Low Electrical Resistivity Research Articles

Impact of Curing Temperature and Steel Slag Aggregates on High-Strength Self-Compacting Alkali-Activated Concrete

There is a growing demand for sustainable solutions in civil engineering concerning the carbon footprint of cementitious composites. Alkali-Activated Binders (AAB) are materials with great potential to replace ordinary Portland cement (OPC), with similar strength levels and lower environmental impact. Despite their improved environmental performance, their durability remains a gap in the literature, influenced by aspects of mechanical behavior, physical properties, and microstructure. This paper aims to assess the impact of steel slag aggregates and curing temperature of a proposed AAB based concrete formulation by characterizing fresh state, mechanical behavior, and microstructure. The proposed AAB is composed of fly ash (FA) and basic oxygen furnace (BOF) steel slag (SS) as precursors, sodium silicate and sodium hydroxide solution as activators, in total replacement of OPC, using baosteel slag short flow (BSSF) SS as aggregate in comparison with natural aggregate. The concrete formulation was designed to achieve a high-performance concrete (HPC) and a self-compacting concrete (SCC) behavior. Mechanical characterization encompassed hardened (compressive strength and Young’s modulus), fresh state (J-ring, slump flow, and T50), and durability tests (scanning electronic microscopy, water penetration under pressure, and chloride ion penetration). The compressive strength (64.1 ± 3.6 MPa) achieves the requirements of HPC, while the fresh state results fulfill the SCC requirements as well, with a spread diameter from 550 mm to 650 mm (SF-1 class). However, the flow time ranges from 3.5 s to 13.8 s. There was evidence of high chloride penetrability, affected by the lower electrical resistance inherent to the material. Otherwise, there was a low water penetration under pressure (3.5 cm), which indicates a well-consolidated microstructure with low connected porosity. Therefore, the durability assessment demonstrated a divergence in the results. These results indicate that the current durability tests of cementitious materials are not feasible for AAB, requiring adapted procedures for AAB composite characterization.

Development of a mussel-inspired conductive graphene coated cotton yarn for wearable sensors.

Graphene-based flexible yarn sensors are promising due to their exceptional conductivity and user-friendly properties, but ensuring stable graphene adsorption on fibers for long-term durability remains challenging. Herein, we produce a flexible polydopamine (PDA)-modified cotton yarn via a simple dip-coating process using a self-made sodium deoxycholate (SDC)-modified graphene dispersion, avoiding non-biodegradable, corrosion-prone metallic coatings. The resulting sensor exhibits low electrical resistance (as low as 21.1Ω± 0.2/cm), high bending sensitivity (resistance change rate of 3.557± 0.002 for bending ranges from 40% to 100%), and outstanding durability over 2,000 flexural bending cycles. It can monitor various human body movements and physiological states and be integrated into wearable electronic textiles (e-textiles) for applications like monitoring knee movements, recognizing hand gestures, and detecting thoracic respiratory status. This work highlights the sensor's potential in personal and public healthcare applications.

Boosting Electrode Performance and Bubble Management via Direct Laser Interference Patterning.

Laser-structuring techniques like Direct Laser Interference Patterning show great potential for optimizing electrodes for water electrolysis. Therefore, a systematic experimental study is performed to analyze the influence of the spatial period and the aspect ratio between spatial period and structure depth on the electrode performance for pure Ni electrodes. Using a statistical design of experiments approach, it is found that the spatial distance between the laser-structures is the decisive processing parameter for the improvement of the electrode performance. Thus, the electrochemically active surface area could be increased by a factor of 12 compared to a nonstructured electrode. For oxygen evolution reaction, a significantly lower onset potential and overpotential (≈ -164 mV at 100mAcm-2) is found. This is explained by the superhydrophilic surface of the laser-structures and the influence of the structured surface on the bubble growth, which leads to a lower number of active nucleation sites and, simultaneously, larger detached bubbles. Combined with the fully wetted electrode surface, this results in reduced electrode blocking and thus, lower ohmic resistance.

Conductive Textile Embedded with Bioinspired Wettability for Prolonged and Energy Efficient Thermal Management.

The design of electrically conductive textiles appears to be a promising approach to combat the existing challenge of deaths caused by severe cold climates around the globe. However, reports on the scalable fabrication of tolerant conductive textiles maintaining a low electrical resistance with an ability for unperturbed and prolonged performance are scarce. Here, a breathable and wrappable water-repellent conductive textile (water-repellent CT) with electrothermal and photothermal conversion abilities at low external voltage and in weak solar light is introduced, respectively. In the current approach, less carbon-containing silver nanowires (AgNWs) are selected to spray deposit on a commercially available woven textile to attend a uniform and highly conductive network over a large dimension. The subsequent spray deposition of a reaction mixture of selected small molecules prevents aerial oxidation of deposited AgNWs even at elevated temperatures and provides bioinspired extreme water-repellence. Thus, it maintains an unperturbed performance even when exposed to different aqueous environment. Using the scalability of current approach and durability of prepared water-repellent CT, relevant wearable devices are derived to demonstrate personal heat management ability with rechargeable and portable battery for prolonged duration in severely cold conditions. Thus, the prepared water-repellent CT enabled an energy-efficient and "wrappable" heating, providing a basis for various potential applications.

Lattice defect engineering advances n-type PbSe thermoelectrics

Te-free thermoelectrics have garnered significant interest due to their immense thermoelectric potential and low cost. However, most Te-free thermoelectrics have relatively low performance because of the strong electrical and thermal transport conflicts and unsatisfactory compatibility of interfaces between device materials. Here, we develop lattice defect engineering through Cu doping to realize a record-high figure of merit of ~1.9 in n-type polycrystalline PbSe. Detailed micro/nanostructural characterizations and first-principles calculations demonstrate that Cu-induced interstitial defects and nanoprecipitates simultaneously optimize electron and phonon transport properties. Moreover, a robust Co/PbSe interface is designed to effectively prevent chemical reactions/diffusion; this interface exhibited a low electrical contact resistivity of ~10.9 μΩ cm2, excellent durability, and good stability in the thermoelectric module, which achieves a record-high conversion efficiency of 13.1% at a temperature difference of 460 K in segmented thermoelectric modules. This study lays the groundwork for advancing the development of Te-free selenide-based thermoelectric materials.

Features of isolation and nature of low-resistivity oil-saturated reservoirs of the Middle Jurassic deposits of the Akshabulak Central field of the South Torgai oil and gas basin

At the current stage of development of the oil and gas industry of our country, additional exploration of existing fields, understudied promising areas, identification of missed horizons, methods of evaluation and development of non-standard reservoirs are of particular relevance. Reservoirs with low specific electrical resistivity can be referred to non-standard reservoirs, and there are some difficulties in assessing hydrocarbon prospects of these reservoirs. Low resistivity reservoirs can be productive reservoirs with high residual water saturation as well as reservoirs for which generally accepted interpretation techniques are ineffective. Proper analysis of the reasons that lead to underestimation of the resistivity of productive reservoirs allows choosing the most effective interpretation methods. The article is devoted to the study of the features of reservoirs with low electrical resistivity, their nature and role in the process of fluid accumulation. The basic methods of identification of low resistivity zones in reservoir rocks, their physical and chemical characteristics that cause low resistivity, including mineralogical composition, saturation, porosity, permeability and pore space structure, are considered, and their influence on the filtration-capacitance characteristics is analyzed. Approaches to integrating data from various methods (geophysical and geological-technological studies, laboratory measurements) are described. Special attention is paid to the influence of low resistivity on the interpretation of data from geophysical methods. The results of the study have significant practical potential for optimization of field development.

Mechanical Performance and Tribological Behavior of WC-ZrO2 Composites with Different Content of Graphene Oxide Fabricated by Spark Plasma Sintering

This paper presents research on the effects of the addition of various contents of graphene oxide and sintering temperature on the mechanical, tribological, and electrical characteristics of WC-ZrO2 composites. Wet processing and spark plasma sintering provided dense samples with simultaneous reduction of graphene oxide (rGO) during sintering. The obtained results showed that the best mechanical properties were observed at a sintering temperature of 1700 °C in samples with 0.5 vol.% rGO content; namely, indentation fracture toughness (5.8 ± 0.4 MPa·m1/2) and flexural strength (872 ± 43 MPa) increased by 9% and 24.3% compared with the sample without rGO. In addition to improved mechanical performance, rGO-reinforced composites exhibited lower wear rates and friction coefficients than non-rGO composites, due to the formation of a graphitic lubricating tribolayer on worn surfaces and counterbodies in a friction pair, which provided sufficient lubrication to reduce the coefficient of friction and wear rate. The resulting composites also showed low electrical resistivity, suggesting the possibility of using electrical discharge machining to manufacture ceramic products of complex shapes from them.

Constructing O doped g-C3N4 nanosheets as photocatalysts for photocatalytic water splitting derived hydrogen isotopic water separation

The disposal of tritium-containing wastewater has been an enormous challenge because of its severe hazards to ecological environment. Due to the nearly identical physicochemical properties of hydrogen isotopes, the present disposal methods usually deliver low separation efficiency and high energy-intensive. Herein, photocatalytic water splitting has been firstly carried out to separate hydrogen isotopic water through the hydrogen evolution processes. The O doped graphitic carbon nitride (OGCN) as photocatalyst delivers a competitive separation factor of 4.69 with a gas evolution rate of 6.511 mmol g−1 h−1. The OGCN samples show lager surface area and abundant O dopants after the thermal oxidative etching, thus boosting the diffusion of photogenerated charge carries and delaying the recombination of photogenerated hole-electrons. The separation of hydrogen isotopes is mainly attributed to the kinetic isotope effect and the difference of bond energy between H2O and D2O. The electrochemical impedance spectra imply a lower electrical resistance of H2O than that of D2O, leading to a faster migration rate of charge carriers in H2O solution.

Lignin-coated liquid metals-induced synthesis of deep eutectic solvent-based hydrogels with environmentally tolerant for strain sensors

In the work, alkali lignin (AL) was used as a coating layer for dispersing liquid metals (LM) in a ternary DES (choline chloride/ethylene glycol/water) system and generating free radical-catalyzed acrylic acid (AA) polymerization. The preparation of flexible sensors had high electrical conductivity (0.33 S·m-1), excellent self-healing and mechanical properties (84.7 KPa). The presence of AL facilitated the dispersion of LM in the DES system and the formation of a flexible hydrogel without the addition of an initiator. Moreover, DES was used as the liquid component of the PAA-AL2@LM2 hydrogel made it more environmentally tolerant and had better water retention. Even at -20 °C, the hydrogel exhibited low electrical resistance (131.4 Ω). The moisture loss of the prepared hydrogel was only 9% after 7 days at room temperature. This work exploited the significant advantages of DES and lignin-based materials in dispersing LM to provide a new technique for the preparation of metal-polymer composite hydrogels, which has great potential in the field of flexible sensors.

Insightful database-driven prediction and sensitivity analysis of electrical resistivity of nano-graphite-modified cementitious composites: a supervised machine learning regression

This study presents a novel approach to assessing electrical resistivity (ER) in nano-graphite-modified cementitious composites, a key factor for enhancing their durability and integrity. This innovative framework establishes a new paradigm in the application of ML to material science, highlighting the ability to bridge experimental and computational methods for more reliable and efficient outcomes. Leveraging a dataset of 539 cement-based materials, advanced machine learning (ML) techniques were applied, including the extremely randomized trees (XRF) algorithm, which outperformed traditional models with minimal error metrics (MAE: 37.093, MSE: 4992.581, RMSE: 8.406). The integration of Shapley’s additive explanations (SHAP) analysis further highlights the novelty of this work, revealing testing protocol (MM), ultrasonication time (SN), and graphene dosage (GN) as the most significant factors influencing ER. Longer SN times and higher GN doses reduced ER, while smaller graphene particles (2µm) increased it. Additionally, the water-to-binder (W-B) ratio and sand-to-cement (S-C) ratio showed peak ER values at 0.47 and 2.8, respectively. The four-probe method and lime-water curing produced more reliable and lower ER values compared to other methods. This data-driven methodology offers unprecedented insights into the complex interactions between material properties and ER, providing a powerful tool for optimizing composite formulations. Future research may focus on scaling this approach to larger datasets, investigating the long-term durability of composites, and refining ultrasonication techniques for better graphene dispersion.

Regulating Molybdenum Dissolution through Controlled Oxide Phase Formation in CMP with Catalytic Oxidation

Molybdenum (Mo) is a promising candidate for replacing tungsten in next-generation semiconductor processes due to its lower electrical resistivity and superior gap-filling capabilities. Despite its properties, the high dissolution of Mo during chemical mechanical planarization (CMP) leads to surface deterioration and device failure, limiting its practical application.Mo CMP, like other metal CMP, uses hydrogen peroxide (H2O2) to form and then remove metal oxide layers. However, H2O2 is a strong oxidant at a commonly used pH, and thus soluble Mo (Ⅵ) oxide (i.e., MoO3) formation cannot be avoided. One of Mo's oxides, MoO3, has a solubility of 4.9-70 g/L at room temperature, and Mo film reacts with H2O2 to form it in a chain. Excessive oxidation of Mo results in defects such as Mo dissolution and local corrosion during the CMP process, affecting the performance and reliability of the device.We control the formation of Mo oxide phases, affecting the dissolution properties of Mo, by modulating the activity of the oxidant and catalyst. Catalytic oxidation with Fe ion catalyst and H2O2 oxidant promotes the formation of the insoluble MoO2 and Mo2O5 phases while reducing the formation of the soluble MoO3 phase. With catalytic oxidation facilitated by Fe ions, during CMP, the removal rate of Mo increased from 780 to 1500 Å/min, and the dissolution rate decreased from 636 to 57 Å/min. In addition, surface roughness (Rq) also decreased from 3.38 to 0.35 nm. These results indicate that the improvement in Mo CMP performances could be achieved by employing Fe ions in catalytic oxidation.

Self-Supported Transition Metal Based-Textile Electrodes through Interfacial Assembly for Overall Water Splitting in Alkaline Media

Water splitting holds significant promise for sustainable hydrogen production without carbon emissions. To develop electrodes suitable for large-scale hydrogen generation, characteristics such as large surface area, low electrical resistance, high electrocatalytic activity, and enduring operational stability are paramount. In our investigation, we've engineered high-performance water-splitting electrodes (WSEs) with exceptionally low overpotentials and robust stability through a process integrating carbonization and interfacial assembly-induced electrodeposition. These electrodes feature high-quality electrocatalytic structures based on transition metals (Ni, Fe, and Co), facilitated by strong electronic interactions. They exhibit low sheet resistance akin to bulk metals, a porous 3D architecture with ample specific surface area, and robust interfacial adhesion between the textile-based support and electrocatalysts. Our methodology begins with textiles, transformed into hydrophilic conductive substrates via carbonization and acid treatment, with additional amine molecule incorporation to enhance support-electrocatalyst interactions. Notably, our hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrodes demonstrate extremely low overpotentials (12 mV at 10 mA cm−2 for HER, 186 mV at 50 mA cm−2 for OER) under alkaline conditions. Furthermore, our full-cell electrodes exhibit sustained water-splitting activity at diverse current density from 10 to 2000 mA cm−2 for at least 2100 hours in 1 M KOH solution. We anticipate that our methodology lays a foundational framework for the development of commercially viable, high-performance WSEs.

Macroscopic Access Resistances Hinders the Measurement of Ion-Exchange-Membrane Performances for Electro-Dialysis Processes

Ion exchange membranes (IEMs) are widely used in industrial sectors from batteries and energy harvesting, to water treatment and desalination. They are designed with a high selectivity and a low electrical resistance. However, the way to measure such performances independently from interpretation and device parameters (geometrical sizes, water flux, electrodes, measurement type, etc.) remains a challenge. Therefore, many performances announced in the current literature are not reliable. This study focuses on membranes prepared for reverse electro-dialysis applications, but could be generalized to other membrane based processes.Due to the rising energy demand and the severe environmental crisis, worldwide reduction of conventional fossil fuel consummation is needed. As a renewable and clean energy resource, the Blue energy is an osmotic energy released during the mixing of solutions of different salinity. Naturally, an irreversible mixing of river water and sea water happens at the estuary. A precise and engineering control of this mixing enables the blue energy harvesting. The worldwide salinity gradient energy could reach 70 GW, which is not negligeable.Since the beginning of blue-energy harvesting research, a lot of advances have been made about membrane design and nanofluidic diffusio-osmotic transport, but the efficiency gap of 6 orders of magnitude between nano-scale designs and industrial power plants remains unsolved.Just after synthesis, selective membranes are benchmarked on very small samples on the basis of the output power. It is usually calculated based on the membrane resistance per unit area, and the measured Donnan potential. This method of power per unit area based on membrane resistance is therefore a key point to compare several devices and their efficiency.A classical electrochemical cell has been used to place a Nafion selective membrane of varying area between two electrodes. The membrane resistance and power density have been experimentally measured. Homogeneous salt concentration or gradient of concentration have been used to measure different parameters.This systematic study shows that for classical measurement cells, the membrane resistance is inversely proportional to the square root of its area. Whereas it's currently assumed in the literature that the resistance and the area of a membrane are inversely proportional. Based on this assumption, the power density is believed to be independent of the membrane area (reason why it is used as a comparison criteria), which we prove to be wrong. This result has a big impact on the reliability of the power density announced in the literature for different devices: the smaller the area of the tested membrane the higher is the output power density: from 0,5 W/m² up to 150 W/m² for the same membrane, same salt ratio (100) different membrane areas. This leads to overly optimistic extrapolation of electrical performances for membranes engineered and tested at sub millimeter sizes that will be industrially used at meter sizes.To explain these results, we show that for small membranes (compared to the electrode size and distance) there is an access resistance at the scale of the membrane. It results that the area mismatch between the membrane and the electrodes add a new resistance in the system that does not scale with the membrane area and that is taken into account in membrane characterizations. Experimental data and theoretical modeling are corroborating without any adjustment parameters.Consequently, the power per unit area obtained at micro scale cannot be extrapolated a priori to larger membranes. So, the comparison is biased between large scale commercially available membranes, and nano-engineered microscale membranes. This raises the urgent need for new indicators or standard measurement protocols.Based on these conclusions, we formulate a few recommendations to perform scalable and meaningful measurements of membrane resistance and power density.

Controlling Surface Morphology of Electrodeposited Sn-Bi through Additives

Establishing robust electrical connections between chips is crucial in semiconductor packaging structures to manufacture high-performance electronics. Microbumps and low-temperature solders have become preferred alternatives to conventional metal wiring processes, aiming to enhance electronics integration. Microbumps, typically made of Cu for its low electrical resistivity, play a vital role in facilitating efficient electrical connections. Meanwhile, a commonly used solder material is Sn-Ag. However, traditional thermo-compression (TC) bonding utilizing Cu pillars and Sn-Ag solder typically requires temperatures around 230-250°C, raising concerns about stability in the bonding system. The high temperatures involved in the bonding process can lead to wafer warpage due to the different thermal expansion coefficients of front and backside wafer, resulting in the misalignment of bonding wafers that significantly impact yield management and electronic performance. This limitation is one of the hurdles for the fabrication of sub-micrometer pitch interconnections using microbumps and solder. Hence, reducing bonding temperature is imperative, and low melting temperature solder materials like Sn-Bi offer a solution. Sn-58 wt% Bi, for instance, boasts a promising melting temperature of approximately 139°C, significantly lower than Sn-3.5 wt% Ag (~221°C). Despite its potential advantages, the electrodeposition process for Sn-Bi is still in its developmental stages compared to Sn-Ag. To mitigate defects at the bonding interphase, it is crucial to develop an electrodeposition technique capable of producing smooth Sn-Bi films with uniform distributions of Sn and Bi atoms. This study aims to investigate the impact of various additives on manipulating the surface morphology of Sn-Bi films, exploring the effects of electrolyte composition, current density, and the type and concentration of additives on Sn-Bi electrodeposition.

Developing Routes for 3D Printed Carbon Aerogel Electrodes

Aerogels are porous solids used in a number of electrochemical applications including catalysis, batteries, and supercapacitors due to their high internal surface, composition, and small pore/particle size. Carbon electrodes (e.g. nanotubes, graphene, etc.) are particularly attractive due to their low electrical resistance. The efficient transport of charged species within energy storage devices, in particular, is critical to realizing both high power and energy densities, especially when operating under extreme conditions (e.g. ultralow temperatures, high charge/discharge rates, etc.). A number of resistances can contribute to sluggish ion/electron transport in a cell such as charge transfer at interfaces, electrolyte resistance, electrode resistance, and diffusive transport within porous electrodes. Several strategies have been pursued to address these transport limitations. Electrode materials discovery and development is a popular strategy as the charge storage mechanism and electrode resistance play a key role in kinetics of the device. Within electrode materials development, engineering of the electrode pore architecture is an extremely effective strategy to decrease the diffusive transport lengths and electrode resistances. This pore engineering can be achieved through synthetic chemistry for small pores (e.g. <10 um) and via additive manufacturing for larger pores (> 10 um). Here we show how electrode materials development can be used to overcome sluggish transport in aerogel-inspired electrodes. Particular focus will be given to the use of synthetic means to tune to the properties of electrode material (e.g. surface area, pore size, mechanical properties) and 3D printing to define the larger pore structure to improve the ultimate performance of the device. We explore a number of additive manufacturing techniques (e.g. direct ink write, projection microstereolithography, etc.) to print a variety of simple and complex structures to determine the optimal electrode architecture. The impact of these different methods on both aerogel properties and device function will be discussed.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

(Invited) Advanced Plated Cu Metallization for Hybrid Bonding and 3D Interconnects

Semiconductor packaging has been developed to meet the requirement of high-density input/output terminals and downsizing. For further high performance and functionality, the research and development on System in Package (SiP), which achieves interconnection between heterogeneous devices in a package, goes on. There are various packaging configurations suggested, such as 2.1D SiP and 2.3D SiP using organic substrates, 2.5D SiP using Si substrates with TSV, and 3D SiP using TSV with microbump or Cu-SiO2 hybrid bonding [1][2][3]. Hybrid bonding using Cu-Cu direct bonding technology is gaining greater momentum owing to its ability to form the ultra-scaled interconnection at much reduced pitches below 5 µm. While improving the quality of Cu-Cu bonding plays a critical role in enhancing the performance of 3D SiP, reducing the resistance of Cu-Cu junctions is one of the most important strategies. Therefore, the additive chemistry for plated Cu plays a significant impact in advanced 3D packaging.In our recent study, we succeeded in making large Cu grain at low temperature, which shows good physical properties by controlled Cu grain size and orientation We defined plating solution A as the low crystal growth process and solution B as the high crystal growth process. Fig.1 shows the SIM images of the cross-section of Cu pretreated with FIB; it was indicated that Cu film plated with solution A shows a grain size under 2 µm, while solution B shows a grain size over 5 µm. Plated Cu with large grains showed high electrical conductivity and thermal conductivity. We concluded that the results are due to the large Cu grains exhibited less grain boundary than polycrystalline Cu having various orientations; therefore, the large grains are appropriate as an interconnecting material [4]. Additionally, we applied the large Cu grains to Cu-SiO2 hybrid bonding and confirmed quite low electrical resistance. We demonstrated that the interface of Cu bonding plated with solution B showed large Cu grains, and Cu crystal orientation of the top and bottom are identical compared with solution A.On the other hand, it is also important to control oxidation since copper oxide film is expected to affect electrical properties in Cu-Cu direct bonding. Therefore, we have investigated the dominant factors that affect the oxidation of plated Cu. Generally, the oxidation reaction of Cu first produces the monovalent Cu ion Cu+, which undergoes CuOH to form a cuprous oxide Cu2O film on the Cu surface. When exposed to an oxidizing environment, cupric oxide CuO is grown. The thickness of copper oxide film formed after annealing at 150 degrees Celsius for 1 hour was measured by the sequential electrochemical reduction analysis (SERA) method, which is capable of distinguishing CuO and Cu2O. Consequently, the copper oxide film grown after annealing mainly consisted of Cu2O, and we have confirmed that the thickness of Cu2O was highly related to additive factors such as concentration and molecular weight. For instance, it was increased logarithmically with increasing molecular weight of polyethylene glycol (PEG), a commonly used suppressor in acid plating solution. The concentration of the brightener showed a proportional relationship to the thickness of Cu2O, and the charge density of the levelers was one of the most significant factors affecting the oxidation of plated Cu among the factors examined in this study. Further evaluation of how additives in the plating solution affect oxidation and its applications, such as Cu-Cu bonding, will be presented at the conference.

Simulation of Voltammetric Measurements of Uranium Electrodeposition in Molten LiCl-KCl Eutectic

The electrochemical behavior of uranium in high-temperature molten salts is central to the development of advanced nuclear reactors (e.g., molten salt reactors) and reprocessing technologies (e.g., pyroprocessing). Numerous studies have been performed on uranium in molten salts, especially LiCl-KCl eutectic. However, many studies rely on models, such as Berzins-Delahay model, which assume mass transfer by diffusion only and a pure deposit (i.e., unit activity for the reduced species).1 In many situations, these assumptions may not be appropriate for analyzing electrochemical data in molten salts and may introduce significant error in the estimation of properties, such as diffusion coefficients. For example, a foreign substrate, such as tungsten or molybdenum, is often used as the working electrode in electroreduction of uranium ions to metal in molten salts. Hence, nucleation effects and incomplete coverage of the WE can affect measurements, especially at dilute concentrations. Additionally, macro electrodes are often used in molten salts due to a lack of compatible insulating material for construction of microelectrodes. This results in large currents which can introduce significant ohmic losses despite the relatively low ohmic resistance of molten salts. Furthermore, additional effects, such as migration and natural convection, can significantly impact electrochemical measurements in molten salts containing a heavy analyte, such as uranium ions.To address these challenges, a model was developed specifically for electrodeposition in molten salts based on the Nernst-Plank equation, Nernst equation, adsorption isotherms, and activity models. The initial iteration of the model has been designed to account for the combined effects of diffusion, migration, ohmic resistance, deposition onto a foreign substrate, and activity of non-ideal solutions. The significance of each effect and combination of effects has been examined for linear sweep voltammetry at various uranium ion concentrations and scan rates. Furthermore, the model has been validated against uranium electrodeposition measurements on a tungsten WE in molten LiCl-KCl eutectic.1. T. Berzins and P. Delahay, J. Am. Chem. Soc., 75, 555–559 (1953) http://dx.doi.org/10.1021/ja01099a013.

Enhanced Performance and Durability of Ruddlesden-Popper Oxide Anodes Decorated with Fe Nanoparticles for Direct Ammonia-Fed Solid Oxide Fuel Cells

Direct ammonia-fed solid oxide fuel cells (DA-SOFCs) efficiently convert ammonia into electricity, aligning with the necessary temperatures for thermal decomposition of ammonia. However, challenges such as nitridation of anode metal catalysts and decreased cell durability hinder further development. To address these issues, this study explores the partial substitution of Sr with Ba at the A-site of the Ruddlesden-Popper (RP) structure, enhancing the structure's mixed ionic and electronic conductivity (MIEC). This modification aims to improve ammonia's thermal decomposition and the overall electrochemical performance of SOFCs. Incorporating Ba modifies the RP crystal lattice to facilitate metal nanoparticle exsolution and increase basicity, crucial for enhancing nitrogen recombination and desorption during ammonia decomposition. This adaptation helps maintain active catalyst sites and improves durability against nitridation. The study focuses on in-situ exsolution of Fe nanoparticles (NPs) and partial Ba substitution, both of which enhance not only catalytic and electrochemical performance but also durability under operating conditions.Advanced characterization methods, including X-ray diffraction complemented by Rietveld refinement and high-resolution electron microscopy, elucidate the lattice changes and phase transitions induced by Ba. These modifications promote the exsolution of Fe NPs, pivotal for enhancing electrochemical performance. Electrochemical assessments show that the new Fe NPs exsolved La1.2Sr0.4Ba0.4Mn0.4Fe0.6O4- δ (R-LSBMF) anode material achieves nearly 100% ammonia decomposition conversion at 650oC and sustains this activity over time, demonstrating its durability. The in-situ reduced LSBMF mixed with GDC (Ce0.9Gd0.1O2) as a DA-SOFC anode shows a maximum power density (MPD) of 1.019 W cm-2 and significantly low ohmic resistance (0.154 Ω cm²) at 800 oC.This research advances the understanding of elemental substitution in anode materials and underscores the potential of Ruddlesden-Popper phase perovskites for high-efficiency, durable DA-SOFCs. It also enhances the prospects for ammonia as a viable fuel for SOFCs, driving the technology toward sustainable, eco-friendly energy solutions. Therefore, the outstanding catalytic and durability features of the R-LSBMF anode material open paths for commercializing DA-SOFCs, which is essential for addressing environmental challenges. Figure 1

PEEK-Reinforced Sulfonated Poly(phenylene sulfone)-Membrane for Water Electrolysis with Lower Gas Crossover and Lower Resistance Than N115

Fluorine-free hydrocarbon polymers have the potential to be more environmentally friendly and cost-effective than current perfluorinated sulfonic acids (PFSA). These hydrocarbon polymers have a unique morphology that reduces gas transfer while maintaining high proton conductivity, making them a promising alternative to PFSA membranes in water electrolysis.[1] In an initial study, we demonstrate the potential of hydrocarbon membranes in electrolyzers using sulfonated polyphenylene sulfone (sPPS).[2] However, to achieve good performance, a high ion exchange capacity (2.17 - 3.57 meq/g) is required. This results in a high water uptake, which leads to membrane softening and detachment of the electrodes. In addition, excessive swelling makes upscaling, i.e., coating of the electrodes directly onto the membrane, impossible. To solve this problem, we have integrated a woven, open-mesh PEEK substrate (Fig.1, right).[3] The reinforced membrane shows a significant enhancement in the mechanical robustness and dimensional stability of the membrane, which leads to a strong reduction of water uptake from 294% to 115%. This allows direct casting of electrodes onto the membrane, an essential step for scaled production. Moreover, the reinforced membrane demonstrates a significantly lower electrical resistance of 70 mΩ cm² (versus 159 mΩ cm² for Nafion), attributed to its reduced thickness (74 µm compared to 127 µm) and higher ion exchange capacity. At the same time, the crossover is also strongly reduced as displayed in Figure 1. This leads to a better figure of merit, given by the ratio of conductivity to permeability, as shown in Figure 1 (right bottom), where crossover current densities are plotted over the high frequency resistance.[3] Figure 1Illustration of the casting Process of the reinforced membrane and fabrication of a one side coated CCM (left). IV-curve of the PEEK-sPPS membrane and a Nafion 115 reference (top right) and the figure of merit for PEEK-sPPS and two reference membranes (N115 and N212). Literature: [1] Miyake, J.; Taki, R.; Mochizuki, T.; Shimizu, R.; Akiyama, R.; Uchida, M.; Miyatake, K. Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells. Sci. Adv. 2017, 3(10), eaao0476. DOI: 10.1126/sciadv.aao0476[2] Klose, C.; Saatkamp, T.; Münchinger, A.; Bohn, L.; Titvinidze, G.; Breitwieser, M.; Kreuer, K.; Vierrath, S. All‐Hydrocarbon MEA for PEM Water Electrolysis Combining Low Hydrogen Crossover and High Efficiency. Adv. Energy Mater. 2020, 10 (14), 1903995. DOI: 10.1002/aenm.201903995[3] Qelibari, R.; Cruz Ortiz, E.; van Treel, N.; Lombeck, F.; Schare, C.; Münchinger, A.; Dumbadze. N.; Titvinidze, G.; Klose, C.; Vierrath, S. 74 µm PEEK-reinforced sulfonated poly(phenylene sulfone)-membrane for stable water electrolysis with lower gas crossover and lower resistance than Nafion N115. Adv. Energy Mater. 2023, 14 (5), 2303271. DOI: 10.1002/aenm.202303271 Figure 1

Characterization of Cu and SiCn Surface for Hybrid Bonding

The miniaturization of integrated circuits (ICs) comes with many challenges caused by R&D costs, physical constraints, and connectivity bottlenecks. Consequently, 3D integration and chiplet have gained a lot of interest as an alternative technique to address such problems. It is expected to offer reduced wire lengths for interconnects, low power consumption, and heterogeneous integration capabilities, among other benefits [1]. 3D integration and chiplets require high-density, and fine-pitch interconnects, which make the conventional solder bumps, commonly used as a bonding technique, face reliability issues. Thus, Cu–Cu direct bonding has emerged as a promising bonding method [1-3]. Compared to conventional solder base interconnects, direct Cu-Cu bonding offers the advantages of significantly lower electrical resistivity, ultra fine-pitch (high density), and lower electromigration. Direct bonding interconnection (DBI) is one of the technologies used for hybrid bonding, which combines a dielectric bond with a Cu-Cu bond (metal bond).The Cu pads, for hybrid bonding, are created by the electrochemical deposition (ECD) method. After the Cu deposition, reducing the roughness and cleaning the Cu surface prior to the bonding process is necessary to achieve high yield and reliability [4]. Therefore, surface planarization is a key factor for Cu-Cu hybrid bonding, and chemical mechanical polishing (CMP) using a chemical slurry can flatten and decrease the roughness of Cu surfaces [2]. However, CMP slurries contain chemical species, such as oxidizers, chelating agents, corrosion inhibitors, surfactants, and pH adjustors that need to be removed by applying a post-CMP (P-CMP) process [5]. For instance, if BTA (common corrosion inhibitor) remains on the Cu surface after the P-CMP process, it might inhibit Cu interdiffusion during hybrid bonding, which may require a high post-bond annealing temperature [6]. P-CMP process has shown that it can remove the contaminants through the cleaning process, plasma activation, and DIW rinsing before hybrid bonding [6].This work aimed to evaluate pre and post-CMP surfaces for Cu-SiCN hybrid bonding. Alkaline and Acidic cleaning agents were investigated. Fig 1(a) and (b) show the Open Circuit Potential (OCP) data of the Cu surface when an acidic and an alkaline solution was used as a cleaning agent, respectively. In the alkaline solution, Post-CMP Cu and Oxidized Cu samples showed a decreased response over time until they achieved a steady state, progressing to the Pure Cu values. It suggests that the Pure Cu surface did not show CuO film growth, hence, demonstrating a better cleaning potential than the acidic solution. Cu surface before and after the cleaning process was analyzed by X-ray photoelectron spectroscopy (XPS). The organic residue, BTA, could be removed from the surface after the cleaning process by PVA brush using the alkaline solution, though there were remaining residues after cleaning with the acidic solution. The effect of plasma activation was analyzed in order to reduce the removal of Cu residues, as well. On top of the above mentioned, we will analyze the different Cu types for corrosion inhibition. Figure 1