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Point defect color centers acting as single-photon emitters are promising for quantum technology applications and have been extensively studied, e.g., in the 4H polytype of silicon carbide (SiC). However, the physics of such color centers in other SiC polytypes is much less explored. Herein, we study the formation and thermal stability of such color centers in 6H-SiC using photoluminescence spectroscopy. The emissions from typical single-photon emitters, such as silicon vacancies, divacancies, and carbon antisite-vacancy pairs in 6H-SiC, were monitored as a function of the proton irradiation fluence and post-irradiation annealing, and compared to that in 4H-SiC. Overall, at the background of similarities between the emission behavior in 4H- and 6H-SiC polytypes, we observed prominent differences; e.g., for the thermal stability of the carbon antisite-vacancy pair, which exhibited maximized emissions upon 300 and 900 ° C anneals in 4H- and 6H-SiC, respectively. Moreover, we observed a range of defect emission signatures not previously reported for 6H-SiC in the literature and discussed their potential origin in the context of the thermal stability. For example, among the PL-lines in 6H-SiC, we detected periodically repeatable emission signatures, resembling the so-called L-lines recently reported in 4H-SiC, even though their exact origin has not yet been settled in the literature. Thus, we use color centers comparison in different polytypes to better understand the nature of the single-photon emitters in SiC. [ABSTRACT FROM AUTHOR]

4H Silicon carbide (SiC) is widely recognized as one of the most advanced wide bandgap semiconductors used in the production of high-efficiency power electronic devices. Impurities play a crucial role in achieving the desired electrical properties in 4H-SiC, yet the understanding of impurities in this material remains limited. In this study, first-principles formation-energy calculations were employed to establish a comprehensive database of formation-energy diagrams for impurities in 4H-SiC. This database includes valuable information on site preference, lattice distortion, solubility, and charge transition levels (CTLs) of the impurities. The site preference for each impurity is closely related to factors such as the Fermi energy, chemical potential, and the impurity species itself. To assess the lattice distortion caused by each impurity, a comparison was made between the volume changes before and after doping. Moreover, the solubility of each impurity was determined using the detailed balance theory, thereby enabling a direct measure of the maximum impurity concentration achievable in the material. Based on the CTLs, the impurities in 4H-SiC were classified into four categories: n-type impurities, p-type impurities, amphoteric impurities, and non-electroactive impurities. This comprehensive property database for impurities in 4H-SiC provides valuable insights for tailoring the material properties through controlled doping, thereby ultimately leading to enhanced performance of power electronic devices. [ABSTRACT FROM AUTHOR]

4H Silicon carbide (4H-SiC) is widely recognized as a highly promising material for high-voltage and high-power electronic applications due to its exceptional properties. The performance of devices based on 4H-SiC is often weakened by the presence of carbon-related point defects, particularly carbon vacancies (VC). The defects of VC introduce deep-level traps (e.g., Z1/2 and EH6/7) that deteriorate device functionality. Experimental and theoretical studies on VC have led to some conflicting results about the charge states of VC, especially for the charge state ordering of EH6/7. We now employ ab initio metadynamics (META) to systematically investigate configuration space including the direction and magnitude of bond distortion and identify the most stable structures of VC. Eventually, the charge states of VC in 4H-SiC are identified. The Z1 (EH6) and Z2 (EH7) indicate transitions from acceptor (donor) levels of VC, located on the h and k sublattice sites, respectively. Z1 and Z2 demonstrate negative-U ordering, characterized by U values of −0.16 and −0.37 eV, respectively. Conversely, EH6 and EH7 display positive-U ordering, with U values of 0.16 and 0.08 eV, respectively. The current results provide insights into the properties of VC in 4H-SiC, highlighting the effectiveness of META in the exploration of complex potential energy surfaces associated with point defects in solids. [ABSTRACT FROM AUTHOR]

Based on the transport and polarization relaxation theories, the effects of hydrogen, fluorine, and chlorine atom passivation on the conductivity and dielectric properties of silicon carbide nanowires (SiCNWs) were numerically simulated. The results show that passivation can decrease the dark conductivity of SiCNWs and increase its ultraviolet photoconductivity. Among them, the photoconductivity of univalent (H) passivated SiCNWs is better than that of seven-valent (Cl, F) passivated SiCNWs. In terms of dielectric properties, the passivated SiCNWs exhibit a strong dielectric response in both deep ultraviolet and microwave regions. Hydrogen passivation SiCNWs produce the strongest dielectric response in deep ultraviolet, while fluorine passivation SiCNWs produce the strongest dielectric relaxation in the microwave band, which indicates that atomic passivation SiCNWs have a wide range of applications in ultraviolet optoelectronic devices and microwave absorption and shielding. [ABSTRACT FROM AUTHOR]

A non-destructive method for detecting sub-micrometer-sized micropipes on an entire wafer surface is investigated. Since it is difficult to detect sub-micrometer-sized micropipes due to their small core size, a non-destructively and accurately detecting method is required. To solve the issue, we focus on a characteristic depression generated around micropipes, namely, line-shaped depressions. In this paper, the location of line-shaped depressions is identified by using optical inspection, and the line-shaped depressions are distinguished whether micropipes exhibit line-shaped depression or not by using mirror electron microscope observation as high-resolution inspection. The accuracy of the distinction results is confirmed by scanning electron microscope observation, and electrical characteristics of the P–N diode are fabricated using the inspected wafer. Furthermore, the sub-micrometer-sized micropipes are observed at the sites of leakage current identified by emission microscopy. Additionally, device simulation of the blocking-voltage characteristics of P–N diodes suggests that the increase in leakage current depends on the electric field at the sub-micrometer-sized micropipes, regardless of their core size. [ABSTRACT FROM AUTHOR]

4H silicon carbide (SiC) polytype is preferred over other SiC polytypes for high-power, high-voltage, and high-frequency applications due to its superior electrical, thermal, and structural characteristics. In this manuscript, we provide a comprehensive study of the spin coupling dynamics between conduction electrons and nitrogen (N) donors in monocrystalline 4H SiC with various concentrations of uncompensated N donors from 1017 to 5 × 1019 cm−3 by continuous wave, pulsed electron paramagnetic resonance (EPR), and microwave perturbation techniques at T = 4.2–300 K. At low temperatures, two triplets due to N donors in cubic (Nk) hexagonal (Nh) positions and triplet arisen from spin-interaction between Nh and Nk were observed in 4H SiC having Nd − Na ≈ 1017 cm−3. A single S-line (S = 1/2) dominates the EPR spectra in all investigated 4H SiC monocrystals at high temperatures. It was established that this line occurs due to the exchange coupling of localized electrons (dominate at low temperatures) and non-localized electrons (dominate at high temperatures). The localized electrons were attributed to Nh for Nd − Na ≈ 1017 cm−3 and Nk donors for Nd − Na ≥ 5 × 1018 cm−3. We have concluded that the conduction electrons in 4H SiC monocrystals are characterized by g|| = 2.0053(3) and g⊥ = 2.0011(3) for Nd − Na ≤ 5 × 1018 cm−3 and g|| = 2.0057(3) and g⊥ = 2.0019(3) for Nd – Na ≈ 5 × 1019 cm−3. Using the theoretical fitting of the temperature variation of S-line EPR linewidth in 4H SiC having Nd – Na ≤ 5 × 1018 cm−3, the energy levels of 57–65 meV that correlate with the valley-orbit splitting values for Nk donors in 4H SiC monocrystals were obtained. [ABSTRACT FROM AUTHOR]

Optically active spin defects in semiconductors can serve as spin-to-photon interfaces, key components in quantum technologies. Silicon carbide (SiC) is a promising host of spin defects thanks to its wide bandgap and well-established crystal growth and device technologies. In this study, we investigated the oxygen-vacancy complexes as potential spin defects in SiC by means of ab initio calculations. We found that the OCVSi defect has a substantially low formation energy compared with its counterpart, OSiVC, regardless of the Fermi level position. The OCVSi defect is stable in its neutral charge state with a high-spin ground state (S = 1) within a wide energy range near the midgap energy. The zero-phonon line (ZPL) of the OCVSi0 defect lies in the near-infrared regime, 1.11–1.24 eV (1004–1117 nm). The radiative lifetime for the ZPL transition of the defect in kk configuration is fairly short (12.5 ns). Furthermore, the estimated Debye–Waller factor for the optical transition is 13.4%, indicating a large weight of ZPL in the photoluminescence spectrum. All together, we conclude that the OCVSi0 defect possesses desirable spin and optical properties and thus is potentially attractive as a quantum bit. [ABSTRACT FROM AUTHOR]

For the preparation of SiC nanowires (SiC NWs) by carbothermal reduction, it is of great significance to study the formation mechanism of sic nanowires for process optimization and the controllable preparation. Although first-principles molecular dynamics (FPMD) can simulate systems of hundreds of atoms on a picosecond time scale, the results of FPMD are still insufficient to elucidate the formation mechanism of core-shell SiC nanowires. To make up this deficiency, this article has conducted Deep Potential Molecular Dynamics (DPMD) simulation on nanoseconds timescales with near FPMD accuracy for systems containing thousands of atoms, the results more concretively show the formation process of core-shell SiC nanowires. DPMD simulation results show when CO molecules react with SiO molecules, CO molecules are wrapped by SiO molecules to form agglomerates, SiO molecules in the agglomerates that can come into contact with the wrapped CO molecules will react with wrapped CO molecules to form the SiC core, and SiO molecules that in the outer layer of the agglomerates will disproportionate into the amorphous SiO 2 shell. Furthermore, the formation mechanism of SiC nanowires was validated in combination with thermodynamics and experimental methods. Thermodynamic results show that vacuum conditions are favorable for the formation of SiO and CO and lower the temperature of SiC preparation. Finally, the core-shell structure of SiC NWs with good luminescence properties were successfully prepared by carbothermal reduction method using carbon black and silicon dioxide as raw materials under the pressure of less than 5 kPa. [ABSTRACT FROM AUTHOR]

This study investigates the effects of applied tensile and compressive stresses on the evolution of defects in He-irradiated silicon carbide (SiC) materials. By combining experimental studies with density-functional theory (DFT) simulations, we systematically analyzed the microstructural changes and defect formation mechanisms in SiC under stress. The research focused on He irradiation of SiC at 750 °C, with a fluence of 1 × 101⁷ He/cm2. The results revealed that the strain resulting from radiation damage depends on the applied stress during irradiation. Moreover, the formation of platelets is influenced by this applied stress: tensile stress promotes platelet growth, while compressive stress inhibits it. DFT simulations further supported these experimental findings by showing that under tensile strain, both carbon vacancies (Cv) and He atoms exhibit low energy barriers for migration. This phenomenon facilitates platelet growth, aligning well with the observations made in the experiments. However, when considering applications like semiconductor thin film transfer, such as the Smart-cut technique, He implantation under tensile stress can actually be advantageous. This approach enables the use of lower He fluence, which in turn reduces the overall cost of the operation. By strategically leveraging the effects of tensile stress on He implantation, it becomes possible to optimize processes like Smart-cut for more efficient and cost-effective thin film transfer in semiconductor manufacturing. [ABSTRACT FROM AUTHOR]

As a representative of third-generation semiconductors, silicon carbide serves as a new platform for quantum nano-optics with readable paramagnetic color centers such as silicon vacancies. The potential applications include biomedical imaging, quantum sensing and micro/nano environment detection. Color centers are usually prepared based on ion-irradiated substrates, then annealed at high temperature to increase the yield. Currently, annealing furnaces have been the main method to heat the substrate and achieve annealing of the whole sample. However, further exploration is still necessary for fine processing requirements such as specialized annealing regions with certain shapes. In this work, we applied femtosecond laser to achieve controllable annealing at micron scale, based on silicon carbide substrate after ion injection. The whole process of point, line and pattern annealing was realized. The annealing area demonstrates enhanced photoluminescence, attributed to silicon vacancy color centers. Raman and photoluminescence spectra reveal that the annealing effect is primarily influenced by the number of pulses per unit area. The mechanism of femtosecond laser annealing was introduced. Finally, the controllable annealing areas with various shapes were prepared based on the comprehensive optimal parameters (100 kHz pulse repetition frequency, 105 point annealing pulses, 10 μm/s line scanning speed). This annealing strategy demonstrates excellent stability and uniformity, as well as micron scale accuracy. Additionally, the excited state lifetime of silicon vacancy was extracted and quantified. The result means that femtosecond laser annealing enhances the optical properties and quantum application potential of color centers. This work can be further extended to other semiconductors as well as patterned modification of local surface/planes at some depth, and helpful to explore the mechanism and applications of femtosecond laser annealing. [ABSTRACT FROM AUTHOR]

In this study, in-situ growth of columnar mullite reinforced silicon carbide porous membrane supports were prepared, and the addition of TiO 2 helped to reduce the sintering temperature for the anisotropic growth of necked columnar mullite crystals. The synthesis of in situ columnar mullite makes reasonable use of the oxidized silica of silicon carbide, and in turn reduces the loss of the silicon carbide porous membrane support under strong corrosive conditions. The material showed a flexural strength of up to 72.95 MPa, and a water flux of 31612.83 L·m−2·h−1·bar−1 when sintered for 2 h in an air environment at 1250 °C. The flexural strength after corrosion in 20 vol% H 2 SO 4 and 1 wt% NaOH solution (90 °C) exceeded 93 %. This shows that this porous silicon carbide ceramic membrane scaffold has potential applications in the field of water treatment under harsh environments. [ABSTRACT FROM AUTHOR]

At present, wire sawing technology is the primary slicing method used for certain brittle materials, including monocrystalline silicon, sapphire, and silicon carbide. The surface quality of the sawn wafers significantly impacts subsequent machining processes, such as grinding and polishing. A theoretical model was developed to predict the amount of material removed per unit length of wire during the slicing of circular workpieces by a wire saw with reciprocating and rocking functions. Experiments were conducted during this study in which crystal ingots were sliced using a multi-wire saw, and the amount of material removed per unit length of wire was determined at different cutting positions on the workpiece cross-section. The surface roughness of each crystal wafer was measured systematically. The experimental results revealed that the surface roughness values measured at different points at the same y-coordinate position on a single wafer were approximately equal. However, the surface roughness was greatest on both the initial and final cutting edges and gradually decreased toward the wafer center. The surface roughness was also greatest for the wafer cut nearest to the new wire side, though it gradually decreased for wafers cut nearer to the center of the workpiece and remained relatively consistent from the middle wafer to the wafer cut nearest to the used wire side. The results also indicated that both the material removed per unit length of wire and the surface roughness of the wafer decreased with increases in the wire speed. The relationship between the material removed per unit length of wire and the surface roughness was approximately linear. When the material removed per unit length of wire was set to 0.00333 mm3/m, the average wafer surface roughness was 0.45 μm. [ABSTRACT FROM AUTHOR]

As the most prospective media material for porous media burners, silicon carbide reticulated porous ceramic (SiC RPC) is required to possess a high porosity to fulfill efficient combustion, as well as exceptional thermal shock resistance to withstand the thermal stress generated during the start-up and shutdown processes. To achieve the strengthening and toughening of highly porous SiC RPC, three-layered struts were constructed, and in-situ whiskers were formed in SiC RPC through vacuum infiltration and sintering under a nitrogen atmosphere in this work. The results indicated that the three-layered struts were formed after the preform was conducted with vacuum infiltration, encompassing a mullite coating, a silicon carbide layer and a mullite inner layer. When Si powder and flake graphite were incorporated into the SiC slurry, numerous SiC whiskers were formed in situ within the SiC skeleton. The formation of SiC whiskers was attributed to the enhancement of SiC RPC, resulting in an increase in CCS from 0.22 MPa to 0.55 MPa. Additionally, the residual strength retention rate after water quenching at 1100 °C was elevated from 41.6 % to 70.2 %. Moreover, the SiC RPC containing SiC whiskers exhibited an impressively high porosity of 83 %, leading to a surface temperature of 688 °C and a heating efficiency of 16.4 °C/min during the combustion process. [ABSTRACT FROM AUTHOR]

Face index is a critical topological descriptor that provides important information about the structural variations of various materials. Initially introduced as a novel metric, the face index has become essential in characterizing the complexity and properties of molecular structures like silicate networks, carbon sheets, and nanotubes. This analysis focuses on the face index within the Silicon Carbide structure, highlighting its profound significance as a pivotal structural descriptor. By shedding light on its implications for the fundamental properties of three different Silicon Carbide structures: S i 2 C 3 -I[m, n], S i 2 C 3 -II[m, n] and S i 2 C 3 -III[m, n], this study aims to advance our understanding of the structural complexities and potential applications of this unique material system. [ABSTRACT FROM AUTHOR]

In this paper, highly electrically and thermally conductive copper powders (Cu) and electrically insulative yet thermally conductive silicon carbide whiskers (SiCw) were selected as functional fillers and high‐density polyethylene (HDPE) was used as the matrix to prepare thermal conductive composites. By controlling the amount of Cu at 30 vol% which is below percolation threshold, the volume resistivity of the composites is maintained above 1014 Ω cm. The results showed that SiCws entered the area which was not occupied by Cu particles and they played a bridging effect among Cu particles, thereby promoting the formation of intact thermal conductive pathways that contributed to improving the thermal conductivity of corresponding composites. The combination of SiCw:Cu = 3:1 at a filler content of 30 vol% resulted in a thermal conductivity as high as 1.921 W/mK, which is 380% higher than pure HDPE. [ABSTRACT FROM AUTHOR]

In this study, three distinct low-temperature glass fillers for vacuum-assisted joining of reaction-bonded silicon carbide (RB-SiC) were designed. Additionally, the physical properties, microscopic morphologies and joints strength of these glass fillers were investigated. The results indicate that Zinc Borosilicate (ZBS) glass filler is the most effective for joining RB-SiC under the specified conditions. ZBS demonstrates optimal glass skeleton for joining, a compatible coefficient of thermal expansion, and superior wettability compared to the other tested powders. Notably, the shear strength of the RB-SiC joints with ZBS reached 80 MPa, markedly surpassing that of Lead zinc borate (PZB) and Lead borosilicate (PBS) by 381 % and 400 %, respectively. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramic lattice structures (CLSs) hold significant potential for use in structural components and optical mirrors in space exploration due to their light weight, high strength, and excellent dimensional stability. However, they face challenges such as poor curing performance and weak mechanical strength during the digital light processing (DLP) additive manufacturing process. In this study, SiC@Al 2 O 3 powder was prepared, resulting in a 21 % reduction in absorptivity compared to bare SiC powder. The ceramic paste derived from this powder achieved a curing thickness of up to 80 μm, exhibited a reduced over-curing width, and demonstrated a 75 % improvement in stability compared to bare SiC paste. Consequently, high-quality triply periodic minimal surfaces (TMPS) structured SiC@Al 2 O 3 CLSs green bodies were successfully fabricated. By integrating precursor impregnation pyrolysis with the reaction melting infiltration (PIP-RMI) post-treatment densification method, SiC@Al 2 O 3 /Si CLSs were produced, exhibiting superior mechanical properties with low dimensional shrinkage. At 30 % volume fraction, the specific compressive strength of the primitive-TPMS SiC@Al 2 O 3 /Si CLSs reached 24.79 MPa. This study presents an effective method for fabricating SiC-based CLSs and establishes a foundation for the optimization of SiC ceramic fabrication processes. [ABSTRACT FROM AUTHOR]

The reliable connection between ceramics and metals achieved through brazing is a crucial method to promote their application. In this study, the FeCoCrNi high entropy alloys was adopted as the filler to connect SiC and Mo through vacuum brazing. The microstructure evolution and mechanical properties of the SiC/FeCoCrNi/Mo brazed joint at different brazing temperature and holding time were systematically investigated. With the increase of the brazing temperature or the extension of the holding time, the reaction layer gradually thickened with the increasing precipitation of the soft FCC phase. Notably, the FCC solid solution phase with good plastic deformation ability and the brittle Cr 0.46 Mo 0.4 Si 0.14 phase have good interface bonding (lattice mismatch degree ∼ 3.12 %). The dispersive and staggered distribution of FCC phase and Cr 0.46 Mo 0.4 Si 0.14 phase can effectively alleviate the joint stress and hinder crack propagation. This work is expected to provide theoretical guidance for the connection of ceramics and metals through high-entropy alloys. [ABSTRACT FROM AUTHOR]

Silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al) have been widely used in many areas due to their good physical and mechanical properties. However, because the material contains SiC particles with high hardness, processing is difficult and the processing quality of milling is poor. Ultrasonic vibration-assisted longitudinal torsion milling (LTUVAM) has great advantages in cutting difficult materials because it can effectively reduce the cutting force and cutting heat and improve the surface quality of the workpiece. Therefore, the kinematic analysis of LTUVAM is carried out, the material removal mechanism of 60% SiCp/Al is studied by the method of simulation and experiment, and the effects of machining parameters on the cutting force, cutting heat, and surface quality of the material were analyzed and using the traditional milling (CM) compared. The simulation and experimental results show that LTUVAM can improve the particle crushing rate, effectively reduce the cutting force and cutting heat under the relevant parameters, and improve the surface quality. [ABSTRACT FROM AUTHOR]

A new preparation process for silicon carbide (SiC) powder is developed. In the Si–(C) –PTFE–Ar system, the grain size and morphology of the product 3C–SiC were controlled by adding a carbon source (graphite) and changing the percentage of polytetrafluoroethylene (PTFE) (0%, 10%, and 20%). The experimental results showed that the SiC powders prepared using a molar ratio of 1:1 silicon powder to graphite, plus 20% PTFE have a uniform particle size distribution (∼130 nm), a lamellar structure made of spherical particle stacking, a small bandgap (1.80 eV), a high carrier concentration, and a large number of lattice defects. These properties are expected to increase the electrical conductivity of 3C–SiC and decrease its thermal conductivity, thus providing a promising feedstock preparation option for SiC thermoelectric materials. In addition, the mechanism of PTFE in the preparation of SiC reactions was studied in detail. [ABSTRACT FROM AUTHOR]

The major purpose of this study is to analyze the resistance of honeycomb ceramic matrix composites to penetration and to explore the effect of the performance characteristics of the filler materials on this capability. We used alumina ceramics, polyurea, quartz sand powder, and boron carbide powder to manufacture composite materials, and conducted impact tests and numerical simulations on them. The simulation results of Abaqus were found to be very consistent with the test results. The results demonstrate that the polyurea coating and filler materials may effectively improve the anti-penetration penetration performance of the composites, and different filler materials have varying energy absorption effects. Extended research on composites was carried out utilizing experimentally validated numerical models with filler materials comprising silicon carbide, aluminum nitride, and silicon nitride. After a comparative analysis of the simulation results of different composites, compared to quartz sand composites, the energy absorption efficiency of boron carbide composites increased by 12.03 %, silicon carbide composites increased by 14.63 %, aluminum nitride composites increased by 15.16 %, and silicon nitride composites increased by 18.29 %. Among the relevant materials in this study, there exists an optimal value of the stress wave impedance difference between the matrix material and the filler material. Honeycomb ceramic matrix composites with an ideal combination of stress wave impedance differences can considerably increase the anti-penetration efficiency of the composites. [ABSTRACT FROM AUTHOR]

High-purity SiC ceramic membrane has gained tremendous attention in the treatment of various corrosive wastewaters. Additive manufacturing technique makes it possible to fabricate high-purity SiC ceramic membrane with complex configurations. Here, we proposed a route for the preparation of high-purity SiC ceramic membrane support using digital light processing and SiC whisker reinforcement. With the increase of whisker content, the viscosity of SiC w /SiC photosensitive slurry increased due to the formation of whiskers agglomerations; the average pore size shifted from 3.15 μm to 1.35 μm with the occupation of large pores by SiC whiskers. In addition, the compressive strength of the ceramic support increased from 10.7 MPa to 16.7 MPa because of the decline in pore size and the toughening effects by SiC whiskers. So, the introduced SiC whiskers enhanced the pore connectivity and mechanical strength of the porous ceramics. This work provides a feasible path to manufacture high-purity SiC ceramic membrane support with complex configuration, high pore-connectivity and excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Lightweight, flexible and highly conductive electromagnetic interference (EMI) shielding materials are of great importance for protecting flexible electronics and telecommunication devices under extremely high temperature conditions. A potential solution is to incorporate ceramic phases with highly conductive flexible carbon nanotube films to improve their thermal stability. However, the grain size of the ceramic phase generally increased significantly as the temperature increased which led to brittleness. In this work, a highly flexible carbon nanotube (CNT) film with controllable ceramic nanocrystals was prepared by precursor infiltration and pyrolysis. The silicon carbide (SiC) grain size in the nanocomposites was inhibited by the spatial confinement effects of CNT networks and a second amorphous SiBCN phase. The SiC grain size in the composite film decreased with the increase of the SiBCN content and the elongation at break of the nanocomposites improved significantly by 45 %. Moreover, the initial thermogravimetric temperature of the prepared films has been significantly improved to exceed 600 °C compared to the raw CNT film. Importantly, the nanocomposite film exhibited an average EMI shielding effectiveness of ∼40 dB from 8.2 to 12.4 GHz. Benefiting from the ultrafine grain size, the nanocomposite films could be folded and extended without micro-cracks over 1000 times. Combining the performance and mechanical properties of the nanocomposite film, this approach provides important guidance for designing high-performance CNT-based electromagnetic shielding materials with superior flexibility at elevated temperatures. [ABSTRACT FROM AUTHOR]

Systematic atomistic simulations of oblique collisions between spherical crystalline, 6H and 3C, and amorphous SiC nanoparticles (NPs) are performed in the bouncing and fragmentation regimes for the particles with diameters from 8 nm to 30 nm, impact velocities from 100 ms−1 to 5000 ms−1, and in the whole range of the geometric impact parameter. The critical sticking velocity of 6H-SiC NPs reduces from ∼490 ms−1 to ∼150 ms−1 when the NP diameter increases from 10 nm to 30 nm. Below the melting threshold, the collision of crystalline NPs induces the formation of localized zones of densified material, while the remaining parts of NPs are not affected by plastic deformations. The impact of amorphous NPs results in the plastic deformation of significant parts of the NP material and much larger irreversible losses of mechanical energy. The post-collision translational and rotational velocities of crystalline NPs as well as coefficients of restitution (CORs) demonstrate weak dependence on the NP size if the NP diameter is greater than 20 nm. At constant impact velocity, the normal COR only marginally varies for head-on and oblique collisions, when the collision angle is smaller than ∼53°. The tangential center-of-mass and point-of-contact CORs, as functions of the impact parameter, demonstrate extremal behavior with the minima at collision angles from ∼27° to ∼37°. The normal COR exhibits a linear decay as a function of the impact velocity where the slope coefficient is different below and above the melting threshold. The tangential CORs attain the minimum values at the impact velocity of ∼300 ms−1. The obtained results are summarized in the form of fitting equations for CORs as functions of the impact parameter and velocity, which can be readily used to predict the post-collision translational and angular velocities of NPs in large-scale simulations of granular gas flows. [ABSTRACT FROM AUTHOR]

In sophisticated engineering machining, ceramic materials are in great demand in today's precision industries because they have a wide range of potential applications, including automobiles, aircraft, and biomedical engineering. Silicon nitride ceramics (Si3N4) are difficult to manufacture using conventional machining processes. Modern technology allows Ultrasonic Micro-machining (USMM) to create almost any kind of material. Abrasive particles made of silicon carbide are used in this research work to look into the Si3N4 USMM process parameters. The physical structure and chemical composition have been examined in a scanning electron microscope with an integrated energy-dispersive X-ray analyzer. Particle swam optimization and Response Surface Methodology (RSM) desirability were the two types of optimizations used to find the best USMM process parameters. It has been shown that both techniques can be used together to get the best Material Removal Rate (MRR). The best settings were Slurry Concentration: 50 (g/l), Power Rating: 329 (W), and Tool Feed Rate: 1.06 (mm/min). Similarly, to minimize Overcut (OC) and Taper Angle (TA), the ideal method is to use a slurry concentration of 50 (g/l), a power rating of 400 (W), and a tool feed rate of 1.2 (mm/min). Finally, using the RSM, the USMM process was optimized in a way that maximized the MRR while minimizing OC and TA. It was found that the slurry concentration of 42.7 g/l, the power rating of 357.6 W, and the tool feed rate of 1.2 mm/min were the ideal settings for the USMM process. [ABSTRACT FROM AUTHOR]

The current study focuses on the role of composition in the oxidation behavior of three commercial SiC fibers (Hi‐Nicalon Type S (HNS), Tyranno ZMI, and Tyranno SA) in a steam‐containing environment at 1000°C. Oxide scales that form on each of the three fiber types differ in morphology, microstructure, and composition. Differences are attributed to O and C contents, crystallinity, and minor alloying elements. Oxidation kinetics of the HNS fibers follow linear/parabolic (Deal–Grove) predictions over the entire range of exposure times (to 96 h). In the other fibers, deviations from the initial linear/parabolic trend occur when either the scale crystallizes in situ during oxidation (as on the ZMI fibers) or when structural changes internal to the fiber alter the chemical environment at the scale/fiber interface (on the SA fibers). Adaptations of the linear/parabolic oxidation model are used to rationalize the growth kinetics in the latter two cases. Collectively, the data and analyses indicate a two‐fold difference in permeabilities of crystalline and amorphous silica scales. Inferred interface reaction rates further suggest faster oxidation for fibers with greater amounts of amorphous Si–O–C. Moreover, crystalline scales are more prone to cracking, because of their higher viscosity at elevated temperatures and a deleterious phase transformation upon cooling. [ABSTRACT FROM AUTHOR]

Ceramic membranes based on SiC have a number of advantages, namely high surface hydrophilicity, good water permeability and negative surface charge, which leads to better performance during their operation, but they require high sintering temperatures due to covalent bonds. The use of sintering agents can significantly reduce the final sintering temperature. The aim of this work was to synthesise ceramic membranes based on silicon carbide and to study the effect of liquid glass on their mechanical, electrical and antibacterial properties. The physicochemical properties of SiC ceramic membranes were investigated by diffraction analysis and scanning electron microscopy. It was found that, regardless of the type of carbonate, only two phases are identified: the main phase of the initial mixture, silicon carbide and the phase added to the mixture, corundum. The obtained SiC ceramic membranes are macroporous, as indicated by the transport properties (9.03–18.66 cm3/(min-cm2)) and the results of electron microscopy (13–20 μm). SiC ceramic membranes obtained are characterised by high strength (16.3–46.8 MPa). Studies of antibacterial properties have shown that SiC-based ceramic membranes do not exhibit antibacterial properties, but modification of ceramic membranes with titanium oxide inhibits the growth of gram-negative bacteria. The results of this study are useful for enriching the knowledge about the production of silicon carbide membranes and are aimed at further research and development of selective membranes (micro- and ultrafiltration) based on them. [ABSTRACT FROM AUTHOR]

Silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al) have found extensive use in electronic packaging, aircraft manufacturing, and various other industries due to their exceptional strength, low density, and high wear resistance. Nevertheless, owing to the multiphase microstructure resulting from SiC particles embedded in an Al matrix, the presence of non-ideal regions within the material poses a significant challenge in achieving high surface integrity. Ultrasonic vibration-assisted grinding (UVAG) has been proven to be an effective machining technique for improving the machinability of reinforced particles. The axial ultrasonic vibration grinding with a single diamond grain was conducted to realize the material removal mechanism of SiCp/Al composites. Furthermore, a 3D model of diamond grains with a cohesive force unit was constructed to simulate the material removal evolution of SiC particles under UVAG. Results demonstrate that the utilization of ultrasonic vibration-assisted grinding facilitates the plastic-like removal of hard particles and promotes the transformation of brittle SiC material removal into a plasticized form. UVAG could effectively mitigate the occurrence of pit formation caused by SiC particles, which would otherwise result from extensive crushing and detachment during the conventional grinding process, thus, enhancing the integrity of the machined surface. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) substrates are widely used in semiconductor and photoelectric applications due to excellent electrical and chemical properties. However, due to its inherent hard-brittle properties and chemical inertness, traditional polishing processes are facing great challenges to obtain excellent surface and subsurface quality for the SiC substrates. In this work, a novel polishing process i.e. magnetorheological shear thickening polishing (MRSTP) was proposed to explore the feasibility for the polishing of the SiC substrates. The MRSTP experiments were conducted using multiple magnetic-pole-coupled tools. The magnetic field characteristics of the polishing area were investigated via finite element simulation and actual measurements. The magnetic-pole-coupled tool was capable of generating high magnetic induction strength in the polishing area. The MRSTP medium was designed and prepared. The media were formed magnetic brushes by the excited magnetic field. The MRSTP experiments were conducted to investigate the effects of processing parameters on the polished surface roughness. The optimum process parameters were determined as the spindle rotational speed of 700 rpm, the feed rate of 600 mm/min, the work gap of 0.5 mm and MRSTP media CIPs particle size of 100 μm. The surface roughness of the workpieces was improved from initial 1.414 μm to 27.6 nm. It is verified that the MRSTP is the feasible ultraprecision polishing process for the SiC substrates. [ABSTRACT FROM AUTHOR]

In order to achieve low-temperature densification of SiC ceramic, β-SiC nanopowder was doped with Li 2 O together with Y 2 O 3 –Al 2 O 3 –MgO as sintering aids, and then spark plasma sintered at temperatures ranging from 1450 °C to 1600 °C for 30 min under 30 MPa pressure in argon. The densities, microstructures and mechanical properties of SiC ceramics were systematically investigated, in comparison to the counterparts sintered with Y 2 O 3 –Al 2 O 3 –MgO additives. Since Li 2 O has a low melting point, Li 2 O addition effectively decreased the formation temperature of liquid secondary phase, enabling SiC ceramics to obtain higher density and lower porosity after low-temperature sintering (T ≤ 1550 °C). Besides, Li 2 O addition was found to decrease the viscosity of liquid phase and enhance grain growth of SiC through dissolution-reprecipitation process. When sintered at 1550 °C, Li 2 O addition led to a remarkable increase of density from 3.03 g/cm3 to 3.21 g/cm3 for SiC ceramic. Meanwhile, the SiC ceramic with Li 2 O addition exhibited a high Vickers hardness of 22.75 ± 0.35 GPa and a good fracture toughness of 3.83 ± 0.27 MPa m1/2. The research results are expected to benefit the low-cost fabrication of SiC ceramics based on pressure-assisted sintering and alleviate the thermal damage of SiC fiber in hot-pressed SiC f /SiC composites. [ABSTRACT FROM AUTHOR]

The further applications of silicon carbide (SiC) are limited due to the ease of being contaminated and tendency for icing at low temperature caused by its intrinsically hydrophilicity. In recent years, superhydrophobic surface has been widely employed due to the potential value in anti-fouling and passive anti-icing. In this work, a novel laser ablation-silicone oil heat treatment (LASH) composite process is proposed to fabricate superhydrophobic SiC surface. Many microscale "fence" structures and nanoscale "broccoli" fragmental structures are successfully obtained, which can be adjusted by using different laser processing parameters. Besides, the X-ray photoelectron spectroscopy analysis demonstrates that the effective deposition of low surface energy chemical functional groups is the key to realize the superhydrophobic properties of SiC surface. The coupling effect between the micro/nano structures and low surface energy is confirmed to be important for the stability of Cassie-Baxter state at low temperature. In addition, the freezing process of water droplets on the LASH surface at low temperature and the mechanism of the rapid transition from Wenzel state to Cassie-Baxter state are analyzed. The experimental results indicate that the LASH surface possesses a longer static icing time and keeps good hydrophobicity at −5 °C. The icing temperature of the LASH surface decreases to −17.6 °C while the temperature of the untreated surface is −3.7 °C. Moreover, the LASH surface possesses a lower ice adhesion strength which means it is easier for the ice droplets to break away from the surface. After 20 cycles of icing-deicing experiments, the WCA of the LASH surface is still higher than 150° and its ice adhesion strength slightly increases to 240 kPa. Finally, the mechanical robustness of the LASH surface is studied through the abrasive belt and tape stripping tests, and the anti-fouling property is also evaluated. The change of ice adhesion strength on the LASH surface under cyclic icing experiment is analyzed. The experimental results show that the LASH surface has great mechanical durability and anti-fouling property, which is expected to further expand the application prospects of SiC in different fields. [Display omitted] • LASH composite process is developed to fabricate superhydrophobic silicon carbide surface. • Micro/nano structures and surface chemistry play important roles for superhydrophobicity. • Wettability of the surface can be controlled by adjusting the laser processing parameters. • LASH surface can achieve free transition from Wenzel state to Cassie-Baxter state. • LASH surface possesses excellent mechanical durability and anti-icing properties. [ABSTRACT FROM AUTHOR]

Highlights Silicon carbide (SiC)‐resin composites with porous structures exhibit excellent energy absorption characteristics. In this study, three types of triply periodic minimal surface (TPMS) structures (Schwarz primitive, Schwarz diamond, and Schwarz I‐graph‐wrapped (IWP)) were fabricated using the digital light processing (DLP) technique. Under static compression, the TPMS structures mainly fracture at the four ends of the X crossband. The SiC‐reinforced resin exhibited superior specific energy absorption in quasistatic compression performance compared with the same structure constructed of metal at the same density. Moreover, the transient impacts under dynamic strain rates did not cause significant irregular or asymmetric shear damage to the structure. The dynamic energy absorption of SiC‐reinforced resin with a primitive structure was relatively superior to that of the IWP and diamond structures. Therefore, the TPMS structure of the 5 wt.% SiC‐resin composite possesses significant energy absorption characteristics and can be extended for applications in aerospace. SiC reinforced resin exhibits superior specific absorption energy in quasi‐static compression performance. The yield strength of the static compression of the primitive structure is averaging nearly 17 MPa. The dynamic energy absorption of SiC reinforced resin with primitive structure is relatively superior between 65.68 and 71.63 J/g. The TPMS structure of 5 wt.% SiC/resin possesses significant energy absorption characteristics. [ABSTRACT FROM AUTHOR]

Phonon-polaritons are known to emerge at the surface of solids under infrared (IR) irradiation at frequencies close to the optical phonon resonance. Metal, patterned on the top of the polariton-active surface, locally blocks the excitation of surface waves due to plasmonic screening and can be used for the design of wave patterns. We excite polaritonic waves at the surface of SiC under the irradiation of a CO2 laser (λ ∼ 10 μ m) and visualize them using apertureless near-field interference scanning probe microscopy. From the near-field scans in the vicinity of gold film periodical strip structures, we identify the Bragg scattering (diffraction) outside the grating with the contribution from separate strips coherently summed up, provided that the wavelength matching condition is fulfilled. The observed phenomena agree with wavefield calculations. Our observations demonstrate the potential of metal-patterned silicon carbide for the fabrication of on-chip polaritonic IR circuits. [ABSTRACT FROM AUTHOR]

Oxide‐bonded SiC porous ceramics (SCPCs), synthesized via reaction bonding, exhibit significant potential for high‐temperature applications. However, incorporating sintering aids inevitably results in a considerable quantity of amorphous glass phase within SCPCs, thereby introducing risks to their high‐temperature mechanical performance. In this study, we employ in‐situ characterization techniques to investigate the high‐temperature behavior of SCPCs. Our findings reveal that SCPCs demonstrate remarkable high‐temperature self‐enhancing properties, with a critical bending strength at 800°C. Beyond this temperature, the strength declines sharply. Intriguingly, the critical bending strength is 36.6% greater than at ambient temperature. Moreover, elevated temperatures enhance the elastic modulus and promote the transition of SCPCs from multilinear to nonelastic fracture. The neck phase, which imparts strength to the SCPCs, is composed of four distinct layers along the depth direction: silicate glass, oxygen‐containing, silicon‐rich, and SiC region, as revealed by FIB‐TEM. The transformation from α to β‐cristobalite in the oxygen‐containing region improves the thermal expansion match with SiC, thereby mitigating local stress concentration. Furthermore, the compressive stress within the neck region intensifies with increasing temperatures, thereby inhibiting crack propagation. This work provides a basis for the high‐temperature applications of SCPCs. [ABSTRACT FROM AUTHOR]

Tristructural isotropic (TRISO) fuel particles, developed for use in high‐temperature gas‐cooled nuclear reactors, can be subjected to oxidizing environments in off‐normal accident scenarios. In this study, surrogate TRISO fuel particles were oxidized at 1000–1350°C for 4 h in 20 kPa water vapor atmosphere balanced with ultrahigh‐purity helium gas. The oxide scale morphology and thickness were studied via scanning electron microscopy, focused ion beam, and transmission electron microscopy. The oxide thickness increased as the oxidation temperature was increased. Although the oxide scale at 1000°C was completely amorphous, pockets of crystalline oxide were observed on particles oxidized at 1200 and 1300°C. Kinetic analysis was performed to deduce the oxidation mechanism by determining the apparent activation energy using linear regression analysis. The oxidation mechanism was consistent for temperatures from 1000 to 1200°C with an activation energy of 412.4 ± 8.8 kJ/mol. The activation energy then dropped to approximately 201 ± 7.1 kJ/mol for temperatures 1200–1350°C. Therefore, there is a change in oxidation mechanism at ∼1200°C. This change is attributed to the existence of a network of significant bubbles in the oxide layer at higher temperatures, which serve as rapid diffusion pathways for the transport of oxidants from the surface to the SiC/SiO2 interface, instead of relying on the bulk diffusion through the SiO2 layer at lower temperatures where only small bubbles are present along the SiC/SiO2 interface. [ABSTRACT FROM AUTHOR]

The main objective of this investigation is the consolidation and flexural strength of alpha silicon carbide ceramics produced without additives by spark plasma sintering. Using the design of the experiment method, we optimized temperature and dwell to achieve fully dense silicon carbide bulks. The consolidation process of silicon carbide was analyzed similarly to the creep of bulk ceramics, and it was determined that the activation energy for the densification process was 596 ± 39 kJ/mol, while the stress exponent n was below 2. Bulk additive‐free silicon carbide ceramics gradually increased flexural strength as the temperature rose to 2000°C. The flexural strength at 2000°C was influenced by the loading rate, and under 2.5 mm/min, it reached a maximum of 2.08 GPa. To explain this phenomenon, a deformation mechanisms map was created, indicating that diffusion creep is the most probable mechanism for the strain sensitivity of SiC at 2000°C. Transmission electron microscopy indicated a substantial rise in twin density within the α‐SiC grains at 2000°C, indicating the activation of a previously unreported self‐reinforcing mechanism. [ABSTRACT FROM AUTHOR]

In so-called Field Assisted Sintering Techniques such as Spark Plasma Sintering (SPS) or Flash Sintering (FS), ceramic powder compacts are densified at high sample temperature in the presence of an electrical field. The formation of a plasma is often discussed without actual evidence for its appearance. In this work, which is the first of two parts, the mechanisms of plasma formation as well as its properties under FS conditions were investigated. Field induced breakdown of various atmospheres was conducted by a DC-field (up to 350 V/cm) at temperatures between 1000 and 1500 °C. Experiments were conducted both with and without a sample mounted between the electrodes. Alumina, boron carbide and silicon carbide in green or sintered form were used as the samples. The electrical and optical properties of the plasma were characterised, and the early stages were visualised by high-speed camera recordings. The results showed that the breakdown is caused by a flashover mechanism and the conductance of the plasma under the present conditions was of the same order as the conductivity of a boron or silicon carbide green body. Plasma formation did not lead to extensive sintering but the plasma was able to infiltrate the green body and cause transfer of matter from the interior to the surface and beyond. Based on the present results, it seems unlikely that a gas plasma is formed under the normal conditions of SPS or FS. [ABSTRACT FROM AUTHOR]

Although the irreplaceable position of silicon (Si) semiconductor materials in the field of information has become a consensus, new materials continue to be sought to expand the application range of semiconductor devices. Among them, research on wide bandgap semiconductors has already achieved preliminary success, and the relevant achievements have been applied in the fields of energy conversion, display, and storage. However, similar to the history of Si, the immature material grown and device manufacturing processes at the current stage seriously hinder the popularization of wide bandgap semiconductor-based applications, and one of the crucial issues behind this is the defect problem. Here, we take amorphous indium gallium zinc oxide (a-IGZO) and 4H silicon carbide (4H-SiC) as two representatives to discuss physical/mechanical properties, electrical performance, and stability from the perspective of defects. Relevant experimental and theoretical works on defect formation, evolution, and annihilation are summarized, and the impacts on carrier transport behaviors are highlighted. State-of-the-art applications using the two materials are also briefly reviewed. This review aims to assist researchers in elucidating the complex impacts of defects on electrical behaviors of wide bandgap semiconductors, enabling them to make judgments on potential defect issues that may arise in their own processes. It aims to contribute to the effort of using various post-treatment methods to control defect behaviors and achieve the desired material and device performance. [ABSTRACT FROM AUTHOR]

A quasi‐vertical gallium nitride (GaN) fin field effect transistor (FinFET) is designed and analyzed to assess the performance of electrical parameters. The device is deployed on a silicon carbide (SiC) substrate and analyzed using technology computer‐aided design (TCAD). The donor concentration in the critical regions is identified as a significant limiting factor for FinFET electrical properties. Hence, the influence of channel and drift layer doping concentrations (Nd) on performance characteristics is investigated in this work. The electrical characteristics such as threshold voltage, ION/IOFF ratio, subthreshold swing (SS), specific ON‐resistance, and breakdown voltage (VBV) are evaluated for various doping profiles. The doping profile with channel and drift layer concentration of 4 × 1015 cm−3 for a 300 nm fin width and 1 μm thick drift layer exhibits normally OFF behavior with a threshold voltage (Vt) of 1.5 V. It also demonstrates a VBV of 139 V. The corresponding doping profile reveals a low SS of 61 mV dec−1, which is comparable to other similar power devices. This demonstrates the significant potential of the device for medium‐power switching applications. [ABSTRACT FROM AUTHOR]

The challenging machinability of silicon carbide (SiC) ceramic, due to its hardness and brittleness, has traditionally constrained its machined quality and the creation of functional surfaces. Compared to direct laser machining (DLM), waterjet-assisted laser micromachining (WJALM) is an alternative technique for SiC ceramic that is capable of reducing thermal-induced damages. In this paper, high-aspect-ratio (HAR) microchannels are fabricated on silicon carbide ceramic by WJALM, and its effectiveness is verified through comparative experiments with DLM. The effects of the parametric combination of waterjet and laser parameters on machining responses of geometric structural features and sidewall surface quality are investigated by controlled variable experiments. The results revealed that HAR microchannels with almost no recast layers could be obtained when the SiC workpiece was fabricated by a nanosecond laser under the flowing water medium layer, and higher average laser power of 27 W, lower scanning speed of 600 m/s, and medium waterjet velocity of 12/16 m/s contributed to larger aspect ratio, more ablation area and superior sidewall quality of HAR microchannels. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramic membranes are highly sought-after for their exceptional properties including high temperature resistance, corrosion resistance, good hydrophilicity, high flux, and high mechanical strength. However, achieving stable regulation of high solid content SiC slurries for membrane preparation remains a significant challenge. This study presents a novel approach to stabilize the dispersion of high solid content SiC slurries by controlling parameters such as solid content, pH, ball milling time and spray coating parameters. Furthermore, the impact of different milling durations on SiC particle size and membrane performance is systematically investigated, establishing, for the first time, a direct correlation between milling time and particle size. The investigations reveal that prolonged ball milling, specifically 18 h, results in a notable reduction in membrane pore size by approximately 40 %, accompanied by a remarkable enhancement in retention performance, as evidenced by a substantial increase in the average retention rate for 500 nm fluorescent microspheres from 54.61 % to 98.89 %. This study not only offers a practical method for the stable preparation of ceramic slurries, but also provide important reference for membrane morphology control and pore size regulation. These insights hold significant promise for advancing SiC membrane technology in applications such as wastewater treatment and resource recovery. [ABSTRACT FROM AUTHOR]

The rapid development of additive manufacturing techniques enables the preparation of SiC ceramics with complex configurations; however, the high sintering temperature and defects-control are still great challenges during processing. Thus, SiC ceramics were prepared by digital light processing followed by liquid phase sintering using Al 2 O 3 –Y 2 O 3 additives in this study. The photopolymerization of the SiC slurry, microstructures and mechanical properties of the sintered ceramics were investigated. The Al 2 O 3 –Y 2 O 3 additives enhanced the curing ability of the photosensitive SiC slurries by reducing the absorbance and scattering of UV light. The liquid phase accelerated the densification of the ceramics by particles rearrangement and interfacial bonding. Thus, the flexural strength of the ceramics increased from 41.0 MPa to 62.8 MPa with sintering temperature increasing. [ABSTRACT FROM AUTHOR]

Hierarchical porous silicon carbide (SiC) ceramics were fabricated by combining particle‐stabilized emulsions and three‐dimensional (3D) printing. Direct ink writing (DIW) was used as the 3D printing technique. The formulation for successful printing is discussed in relation to the rheology of the emulsions. The SiC emulsions were able to be printed with a lower storage modulus (G′) and apparent yield shear stress (τy) than previously reported SiC ink pastes. The printed and sintered porous SiC ceramics possess a total porosity of 73.7% with an average pore size within the filaments of 2.2 µm in diameter. A hierarchical pore structure that contains pore sizes of about 250 µm, around 1–10 µm and smaller than 0.5 µm can be observed in the microstructure and pore size distribution. The mechanical properties showed a good strength‐to‐density ratio, and the thermal conductivity was reduced to 4.9 W/m·K. This study provides a new reliable approach for fabricating hierarchical porous SiC ceramics with low thermal conductivity. [ABSTRACT FROM AUTHOR]

Instead of the expected 3.8–5.4% increase in the heat transfer coefficient due to the better thermal conductivity of silicon carbide tubes compared to glass tubes, the observed increase was 18–22% for 150–275 kg·h−1 airflow and 6 kg·s−1 propane-1,2-diol coolant in tubes. This additional 15–17% increase is probably due to local flow turbulisation due to the roughness of the sintered carbide of 4–10 µm, which unfortunately also causes a 17–24% higher air pressure drop. The hand calculation model used underestimates the heat transfer coefficient by −2% to 10%, which is better than CHEMCAD 8 modeling results. [ABSTRACT FROM AUTHOR]

Over the past years, nanostructured metalenses with thin form factors have been extensively studied for their potential in consumer and industrial applications. Despite significant advancements, current metalenses struggle to achieve high numerical aperture (NA), manufacturable structures, broad working bandwidth, and extended depth of focus (DOF) simultaneously. This paper introduces a comprehensive inverse design framework that facilitates the rapid development of polarization‐insensitive 3D metalenses, effective in both frequency and spatial domains. The framework employs shape‐constrained topology optimization to define horizontal ring profiles, along with discrete particle swarm optimization to manage discretized ring heights. Two immersed silicon carbide metalenses are demonstrated to showcase this framework's capability, providing near‐unity NAs for enhanced photon collection. The first design is an extended DOF metalens, exhibiting a DOF over four times the light wavelength and achieving a maximum diffraction efficiency of 23%, close to the theoretical limit. The second design achieves broadband achromaticity, suppressing chromatic aberrations across a wide 300 nm bandwidth (850–1150 nm) while maintaining an average diffraction efficiency of 10%. This methodology serves as a valuable tool for deploying functional metalenses with implications for nanophotonics, quantum optics, and quantum nanotechnology. [ABSTRACT FROM AUTHOR]

Dielectric elastomers (DEs), have attracted interest because they can replicate the behavior of muscles. They can change shape when subjected to an electric field. A novel DE is proposed in this study that incorporates silicon carbide (SiC) nanowires into silicone rubber (SR). The nanowires were propagated using polycarbosilane via a chemical vapor reaction (CVR). A boronate polymer was employed to promote compatibility between SR and SiC nanowires which modified the nanowire surfaces, leveraging a strong adhesive quality of the catechol moiety. Electrohydrodynamic (EHD) inkjet printing was then used to form the DEs into various shapes. These DEs had substantial dielectric constants of the order of 4.46. Significantly, one of the DEs achieved the highest actuated area strain of 20.36% in an electric field of 16.5 V/μm, demonstrating excellent driving performance. Furthermore, when used the fabricated DEs showed pronounced long‐term stability, meaning they are capable of finding applications in artificial intelligence, biomimetics, aerospace, and other disciplines. Highlights: The SiC nanowires were obtained through a chemical vapor reaction.A boronate polymer with catechol moiety was used to modify the SiC nanowires.DEs were formed various shapes by inkjet printing.DEs achieved very large actuated strains of up to 20.36% at 16.5 V/μm. [ABSTRACT FROM AUTHOR]

This study aims to enhance the properties of biodegradable plastics by blending poly(lactic acid) (PLA) as well as poly(butylene succinate) (PBS) with silicon carbide (SiC). SiC content was varied from 10 to 40 phr using an internal mixer, maintaining a 90/10 wt% ratio of PLA/PBS as the matrix. The investigation covered mechanical, thermal properties, chemical structure, and composite morphology. The morphological analysis confirmed even dispersion of SiC within the PLA/PBS matrix, possibly due to improved compatibility via a silane coupling treatment. This resulted in the maximum Young's modulus and impact strength with 40 phr SiC, showing a 40% and 76% enhancement, respectively, compared to pure PLA. Concerning thermal properties, SiC addition influenced the mobility of PLA/PBS molecular chains and crystalline structure, leading to an increase in Tg with higher SiC fractions. However, ΔHm of PLA, PBS, and Xc,PLA decreased, which corresponds to reduced viscosity in the PLA/PBS blend and increased mobility with higher SiC content, as indicated by the elevated MFI value. Highlights: Young's modulus increased by 40% and impact strength by 76% than pure PLA.Even SiC dispersion in PLA/PBS, possibly aided by silane coupling.SiC alters chain mobility, boosts crystalline structure, raising Tg.ΔHm and Xc,PLA reduced, suggests reduced viscosity in PLA/PBS at more SiC.Elevated MFI value shows increased chain mobility in PLA/PBS blend at more SiC. [ABSTRACT FROM AUTHOR]

Summary: This paper introduces an equivalent model including the parasitic parameters analysis of silicon carbide (SiC) MOSFETs in order to enhance their performance for high‐power density applications. The model is used to establish a mechanism that evaluates the effect of drive parameters on switching losses and electrical stress of power devices, providing a theoretical basis for optimizing the design of drive parameters. The paper finds the Pareto solution of the multi‐objective optimization model through iterative calculation of design variables, using this mechanism. The methodology is validated through experimental results from an SiC power prototype, showing an efficiency of 98.9% and safe electrical stress levels under 1500 V/100 kW operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents thermal expansion coefficient (TEC) and amorphization in 4H-SiC containing point defects at different concentrations. We considered vacancy defects, interstitial defects, and Frenkel pair defects and investigated the thermomechanical response of the lattice over a wide range of temperatures using classical molecular dynamics simulations. The results show that 4H-SiC with vacancy defects exhibits a negative TEC above a critical defect density of around 9% (irrespective of the temperature). With interstitial defects, it exhibits a positive TEC (regardless of the defect density), and with Frenkel pair defects it shows a transition from positive TEC to negative TEC for a defect density greater than 8%. The coupling between temperature-induced expansion and defect-introduced stress in the lattice forms the mechanistic basis for the observed variation in TEC. Furthermore, the specific heat decreases rapidly with an increase in defect density at room temperature, with the highest sensitivity of the lattice observed for the Frenkel pair defects followed by interstitial defects and then by vacancy defects. These findings highlight the critical implications of defects on thermal expansion behavior of 4H-SiC with applications in radiation environments. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is one of the superior materials used in the manufacture of electronic components designed to work at high temperatures, high frequencies and high-power. In the past two decades, the application of SiC materials has been expanding as a result of much improved production and processing techniques. Although most SiC chips are still mainly made from 6 inch (1 inch =25. 4 mm) wafers, leading manufacturers have begun developing next-generation parts and chips based upon 8 inch SiC wafers. This study collaborates with leading enterprises in the upstream and downstream of the domestic silicon carbide industry chain in order to facilitate domestic production of 8 inch SiC chips, with the focus being wafer preparation and epitaxial growth. In this work, 8 inch conductive 4H-SiC substrate wafer was prepared by diameter expansion growth, with low average base plane dislocation (BPD) density (251 cm-2) and virtually 'zero threading screw dislocation (TSD)' density (< 1 cm-2) that meet the production requirements. Based on these 8 inch substrates, we achieve fast epitaxial growth (68. 66 μm/h) with domestically produced 8 inch epitaxy equipment and processing packages. The thickness uniformity of the resultant wafers is 0. 89% and the doping uniformity is 2. 05%. These parameters, as well as the defect density, are on par with those of high-quality 6-inch wafers, fully meeting production requirements. The 8 inch wafers prepared in this paper are better than those described in international publications in terms of thickness and doping uniformity. The defect density is only 1/4 of international data. In this paper, multi-wafer repetative text was designed and executed, to verify the stability of 8 inch epitaxy. [ABSTRACT FROM AUTHOR]