Multilayer ceramic batteries (MLCBs) have attracted increasing attention as compact all-solid-state energy-storage devices that can be manufactured using multilayer ceramic processing technologies. In this study, an MLCC-compatible fabrication process for oxide-based MLCBs was developed using Li₁₊ₓAlₓTi₂₋ₓ(PO₄)₃ (LATP) solid electrolytes, Li₃V₂(PO₄)₃ (LVP) cathodes, and Cu current collectors. Commercial LATP powders were evaluated in terms of particle-size distribution, phase purity, thermal stability, and ionic conductivity. The selected LATP powder was subsequently employed for tape-cast green-sheet fabrication, and the effects of polyvinyl butyral (PVB) binder content on slurry rheology and sheet microstructure were investigated. An optimized binder composition containing 11 wt% PVB (BM-2/BH-3 = 3:7) provided improved processability and microstructural uniformity. Drying conditions during sequential electrode printing were also optimized to suppress sheet warpage and improve multilayer registration. Thermogravimetric and differential thermal analyses (TG–DTA) were used to establish an optimized two-step debinding and co-firing process under a controlled reducing atmosphere. The resulting multilayer structures exhibited uniform densification without significant blistering, delamination, or interfacial defects. Charge–discharge measurements confirmed that electrochemical functionality was retained after the complete manufacturing process, yielding a discharge capacity of approximately 2.5–2.7 μAh.

The 0.2Pb(Zn_1/3Nb_2/3)O₃-0.8Pb(Zr_0.5Ti_0.5)O₃ (0.2PZN-0.8PZT) ceramic system exhibits excellent piezoelectric properties; however, its high sintering temperature (~1,250°C) causes severe PbO volatilization, increases processing cost, and limits co-firing with low-melting-point electrodes in multilayer devices. In this study, LiBiO₂ was introduced as a sintering aid to enable lowtemperature densification of 0.2PZN–0.8PZT ceramics. The optimal composition of x = 0.3 mol% sintered at 1,050°C achieved d₃₃ = 367 pC/N, k_p = 0.54, and ε^T₃₃/ε₀ = 1,643. The Curie temperature was also enhanced to 347.8°C, compared with 297.2°C for the reference specimen sintered at 1,250°C. These results demonstrate that LiBiO₂ addition enables a 200°C reduction in sintering temperature while maintaining piezoelectric performance and improving thermal stability.

In this study, we systematically investigated the effects of thermal atomic layer deposition (ALD) conditions on the electrical characteristics of conductive-filament-based volatile threshold switching memristors with a Pt/Al₂O₃/Ag structure. Although volatile threshold switching memristors have attracted significant attention for neuromorphic computing applications such as spiking neural networks, the impact of dielectric deposition conditions on their switching behavior remains relatively unexplored. The number of ALD cycles was varied from 40 to 200, and the deposition temperature was varied from 50 to 250°C to evaluate their effects on threshold voltage (V_th), off-state resistance (R_off), and device yield. Devices fabricated using 75–150 ALD cycles showed clear volatile threshold switching behavior with relatively high device yield, whereas excessively low or high cycle numbers resulted in short-type and open-type failures, respectively. In addition, V_th and R_off tended to increase at higher deposition temperatures, while the device yield significantly degraded above 150°C. These results indicate that the number of ALD cycles and the deposition temperature define a critical process window for achieving volatile threshold switching while suppressing both short-type and open-type failures. This study provides practical guidelines for optimizing dielectric ALD conditions in conductive-filament-based volatile threshold switching memristors for future neuromorphic hardware applications.

The phase transition of Li₃PO₄ solid electrolyte for secondary batteries in vacuum has been studied by using real-time synchrotron X-ray scattering. According to the vacuum heating results, the crystal β-Li₃PO₄ phase was stable only from room temperature to 400°C. The crystal γ-Li₃PO₄ phase appeared at 410°C and the crystal β-Li₃PO₄ phase completely disappeared at 430°C. The transition from the β-Li₃PO₄ to the γ-Li₃PO₄ phases occurred primarily at 410°C, which is 40°C lower than the transition temperature of 450°C in air. The decrease in the phase transition temperature in vacuum, compared to that in air, is attributed to a relatively high concentration of oxygen vacancies. As the isothermal annealing time at 390°C was increased to 8 hours, the β-Li₃PO₄ phase was completely transitioned into the γ-Li₃PO₄ phase. Our study revealed the detailed transition behavior from the β-Li₃PO₄ to the γ-Li₃PO₄ phases during real-time annealing in vacuum.

The effects of BaZrO₃ addition on the structural and electrical properties of BaTiO₃-based base-metal-electrode (BME) multilayer ceramic capacitor (MLCC) ceramics were investigated. Dielectric compositions containing 0–9 wt% BaZrO₃ were fabricated using a conventional MLCC process, and their crystal structure, dielectric behavior, temperature stability, frequency stability, and insulation resistance were evaluated. X-ray diffraction and Rietveld refinement confirmed the formation of a single-phase perovskite structure for all compositions. Increasing BaZrO₃ content resulted in a systematic shift of diffraction peaks toward lower angles and an increase in unit-cell volume from 64.61 to 66.05 ų, indicating successful Zr incorporation into the BaTiO₃ lattice. The dielectric permittivity increased with BaZrO₃ addition and reached a maximum value of approximately 2,110 at 6 wt%, while dielectric loss decreased significantly. Capacitance stability against temperature and frequency variations was markedly improved with increasing BaZrO₃ content. In addition, insulation resistance increased substantially over the investigated temperature range, demonstrating enhanced electrical reliability.

Smart windows capable of dynamically controlling light transmission are gaining increasing attention as a means of reducing building energy consumption while improving indoor comfort. However, indium tin oxide (ITO), the most widely used transparent electrode in such devices, suffers from poor mechanical flexibility due to its intrinsic brittleness, limiting its use in curved or flexible window applications. Here, we demonstrate a flexible ITO/DPP hybrid transparent electrode, fabricated by depositing a dimethyl sulfoxide (DMSO)-doped PEDOT:PSS (DPP) layer on ITO, that achieves markedly improved bending durability while maintaining electro-optical performance comparable to bare ITO. The hybrid electrode with an optimized DPP thickness of 120 nm exhibited a sheet resistance of 23.3 Ω/sq., about 20% lower than that of ITO (29 Ω/sq.), while maintaining comparable visible-range transmittance. A polymer-dispersed liquid crystal (PDLC) device fabricated with this electrode showed only a slight decline in driving voltage and transmittance relative to ITO. Notably, its resistance change under repeated bending at a curvature radius of 30 mm was only 25.1%, less than half that of ITO (51.6%). These results suggest that the ITO/DPP hybrid electrode is a promising candidate for transparent electrodes in curved and flexible smart windows and other flexible optoelectronic devices.

We have studied the thermal stability of NCM622 cathode material for Li-ion batteries using real-time synchrotron x-ray scattering below 600°C in both air and vacuum. The expansion of the mean particle size, which reached maximum values of 10.3 μm in air and 10.6 μm in vacuum at 200°C, was attributed to the dehydration of intergranular water within the NCM622 powders. Across all annealing temperatures, the amount of crystal NCM622 phase in air was consistently higher than that in vacuum. The crystal domain sizes in air showed less variation than that in vacuum during annealing from RT to 500°C. These indicate that the crystal NCM622 phase is more thermally stable during annealing in air than in vacuum. This stability is attributed to the presence of 21% oxygen in air, which is absent under vacuum conditions.

The direct utilization of steelmaking by-product gases in solid oxide fuel cells (SOFCs) offers a promising pathway to improve energy efficiency and reduce carbon emissions in the steel industry. In this study, a Sr-deficient and Ni-doped double perovskite oxide, Sr_1.95Fe_1.35Ni_0.15Mo_0.5O_6-δ (SFNM), was investigated as an anode material for direct Linz-Donawitz converter gas (LDG)-fueled SOFCs. A single-phase double perovskite structure was successfully obtained after calcination at 1,200°C for 12 h, while exsolved metallic Ni nanoparticles were generated on the SFNM surface after reduction at 800°C. Electrochemical performance was evaluated using H₂, simulated-LDG, and CO/CO₂ (85:15) fuels at 800°C. The maximum power densities achieved were 1.23, 0.70, and 0.40 W cm^-2 for H₂, simulated-LDG, and CO/CO₂ fuels, respectively. Although CO-containing fuels exhibited lower opencircuit voltages and power outputs than H₂, the SFNM anode maintained stable operation and appreciable performance under direct simulated-LDG utilization. Impedance analysis revealed that the increased polarization resistance in simulated-LDG and CO/CO₂ atmospheres was mainly associated with fuel adsorption/desorption and gas diffusion, while interfacial charge-transfer resistance remained relatively small. The superior performance obtained with simulated-LDG compared to the CO/CO₂ mixture was attributed to the presence of a small amount of H₂, which facilitated anode reaction kinetics. These results demonstrate that SFNM is a promising mixed ionic-electronic conductor anode for the direct electrochemical conversion of CO-rich steelmaking by-product gases into electricity.

Wearable temperature sensors are becoming increasingly important for continuous health monitoring, personalized healthcare, and biointegrated electronic systems. However, conventional temperature-sensing platforms often suffer from limited thermal sensitivity, insufficient mechanical compliance, and unstable performance under repeated deformation, making it difficult to detect subtle physiological temperature variations in real time. Here, this tutorial status report presents a fabrication strategy for highly sensitive wearable temperature sensors based on gold-doped crystalline silicon nanomembranes. Gold diffusion into crystalline silicon introduces deep-level impurity states that modulate the Fermi level and shift the freeze-out region toward the physiological temperature range, enabling an ultrahigh negative temperature coefficient of resistance. By integrating the gold-doped silicon nanomembrane with a polyimide-supported ultrathin platform, neutral mechanical plane design, and serpentine mesh interconnects, the resulting device can provide high thermal sensitivity, fast response, conformal skin attachment, and stable operation under mechanical deformation. This fabrication approach is expected to broaden the use of impurity-engineered silicon nanomembranes in next-generation wearable sensors, flexible bioelectronics, and multifunctional healthcare monitoring systems.

Renewable energy harvesting technologies, which convert ambient resources such as wind into electrical energy, have attracted significant attention as sustainable power sources for self-powered systems. However, the long-term applicability of wind energy harvesters in remote or extreme environments has not yet been fully discussed, particularly in terms of structural robustness and environmental adaptability. In this study, we designed a double-clamped flutter-type triboelectric generator (DFTEG) for efficient wind energy harvesting and evaluated its output performance under various simulated outdoor conditions. The DFTEG features a modular acrylic frame with a magnet-based assembly for easy maintenance and film replacement, utilizing PTFE films and aluminum electrodes to maximize the charge density difference according to the triboelectric series. Structural optimization revealed that a single-film configuration with a length of 110 mm produced the most stable flutter vibration and a large effective contact area, achieving a maximum open-circuit voltage of 42.28 V and a short-circuit current of 2.89 μA. Furthermore, performance evaluations under various environmental variables, including relative humidity, temperature, and sand particles interference, confirmed consistent electrical output across diverse environmental conditions. These results demonstrate the potential of the proposed DFTEG as an environmentadaptive independent power source capable of stable operation under complex environmental factors.

With the rapid expansion of electric vehicles (EVs) and energy storage systems (ESS), ensuring the operational safety of lithium-ion batteries has become a critical technical challenge. Conventional battery management systems (BMS) primarily rely on threshold-based rule logic, which is limited in detecting coupled anomalies and early-stage degradation patterns. In this study, a deep learning-based framework for multivariate anomaly detection is proposed using BMS sensor data, including voltage, current, temperature, state of charge (SOC), and state of health (SOH). Five representative fault scenarios were defined, including thermal runaway precursors, cell voltage imbalance, SOC inconsistency, internal resistance increase, and communication delay. The proposed CNN-LSTM model was compared with conventional Rule-based methods and machine learning models, including Isolation Forest, Autoencoder, and LSTM. Experimental results show that the proposed model achieved the highest performance, with an F1-score of 0.885, an AUC of 0.94, and a detection delay of 8.1 s. In contrast, the Rule-based method exhibited a significantly higher false negative rate of 42.0%, indicating limitations in detecting complex anomaly patterns. These results demonstrate that the proposed spatiotemporal deep learning approach can significantly improve the accuracy and responsiveness of battery anomaly detection. Furthermore, the proposed method is expected to contribute to enhancing safety, reliability, and predictive diagnostics in next-generation intelligent BMS platforms.

This study proposes an optimization strategy for the over-current protection (OCP) parameters of a lithium iron phosphate (LiFePO₄, LFP) battery system used in electric golf carts operating under high motor-load conditions. Real-world hillclimbing tests were conducted under four clearly defined payload/passenger conditions to analyze the transient discharge-current pro-file, voltage sag, and cell-temperature response. The maximum discharge current reached -238.2 A under the 200 kg cargopayload and one-passenger condition, and the current interval exceeding 150 A lasted up to 27 s. The maximum instantaneous power was 11.05 kW. Thermal analysis showed that the cell-temperature rise was within 2°C and the maximum measured cell temperature was 22.3°C. Linear regression of voltage and current yielded R² = 0.9368 and dV/dI = 0.0126 Ω, which was used as the DC internalresistance estimate. Based on these quantitative results and the cell specification limit of 300 A continuous discharge, the OCP threshold was reviewed from 250 A to 280 A to improve driving continuity while remaining below the allowable continuous-discharge current. EIS-based SOH estimation and the AI-BMS variable protection logic are presented as an extension framework for reflecting temperature and aging effects in future OCP-setting decisions.

Organic solar cells based on bulk heterojunction (BHJ) structures have attracted considerable attention because of their low fabrication cost, mechanical flexibility, and compatibility with solution-processing techniques. In BHJ organic photovoltaic devices, nanoscale morphology and crystallinity of the photoactive layer critically influence photovoltaic performance. In this study, the effects of solvent selection and thermal annealing on crystallization evolution and photovoltaic characteristics of P3HT:PCBM organic solar cells were systematically investigated. Three different solvents, including toluene, chlorobenzene (CB), and dichlorobenzene (DCB), were employed for active-layer fabrication, followed by post-thermal annealing treatment. UV–visible absorption spectroscopy revealed solvent-dependent differences in molecular ordering and intermolecular π–π interactions within the active layer. X-ray diffraction analysis confirmed that thermal annealing significantly enhanced crystallinity and lamellar ordering of P3HT domains, particularly for CB-processed films. Electrical characterization demonstrated that solvent evaporation behavior strongly affects photovoltaic performance. Among the investigated devices, the thermally annealed CB-processed device exhibited the highest power conversion efficiency of 1.83% with an enhanced short-circuit current density of 7.057 mA cm⁻². The improved device performance is attributed to optimized crystallization behavior and balanced nanoscale phase separation induced by the moderate evaporation characteristics of CB. In contrast, although DCB-assisted films exhibited relatively strong optical absorption and enhanced crystallinity, excessively slow solvent evaporation likely induced excessive aggregation and coarse phase separation, limiting efficient photovoltaic characteristics. These results demonstrate that solvent engineering combined with thermal annealing is an effective strategy for controlling morphology evolution and crystallization behavior in P3HT:PCBM bulk heterojunction solar cells.

This paper reviews the energy yield enhancement characteristics of bifacial photovoltaic systems combined with solar tracking, focusing on their performance relative to conventional monofacial fixed-tilt configurations. The fundamental mechanisms of yield improvement are summarized, highlighting the largely additive contributions of solar tracking, which increases front-side irradiance, and bifacial modules, which utilize rear-side reflected and diffuse radiation. Reported results from previous studies indicate that bifacial systems with single-axis tracking typically achieve 25–35% higher annual energy yield compared with standard monofacial fixed-tilt systems, with variations depending on environmental and design conditions. Key design and environmental considerations influencing system performance are discussed to provide practical insights for the application of bifacial tracking systems in utilityscale photovoltaic installations.

Polymer nanocomposites incorporating inorganic nanofillers have emerged as highly promising electromagnetic interference (EMI) shielding materials, combining mechanical compliance with robust conductive percolation networks. Carbon nanotubes (CNTs) are particularly attractive as conductive fillers because their high aspect ratio facilitates percolation at low loadings. Also, CNTs offer superior mechanical durability under deformation compared to rigid, fracture-prone metal nanowires. For EMI shielding, high electrical conductivity is critical as it enhances both reflection and absorption through efficient charge dissipation and conduction losses. However, achieving highly aligned conductive pathways without degrading the intrinsic electrical properties of CNTs remains a significant challenge. Here, we demonstrate a non-destructive magnetic surface-functionalization and alignment strategy. Using a polydopamine (PDA)-mediated route, pristine multiwalled CNTs are uniformly decorated with Fe₃O₄ nanoparticles (FMWCNTs). This enables highly effective magnetic field-driven alignment at fields as low as 10 mT, promoting the strategic formation of percolation networks. By optimizing the Fe₃O₄/MWCNT ratio for high saturation magnetization and uniform coverage, the aligned FMWCNTs exhibit significant electrical anisotropy, delivering a 10.7-fold higher electrical conductivity in the parallel configuration compared to the vertical configuration. These findings present a scalable, room-temperature platform for engineering directionally enhanced conductivity in polymer nanocomposites, with broad applicability in advanced EMI shielding, flexible electronics, and advanced packaging technologies.

Citations

• Interfacial Engineering of Composite Piezoelectric Fibers Via an Anchor-Chain Architecture
  Jun Liu, Qiao Zhou, Pengcheng Zhang, Shuying Hu, Fang Zhou, Shuangshuang Ren, Ting Guo, Leiying Miao
  ACS Applied Engineering Materials.2026; 4(8): 4367.     CrossRef

GaN nanowire (NW)-based hybrid structures have attracted attention for optoelectronic applications due to their high surface area and efficient carrier transport. However, the optical transparency of GaN NWs is often limited by unintended residual species accumulated on the surface and in the inter-wire regions, as well as defect-related absorption, leading to reduced light transmission. In this work, we demonstrate that thermal annealing significantly improves the optical transparency of GaN NWs grown on indium tin oxide (ITO)/glass substrates. The transmittance increased from 47.9% to 78.5% at 550 nm after rapid thermal annealing at 800^oC for 3 min, while a comparable value (~75.5%) was achieved at 600^oC for 5 min. PbBr₃ was deposited onto the GaN NWs to form hybrid structures, and temperature-dependent photoluminescence (TDPL) measurements revealed enhanced emission stability with suppressed peak shift and reduced spectral broadening. Arrhenius analysis based on a two-channel model revealed that the activation energy of the dominant non-radiative recombination pathway increased from 62 meV in the as-grown sample to 85 meV after thermal annealing, while its relative contribution remained nearly unchanged. In contrast, the shallow trap-assisted pathway exhibited a similar activation energy of approximately 6 meV in both samples, but its contribution decreased from 0.35 to 0.17 after annealing. As a result, the internal quantum efficiency (IQE) improved from 75.9% to 87.4%. These results show that thermal annealing improves optical transparency by removing residuals and suppresses defect-related recombination, leading to enhanced carrier dynamics and improved optical performance of PbBr₃-based hybrid structures.

This paper proposes a circular sequential lighting control method to reduce current imbalance and luminance deviation among multiple LED modules in AC-powered LED lighting systems. Conventional fixed-sequence lighting control repeatedly prioritizes the same LED modules in every rectified voltage cycle, which leads to unequal current distribution, luminance non-uniformity, and the accelerated degradation of specific modules during long-term operation. To address these limitations, a circular sequential lighting strategy is introduced, in which the lighting order is cyclically rotated at every rectified cycle, ensuring that all LED modules experience equal lighting opportunities. A prototype AC-LED lighting system consisting of four series-connected LED modules was implemented and experimentally evaluated. The results demonstrate that, while the conventional fixed-sequence method produces a maximum average current deviation of up to 1.6 mA among modules, the proposed method equalizes the average current across all modules to approximately 17.1 mA. Furthermore, the flicker index remains at 0.13, which is comparable to that of the conventional method, indicating that luminance uniformity is improved without degradation of optical performance. The proposed circular sequential lighting control effectively distributes electrical stress, enhances luminance uniformity, and improves long-term reliability, making it a practical and efficient solution for high-quality AC-LED lighting applications.

Long lifetime, low power consumption, and environmental friendliness have enabled light-emitting diode (LED) lighting to rapidly replace conventional light sources such as incandescent and fluorescent lamps. In particular, AC-LED lighting systems can be directly powered by commercial alternating current (AC) sources; however, they suffer from significant luminance deviation caused by uneven current distribution among LED light-emitting modules. This paper proposes a lighting control method that improves flicker performance while maintaining lamp brightness and effectively reduces luminance deviation in AC-LED lighting. The proposed method reduces luminance deviation by controlling the lighting order of multiple LED light-emitting modules. Among four LED modules, only the required number of modules is continuously turned on, and the lighting priority alternates between rectification cycles. Specifically, during odd rectification cycles, LED modules are activated sequentially in ascending order (11→12→13→14), whereas during even rectification cycles, they are activated in descending order (14→13→12→11). By alternately applying continuous lighting control with opposite activation orders, the proposed reverse alternating lighting control method equalizes the current distribution among LED modules. As a result, luminance uniformity is improved, electrical stress concentration on specific modules is reduced, and the operational lifetime of the LED modules is extended compared with the conventional fixed-sequence lighting control method.

Citations

• Reduction of Luminance Deviation in Multi-Module AC-LED Lighting Systems Using a Circular Sequential Lighting Control Method
  Dong Won Lee, Byungcheul Kim
  Journal of Electrical and Electronic Materials.2026; 39(3): 267.     CrossRef

This study investigates the effect of dielectric layer thickness on the electrical and reliability characteristics of BaTiO₃- based X8R multilayer ceramic capacitors (MLCCs) for automotive applications. MLCCs with 30 dielectric layers and thicknesses ranging from 5 to 30 μm were fabricated, and key parameters―including capacitance, equivalent series resistance (ESR), insulation resistance (IR), breakdown voltage (BDV), DC-bias characteristics, temperature coefficient of capacitance (TCC), and ripple current-induced heating―were evaluated. The dielectric constant (~2,000) and sintering shrinkage (~-25%) were nearly independent of thickness, confirming stable microstructure formation. ESR increased with thickness, while normalized BDV (V/μm) decreased due to defect accumulation. IR improved with increasing thickness but dropped sharply above 125℃. Dielectrics thinner than 10 μm exhibited significant capacitance degradation under DC-bias and temperature variation, reflecting strong internal field effects. Ripple-induced heating correlated directly with ESR. These results indicate that, although thinner layers enhance capacitance density, reducing the thickness below 10 μm compromises bias stability and thermal reliability. A minimum dielectric thickness of 10 μm is therefore recommended to achieve an optimal balance between electrical performance and durability in high-reliability X8R MLCCs.

Citations

• Structural Analysis of Electric Field-Induced Polarization and Strain in Ferroelectric BaTiO₃
  Jae Hwan Park
  Journal of Electrical and Electronic Materials.2026; 39(4): 374.     CrossRef

Electrochemical water splitting has emerged as a pivotal technology for green hydrogen production, offering a viable pathway toward a sustainable energy future. Among various electrolysis systems, Anion exchange membrane water electrolysis is particularly noteworthy as a cost-effective solution capable of operating under the fluctuating power inputs typical of renewable energy sources. However, the overall efficiency of water splitting is fundamentally limited by the oxygen evolution reaction, which exhibits sluggish kinetics compared to the hydrogen evolution reaction. While IrO₂ and RuO₂ serve as current benchmarks, their scarcity and high cost necessitate the development of earth-abundant alternatives. This review provides a comprehensive overview of fundamental OER mechanisms including the adsorbate evolution mechanism, lattice oxygen mechanism, and oxide path mechanism while highlighting how new pathways can circumvent traditional scaling relations. We discuss recent advancements in transition metal-based electrocatalysts, encompassing oxides, hydroxides, chalcogenides, phosphides, nitrides, and carbides, with a focus on innovative design strategies such as defect engineering, heteroatom doping, and heterostructure construction. This paper concludes by addressing current challenges and offering perspectives on future directions for the development of highly efficient and economically viable oxygen evolution electrocatalysts for large-scale applications.

The safety and stability concerns of liquid electrolytes in conventional lithium-ion batteries have accelerated the development of solid-state alternatives. NASICON type ceramics Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) offer promising properties, including high bulk ionic conductivity and good compatibility with lithium anodes. However, their practical application is hindered by grain boundary resistance and relatively low total ionic conductivity. This study investigates the effect of Ta₂O₅ doping on LATP to overcome these limitations. Doping with 5 wt% Ta₂O₅ improved the ionic conductivity to 2.95 × 10-4 S/cm by enhancing lattice structure, reducing grain boundary resistance, and suppressing the formation of secondary phase. Additionally, Ta₂O₅ positively influenced the sintering behavior, resulting in a denser, and more uniform microstructure. These enhancements suggest that Ta₂O₅-doped LATP is a strong candidate for next-generation all-solid-state lithium-ion batteries.

Citations

• Manufacturing Process Optimization of Oxide-Based Multilayer Ceramic Batteries Using Multilayer Ceramic Processing Technologies
  Won-Su Lee, Jong Kyu Lee, Jung Rag Yoon
  Journal of Electrical and Electronic Materials.2026; 39(5): 519.     CrossRef

Bismuth layer-structured ferroelectrics with high Curie temperatures have recently attracted significant attention as promising candidates for high-temperature piezoelectric applications. However, the conventional solid-state reaction method entails high-temperature processing that induces bismuth volatilization, thereby degrading device reliability. In this study, we employed a co-precipitation method enabling atomic-level mixing to significantly lower the synthesis temperature of Nb/Tadoped Bi₄Ti₃O₁₂ ceramics compared to the solid-state reaction method. Experimental results demonstrated that the coprecipitation method yielded a pure single phase at 600℃ without intermediate phases. Furthermore, the synthesized nanopowders, with an average size of 100 nm, lowered the onset temperature of sintering shrinkage to 650℃, approximately 200℃ lower than that of the solid-state counterpart. The low-temperature synthesis process proposed in this work is expected to contribute to the performance enhancement of high-temperature piezoelectric devices by effectively suppressing bismuth volatilization and ensuring compositional stability.

The increasing global demand for renewable energy has accelerated the deployment of offshore wind farms, thereby highlighting the need for advanced development and performance assessment techniques for dynamic submarine cables used in floating offshore wind systems. These cables are continuously subjected to combined thermal, electrical, and mechanical stresses, with mechanical loading playing a particularly dominant role. As a result, dynamic submarine cables exhibit degradation behaviors that differ significantly from those of conventional fixed submarine cables. This paper presents the design and implementation of a comprehensive evaluation system capable of applying combined thermal, electrical, and mechanical stresses to dynamic submarine cables. The system was validated using a 66 kV wet type submarine cable through commissioning tests and insulation performance measurements. Electrical stress of 72 kV, thermal stress exceeding 95°C, and mechanical stress corresponding to a bending radius of 20 times the cable diameter over 20 cycles were applied to verify system reliability. The subsequent insulation assessments quantitatively confirmed performance variations induced by the combined stresses. The results demonstrate that the proposed platform is the first system capable of simultaneously applying thermal, electrical, and mechanical stresses to dynamic submarine cables, and its operational performance has been successfully validated. This platform enables realistic reliability evaluation of dynamic cables used in floating offshore wind farms and is expected to improve the overall operational reliability of offshore wind power systems.

As electric vehicles (EVs) are rapidly adopted worldwide, large numbers are now transported by sea on dedicated car carriers. With this trend, concerns are increasing about fires and explosions caused by battery thermal runaway during marine transport, while existing SOC limits before loading remain largely empirical. This study experimentally investigates gas generation and explosion characteristics of EV lithium-ion cells under thermal runaway conditions representative of enclosed vehicle decks. We identify and quantify the main off-gas components and clarify the flammability behavior and explosion limits of key combustible species. The results provide basic data for assessing EV battery accidents at sea and support the development of safer ventilation and gas-management strategies for ships.

The rapid proliferation of artificial intelligence (AI) servers and high-performance computing systems has significantly elevated the technical and reliability requirements for multilayer ceramic capacitors (MLCCs). In such systems, MLCCs are critical passive components that must deliver high capacitance, fast transient response, and robust insulation performance under high temperature, voltage, and current density. This review examines the material, structural, and process innovations that underpin MLCC performance in AI applications. Key topics include the development of ultrathin dielectric layers (<0.5 μm), rare-earth doped BaTiO₃-based dielectrics with enhanced DC bias stability, and core-shell microstructures designed for temperature and field resilience. The paper also explores insulation degradation mechanisms―such as vacancydriven conduction and demixing―and advanced reliability assessment methodologies, including HALT, TSDC, and the tipping point framework. Comparisons with automotive-grade MLCCs highlight the unique requirements of AI systems, such as ultraminiaturization, high volumetric efficiency, and ppm-level field failure rates. Finally, the review discusses emerging trends in MLCC technology, including particle engineering, interface stabilization, and advanced lamination techniques, and provides insight into the future direction of capacitor development tailored to AI data center environments.

Citations

• Reliability enhancement in Dy-doped BaTiO3 nanoceramics: from core–shell structure to phase-field modeling
  Shuyan Huang, Xinjie Wang, Mengjian Xiao, Xu Cheng, Xiaohui Wang
  Journal of Materials Science.2026; 61(37): 27665.     CrossRef
• Key factors determining high-temperature operating lifetime of multilayer ceramic capacitors (MLCCs)
  Yuto Tomura, Tzu-han Weng, Yusuke Oba, Tomohiro Kajita, Daiki Ishii
  Japanese Journal of Applied Physics.2026; 65(16): 16SP05.     CrossRef
• Effect of BaZrO3 Addition on the Frequency and Temperature Dependent Dielectric Properties of BaTiO3-Based Ceramics
  Won-Su Lee, Jong Kyu Lee, Moon-Taek Cho, Jung Rag Yoon
  Journal of Electrical and Electronic Materials.2026; 39(5): 478.     CrossRef
• Manufacturing Process Optimization of Oxide-Based Multilayer Ceramic Batteries Using Multilayer Ceramic Processing Technologies
  Won-Su Lee, Jong Kyu Lee, Jung Rag Yoon
  Journal of Electrical and Electronic Materials.2026; 39(5): 519.     CrossRef

This study investigates the effect of mask material and thickness on the silicon etching profile using a high-density plasma (HDP) etching system, aiming to reduce optical loss in silicon-based optical waveguides. As the mask thickness increased, the etching sidewall angle became steeper. An etching profile angle of 87° was obtained when tetraethyl orthosilicate (TEOS) was used as the mask material, while 80° was obtained for photoresist (PR). This is attributed to electron charging on the mask surface in the plasma. The charged mask modifies the distribution and strength of the electric field depending on its thickness, thereby affecting the trajectory of positive ions accelerated toward the substrate by the bias voltage. Furthermore, Plasma diagnostics using optical emission spectroscopy (OES) and surface composition analysis using field emission Auger electron spectroscopy (FE-AES) revealed that changes in the mask material also alter the reaction pathways and formation characteristics of active species and silicon by-products in the plasma. These results suggest that the mask material influences the overall plasma characteristics, including electron density and ion energy, and plays a critical role in the precise control of silicon etching profiles for high-performance optical device fabrication.

The quench behavior of wires for superconducting fault current limiters at DC faults was simulated, with a focus on the effect of capacitor discharge on the quench. The behavior was also expressed in mathematical forms to facilitate a better understanding of the simulation results and for rough analytical estimations of the wire length suitable for the circuit voltage and capacitance. The quench resistance development behavior for various wire lengths and circuit capacitances was simulated using the model developed in the previous work. The quench behavior was expressed in mathematical forms, reflecting the concept of heat balance. During the quench, the wire temperature increased more slowly for longer wires, but was found to increase in a similar pattern. The wire length estimated by the mathematical formula was close to the one obtained by the simulation, with an error range of a few %. The calculations will be used to estimate effectively the length of wires needed to build superconducting fault current limiters for applications in DC power systems.

Flexible and wearable electronics, which require stable operation under mechanical deformation, are increasingly utilizing Eutectic Gallium-Indium (EGaIn) for their conductive components. This study presents a systematic approach to fabricating highly reliable, deformable electrodes via a direct-ink-writing (DIW) 3D printing process using EGaIn as the functional ink. We conducted a thorough optimization of key printing parameters, specifically the extrusion pressure and printing speed, to achieve stable and uniform conductive lines. Through this optimization, we successfully established an optimal process window, achieving a stable line width of approximately 130 μm at an extrusion pressure of 300 kPa and a printing speed of 16 mm/s. The fabricated flexible electrodes exhibited exceptional electromechanical stability, maintaining negligible resistance change (< 0.82%) both under severe bending (3 mm radius) and after 100 repetitive bending cycles. This work demonstrates that the 3D printing of EGaIn is a viable and effective method for creating robust, high-performance electrodes for the next generation of deformable and wearable electronic devices.

Humidity monitoring of exhaled breath has emerged as a vital approach for noninvasive respiratory health assessment, underscoring the need for sensitive and reliable humidity sensors. Despite its high conductivity and hydrophilic functional groups, reduced graphene oxide (rGO) often undergoes irreversible moisture adsorption and gradual oxidation by residual water, resulting in sensitivity degradation and long-term instability during cycling. In this study, a montmorillonite/reduced graphene oxide (MMT/rGO) composite is developed as a room-temperature humidity-sensing material, exhibiting an optimized response of 115%, more than 14 times higher than that of pristine rGO. This superior performance originates from the synergistic interaction between the reversible MMT swelling and the conductive rGO network near the electrical percolation transition, which ensures excellent stability and repeatability under repeated humidity cycles. These findings suggest that the MMT/rGO composite provides a cost-effective and biocompatible platform for next-generation wearable humidity sensors capable of continuous respiratory monitoring.

e investigated the effects of post-annealing in vacuum, nitrogen, and hydrogen atmospheres on the structural, electrical, and optical properties of 600 nm thick Al-doped ZnO (ZnO:Al) thin films deposited by RF magnetron sputtering at room temperature. Post-annealing in hydrogen atmosphere at 400℃ for 1 hour showed the most significant improvement in electrical properties. Resistivity decreased from 9.11×10⁻³ to 1.4×10⁻³ Ω·cm, electron mobility increased from 4.11 to 18.23 cm²/V·s, and electron carrier concentration increased from 1.63×10²⁰ to 4.85×10²⁰ cm⁻³. In contrast, post-annealing in vacuum and nitrogen atmospheres resulted in degraded electrical properties due to oxygen and nitrogen chemisorption at grain boundaries. The enhancement in hydrogen-annealed films was attributed to the formation of additional oxygen vacancies and desorption of adsorbed oxygen species from grain boundaries. All films maintained excellent optical transparency of 80-90% in the visible range. The optical bandgap exhibited a blue-shift from 3.365 eV to 3.624 eV due to the Burstein-Moss effect induced by the increased electron carrier concentration. These results confirmed that hydrogen atmosphere post-annealing is the most effective method for enhancing the electrical conductivity of ZnO:Al thin films while maintaining high optical transparency.