experimentally investigated. During dissolution of the synthetic solids (Ni-bearing calcite, amorphous Ca-bearing NiCO3 and their mixtures), the Ni-calcite and the Ca-NiCO3 dissolved first followed by the formation of the Ni-bearing aragonite-structure phases. After 240–300 days of dissolution in NDW, the water solutions achieved the stable Ca and Ni concentrations of 0.592–0.665 and 0.073–0.290 mmol/L for the solids with lower Ni/(Ca + Ni) mol ratios (XNi), or 0.608–0.721 and 0.273–0.430 mmol/L for the solids with higher XNi, respectively. After 240–300 days of dissolution in CSW, the water solutions achieved the stable Ca and Ni concentrations of 1.094–3.738 and 0.831–4.300 mmol/L, respectively. For dissolution in NDW and CSW, the mean values of log IAP (Ion activity products) in the final stable state (≈ log Ksp, Solubility product constants) were determined to be − 8.65 ± 0.04 and − 8.16 ± 0.11 for calcite [CaCO3], respectively; − 8.50 ± 0.02 and − 7.69 ± 0.03 for the synthetical nickel carbonates [NiCO3], respectively. In respect to the bulk composition of the (Ca1−xNix)CO3 solid solutions, the final log IAP showed the highest value when XNi = 0.10–0.30. Mostly, the mean values of log IAP increased with the increasing XNi in respect to the Ni-calcite, the Ni-aragonite and the amorphous Ca-Ni carbonate. The plotting of the experimental data on the Lippmann diagram for the (Ca1−xNix)CO3 solid solution using the predicted Guggenheim parameters of a0 = 2.14 and a1 = − 0.128 from a miscibility gap of XNi = 0.238 to 0.690 indicated that the solids dissolved incongruently and the final Ca and Ni concentrations in the water solutions were simultaneously limited by the minimum stoichiometric saturation curves for the Ni-calcite, Ni-aragonite and the amorphous Ca-Ni carbonate. During dissolution in NDW, the Ni2+ preferred to dissolve into the water solution and Ca2+ preferred to remain in the solid, while during dissolution in CSW for the solids with higher XNi, the Ca2+ preferred to dissolve into the water solution and Ni2+ preferred to remain in the solid. These findings provide valuable insights into understanding the mechanisms governing Ni geochemical cycle in natural environments.

The chemical and Sm–Nd isotopic behaviour of accessory minerals in metasediments along the LP-HT Chugach Metamorphic Complex (Alaska)

The study of accessory phases, including trace element concentrations and radiogenic isotopes, provides powerful information for a better understanding of geological processes such as crustal anatexis. These accessory minerals are the primary carriers of many incompatible elements and Rare Earth Elements (REE) in crustal rocks. In this contribution, we provide a detailed study on the chemical and isotopic (Nd isotopes) behaviour of accessory minerals within the Chugach Metamorphic Complex in Alaska. This Eocene (55− 50 Ma) metamorphic complex developed in a Late Cretaceous to Paleogene accretionary prism consisting of metapelitic and metagreywacke rocks. The complex exposes a systematic N-S metamorphic gradient from greenschist to upper amphibolite facies (500 to ~ 700 °C) with anatexis under water-saturated conditions and minor muscovite breakdown. Trace element concentration data for apatite, monazite and titanite reveal a strong influence of bulk composition (greywacke vs. pelite) on their REE signatures in the migmatitic gneisses. In xenotime-bearing metapelitic samples, we show that monazite and apatite, which crystallised close to peak metamorphism, have their HREE-Y contents increasing with temperature within a narrow range of ~ 150 °C (550 to ~ 700 °C). While the influence of temperature on the Y content of monazite was already demonstrated before, we prove that apatite follow the same chemical behaviour. In these samples, partial melting process can be tracked via Eu/Eu* which decreases systematically from schist to migmatitic gneisses and is interpreted to be related to plagioclase crystallisation. Among all analysed samples (schists and migmatites), we observe no significant differences in εNd between monazite, allanite and whole-rock, regardless of rock type. This suggests (i) a general homogeneity of Nd isotopic composition above 550 °C up to crustal anatexis, and (ii) an isotopic equilibrium between mineral and whole-rock, indicating Nd isotopic disequilibria induced by partial melting are unlikely in this case study.

Enhancing the Potential of PHAs in Tissue Engineering Applications: A Review of Chemical Modification Methods.

Polyhydroxyalkanoates (PHAs) are a family of polyesters produced by many microbial species. These naturally occurring polymers are widely used in tissue engineering because of their in vivo degradability and excellent biocompatibility. The best studied among them is poly(3-hydroxybutyrate) (PHB) and its copolymer with 3-hydroxyvaleric acid (PHBV). Despite their superior properties, PHB and PHBV suffer from high crystallinity, poor mechanical properties, a slow resorption rate, and inherent hydrophobicity. Not only are PHB and PHBV hydrophobic, but almost all members of the PHA family struggle because of this characteristic. One can overcome the limitations of microbial polyesters by modifying their bulk or surface chemical composition. Therefore, researchers have put much effort into developing methods for the chemical modification of PHAs. This paper explores a rarely addressed topic in review articles-chemical methods for modifying the structure of PHB and PHBV to enhance their suitability as biomaterials for tissue engineering applications. Different chemical strategies for improving the wettability and mechanical properties of PHA scaffolds are discussed in this review. The properties of PHAs that are important for their applications in tissue engineering are also discussed.

The behaviour of scandium during crustal anatexis: Implications for the petrogenesis of Sc-enriched granitic magma

Scandium (Sc) is a compatible element in mafic silicate minerals, in particular amphibole, garnet and clinopyroxene, and is enriched in ultramafic rocks. Nevertheless, its concentration is also sufficiently high in some evolved granites and granite pegmatites to form minerals with essential Sc. In some granitic occurrences, Sc-bearing minerals occur in miarolitic cavities, indicating the importance of late- to post-magmatic fluids. In contrast, some granite pegmatites have thortveitite (Sc2Si2O7) and other Sc-rich minerals, including Sc-enriched garnet as part of evolved magmatic mineral assemblages. The maximum Sc concentration in garnet in thortveitite-bearing, Mesoproterozoic granite pegmatites of probable anatectic origin in South Norway is ca. 2000 ppm, corresponding to ca. 100 ppm in a coexisting silicate melt. As for any trace element, the behaviour of Sc during crustal anatexis is controlled by the amount of melt formed and the mineralogy of the solid residue. The melting process can be modelled from thermodynamical data on solids and melts for given protolith compositions, temperature and pressure. Simulations in a range of mafic/ultramafic to felsic systems show that mafic protoliths will form Sc-depleted anatectic melts, and correspondingly Sc-enriched solid residues under relevant pressure and temperature conditions (2-10 kbar, 700-800 °C). Limited enrichment in melt relative to protolith is only seen in granodioritic-tonalitic bulk compositions, reaching maximum concentrations of 30–60 ppm. The effect of fluorine during melting and subsequent fractionation is to lower the solidus temperature, depolymerise the silicate melt, and lower partition coefficients for Sc between mafic silicate minerals and felsic melt. Contamination with mafic material has only limited effect, as it will eventually sequester Sc into hybrid mafic silicate mineral assemblages and lead to reduction of the Sc concentration of the remaining melt fraction. Further increase of the Sc concentration requires fractional crystallisation of minerals with low KD, i.e. mainly feldspar minerals and quartz, which may be facilitated by selective, local contamination by quartz and feldspar from granitic country rocks.

Electrochemical CO2 Reduction over Cu-Based Gas Diffusion Electrodes: A Complementary Spectroscopic Study

Electrochemical CO2 reduction (eCO2R) over copper gas diffusion electrode (Cu-GDE) has the potential to generate multi carbon products (C2+ such as ethylene and ethanol) with renewable electricity at a commercial scale [1-3]. To unlock the potential, selectivity towards a desired product with acceptable current densities are a must [1-3]. Efforts are being made to understand catalyst structure, activity and selectivity relationships by different techniques, including a few in situ and operando X-ray absorption spectroscopy (XAS) studies [3-7]. However, there is no consensus on the active and selective site/phase composition of copper for ethylene production. On the one hand, the occurrence of only metallic Cu during the reaction is reported [3-7] while on the other hand, some of these studies find no correlation between the metallic Cu and eCO2R products distribution [3,4]. Differently, the occurrence of Cu(OH)2 and Cu2O (along with metallic Cu) during the reaction is also reported [5,6]. The discrepancies could be a result of varied experimental conditions and in situ / operando cell designs [3-7]. The latter could play a key role in obtaining reliable structure-activity data [8]. The observations emphasise the need for targeted and cell specific operando spectroscopic studies to unravel structure, activity and selectivity relationships [3].In the present study we report a novel operando XAS GDE flow cell with a three-phase system (i.e., gaseous CO2, liquid electrolyte and solid catalyst) to conduct experiments in a transmission mode that probes the Cu-GDE from surface to bulk and provides information on the copper oxidation and coordination states during the reaction. It would, however, not be able to distinguish between the surface and bulk composition [3] and hence complementary surface sensitive quasi in situ X-ray photoelectron spectroscopy (XPS) is employed to probe copper dynamics on the Cu-GDE surface [9]. The data are then complemented by Raman spectroscopy that monitors not only the surface adsorbed species but also the evolution of copper speciation (even very amorphous species) during the reaction [10].The dynamic behaviour of copper during the reaction is captured by X-ray absorption near edge structure (XANES) spectra. Linear combination analyses (LCA) show that within the first 20 min of the reaction, copper is only in oxidised state (mainly CuO and minority Cu2O), which is corroborated by the quasi in situ Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The majority of CuO is reduced to Cu2O (44%) and metallic Cu (44%) at 30 min of the reaction. The metallic Cu content increased to 77% at 60 min of the reaction, however remarkably the remainder (23%) of the copper is in the Cu2+ oxidation state. The latter is not detected by quasi in situ XPS that instead shows copper only in < 2+ oxidation state, potentially as metallic Cu. This implies that the bulk composition is different from the surface composition which is further confirmed by the quasi in situ Raman that shows the presence of copper oxides, Cu(OH)2 and CO adsorbed metallic Cu at 60 min. Based on the complementary spectroscopic data, eCO2R data will be correlated with the catalyst structure dynamics and structure-activity relations will be discussed.

(Invited) Metallization for Advanced Semiconductor Technology Nodes: Wet-Chemical Deposition and Etching, Characterization, and (Semi) Damascene Approaches

To ensure semiconductor technology scaling to continue for the decades to come, the industry focuses on identifying alternative metals (elemental or alloys), that can replace copper in the back end of line (BEOL) integration scheme, for which the metal is used as main conductor for most of the metallization levels. Recently, the semi-damascene process is being developed, in which the interconnect metal is first deposited and then patterned using a dry etching process (‘direct metal etch’), in a fashion closely resembling the traditional Al metallization. One of the advantages is that any metal that can be deposited as a blanket thin film (either by physical vapor deposition (PVD), electrochemical deposition (ECD), electroless deposition (ELD), chemical vapour deposition (CVD), or atomic layer deposition (ALD)) can subsequently be patterned, provided that the critical requirement for dry etching of ‘volatilization’ of the metal is fulfilled. Furthermore, it allows the integration of materials for which no ECD, ELD, CVD or ALD process is available to fill damascene trenches.In this contribution, intrinsic material properties (bulk resistivity, electromigration, ...) and composition (surface versus bulk composition as well as surface oxide) of a wide range of metals and alloys of interest to the BEOL will be compared. An overview of wet-chemical deposition approaches of a few selected metals (Cu and Rh) will be given. For ELD, the focus will be on discussing the mechanistic understanding of the intrinsically complex process, for which the stability and reactivity of the reducing agent is affected by solution pH and composition as well as the presence of oxygen. For ECD, results will be discussed for Rh and Ni, for which an electrochemical quartz crystal microbalance (EQCM) was used to quantify the amount of material deposited and interpret the various features detected in cyclic voltammograms. Metal ion solution speciation as well as stability, of importance for both deposition methods, has been studied using UV-vis spectroscopy and electrochemical characterization (linear sweep and cyclic voltammetry). Deposits were analysed morphologically using transmission electron microscopy and the chemical composition was assessed by elemental mapping.During process integration, the surface-chemical composition of metals / alloys needs to be carefully controlled, as this can, for instance, critically impact metal line resistance or result in wet etching or corrosion. A few example cases in which this is relevant will be presented, e.g. the reversible surface oxidation and reduction of Cu was studied using EQCM, the surface chemistry of NiAl was characterized using electrochemical measurements, and the reversible surface nitridation of a model metal (Mo) is demonstrated as a method to protect against unwanted metal dissolution.

On a fully three-dimensional bending analysis of very thick smart composite cube-like bulk structures

Here we discuss the behaviour of very thick composite plates considering electro-magneto-elastic coupling of various types using fully three-dimensional (3D) kinematics. Published research highlights a lack of studies on the 3D mechanics of smart composite plates that integrate both higher-order (flexoelectric/flexomagnetic) and lower-order (piezoelectric/piezomagnetic) multiple physical fields (electro-magneto-elastic). The common approach to achieving the targeted and desired mechanical behavior within such composites could involve using structural elements. This gap can potentially be addressed by amalgamating the term ∂/∂z with the 2D governing equations of plates. This expression indicates alterations in thickness, in which z is the coordinate dedicated to the thickness. The governing equations can be created by operating on the variational method which enables us to establish and settle the 3D bending equations of the bulk structure. The pointed-out equations have been influenced by the implementation of additional hypotheses, such as von Kármán’s strain and complicated 3D tensor relations. Inserting the term ∂/∂z into the mathematical model renders that the analytical solution techniques are unable to assist us in obtaining numerical results. Consequently, a semi-analytical solving method grounded on the polynomial phrases facilitates the acquisition of the required solution. This fully 3D bending study of very thick piezocomposite cube-like bulk structures (CBS) can be an original reference in the field of mechanics of intelligent plate-like structures.

New insights into the dissolution mechanisms of iron oxides and combusted iron particles in oxalic acid.

The influence of oxidation state and crystalline structure on the dissolution mechanisms of both pure iron oxides and combusted iron particles in aqueous oxalic acid (0.5 mol/l) at 60 °C was systematically investigated. Dissolution experiments were carried out in a temperature-controlled, continuous-flow capillary reactor, allowing for the removal of reaction products and thereby suppressing the autocatalytic reaction mechanism. The non-reductive dissolution of α-Fe2O3 was observed through in situ x-ray absorption measurements. In contrast, the dissolution of spinel-type oxides such as γ-Fe2O3 and Fe3O4 proceeded reductively, indicated by gradual changes in characteristic spectral features. Given that γ-Fe2O3 and Fe3O4 share a similar crystal structure but differ in the nominal oxidation state, this implies that the phase composition is decisive for the reductive dissolution. For mixed-phase particles consisting of spinel and rhombohedral phases (maghemite and hematite), the preferential dissolution of the spinel phase was observed. Despite the similar bulk composition of spinel and rhombohedral phases in the combusted iron particles (as confirmed by Mössbauer spectroscopy and x-ray diffraction analysis), dissolution predominantly follows a non-reductive pathway, with no preferential dissolution of the γ-phase. This unique dissolution behavior of combusted iron particles arises from their layered microstructure.

Kinetic instabilities in two-isotopic plasma in the gas-dynamic trap magnetic mirror

A fusion neutron source (FNS) based on the gas-dynamic trap (GDT, Budker Institute, Novosibirsk) is considered for confinement of two-species plasma heated by neutral beam injection in a regime where the fast ion distribution function is far from Maxwellian. Kinetic instabilities are expected to develop in this regime, and in this paper we investigate the ion-cyclotron instability evolving in moderate densities of pure hydrogen and mixed deuterium–hydrogen target plasmas. The properties of the studied unstable mode, such as its azimuthal wavenumbers, propagation direction and its being affected by changes in the bulk plasma density and composition, allow us to identify it as the drift cyclotron loss cone (DCLC) instability. This mode scatters fast ions and thereby leads to drops in diamagnetic flux signals and increases longitudinal energy and particle losses, with the average energy of the lost ions estimated to be far above the temperature of warm Maxwellian ions. Our interpretation is that the unstable wave grows due to interaction with the fast ions located near the loss cone in the velocity space and scatters them. Applying the method of suppressing the DCLC instability by filling the loss cone with warm plasma, we have determined the values of plasma density and deuterium percentage that allow us to suppress the DCLC instability in the GDT. These findings justify using mixed bulk plasmas in fusion neutron source operation.

Eshelby's inhomogeneity model within Mindlin's first strain gradient elasticity theory and its applications in composite materials

Eshelby's inhomogeneity problem is solved within the second form of Mindlin's first strain gradient elasticity theory for the prediction of the effective elastic properties of composites. Considering Green's function technique, an integral equation is established for an ellipsoidal inhomogeneity embedded in a homogeneous elastic medium and subjected to non-uniform boundary conditions. Within isotropic elasticity, the mean strain inside a spherical inhomogeneity is detailed to provide analytical results. In addition to the elastic properties of the inhomogeneity and the matrix, the strain localization depends on five gradient elastic constants, introduced by the first strain gradient elasticity theory. The effective bulk and shear moduli of a two-phase composite are predicted through Mori-Tanaka's scheme. The strain localization and the effective elastic moduli are then expressed within some simplified gradient elasticity theories. To test the relevance of the developed model, its predictions are compared with those of some investigations and the effective elastic properties are analyzed for a metal matrix composite. Finally, some comparisons with experimental data are performed to estimate the characteristic length scale parameters and gradient elastic constants of local phases.

Petrogenesis of lunar granulitic breccia meteorites Northwest Africa 15062 and 15063

AbstractWe present petrology and mineralogy for two lunar granulitic breccia meteorites that were detected in Northwest Africa (NWA), the samples NWA 15062 and NWA 15063. The fragments primarily consist of plagioclase and olivine mineral clasts, with minor amounts of anorthosite clasts and one troctolite clast. The anorthosite clasts are dominated by plagioclase/maskelynite, with minor olivine and pyroxene. A troctolite clast, composed of olivine and maskelynite, occurs in NWA 15063. The olivine clasts display mosaic extinction and usually have a homogeneous Mg‐rich composition. However, all olivine mineral clasts exhibit two distinct ranges of their major element composition (Mg#: 85–88 and 77–78, respectively). Large individual plagioclase clasts show heterogeneous compositions (Ab content: 2.5–4.8) and have different Raman peak positions in different domains. The matrix of the meteorites appears semitransparent and is composed of olivine and pyroxene aggregates associated with maskelynite, constituting a granoblastic texture. Pyroxenes of the matrix are dominantly enstatites, associated with a few augites. Both meteorite samples exhibit shock‐induced melt veins ranging from 50 to 200 μm width. These melt veins traverse the entire samples and contain rare, very fine‐grained (2–3 μm) Mg‐rich olivine clasts (Mg# = 90–93) and mafic silicate glass. Some Cr‐spinel grains exhibit slight compositional zonation, characterized by a magnesium‐rich core (Mg# = 56, Cr# = 23) and Cr‐rich rims (Mg# = 50, Cr# = 28), with decomposition at the edges. The significantly differing Mg# contents of the mafic silicate minerals in the matrix, lithic clasts, and mineral clasts of the two meteorites indicate a diverse origin of the clasts. Based on their petrology, mineral chemistry, and bulk composition, NWA 15062 and NWA 15063 are classified as anorthositic troctolitic granulitic polymict breccia. Textural evidence suggests that the parent rocks of NWA 15062 and NWA 15063 were affected by high pressure of up to 30 GPa during impact‐induced shock metamorphism, causing crystal structure deformation in olivine and the transformation of plagioclase to maskelynite. During cooling from peak temperatures of 1600–1700°C, the coarse‐grained maskelynite mineral clasts were partially devitrified, and the granoblastic texture of the matrix was developed. Mg‐rich anorthosite was formed before this shock event. Cr‐spinel was formed in a troctolitic melt, which was probably differentiated after the crystallization of anorthite and magnesium‐rich olivine. However, the possibility of the formation of the Mg‐rich melt through interaction with the lunar anorthositic crust cannot be ruled out. The meteorite NWA 15062/15063 strongly resembles the textural, chemical, and mineralogical characteristics of the NWA 5744 meteorite group. Therefore, we interpret the two samples as a new member of the NWA 5744 meteorite group.