Dissolved oxygen concentration is a key parameter determining the oxidation and corrosion behavior of structural materials in lead-based fast reactor coolants. Therefore, achieving high-precision in-situ oxygen measurement in LBE systems is a fundamental technical requirement for implementing oxygen-controlled corrosion protection. Currently, nuclear-grade Bi/Bi2O3 solid-state electrochemical oxygen sensors have a minimum effective operating temperature of 350 °C, which prevents them from meeting the real-time oxygen monitoring needs under low-temperature conditions. This temperature limitation has become a major bottleneck for the engineering application of oxygen control technology. To address these requirements and challenges, this study develops a novel electrochemical oxygen sensor based on an 8 mol% Y2O3-stabilized ZrO2 (8YSZ) solid electrolyte and La0.6Sr0.4Co0.2Fe0.8O3±δ (LSCF) electrode system. Comparative experiments with Bi/Bi2O3 sensors are conducted to quantitatively assess the advantages of the LSCF/Air sensor in low-temperature applications within 205~550 °C. Furthermore, considering the irradiation environment in nuclear reactors, oxygen ion irradiation was employed as an accelerated simulation method to preliminarily investigate the electrochemical transport properties of 8YSZ after irradiation. The effects of oxygen ion irradiation on the apparent impedance and apparent oxygen ion conductivity of 8YSZ were evaluated. The results show that the LSCF/Air oxygen sensor has the potential to extend the lower operating-temperature limit of 8YSZ-based oxygen sensors in static, oxygen-saturated LBE environments. Oxygen ion irradiation increased the apparent impedance and decreased the apparent ionic conductivity of the tested 8YSZ samples. These results provide preliminary experimental data for the development of oxygen sensors for oxygen monitoring and corrosion control in liquid-metal-cooled reactor systems over a wider temperature range.
Reliable solder joint formation in electronic packaging depends on the coupled effects of solder composition and pad finish on molten solder wetting, yet direct comparisons of Bi-modified SAC305 and SAC405 solders on common surface finishes remain limited. In this study, nominal SAC305- and SAC405-based solders with Bi additions up to 3 wt.% were evaluated on ENIG and Cu-OSP finishes at 250 °C under forming gas. Sessile drop testing was used to measure contact angles, and atomic force microscopy and surface free energy measurements were used to characterize the substrates. The work of adhesion was calculated using the Young–Dupré relationship from contact angle and liquid surface tension values. For both alloy series, contact angle generally decreased with increasing Bi content, indicating improved spreading, with a stronger effect for SAC305 on Cu-OSP. ENIG produced lower contact angles and higher calculated work of adhesion than Cu-OSP. SAC405-based solders generally showed higher calculated work of adhesion than SAC305-based solders because of their higher liquid surface tension. However, the lowest contact angle did not always correspond to the highest calculated work of adhesion. These results show that Bi content, Ag level, and pad finish jointly influence the apparent wettability and calculated solder–substrate interaction of SAC-Bi solders.
This study investigated the optoelectronic synaptic properties of amorphous gallium oxide (GaOx) thin films for low-power physical reservoir computing (PRC) applications. The fabricated devices were irradiated with time series UV-C light to characterize the paired pulse facilitation (PPF) index, a fundamental synaptic property governed by transient photocurrent dynamics. Furthermore, the short-term memory (STM) capacity and parity check (PC) nonlinearity were quantitatively evaluated as essential PRC performance metrics, alongside a practical demonstration using a handwritten digit recognition task. The experimental results revealed a high PPF index when the width and interval of the input light pulses were comparable to or shorter than the inherent photocurrent time constants of the device. Although the evaluated nonlinearity was lower than that of conventional optoelectronic artificial synapses based on other semiconductor materials, the GaOx device exhibited a comparable short-term memory capacity. Consequently, the reservoir layer achieved a high classification accuracy of approximately 90% in the handwritten digit recognition task. As these performance metrics were higher than those of the annealed sample, the device without annealing proved to be more suitable for PRC applications. These findings indicate that the amorphous GaOx thin film device holds significant potential to serve as a robust, UV-C-responsive edge artificial intelligence (AI) sensor in harsh environments, such as outer space.
The von Neumann architecture faces a “memory wall” problem due to the physical separation of memory and processor, posing major challenges to energy efficiency and latency in the era of artificial intelligence. To overcome these bottlenecks, artificial synaptic devices inspired by biological systems have emerged as an important research direction. By integrating sensing and computing functions at the device level, these architectures provide a promising approach for the efficient processing of natural physical signals. Supported by advances in functional materials and artificial neural network (ANN) algorithms, artificial synaptic devices are capable of perceiving and processing various external stimuli, showing strong potential for applications in intelligent electronic skins, robotics, and edge computing. This review provides a comprehensive overview of recent advances in artificial synaptic devices, with particular emphasis on tactile and visual sensing applications. We discuss representative device types and operating mechanisms, analyze critical challenges from the perspectives of material engineering and functional integration, and further summarize potential solutions and future trends toward multimodal sensory–memory–computing systems.
With parylene coatings, conventional layer thickness measurement methods such as gravimetry, reflectometry, and cross-sectional microscopy are performed post-process and do not allow real-time monitoring or control. This paper presents a novel in situ measurement method based on the capacitance change in interdigitated copper electrodes fabricated on a printed circuit board (PCB). As parylene deposits on this sensor, the effective permittivity above the electrodes increases from ϵr≈1 (vacuum) to ϵr=2.1–3.2 (parylene), causing a measurable capacitance change. Finite element simulations were performed to model the relationship between layer thickness and sensor capacitance. Experimental validation with parylene C and F-VT4 demonstrated good agreement between simulation and measurement. Four consecutive parylene C runs with 60 g raw material showed reproducible capacitance increases of 49–53 pF, corresponding to layer thicknesses of 20–25 µm, verified by cross-sectional microscopy. Two coating runs were performed with parylene F-VT4 with target layer thicknesses of 2.5 µm and 5 µm. They show particularly good agreement with the simulation. The proposed method enables real-time process monitoring and provides a foundation for closed-loop control of parylene CVD processes.
Monolayer and few-layer MoS2 are promising two-dimensional electronic materials, but proton irradiation can trigger ultrafast electronic excitation and charge transfer before defect formation. Here, real-time time-dependent density functional theory (RT-TDDFT) is used to investigate proton-induced electronic stopping and localized charge capture in monolayer and bilayer MoS2 under normal incidence. Four impact positions are examined in monolayer MoS2, namely, the hollow channel, the Mo–S bond center, and two trajectories close to Mo and S atoms. Under hollow channel incidence, the stopping power shows a non-monotonic dependence on proton velocity. When comparing the different trajectories, the hollow channel path gives the lowest stopping power, whereas the Mo–S bond center path gives the highest values, indicating strong sensitivity to the in-plane valence charge distribution. By contrast, the time-averaged localized captured charge decreases with increasing velocity and is generally largest for the close to Mo trajectory. Under the same hollow channel condition, the monolayer stopping power exceeds the bilayer value in the main stopping region, whereas the bilayer generally shows slightly enhanced localized charge capture. These results show that electronic stopping and localized charge capture are distinct but coupled microscopic components of proton-induced electronic response in MoS2 and provide first-principles insight relevant to ion-beam processing and radiation-tolerant two-dimensional devices.
In this work, the structural, electronic, optical, and vibrational properties of gallium nitride (GaxNx) nanostructures were systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT). A series of nanoparticles was constructed starting from a cubic-like Ga4N4 building unit, leading to one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and hexagonal configurations. Geometry optimizations and vibrational frequency calculations were performed at the B3LYP/def2-TZVP level, while optical properties were investigated using TD-DFT with the CAM-B3LYP functional. Only dynamically stable structures without imaginary vibrational frequencies were considered for spectroscopic analysis. The results reveal a strong dependence of the optical and vibrational behavior on nanoparticle size and geometry. Larger and lower-symmetry systems exhibit broader and red-shifted UV–Vis absorption spectra together with richer IR vibrational features. In contrast, elongated low-dimensional configurations such as Ga12N12–1D and Ga16N16–1D/2D were found to be dynamically unstable. The investigated nanostructures also show a clear tendency toward structural reorganization from cubic-like motifs to compact hexagonal arrangements related to the wurtzite phase of bulk GaN. Benchmark analysis demonstrates that CAM-B3LYP provides reliable excitation energies at moderate computational cost. Overall, the obtained results highlight the strong coupling between structure and optoelectronic properties in GaxNx nanostructures and indicate their potential for nanoscale optoelectronic and photonic applications.
This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n+-Si and structured into an asymmetric cross junction with 90 nm wide channels. The junction consists of a straight voltage stem (contacts U, L) and slanted current injectors (contacts 1, 2). The differential conductance of the stem, gUL, as a function of back-gate bias, VBG, reveals clear indications of energy gap formation and lateral depletion zones at the edges of the channel. The DC characteristic of the ballistic rectifier, VUL(I12), shows an increase in the output voltage VUL with increasing VBG. We attribute this to reduced diffuse scattering at the rough edges when the lateral depletion zones form smooth barriers.
With the intensification of the energy crisis and environmental issues, thermoelectric conversion technology has become a research focus due to its ability to directly convert thermal and electrical energy. β-Cu2Se thermoelectric materials have garnered considerable attention owing to their distinctive physical and chemical characteristics. However, their practical implementation is hindered by the inherent imbalance between electrical and thermal transport properties. In this work, β-Cu2Se/SnSe composite thermoelectric materials were successfully synthesized via a facile and scalable in situ compositing strategy by introducing SnSe micro-flakes as the secondary phase. The results demonstrate that the introduced SnSe secondary phase effectively modulates the carrier concentration and enhances the density-of-states effective mass through the energy filtering effect and resonant energy level regulation, thereby significantly optimizing the electrical transport properties. Meanwhile, the abundant heterointerfaces formed between the β-Cu2Se matrix and introduced SnSe secondary phase induce intense phonon scattering, which efficiently suppresses the lattice thermal conductivity of the β-Cu2Se/SnSe composites. Benefiting from the synergistic optimization of electrical and thermal transport behaviors, the β-Cu2Se/5 mol% SnSe composite sample achieves a maximum figure of merit (ZT) value of ~0.51 at 750 K, which represents a 70% enhancement compared with the pristine β-Cu2Se and a 60% improvement compared with the direct composite sample. This study provides a simple and effective in situ composite strategy for designing and synthesizing high-performance thermoelectric materials.
Pd-decorated Janus ZrSSe monolayers provide a promising platform for adsorption-coupled electronic modulation in two-dimensional materials. Using first-principles density functional theory, we systematically investigate the structural stability, electronic properties, and adsorbate-induced electronic response of Pd-modified Janus ZrSSe. The results show that Pd is most stably anchored at the hollow site on the S-terminated surface, with a formation energy of −1.45 eV, while substitutional incorporation remains energetically unfavorable even after HSE06 refinement. Compared with pristine ZrSSe, Pd decoration markedly strengthens the interaction with adsorbates, leading to strong chemisorption for CO (−1.026 eV) and C2H2 (−0.748 eV), whereas H2 remains comparatively weakly bound (−0.258 eV). Electronic-structure analysis reveals that CO induces the most pronounced perturbation because of strong orbital hybridization between Pd 4d states and C/O 2p states, resulting in the largest band-edge modulation among the three adsorbates. More importantly, biaxial strain provides an effective external degree of freedom for continuously tuning the electronic structure: tensile strain widens the band gap, whereas compressive strain systematically narrows it and ultimately drives a semiconductor-to-metal transition at sufficiently large compression. These findings establish Pd-decorated Janus ZrSSe as a strain-tunable electronic material in which adsorption, orbital hybridization, and band-edge evolution are intimately coupled, offering fundamental insights into controllable electronic modulation in polar two-dimensional systems.
Recent studies show that titanium (Ti)-based alloys combine established mechanical strength, corrosion resistance, and biocompatibility with emerging electrical and electrochemical properties relevant to bioelectronics. The main goal of the present manuscript is to give a wide-ranging overview on the use of Ti-alloys in electronics and biomedicine, focusing on a comprehensive analysis and synthesis of the existing literature to identify gaps and future directions. Concurrently, the identification of possible correlations between the effects of the manufacturing process, alloying elements, and other degrees of freedom influencing the material characteristics are put in evidence, aiming to establish a global view on efficient interdisciplinary efforts to realize high-added-value smart devices useful in the field of biomedicine, such as, for example, implantable apparatuses. This review mostly summarizes advances in surface modification approaches—including anodization, conductive coatings, and nanostructuring that improve conductivity while maintaining biological compatibility. Trends in applications demonstrate how these alloys support smart implants, biosensors, and neural interfaces by enabling reliable signal transmission and long-term integration with tissue. Key challenges remain in balancing electrical performance with biological response and in scaling laboratory modifications for clinical use. Perspectives for future work include optimizing alloy composition, refining surface treatments, and developing multifunctional designs that integrate mechanical, biological, and electronic requirements. Together, these directions highlight the potential of titanium alloys to serve as foundational materials for next-generation bioelectronic medical technologies.
We present a fresh perspective on the mixed halogen-ion effect (MHE) in lead silicate glasses containing a mixture of halogen ions with a correlative study of optical spectroscopy and halogen ion transport. PbO was partially substituted by either PbCl2 or PbF2 in the ternary glass system: (65 − x) − x(PbF2 or PbCl2)-35SiO2 (where 0 ≤ x ≤ 20 mol%) and by a mixture of PbF2 and PbCl2 in the quaternary glass series: 45PbO − xPbF2 − (20 − x)PbCl2–35SiO2 (where 0 ≤ x ≤ 20 mol%). A suite of improved characterization techniques, including 4-probe van der Pauw resistivity measurements, optical absorption spectroscopy, differential thermal analysis, etc., was employed to correlate composition with physical properties. Replacing PbO with small quantities of PbF2 or PbCl2 in binary 65PbO-35SiO2 glass resulted in a dramatic increase in conductivity by 3–4 orders of magnitude, confirming a shift from Pb2+-mediated to halide ion-mediated conduction and, within the mixed-halogen series, a profound MHE was observed. Contrary to previously reported data, the activation energy for conduction and the resistivity both exhibited maxima at the mixed halogen-ion ratio, MHR = (F/(F + Cl), of 0.5. The glass transition temperature (Tg) exhibited a non-monotonic trend, peaking at 506 °C for the MHR = 0.5 composition. Optical absorption measurements have revealed that the MHR = 0.5 glass has the broadest absorption edge and also exhibits certain features in the near IR region of the Urbach tail, which are suggestive of maximum electronic disorder.
Additive Manufacturing (AM) and printing-based fabrication technologies have emerged as powerful enablers for next-generation electronic integration and packaging, addressing the growing limitations of conventional subtractive manufacturing techniques. As electronic systems continue to scale toward higher operating frequencies (10–110 GHz and beyond) and increased functional density (>104 interconnects/cm2), traditional packaging approaches struggle with rigid design constraints, complex processing steps (>15–25 fabrication steps), high tooling costs ($10,000–$100,000 for mask and molds) and limited compatibility with heterogeneous integration. In this review, a comprehensive and critical overview of major additive manufacturing and printing technologies including aerosol jet printing, inkjet printing, vat polymerization, fused filament fabrication (FFF) and nScrypt printing is presented from the perspective of electronic assembly and packaging. The fundamental working mechanisms, material compatibility, resolution limits, scalability, and reliability considerations of each technique are systematically discussed. From a manufacturing standpoint, AM reduces material waste by 50–90% compared to subtractive PCB processing and eliminates tooling costs, enabling low-volume prototyping with per-unit fabrication costs reduced by 30–70% for small batches (<100 units). Production throughput varies widely, from 1 to 20 cm2/min for high-resolution direct write systems to >100 cm2/min for scalable inkjet systems. Moreover, it is discussed how these technologies enable advanced packaging architectures such as printed signal crossovers, three-dimensional interconnects, ramps, and embedded chip assemblies. Recent research efforts and reported demonstrations are analyzed to highlight the advantages and current limitations of additive manufacturing for high-frequency, RF, and system-on-package (SoP) applications. Finally, future directions and remaining challenges are discussed, including advances in materials, custom and on-demand manufacturing, enhanced design freedom, integration of multifunctionality, cost-effectiveness, and smart packaging solutions. This review aims to serve as a reference for researchers and engineers seeking to leverage additive manufacturing for high-performance electronic integration and next-generation electronic packaging solutions.
Heavily doped metal oxide thin films combining high visible transmittance and low electrical resistance are used in a multitude of optoelectronic devices, where their performance is highly dependent on the structural defects and density of electronic states associated with doping. This study explores the structural, optical, and electronic properties of Sn-doped indium oxide (In2O3:Sn) and Al-doped zinc oxide (ZnO:Al) thin films, which were prepared by sputtering on unheated glass substrates and subsequently annealed in N2 at different temperatures between 250 °C and 450 °C. These samples reach free electron densities above 1020 cm−3 due to the presence of extrinsic donors (mainly substitutional defects of SnIn and AlZn) and also intrinsic donors (oxygen vacancies), which change with the annealing temperature due to oxygen desorption and/or cation migration processes. The volume of the crystal lattice expands (up to a maximum of 1.1%) and the band gap widens (up to a maximum of 17.9%) with respect to the undoped material, increasing with electron density. Additional absorption is due to band tail, at an energy ~10% below the undoped band gap, which varies slightly with the carrier concentration. The same general behavior is observed for both materials, with particularities in terms of crystal lattice and electronic states, which can be tuned by the heating temperature.
The increasing demand for next-generation rechargeable batteries that offer high energy density, a long lifespan, high safety, and low cost has led to a need for better electrode materials for lithium-ion batteries. This also involves developing alternative storage systems using common resources such as sodium-ion batteries, beryllium-ion batteries, or magnesium-ion batteries. Tin carbide (SnC) is highly promising as an anode material for lithium, sodium, beryllium, and magnesium ion batteries due to its ability to form nanoclusters like Sn(Li2)C, Sn(Na2)C, Sn(Be2)C, and Sn(Mg2)C. A detailed study was done using computational methods, including analysis of charge density differences, total density of states, and electron localization function for these hybrid clusters. This research suggests that SnC could be useful in multivalent-ion batteries using Be2+ ions because its properties can match or even exceed those of monovalent ions. The study also shows that the maximum capacity, stability energy, and ion movement in these materials can be understood by looking at atomic-level properties like the coordination between host atoms and ions. Recent findings on using tin carbide in these types of batteries and methods to improve their performance have been discussed.
In this work, we consider the influence of antisite disorder, e.g., Fe ions on Mo sites, FeMo, and vice versa, MoFe, on the resistivity of strontium ferromolybdate ceramics fabricated by the solid-state reaction method. Strontium ferromolybdate ceramics fabricated via solid-state reactions exhibit a low-temperature minimum resistivity owing to the interplay between the bulk metallic resistivity of the grains, which increases with temperature and becomes dominant at higher temperatures, and an intergrain tunneling mechanism of charge carrier conduction, which leads to a decrease in conductivity with decreasing temperature in the low-temperature region. The parameters of the bulk metallic resistivity and fluctuation-induced intergrain tunneling were determined by fitting the experimental data to these resistivity models. The impact of antisite disorder on the resistivity parameters was considered. It turns out that antisite disorder affects the effective barrier height of intergrain tunneling and the effective values of the barrier width and the barrier area. Disorder increases the effective barrier height for intergrain tunneling, increases its barrier width, and decreases the effective barrier area of nanosized barriers. The results are discussed using experimental data available in the literature.
Gallium oxide is an ultra-wide bandgap semiconductor with excellent opto-electronic properties, making it a highly promising material for a wide range of applications and devices. In this article, we report how the optical, morphological, structural, and compositional properties of β-Ga_2O_3 thin films deposited by RF sputtering on silicon substrates are affected by thermal treatments. Ellipsometric spectra recorded at multiple angles of incidence from several samples subjected to thermal annealing in the range of 550-1000 ^∘C were analyzed to extract the optical functions using appropriate multilayer models. This analysis is complemented by compositional, structural, and morphological characterization techniques. A significant increase of the refractive index was found after annealing at 1000 ^∘C, accompanied by a stark improvement in the samples' crystalline structure, as confirmed by complementary structural and compositional characterization techniques.
To address the issues of insufficient responsivity and low imaging contrast of carbon-based HGFET high-sensitivity short-wave infrared (SWIR) detectors under low-light conditions, this paper proposes a high-sensitivity and high-contrast image enhancement algorithm for low-light detection, with FPGA-based hardware verification. The proposed algorithm establishes a multi-stage cooperative enhancement framework targeting key challenges such as low signal-to-noise ratio (SNR), high dark-state noise, and weak target extraction. Unlike traditional direct enhancement methods, the proposed approach first performs defective row-column correction and background noise separation based on dark-state data, which provides a clean foundation for signal reconstruction. Furthermore, an adaptive gamma correction mechanism based on image maximum value is introduced to avoid unnecessary nonlinear transformations in high-contrast regions. During the contrast enhancement stage, an exposure-constrained adaptive histogram equalization strategy is adopted to effectively suppress noise amplification and saturation in low-light scenes. Finally, an innovative dual-mode threshold selection method based on image variance is proposed, which can dynamically integrate the OTSU algorithm with statistical moment analysis to ensure robust background noise separation across both high- and low-contrast scenarios. Experimental results demonstrate that the proposed algorithm significantly improves target contrast in infrared images while preventing detail loss due to overexposure. Under microwatt-level laser power, background noise is effectively suppressed, and both imaging quality and weak target detection capability are substantially enhanced.
In this study, we explore the integration of a cost-effective triboelectric nanogenerator (TENG) with an large silicon PIN detector (diameter: 12 mm) for intelligent wireless recognition applications. Wireless communication eliminates the need for physical connections, enabling greater flexibility and scalability in deployment. It allows for seamless integration of AI systems into a wide range of environments without the constraints of wiring, reducing installation complexity and enhancing mobility. Additionally, we demonstrate the TENG’s functionality as an autonomous communication unit. The TENG is employed to convert various environmentally triggered signals into digital formats and to autonomously power optoelectronic devices, thus eliminating the need for an external power supply. By integrating optoelectronic components within the self-powered sensing system, the TENG can identify specific trigger information and reduce extraneous noise, thereby improving the accuracy of information transmission. Moreover wireless technology facilitates real-time data transmission and processing. This setup not only enhances the overall efficiency and adaptability of the system but also supports continuous operation in diverse and dynamic settings. This paper introduces a novel convolutional neural network-long short-term memory (CNN-LSTM) fusion neural network model. Utilizing the sensing system in combination with the CNN-LSTM neural network enables the collection and identification of variations in the flicker frequency and luminosity of optoelectronic devices. This capability allows for the recognition of environmental trigger signals generated by the TENG. The classification and recognition results of human body trigger signals indicate a recognition accuracy of 92.94%.
This work examines a cylindrical FE-DE heterostructure and compares its performance with that of a cylindrical FE-FE-DE heterostructure. It aims to maximize voltage amplification, increase capacitance, and attain a constant negative capacitance. First, the existence of negative capacitance is shown by analyzing isolated cylindrical ferroelectric capacitors. A cylindrical dielectric capacitor and a cylindrical ferroelectric capacitor are integrated in series to stabilize negative capacitance. Our results indicate that the capacitance of the FE-FE-DE stack, consisting of Si:HfO2 and Zr:HfO2, closely aligns with the dielectric capacitance. Consequently, enhanced performance is anticipated in comparison with the FE-DE arrangement. Additionally, the dynamic response of two distinct configurations was analyzed, yielding a comprehensive understanding of these heterostructures’ behavior.
