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Abstract SeS2 positive electrodes are promising components for the development of high-energy, non-aqueous lithium sulfur batteries. However, the (electro)chemical and structural evolution of this class of positive electrodes is not yet fully understood. Here, we use operando physicochemical measurements to elucidate the dissolution and deposition processes in the SeS2 positive electrodes during lithium sulfur cell charge and discharge. Our analysis of real-time imaging reveals the pivotal role of Se in the SeS2 nucleation process, while S enables selective depositions. During the initial discharge, SeS2 converts into Se and S separately, with the dissolved Se acting as nucleation sites due to their lower nucleation potential. The Se effectively catalyzes the growth of S particles, resulting in improved lithium sulfur battery performance compared to cells using positive electrodes containing only Se or S as active materials. By adjusting the Se-to-S ratio, we demonstrate that a low concentration of Se enables uniform catalytic sites, promotes the homogeneous distribution of S and favours improved lithium sulfur battery performance.

This study introduces the synthesis of a hybrid thermoelectric material with enhanced conductivity and a high Seebeck coefficient, leveraging the properties of Te nanowires (NWs) and the conductive polymer PEDOT:PSS. Te NWs were synthesized using the galvanic displacement reaction. To further enhance conductivity, Ag-Te NWs were synthesized under optimized conditions via the Ag topotactic reaction, achieving desired results within 7 min using ethylene glycol and AgNO3. This hybrid material exhibited an electrical conductivity of 463 S/cm, a Seebeck coefficient of 69.5 μV/K at 300 K, and a power factor of 260 μW/mK2. These metrics surpassed those of conventional Te/PEDOT:PSS hybrids by a factor of 3.6, highlighting the superior performance of our approach. This study represents a significant advancement in thermoelectric materials, improving both conductivity and efficiency.

Free droplets are spherical within capillary lengths and become nonspherical when trapped in a confined space. Confined nonspherical droplets are as common as spherical droplets. Yet, their evaporation dynamics are not fully understood because of their geometrical complexity. We use monochromatic synchrotron x-ray microtomography to investigate the evaporation dynamics of confined nonspherical water droplets trapped by micropillars based on three-dimensional geometrical information with time. We find two types of confined nonspherical droplets: Wenzel droplets with single-sided air-water interfaces, and Cassie-Baxter droplets with double-sided interfaces. Both droplets show similar sphericity at large volumes but approach different ones at small volumes: Wenzel droplets follow a thin film limit, whereas Cassie-Baxter droplets follow a spherical sessile limit. Despite the geometrical complexity of confined nonspherical droplets, the vapor diffusion mechanism suggests that the evaporative flux is maximal at the contact line, which governs the evaporation dynamics, as proven by observations. The proportionality of the evaporation rate to the contact line length demonstrates the contact-line-length-dominant evaporation dynamics of confined nonspherical droplets. The findings of this study can unify the evaporation mechanism for spherical sessile and confined nonspherical droplets, even with geometric complexity.

Alcohol ingested by humans can be analyzed via breath tests; however, approximately 1% can be excreted via the skin. In this paper, we present a capacitive sensor using hydrophobically treated anodic aluminum oxide (AAO) capable of detecting alcohol excreted through the epidermis. The degree of hydrophobicity based on the duration of exposure to 3-aminopropyltriethoxysilane vapor comprising a small number of Si–NH2 functional groups on the AAO surface was confirmed and the optimal exposure time was confirmed to be 60 min. The hydrophobized AAO showed a 4.8% reduction in sensitivity to moisture. Simultaneously, the sensitivity of the sensor to ethanol decreased by only 12%. Lastly, the fabricated sensor was successfully operated by attaching it to an ankle-type breathalyzer.

The understanding of structural defects in basal-faceted sapphire ribbons was improved through X-ray imaging at a synchrotron source. The combination of phase contrast and X-ray diffraction makes it possible to visualize and characterize both gas voids and dislocations in the bulk of the ribbons grown by the Stepanov–LaBelle technology. Dislocations were directly related to gas voids. X-ray diffraction topography was employed to investigate the distribution, configurations, and character of the dislocations. The formation of voids of irregular shapes was detected by large-area mapping with spatial resolution in the μm range. Computer simulations of the experimental phase contrast images of microvoids were performed. The sizes of the spherical microvoids were determined. The results are discussed with reference to the available data on the emission of dislocations from the voids. The evolution of the shape, size, and arrangement of the voids during growth provides clues on the formation of block structure in basal-faceted sapphire ribbons.

Bi–Te-based alloys are potential candidates for use in thermoelectric (TE) modules for low-mid-temperature energy harvesting. However, n-type Bi–Te–Se alloys are inferior to their p-type counterparts in terms of TE performance. It has been found that doping Cu atoms into n-type Bi–Te–Se alloys is effective in improving the TE properties; however, different studies have reported contrasting roles of Cu dopants in the transport properties of Bi–Te–Se alloys. This is attributed to the complex doping behaviors of Cu atoms. In this study, it is demonstrated that employing an appropriate fabrication technique can enable more Cu dopants to be directed to specific atomic sites than others. As part of the study, two n-type polycrystalline Cu0.01Bi1.99Te2.7Se0.3 bulk samples are respectively fabricated via melt-spinning followed by spark plasma sintering, and via ball-milling followed by spark plasma sintering. The majority of Cu dopants in the melt-spun sample are suspected to exist in between Te1–Te1 atomic layers (van der Waals gap), given the elongated c-axis, increased Hall carrier concentration, and improved non-degenerate mobility (intercalated Cu generates one electron and acts as an electric connector). Resultantly, a ~30% enhancement in the TE figure-of-merit (~0.92 at 360–400 K) is achieved in the melt-spun sample, relative to the ball-milled sample, wherein Cu atoms substitute Bi atoms.

Intermetallic copper telluride thin films, which are important in a number of electronics fields, were electrodeposited using a potentiostatic method in low-pH aqueous electrolyte baths with various ion-source concentrations, and the electrical properties of the formed films were investigated after exfoliation from the substrate. The films were electrochemically analyzed by cyclic voltammetry, while surface and cross-sectional morphologies, compositional ratios, and electrical properties were analyzed by scanning electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and Hall-effect experiments. The copper telluride thin films, which were synthesized at various potentials in each bath, exhibit different composition ratios and structures; consequently, they show a variety of electrical and thermoelectric properties, including different electrical conductivities, carrier concentrations, mobilities, and Seebeck coefficients. Among them, the thin film with a 1:1 Cu:Te ratio delivered the highest power factor due to carrier filtering at the interface between the two phases.

Controlling the electronic transport behavior in thermoelectric composites is one of the most promising approaches to enhance their power factor because this enables decoupling of the correlation between the electrical conductivity and Seebeck coefficient. Herein, we show that the unexpected high power factor of the Se nanowire array embedded in poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) can be achieved by controlling the interfacial band structure engineering. The electrical conductivity and Seebeck coefficient simultaneously increased, confirming that the synthesis of organic/inorganic hybrid thermoelectric materials with improved performance was possible. Our exploration can be helpful for the rational design of high-performance thermoelectric composites through interface engineering.

Thermoelectric devices based power generation and cooling systemsystem have lot of advantages over conventional refrigerator and power generators, becausebecause of solid-state devicesdevices, compact size, good scalability, nono-emissions and low maintenance requirement with long operating lifetime. However, the applications of thermoelectric devices have been limited owingowing to their low energy conversion efficiency. It has drawn tremendous attention in the field of thermoelectric materials and devices in the 21st century because of the need of sustainable energy harvesting technology and the ability to develop higher performance thermoelectric materials through nanoscale science and defect engineering. Among various fabrication methods, electrodeposition is one of the most promising synthesis methods to fabricate devices because of its ability to control morphology, composition, crystallinity, and crystal structure of materials through controlling electrodeposition parameters. Additionally, it is an additive manufacturing technique with minimum waste materials that operates at near room temperature. Furthermore, its growth rate is significantly higher (i.e., a few hundred microns per hour) than the vacuum processes, which allows device fabrication in cost effective matter. In this paper, the latest development of various electrodeposited thermoelectric materials (i.e., Te, PbTe, Bi2Te3 and their derivatives, BiSe, BiS, Sb2Te3) in different forms including thin films, nanowires, and nanocomposites were comprehensively reviewed. Additionally, their thermoelectric properties are correlated to the composition, morphology, and crystal structure.

The most promising approach for improving the electrical performance of connectors used in semiconductor test sockets involves increasing their electrical conductivity by incorporating one-dimensional (1D) conductive materials between zero-dimensional (0D) conductive materials. In this study, FeCo nanowires were synthesized by electroplating to prepare a material in which 1D materials could be magnetically aligned. Moreover, the nanowires were coated with highly conductive Au. The magnetization per unit mass of the synthesized FeCo and FeCo@Au nanowires was 167.2 and 13.9 emu/g, respectively. The electrical performance of rubber-based semiconductor connectors before and after the introduction of synthetic nanowires was compared, and it was found that the resistance decreased by 14%. The findings reported herein can be exploited to improve the conductivity of rubber-type semiconductor connectors, thereby facilitating the development of connectors using 0D and 1D materials.

Electron beam melting(EBM) is a useful technique to obtain high-purity metal ingots. It is also used for melting refractory metals such as tantalum, which require melting techniques employing a high-energy heat source. Drawing is a method which is used to convert the ingot into a wire shape. The required thickness of the wire is achieved by drawing the ingot from a drawing die with a hole of similar size. This process is used to achieve high purity tantalum springs, which are an essential component of lithography lamp in semiconductor manufacturing process. Moreover, high-purity tantalum is used in other applications such as sputtering targets for semiconductors. Studies related to recycling of tantalum from these components have not been carried out until now. The recycling of tantalum is vital for environmental and economic reasons. In order to obtain high-purity tantalum ingot, in this study impurities contained in the scrap were removed by electron beam melting after pre-treatment using aqua regia. The purity of the ingot was then analyzed to be more than 4N5 (99.995%). Subsequently, drawing was performed using the rod melted by electron beam melting. Owing to continuous drawing, the diameter of the tantalum wire decreased to 0.5 mm from 9 mm. The hardness and oxygen concentration of the tantalum ingot were 149 Hv and less than 300 ppm, respectively, whereas the hardness of the tantalum wire was 232.12 Hv. In conclusion, 4N5 grade tantalum wire was successfully fabricated from tantalum scrap by EBM and drawing techniques. Furthermore, procedure to successfully recycle Tantalum from scraps was established.

In this study, molten salt electrorefining was used to recover indium metal from In-Sn crude metal sourced from indium tin oxide (ITO) scrap. The electrolyte used was a mixture of eutectic LiF-KF salt and InF3 initiator, melted and operated at 700°C. Voltammetric analysis was performed to optimize InF3 content in the electrolyte, and cyclic voltammetry (CV) was used to determine the redox potentials of In metal and the electrolyte. The optimum initiator concentration was 7 wt% of InF3, at which the diffusion coefficients were saturated. The reduction potential was controlled by applying constant current densities of 5, 10, and 15 mA/cm2 using chronopotentiometry (CP) techniques. In metal from the In-Sn crude melt was deposited on the cathode surface and was collected in an alumina crucible.

In this study, a novel chloride ion (Cl−) sensor based on Ag wire coated with an AgCl layer was fabricated using a gel-type internal electrolyte and a diatomite ceramic membrane, which played an important role in preventing electrolyte leakage from the ion-selective electrode. The sensing performance, including reversibility, response, recovery time, low detection limit, and the long-term stability, was systemically investigated in electrolytes with different Cl− contents. The as-fabricated Cl− sensor could detect Cl− from 1 to 500 mM KCl solution with good linearity. The best response and recovery time obtained for the optimized sensor were 0.5 and 0.1 s, respectively, for 10 mM KCl solution. An exposure period of over 60 days was used to evaluate the stability of the Cl− sensor in KCl solution. A relative error of 2% was observed between the initial and final response potentials. Further, a wireless sensing system based on Arduino was also investigated to measure the response potential of Cl− in an electrolyte. The sensor exhibited high reliability with a low standard error of measurement. This type of sensor is crucial for fabricating wireless Cl− sensors for applications in reinforced concrete structures along with favorable performances.

Thermal stress induced by annealing the Cu filling of through-silicon vias (TSVs) requires further investigation as it can inhibit the performance of semiconductor devices. This study reports the filling behavior of TSVs prepared using direct current and pulse current Cu electrodeposition with and without pre-annealing. The thermal extrusion of Cu inside the TSVs was studied by observing the extrusion behavior after annealing and the changes in grain orientation using scanning electron microscopy and electron backscatter diffraction. The bottom-up filling ratio achieved by the direct current approach decreased because the current was used both to fill the TSV and to grow bump defects on the top surface of the wafer. In contrast, pulse current electrodeposition yielded an improved TSV bottom-up filling ratio and no bump defects, which is attributable to strong suppression and thin diffusion layer. Moreover, Cu deposited with a pulse current exhibited lesser thermal extrusion, which was attributed to the formation of nanotwins and a change in the grain orientation from random to (101). Based on the results, thermal extrusion of the total area of the TSVs could be obtained by pulse current electrodeposition with pre-annealing.

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500°C) on the structure and surface morphology of the FeS2 foam. The optimal temperature for the fabrication of the FeSx treated foam was determined to be 500°C. The FeS2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

Ultra-thin and large-area silicon wafers with a thickness in the range of 20–70 μm, were produced by spalling using a nickel stressor layer. A new equation for predicting the thickness of the spalled silicon was derived from the Suo–Hutchinson mechanical model and the kinking mechanism. To confirm the reliability of the new equation, the proportional factor of stress induced by the nickel on the silicon wafer, was calculated. The calculated proportional factor of λ = 0.99 indicates that the thickness of the spalled silicon wafer is proportional to that of the nickel layer. A similar relationship was observed in the experimental data obtained in this study. In addition, the thickness of the stressor layer was converted to a value of stress as a guide when using other deposition conditions and materials. A silicon wafer with a predicted thickness of 50 μm was exfoliated for further analysis. In order to spall a large-area (150 × 150 mm2 or 6 × 6 in2) silicon wafer without kerf loss, initial cracks were formed by a laser pretreatment at a proper depth (50 μm) inside the exfoliated silicon wafer, which reduced the area of edge slope (kerf loss) from 33 to 3 mm2. The variations in thickness of the spalled wafer remained under 4%. Moreover, we checked the probability of degradation of the spalled wafers by using them to fabricate solar cells; the efficiency and ideality factor of the spalled silicon wafers were found to be 14.23%and 1.35, respectively.

Polycrystalline bulks of Hf-doped Cu0.01Bi2Te2.7Se0.3 are prepared via a conventional melt-solidification process and subsequent spark plasma sintering technology, and their thermoelectric performances are evaluated. To elucidate the effect of Hf-doping on the thermoelectric properties of n-type Cu0.01Bi2Te2.7Se0.3, electronic and thermal transport parameters are estimated from the measured data. An enlarged density-of-states effective mass (from ~0.92 m0 to ~1.24 m0) is obtained due to the band modification, and the power factor is improved by Hf-doping benefitting from the increase in carrier concentration while retaining carrier mobility. Additionally, lattice thermal conductivity is reduced due to the intensified point defect phonon scattering that originated from the mass difference between Bi and Hf. Resultantly, a peak thermoelectric figure of merit zT of 0.83 is obtained at 320 K for Cu0.01Bi1.925Hf0.075Te2.7Se0.3, which is a ~12% enhancement compared to that of the pristine Cu0.01Bi2Te2.7Se0.3.

Herein we report a significantly reduced lattice thermal conductivity of Sb-doped Hf0.35Zr0.35Ti0.3NiSn half-Heusler alloys with sub-micron grains (grain size of ~300 nm). Polycrystalline bulks of Hf0.35Zr0.35Ti0.3NiSn1−xSbx (x = 0.01, 0.02, 0.03) with a complete single half-Heusler phase are prepared using temperature-regulated melt spinning and subsequent spark plasma sintering without a long annealing process. In these submicron-grained bulks, a very low lattice thermal conductivity value of ~2.4 W m−1 K−1 is obtained at 300 K due to the intensified phonon scatterings by highly dense grain boundaries and point-defects (Zr and Ti substituted at Hf-sites). A maximum thermoelectric figure of merit, zT, of 0.5 at 800 K is obtained in Hf0.35Zr0.35Ti0.3NiSn0.99Sb0.01.

Antimony telluride thin films display intrinsic thermoelectric properties at room temperature, although their Seebeck coefficients and electrical conductivities may be unsatisfactory. To address these issues, we designed composite films containing upper and lower Sb2Te3 layers encasing conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)- polyvinylpyrrolidone(PVP) nanowires. Thermoelectric Sb2Te3/PEDOT:PSS-PVP/Sb2Te3(ED) (STPPST) hybrid composite films were prepared by a multi-step coating process involving sputtering, electrospinning, and electrodeposition stages. The STPPST hybrid composites were characterized by field-emission scanning electron microscopy, X-ray diffraction, ultraviolet photoelectron spectroscopy, and infrared spectroscopy. The thermoelectric performance of the prepared STPPST hybrid composites, evaluated in terms of the power factor, electrical conductivity and Seebeck coefficient, demonstrated enhanced thermoelectric efficiency over a reference Sb2Te3 film. The performance of the composite Sb2Te3/PEDOT:PSS-PVP/Sb2Te3 film was greatly enhanced, with σ = 365 S/cm, S = 124 μV/K, and a power factor 563 μW/mK.

We propose a 3D-shape preferred orientation (SPO) measurement method of rigid grains using synchrotron micro-computational tomography (μ-CT). The method includes oriented sampling, 3D μ-CT imaging, image filtering, ellipsoid fitting, and SPO measurement. After CT imaging, all processes are computerized, and the directions of thousands of rigid grains in 3D-space can be automatically measured. This method is optimized for estimating the orientation of the silt-sized rigid grains in fault gouge, which indicates P-shear direction in a fault system. This allows us to successfully deduce fault motion sense and quantify fault movement. Because this method requires a small amount of sample, it can be applied as an alternative to study fault systems, where the shear sense indicators are not distinct in the outcrop and the fault gouge is poorly developed. We applied the newly developed 3D-SPO method for a fault system in the Yangsan fault, one of the major faults in the southeastern Korean Peninsula, and observed the P-shear direction successfully.

The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb) and dopants (Fe). An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects.

The regeneration of bone defects caused by periodontal disease or trauma is an important goal. Porous hydroxyapatite (HA) is an osteoconductive graft material. However, the hydrophobic properties of HA can be a disadvantage in the initial healing process. HA can be coated with TiO2 to improve its hydrophilicity, and ultraviolet irradiation (UV) can further increase the hydrophilicity by photofunctionalization. This study was designed to evaluate the effect of 5% TiO2-coated HA on rabbit calvarial defects and compare it with that of photofunctionalization on new bone in the early stage. The following four study groups were established, negative control, HA, TiO2-coated HA, and TiO2-coated HA with UV. The animals were sacrificed and the defects were assessed by radiography as well as histologic and histomorphometric analyses. At 2 and 8 weeks postoperatively, the TiO2-coated HA with UV group and TiO2-coated HA group showed significantly higher percentages of new bone than the control group (p < 0.05). UV irradiation increased the extent of new bone formation, and there was a significant difference between the TiO2-coated HA group and TiO2-coated HA with UV group. The combination of TiO2/HA and UV irradiation in bone regeneration appears to induce a favorable response.

Hepatic sinusoid, the smallest vessel in the liver, plays important roles in hepatic microcirculation. Although the structure of the hepatic sinusoids affects diverse functions of the liver, little is known about morphological alterations in the sinusoids under pathological conditions. In this study, we show that the structure of hepatic sinusoids can be identified three-dimensionally in normal and carbon tetrachloride-injured mouse liver, using the absorption mode of synchrotron radiation micro-computed tomography. We observed that the hepatic sinusoidal structure on tomographic slice images was similar to that on histological images of normal and acutely injured mice. Moreover, centrilobular necrosis and structural alterations of the sinusoids in the necrotic region were detectable on tomographic slice and volume-rendered images of the acutely injured mice. Furthermore, quantitative analyses on 3D volume-rendered images of the injured sinusoid revealed decrease in the volume of the sinusoid and connectivity of the sinusoidal network. Our results suggest that the use of synchrotron radiation micro-computed tomography may improve our understanding of the pathogenesis of hepatic diseases by detecting the hepatic sinusoids and their alterations in three-dimensional structures of the damaged liver.