Search

A series of topological insulators (TIs) based saturable absorbers (SAs), e.g., Bi2Se3, Bi2SeTe2, and Bi4Br4, are confirmed to exhibit excellent non-linear optical response due to the topological edge states. Here, we demonstrate how a topological crystalline insulator, SnTe thin films, can be prepared on highly oriented pyrolytic graphite and gold-plated mirrors through molecular beam epitaxy. SnTe-SAs incorporated into Er-doped fiber lasers exhibit a large modulation depth of 27.2% and accomplish mode-locking at 1558 nm with a pulse width of 319 fs, indicating preeminent nonlinear optical performance among the reported TI-based SAs. This work illuminates the preparation of SnTe thin films and demonstrates the great potential of SnTe films in ultrafast optical devices. [ABSTRACT FROM AUTHOR]

In this paper, we present a combined experimental and theoretical study that explored the initial sticking of water on cooled surfaces. Specifically, these ultra-high vacuum gas–surface scattering experiments utilized supersonic molecular beam techniques in conjunction with a cryogenically cooled highly oriented pyrolytic graphite crystal, giving control over incident kinematic conditions. The D2O translational energy spanning 300–750 meV, the relative D2O flux, and the incident angle could all be varied independently. Three different experimental measurements were made. One involved measuring the total amount of D2O scattering as a function of surface temperature to determine the onset of sticking under non-equilibrium gas–surface collision conditions. Another measurement used He specular scattering to assess structural and coverage information for the interface during D2O adsorption. Finally, we used time-of-flight (TOF) measurements of the scattered D2O to determine how energy is exchanged with the graphite surface at surface temperatures above and near the conditions needed for gaseous condensation. For comparison and elaboration of the roles that internal degrees of freedom play in this process, we also did similar TOF measurements using another mass 20 incident particle, atomic neon. Enriching this study are precise molecular dynamics simulations that elaborate on gas–surface energy transfer and the roles of molecular degrees of freedom in gas–surface collisional energy exchange processes. This study furthers our fundamental understanding of energy exchange and the onset of sticking and ultimately gaseous condensation for gas–surface encounters occurring under high-velocity flows. [ABSTRACT FROM AUTHOR]

A systematic review and meta-analysis of sputter yield data for xenon ions normally incident on graphite at energies below 2000 eV was undertaken to identify systematic errors, determine the best model parameter values to represent yield as a function of energy, quantify uncertainty, and determine if the data support differences in yields for different types of graphite. A critical examination of the 11 published data sets for high density graphite, pyrolytic graphite, and amorphous carbon showed that, in general, they were carefully controlled to minimize errors. The most significant quantifiable systematic errors were those caused by the neglect of doubly charged ions, chemical erosion, and the impact of secondary electron emission on ion flux measurements. The effects of gas uptake and outgassing on mass loss measurements and unrepresentative surface textures may have biased other experiments, but these effects could not be quantified. The semi-empirical Eckstein model for yield as a function of energy was fit to data for the three graphite types using a hierarchical Bayesian statistical model, producing recommended fit parameters and probability distributions representing uncertainty in yields. The results showed that differences in yield for high density graphite and pyrolytic graphite were not statistically significant. Apparent differences in yield for amorphous carbon disappeared when the single data set available for energies below 150 eV was corrected for reasonable values of double ion content. Recommended procedures to avoid systematic errors and additional experiments and modeling to fill in gaps in our understanding are included. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms. [ABSTRACT FROM AUTHOR]

In this work, we performed transient reflection measurements using the pump–probe protocol to investigate the influence of lattice defects induced by 380 keV argon (Ar) ions on the phonon dynamics of interlayer shearing (E 2 g 1 ) and in-plane carbon stretching (E 2 g 2 ) modes in highly oriented pyrolytic graphite (HOPG). The frequency and decay rate of E 2 g 1 - and E 2 g 2 -mode phonons were changed significantly at the fluence of 1 × 10 14 ions/cm 2. This indicated that significant structural changes in HOPG due to 380 keV Ar-ion irradiation were expressed as changes in the frequency and decay rate of phonons. In HOPG irradiated with 380 keV Ar + at the fluence of 1 × 10 14 ions/cm 2 , our measurement results indicated that compressive and tensile stresses contributed to in-plane and interlayer graphite structures, respectively. [ABSTRACT FROM AUTHOR]

SiBCN ceramic has already been widely used in the thermal insulation field. To further enhance their mechanical properties in high-temperature environments, the preparation of SiBCN and ZrB 2 based pyrolytic carbon (PyC) modified carbon fiber reinforced composite, i.e., 2D C f /SiBCN–ZrB 2 , was proposed in this study. By using five cycles of polymer impregnation and pyrolysis (PIP), the composite could be synthesized with a high flexural strength at room temperature, i.e., 275 ± 15 MPa. To understand the evolution of the microstructure caused by high temperatures and their influences on the mechanical properties, the composite samples were heat treated at 1200, 1400, 1600, and 1800 °C for 2 h, respectively. Comparing the flexural strengths of the samples before and after the heat treatments, and meanwhile combining the advanced microstructural characterizations, it was found that the composite was stable when the treating temperature was below 1400 °C, i.e., the flexural strength was 250 ± 15 MPa with a strength retention rate of over 90 %. However, once the temperature was above 1600 °C, due to the crystallization of SiBCN–ZrB 2 matrix, the pyrolysis of PyC interfaces, the carbothermal reduction reaction and the erosion of carbon fibers, the mechanical properties of the composite would reduce to 74 ± 9 MPa. This study provides a new method for preparing 2D C f /SiBCN–ZrB 2 , which reduces the number of PIP cycles of composite materials and enables rapid prototyping of composite materials. Additionally, this research can help materials scientists understand the mechanical properties of 2D C f /SiBCN–ZrB 2 composite materials in high-temperature environments and the evolution of their microstructure, identifying the range of application temperatures for 2D C f /SiBCN–ZrB 2. [ABSTRACT FROM AUTHOR]

This study describes the preparation of bimodal reinforced Cu/Ti 3 SiC 2 /C laminated-like composites using flake powder metallurgy and vacuum hot-press sintering process. The objective was to accurately modulate the formation of oriented reinforcement network in two-dimensional carbon materials. The powders used in the five designed composites were flake Cu powder (45–60 μm), Ti 3 SiC 2 (1–5 μm), graphite flakes (GFs, 120 μm) and graphene nanoplatelets (GNPs, 15 μm). Among them, the proportions of Ti 3 SiC 2 (10 wt %) and GFs (3 wt %) remained unchanged, GNPs accounted for 0 wt %, 0.5 wt %, 1.0 wt %, and 1.5 wt %, and Cu powder accounted for a decreasing proportion. Formation mechanisms of GFs and GNPs in oriented networks were quantitatively analyzed using the alignment model. Additionally, the related strengthening and failure mechanisms were investigated. According to the study, the bimodal laminated-like Cu/Ti 3 SiC 2 /C composites with 0.5 wt% GNPs added showed the best overall performance. Specifically, it exhibited a hardness of 125.7 HV, tensile strength of 276.3 MPa, thermal conductivity of 207.8 W m−1 K−1, and electrical conductivity of 23.6 MS/m. The network enhanced by the two-dimensional carbon material achieves efficient and orderly load transfer and dissipation mechanisms, optimizing stress distribution and enhancing fracture resistance, resulting in improved mechanical properties. In addition, the formation of the oriented reinforcement network optimizes the orientation arrangement of the reinforcing particles, which somewhat mitigates the scattering of thermoelectric carriers by structural defects in the composites, and the enlarged mean free-range improves the migration efficiency of electrons and phonons. Therefore, the erection of bimodal laminated-like structure achieves the goal of optimizing the properties of the composites. [ABSTRACT FROM AUTHOR]

Continuous silicon carbide fibers (SiC f) reinforced SiC ceramic matrix composites (SiC f /SiC CMCs) are promising thermostructural materials with a broad range of high-end technology applications. For the excellent performance of SiC f /SiC CMCs, the interphase plays a crucial role in tailoring the overall mechanical properties and service lifetime of SiC f /SiC CMCs. During the past decades, tremendous effort has been made to develop better interphase materials and deepen the understanding of their functions and mechanisms. In this paper, an overview of the latest advancements in a variety of interfacial coatings, including pyrolytic carbon, boron nitride, newly developed layered candidates, porous oxides and multilayers, is provided. Emphasis is placed on the engineering of constituents, microstructure and interphase thickness, as well as their effects on the mechanical properties and stability of SiC f /SiC CMCs. Moreover, the challenges and future opportunities to achieve the desired behavior of SiC f /SiC CMCs by interphase engineering are discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Fully ceramic microencapsulated (FCM) fuel is a five-layer intercalation system material consisting of a UO2 core, a sparse pyrolytic carbon layer (Buffer), an inner dense pyrolytic carbon layer (IPyC), an outer dense pyrolytic carbon layer (OPyC), and a silicon carbide matrix (SiC). At first, this paper researched the thermodynamic models of the materials, including heat conduction coefficient, Young's modulus, thermal expansion coefficient, etc. Then DIGIMAT, the finite element software, was used to establish the equivalent volume element (RVE) for the equivalent analysis of the thermodynamic properties of the FCM fuel pellet. Finally, the thermodynamic equivalent performance model of FCM fuel was obtained by multi-factor fitting analysis. The results show that among these thermodynamic properties of FCM fuel pellets, the Young's modulus, thermal expansion coefficient and plastic performance are mainly affected by temperature, fast neutron fluence, and UO2 volume fraction; the specific heat capacity is mainly affected by UO2 volume fraction and temperature; the heat conduction coefficient is mainly affected by temperature and UO2 volume fraction. The thermal conductivity is mainly affected by temperature, burnup and UO2 volume fraction. In this study, the equivalent models obtained through the fitting analysis of RVE model parameters can well describe the thermodynamic behavior of FCM fuel particles. [ABSTRACT FROM AUTHOR]

Layered perovskite-structured thin films of SrBi2Ta2O9 (SBT) were successfully deposited onto highly oriented pyrolytic graphite substrates using a pulse laser deposition technique, resulting in an atomic structure identical to that of the graphene surface. The SBT thin films exhibited enhanced ferroelectric and dielectric properties when the substrate temperature was slightly lowered, attributed to the improvement in a-oriented crystallinity. Due to the enhancement in a-oriented crystallinity, the SBT thin films exhibited an improved remanent polarization of approximately 12.3 μC/cm2 and an enhanced remanent piezoelectric coefficient of approximately 13.6 pm/V. The observations of ferroelectric domain structures using piezoresponse force microscopy confirmed a slight increase in domain boundary energy for SBT thin films with enhanced a-oriented crystallinity. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using ZIF-8 synthesized by static precipitation as a precursor. ZC-Cu has a high specific surface area of 859.78 m2 g−1 and abundant heteroatoms O (10.04%) and N (13.9%), showing the specific capacitance of 222.21 F g−1 at 0.1 A g−1 in three-electrode system, and low equivalent series resistance (Rct: 0.13 Ω), indicating excellent energy storage capacity and electrical conductivity. After 10,000 cycles at 1 A g−1 in 6 M KOH electrolyte, it still has an outstanding capacitance retention of 99.42%. Notably, symmetric supercapacitors ZC-Cu//ZC-Cu achieved the maximum power density and energy density of 485.12 W·kg−1 and 1.61 Wh·kg−1, respectively, positioning ZC-Cu among the forefront of previously known MOF-based electrode materials. This work demonstrates the enormous potential of ZC-Cu in the supercapacitor industry and provides a facile approach to the treatment of transition metal. [ABSTRACT FROM AUTHOR]

Focus on advancement of energy storage has now turned to curbing carbon emissions in the transportation sector by adopting electric vehicles (EVs). Technological advancements in lithium‐ion batteries (LIBs), valued for their lightweight and high capacity, are critical to making this switch a reality. Integrating structurally enhanced LIBs directly into vehicular design tackles two EV limitations: vehicle range and weight. In this study, 3D‐carbon (3D‐C) lattices, prepared with an inexpensive stereolithography‐type 3D printer followed by carbonization, are proposed as scaffolds for Li metal anodes for structural LIBs. Mechanical stability tests revealed that the 3D‐C lattice can withstand a maximum stress of 5.15 ± 0.15 MPa, which makes 3D‐C lattices an ideal candidate for structural battery electrodes. Symmetric cell tests show the superior cycling stability of 3D‐C scaffolds compared to conventional bare Cu foil current collectors. When 3D‐C scaffolds are used, a small overpotential (≈0.075 V) is retained over 100 cycles at 1 mA cm−2 for 3 mAh cm−2, while the overpotential of a bare Cu symmetric cell is unstable and increased to 0.74 V at the 96th cycle. The precisely oriented internal pores of the 3D‐C lattice confine lithium metal deposits within the 3D scaffold, effectively preventing short circuits. [ABSTRACT FROM AUTHOR]

Phenolic resin pyrolytic carbons were obtained by catalytic pyrolysis of phenolic resin at 500 °C, 600 °C, 700 °C, and 800 °C for 3 h in an argon atmosphere using copper nitrate as a catalyst precursor. The effects of copper salts on the pyrolysis process of phenolic resin as well as the structural evolution and oxidation resistance of phenolic resin pyrolytic carbons were studied. The results showed that copper oxide (CuO) generated from the thermal decomposition of copper nitrate was reduced to copper (Cu) by the gas generated from the thermal decomposition of the phenolic resin. Carbon nanofibers with tapered structures were synthesized by Cu catalysis of pyrolysis gas at 500–800 °C. The catalytic pyrolysis of phenolic resin with Cu increased the graphitization degree and reduced the pore volume of the phenolic resin pyrolytic carbons. The combined action improved the oxidation resistance of phenolic resin pyrolytic carbons. [ABSTRACT FROM AUTHOR]

A high-fidelity synthetic diagnostic has been developed for the ITER core x-ray crystal spectrometer diagnostic based on x-ray ray tracing. This synthetic diagnostic has been used to model expected performance of the diagnostic, to aid in diagnostic design, and to develop engineering tolerances. The synthetic model is based on x-ray ray tracing using the recently developed xicsrt ray tracing code and includes a fully three-dimensional representation of the diagnostic based on the computer aided design. The modeled components are: plasma geometry and emission profiles, highly oriented pyrolytic graphite pre-reflectors, spherically bent crystals, and pixelated x-ray detectors. Plasma emission profiles have been calculated for Xe44+, Xe47+, and Xe51+, based on an ITER operational scenario available through the Integrated Modelling & Analysis Suite database, and modeled within the ray tracing code as a volumetric x-ray source; the shape of the plasma source is determined by equilibrium geometry and an appropriate wavelength distribution to match the expected ion temperature profile. All individual components of the x-ray optical system have been modeled with high-fidelity producing a synthetic detector image that is expected to closely match what will be seen in the final as-built system. Particular care is taken to maintain preservation of photon statistics throughout the ray tracing allowing for quantitative estimates of diagnostic performance. [ABSTRACT FROM AUTHOR]

In this study, two types of porous Cf/Cm composites were obtained by introducing pyrolytic carbon (PyC) and pyrolytic carbon/furan resin carbon (PyC/FRC). Subsequently, Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were prepared by introducing SiC and (ZrxHf1−x)C matrices into the porous Cf/Cm composites via the reactive melt infiltration method, specifically termed as Cf/PyC-SiC-(ZrxHf1−x)C and Cf/PyC/FRC-SiC-(ZrxHf1−x)C composites. The microstructures of the porous Cf/Cm and Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were examined, and a comprehensive analysis was conducted on microstructural evolution and mechanical behaviors of the Cf/Cm-SiC-(ZrxHf1−x)C composites. The results indicate that both Cf/Cm-SiC-(ZrxHf1−x)C composites underwent similar microstructural evolution processes, differing only in terms of evolution kinetics and final microstructure. Differences in the pore structures of porous Cf/Cm composites, as well as in the reactivities of carbon matrices, were identified as primary influencing factors. Additionally, both Cf/Cm-SiC-(ZrxHf1−x)C composites exhibited "pseudo-ductile" fracture characteristics, with flexural strengths of 214.1 ± 8.8 MPa and 149.6 ± 12.2 MPa, respectively. In the Cf/PyC-SiC-(ZrxHf1−x)C composite, crack initiation during loading primarily originated from the ceramic matrix, while in the Cf/PyC/FRC-SiC-(ZrxHf1−x)C composite, failure initially arose from the residual FRC matrix. Excessive fiber corrosion and the presence of residual low-modulus FRC matrix resulted in lower mechanical performance. [ABSTRACT FROM AUTHOR]

One-dimensional metallic transition-metal chalcogenide nanowires (TMC-NWs) hold promise for interconnecting devices built on two-dimensional (2D) transition-metal dichalcogenides, but only isotropic growth has so far been demonstrated. Here we show the direct patterning of highly oriented Mo6Te6 NWs in 2D molybdenum ditelluride (MoTe2) using graphite as confined encapsulation layers under external stimuli. The atomic structural transition is studied through in-situ electrical biasing the fabricated heterostructure in a scanning transmission electron microscope. Atomic resolution high-angle annular dark-field STEM images reveal that the conversion of Mo6Te6 NWs from MoTe2 occurs only along specific directions. Combined with first-principles calculations, we attribute the oriented growth to the local Joule-heating induced by electrical bias near the interface of the graphite-MoTe2 heterostructure and the confinement effect generated by graphite. Using the same strategy, we fabricate oriented NWs confined in graphite as lateral contact electrodes in the 2H-MoTe2 FET, achieving a low Schottky barrier of 11.5 meV, and low contact resistance of 43.7 Ω µm at the metal-NW interface. Our work introduces possible approaches to fabricate oriented NWs for interconnections in flexible 2D nanoelectronics through direct metal phase patterning. Nanowires made of transition metal chalcogenides are promising as connecting elements in devices, but so far only isotropic growth is feasible. Here, the authors regulate the growth orientation of nanowires by introducing external stimuli into graphite-confined MoTe2 heterostructures. [ABSTRACT FROM AUTHOR]

In the treatment of kidney diseases such as chronic kidney disease (CKD) and acute tubular necrosis (ATN), prolonged contact between conductivity sensors and patients' bodily fluids is required, necessitating high biocompatibility for the electrodes. However, the widely used graphite electrodes exhibit limited biocompatibility, showing a cell survival rate of only 88% under indirect contact conditions, and <56% under direct contact conditions. Here, the surface detachment of graphite electrodes in liquid environments leading to cell death upon contact is observed and a solution is proposed to enhance biocompatibility and ensure conductivity, by forming a layer of interface‐stable coating (ISC) as a conductive isolation membrane on their surface. For applications with contact requirements, graphite‐like carbon (GLC) coated graphite electrodes are investigated and developed, resulting in an exceptional cell survival rate exceeding 96% under indirect contact conditions, and a relatively high survival rate exceeding 91% under direct contact conditions, both accompanied by significant proliferation. GLC‐coated graphite electrodes are successfully to monitor the dialysate conductivity in a hemodialysis machine and achieve stable monitoring with temperature compensation. The results demonstrate ISC graphite electrodes' potential in biomedical fluid monitoring, with the developed process applicable to other fields. [ABSTRACT FROM AUTHOR]

A well-defined substrate with an array of capillaries was infiltrated at a temperature of 1223 K, a pressure of 40 kPa and a residence time of 0.56 s. After 75 h deposition, the thickness of pyrolytic carbon layer in the capillary was determined along its depth. By coupling a detailed gas-phase reaction mechanism with the parallel-consecutive reaction model, the pyrolytic carbon deposition from propylene pyrolysis was accurately simulated within capillaries. From the simulated results, it was observed that pore sealing could be relieved by reducing residence time. The texture of pyrolytic carbon at the mouth of the capillary was also determined. In addition, Kinetic Monte Carlo simulations were used to analyze how residence time and substrate surface affect the transition in texture of pyrolytic carbon. According to these calculations, it appears that texture is mainly affected by interactions between residence time and active sites on the substrate surface. [ABSTRACT FROM AUTHOR]

The isostatic pressed high-density graphite (HDG) used as an electrode in direct de-oxidation of metal oxides in molten salt medium deteriorates due to anodic reactions. Also, the physically eroded carbon dust poses a threat of short-circuiting and contamination. Highly dense and oriented pyrolytic graphite (PyG) provides excellent sealing for HDG against molten salt corrosion. This study evaluated the corrosion resistance viability of PyG-coated HDG in molten LiCl + 1% Li2O salt. The long exposure chemical compatibility study reveals the selective molten salt attack initiated by the depletion of triple boundary junctions and the formation of pits at high-energy defective centers with normalized weight loss of 24% at the end of 250 h. With increasing exposure time to 500 h, the number density, pore depth, and dimensions increase with pronounced triple boundary depletion by encompassing the adjacent areas with pore tunneling and widening mechanisms producing a weight loss of 38%. The selective PyG corrosion is due to the formation of lithium carbon oxides. Furthermore, the anodic behavior PyG-coated HDG was reviewed in the direct electrodeoxidation process and compared with HDG. The uniform oxidative carbon erosion is primarily due to anodic reactions to reactively discharge O2− ions. [ABSTRACT FROM AUTHOR]

Amphipathic molecules with surfactant like properties have several applications ranging from healthcare to the chemical industry. Their ability to form thin films on surfaces with ordered and controllable patterns determines their applicability. Here, we report two pyridinium oxime‐based surfactants, which possess similar aggregation properties in solution, but exhibit substantially different assembly on highly oriented pyrolytic graphite (HOPG) surface. The two compounds are regioisomers with the oxime unit placed either in meta or para position of the pyridinium ring. While the para isomer assembled to anisotropic one‐dimensional (1D) islands and long rod‐like structures, the meta isomer formed two‐dimensional (2D) islands on the HOPG surface. This difference is rationalized through molecular level force‐field calculations that show anisotropy in the growth of the para isomer resulting from an effective overlap of the alkyl chains and oxime groups, which is distinctly not feasible in the assembly of the meta isomer. The assembly of these compounds is compared with another oxime‐containing compound of similar structure, but without the charged pyridinium unit. The charged unit seems to be crucial for the preferential formation of multilayer islands even at low coverage. [ABSTRACT FROM AUTHOR]

Plastic addition to bitumen increases the stiffness of the binder, reduces its workability due to the increase in viscosity, and causes storage stability issues. Thus, plastic pre-treatment methods are needed. This research aims to address these shortcomings by developing a wax derived from the pyrolysis of polyethylene (PE) waste and investigating its efficacy as an additive in virgin bitumen and bitumen modified with recycled polypropylene (PP). Penetration, softening point, segregation, stress ratio, consistency, stiffness, and viscosity of the modified bitumen were measured. The interior structure and chemical changes of the proposed binders were also studied using a fluorescence microscope and Fourier-transform infrared spectroscopy (FTIR). When virgin bitumen is modified with 7% PE wax, its softening point increases (+ 15%), its viscosity is reduced (− 27%), and no segregation issue is observed. It also presented a stiffness increase (+ 32%) and better resistance to hot climates. Adding 7% of PE wax to bitumen modified with 5% PP reduces its viscosity by 70% and segregation by 26% while increasing its stiffness and rutting resistance in comparison to the bitumen solely modified with PP. These results reveal that, in addition to enhancing bitumen properties, the proposed substance reduces compaction and mixing energy requirements. [ABSTRACT FROM AUTHOR]

This study proposes a multiscale numerical modeling procedure to evaluate the elastic properties of two-dimensional (2D) eight-harness satin woven carbon/carbon (C/C) composites. The multiscale modeling technique consists of analysis at the microlevel and mesolevel. In microscale analysis, a 3D representative volume element (RVE) of C/C composite with carbon fiber, pyrolytic carbon, and pores is considered. The microstructure of the C/C composite is analyzed using scanning electron microscope (SEM) images. Statistical characterization of pore distribution inside the C/C composite is performed, and different probability density functions are generated for pores' number, area, and aspect ratio inside the C/C composite. Carbon fibers and pores are inserted in the 3D RVE using the RSA algorithm. The size and shape of the pores inserted in 3D RVE are based on the probability density functions generated. Effective elastic properties of C/C composite at the microscale are computed by finite element analysis (FE) based homogenization and taken as input for the next level of homogenization. The RVE at mesoscale is modeled using the information from SEM images, and FE-based homogenization is performed to compute the effective elastic properties of 8HS woven C/C composite. The effective elastic properties obtained from the numerical study are validated with the results of the uniaxial tensile test performed on 2D C/C composite. The effect of fiber volume fraction, yarn volume fraction, and porosity on elastic properties of 2D 8HS woven C/C composite are also assessed and presented in this study. [ABSTRACT FROM AUTHOR]

Graphite spheroids are one of the most intriguing forms of aggregation of graphite. They can be found as natural graphite in meteorites and volcanic rocks (metamorphic graphite caused by exposure to heat and pressure in the earth's crust), and in man-made materials such as steel and cast iron, but also in pyrolytic graphite, in carbon nanosheets obtained through vapor deposition, and others. While growth of graphite has been studied in depth during the last decades, the understanding of its physics continues to evolve as modern investigating equipment pushes the knowledge horizon. The complexities of the solidification of cast iron and its dependency on undercooling, a function of the cooling rate and of the nucleation potential, are discussed in conjunction with the asymmetric eutectic coupled zone. A sequential chart summarizes the various stages of graphite aggregation, as the graphite begins growing in contact with the nucleus at the beginning of solidification till it reaches its final crystallography at room temperature. It sets the basis for an in-depth analysis of the multi-mechanisms involved in the growth of graphite in cast iron during solidification and the subsequent solid-state transformation, with emphasis on compacted and spheroidal graphite. It discusses the significance of turbostratic graphite that appears mostly, but not only, at the nucleus/graphite interface and in the initial stages of graphitization, as revealed by recent electron microscopy studies. [ABSTRACT FROM AUTHOR]

In this study, SiO@graphite@C@Al2O3 (SiO@G@C@A) composites are synthesized by varying the content of Al2O3, and their morphology and structure and their electrochemical performance are investigated in detail. The results indicate that the SiO/G@C@A-2 composite exhibits a specific capacity of 977.1 mA h g−1 at a current density of 0.1 A g−1 with a coulombic efficiency of 71.15%. Even after 100 cycles at a current density of 0.5 A g−1, it retains a delithiated specific capacity of 640.7 mA h g−1 and a capacity retention rate of 73.56%. Moreover, when the current density is raised to 2 A g−1, it maintains a delithiated capacity of 568.4 mA h g−1 and a capacity retention rate of 58.51%. The excellent electrochemical performance is ascribed to the synergistic effect of different components. The inclusion of graphite enhances overall conductivity while mitigating the volume expansion of the SiO. The application of asphalt pyrolytic carbon as a coating effectively isolates the SiO from the electrolyte, further reducing volume expansion and enhancing conductivity. The introduction of Al2O3 can absorb trace amounts of hydrogen fluoride (HF) generated during charge and discharge processes. Additionally, it facilitates the formation of an AlF3 film on the particle surfaces, which hinders and decelerates electrolyte dissolution into the electrode. The prepared composites exhibit promising prospects as lithium-ion battery anode materials. [ABSTRACT FROM AUTHOR]

We report on the energy dependence of the photoemission time delay from the single-element layered dielectric HOPG (highly oriented pyrolytic graphite). This system offers the unique opportunity to directly observe the Eisenbud-Wigner- Smith (EWS) time delays related to the bulk electronic band structure without being strongly perturbed by ubiquitous effects of transport, screening, and multiple scattering. We find the experimental streaking time shifts to be sensitive to the modulation of the density of states in the high-energy region (E ≈ 100 eV) of the band structure. The present attosecond chronoscopy experiments reveal an energy-dependent increase of the photoemission time delay when the final state energy of the excited electrons lies in the vicinity of the bandgap providing information difficult to access by conventional spectroscopy. Accompanying simulations further corroborate our interpretation. [ABSTRACT FROM AUTHOR]

Polymer composites offer numerous benefits, including low cost, easy processability, and diverse applications. In this work, we fabricated a composite material with high thermal conductivity and electromagnetic interference (EMI) shielding performance using EGaIn, a liquid metal (referred to as LM in this paper), MXene (MX), and expanded graphite (EG) as multifunctional fillers, along with polyacrylic acid (PAA). LM was used to exfoliate MX under the effect of shear force, which not only reduced the size of MX but also increased the aspect ratio of the 2D‐structured MX. MX was filled into the pores of EG to make a heat transfer path, thereby enhancing its thermal conductivity, mechanical properties, and EMI SE properties. LM served as the initiator of free‐radical polymerization to convert acrylic acid (AA) into PAA. Finally, the LMMX/EG/PAA composite was hot‐pressed to make the heat‐transfer path dense. As a result, the LMMX/EG/PAA composite exhibited a thermal conductivity of 1.88 W/m·K and an EMI shielding effect of 52 dB. [ABSTRACT FROM AUTHOR]

In this study, a flash pyrolysis process is developed using an entrained flow reactor for recycling of waste tires. The flash pyrolysis system is tested for process stability and reproducibility of the products under similar operating conditions when operated continuously. The study is performed with two different feedstock materials, i.e., passenger car (PCT) and truck tire (TT) granulates, to understand the influence of feedstock on the yield and properties of the pyrolysis products. The different pyrolytic products i.e., pyrolytic carbon black (pCB), oil, and pyro-gas, are analyzed, and their key properties are discussed. The potential applications for the obtained pyrolytic products are discussed. Finally, a mass and energy balance analysis has been performed for the developed pyrolysis process. The study provides insight into the governing mechanisms of the flash pyrolysis process for waste tires, which is useful to optimize the process depending on the desired applications for the pyrolysis products, and also to scale up the pyrolysis process. [ABSTRACT FROM AUTHOR]

[Display omitted] Lignin upgrading to various functional products is promising to realize high-value utilization of low-cost and renewable biomass waste, but is still in its infancy. Herein, using industry waste lignosulfonate as the biomass-based carbon source and urea as the dopant, we constructed a heteroatom-doped porous carbon nanosheet structure by a simple NaCl template-assisted pyrolytic strategy. Through the synergistic effect of the NaCl template and urea, the optimized lignin-derived porous carbon catalyst with high content of active nitrogen species and large specific surface area can be obtained. As a result, the fabricated catalysts exhibited excellent electrocatalytic oxygen reduction activity, as well as good methanol tolerance and stability, comparable to that of commercial Pt/C. Moreover, rechargeable Zn-air batteries assembled with this electrocatalyst have a peak power density of up to 150 mW cm-2 and prominent long-term cycling stability. This study offers an inexpensive and efficient way for the massive production of highly active metal-free catalysts from the plentiful, inexpensive and environmentally friendly lignin, offering a good direction for biomass waste recycling and utilization. [ABSTRACT FROM AUTHOR]

The composition and thickness of the interphase are critical factors affecting the strength of SiC/SiC materials. Therefore, SiC/(BN/PyC)/SiC ceramic matrix composites with varying PyC thicknesses were fabricated, and the mechanism by which thickness influences the mechanical properties of the materials was investigated. During the fracture process of the composites, debonding and crack deflection predominantly occurred at the BN/PyC interface. The PyC interphase thickness emerged as a critical factor influencing the mechanical performance of composites. The residual stresses within the PyC and its adjacent SiC matrix were determined by analyzing shifts in Raman peak positions. The findings indicate that a reduction in PyC thickness leads to an increase in residual compressive stress within the PyC and a corresponding increase in residual tensile stress within the SiC matrix, which increases the interfacial shear stress and improves the mechanical properties of the composites. [ABSTRACT FROM AUTHOR]

The design of multifunctional materials with good thermophysical and electromagnetic shielding properties is desirable to overcome overheating and electromagnetic interference (EMI) in electronic devices. In this study, three‐dimensional (3D) continuous SiC skeleton‐reinforced highly oriented graphite flake (GF@SiC) composites were fabricated by combining molten salt synthesis, heat treatment, and spark plasma sintering. When the SiC content was higher than 9 vol.%, a 3D continuous SiC skeleton was formed, which effectively constrained the cross‐plane thermal expansion of the GF@SiC composites. Highly oriented GFs endowed the composites with good thermal conductivity (TC) along the basal plane and effective EMI shielding in the X‐band. The composites with SiC concentrations of 9 vol.% exhibited an optimal comprehensive performance with a high TC of 322 W/m/K in the basal plane direction, a low thermal expansion value of 10.5 × 10−6/K in the through‐plane direction, and EMI shielding effectiveness of 36 dB. Our strategy provides a promising and practical approach for realizing graphite‐based composites to meet the current demands for electronic devices. [ABSTRACT FROM AUTHOR]

Based on the efficient resource utilization of scrap tires, pyrolysis carbon black (PCB), and pyrolysis oil of waste tire (TPO), scrap tires' products were treated using dry styrene-butadiene-styrene (SBS) polymer modification of asphalt. The products of scrap tires, PCB and TPO, were handled using dry SBS polymer modification of asphalt based on the effective resource use of scrap tires. The consequences of scrap tires, PCB and TPO, were taken using dry SBS polymer modification of asphalt based on the effective resource use of scrap tires. PCB and TPO composite effect seriously degraded. Based on this, the impact of dry SBS polymer modification on the functionality of PCB-TPO-modified asphalt and the mechanism of modification was examined. According to the investigation, the SBS polymer was evenly distributed and fully developed in the asphalt mixture, which significantly enhanced the qualities of asphalt and the asphalt mixture and performed a positive role in the internal structure of the asphalt mixture. [ABSTRACT FROM AUTHOR]

TRi-structural ISOtropic (TRISO) nuclear particle fuels are intended for application in several designs of advanced high temperature nuclear reactors. Nanosecond time domain transient thermoreflectance has been applied to the silicon carbide (SiC) and the inner and outer pyrolytic carbon (PyC) coatings of surrogate TRISO particles, measuring mean thermal conductivities of 166 ± 18 W∙m−1K−1, 11.1 ± 1.9 W∙m−1K−1, and 8.6 ± 2.1 W∙m−1K−1, respectively, for each layer. The applicability of the analytical heat diffusion model used to fit the measured traces was examined and it was found that the boundary effect at the SiC/PyC interface becomes perceptible at a lateral distance approximately equal to the thermal penetration depth of SiC (7.1 µm). In addition, steady-state thermal modelling showed that the radial thermal resistance of the particle is dominated by the porous buffer layer. The thermal resistance will likely increase significantly upon circumferential detachment of the porous buffer carbon coating with irradiation. Implications for fuel design and reactor performance are discussed. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) has emerged as an effective method for preparing complex structured silicon carbide (SiC) ceramics. However, the SiC components demonstrate low strength and high brittleness, which remain major challenges limiting its application. To overcome this limitation, short carbon fiber reinforced silicon carbide (C sf /SiC) composites are prepared by combining LPBF and phenolic resin binder impregnation (PRBI)-reactive melt infiltration (RMI), in which high char yield boron-and silicone-containing phenolic resin (BSiPF) impregnation is used to adjust the carbon density of green bodies and to reduce the pore size of green bodies. By optimizing the impregnation process, the carbon density can be brought close to the theoretical optimal value of 0.84 g/cm3, and the reduction of the pore size is conducive to the improvement of the reaction rate at the early stage of the reaction, which enhance the SiC phase content of C sf /SiC composites obtained by RMI. Meanwhile, the application of BSiPF results in a protective pyrolytic carbon (PyC) coating on the surface of C sf , which can reduce the erosion of C sf by molten Si during the RMI process, thus improving the fracture toughness of C sf /SiC composites. The final C sf /SiC composites exhibit the enhanced bulk density, bending strength and fracture toughness, reaching 2.90 ± 0.01 g/cm3, 257 ± 20 MPa, 3.52 ± 0.15 MPa m1/2, respectively. This study provides a new strategy for effective impregnation technique for the additive manufacturing (AM) of high strength and high toughness SiC composites. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing highly-efficient bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts is crucial for the widespread application of rechargeable Zn–air batteries (ZABs). Herein, an efficiency electrodeposition and pyrolytic strategy to synthesize the three-dimensional (3D) N-doped carbon coating multiple valence Co and MnO heterostructures supported on carbon cloth substrate (Co-MnO@NC/CC). It contains Co–Co, Co–N, and Co–O bonds, which synergistically enhance the oxygen reaction activity with MnO. It exhibits a working potential of 1.473 V at 10 mA·cm−2 for OER and onset potential of 0.97 V for ORR. Theory calculations demonstrate that the synergy between cobalt and manganese species could optimize the d-band center and reduce the energy barrier of Co-MnO@NC/CC for both OER and ORR processes. Besides, the MnO acts as the main OER active site could significantly optimize the energy barrier of O* → OOH*, thus further promoting the OER activity. It can be directly used as the air-cathode for both liquid-state and solid-state ZABs, which could afford a small voltage gap of 0.75 V at 10 mA·cm−2, a high power density of 172.5 mW·cm−2 and a long-term durability for 400 h, surpassing those of the Pt/C + RuO2-based ZAB. Importantly, the assembled batteries show potential applications in portable devices. [ABSTRACT FROM AUTHOR]

In this study, we carried out an electrochemical investigation of the palladium electrodeposition process at pH 5 and 8, evaluating the kinetic parameters related to its nucleation and growth processes on a Highly Oriented Pyrolytic Graphite (HOPG) electrode from a plating bath containing 1 mM of Pd and 1 M NH4Cl. The voltammetric study allowed us to identify the potential values at which palladium can be electrodeposited, along with the adsorption and desorption processes of hydrogen absorbed on the deposited Pd. Analysis of the peak currents of the deposited Pd indicated diffusional control at both pH values. The evaluation of kinetic parameters, such as the number of active nucleation sites (N0), the nucleation rate (A), and the rate constant of the proton reduction process (kPR), was determined via potentiostatic studies, revealing their dependence on the applied potential to the electrode. The number of active nucleation sites predicted by the nucleation model correlated well with the number of nuclei observed via Scanning Electron Microscopy (SEM). SEM images revealed that at pH 5, the Pd clusters had an average diameter of 27 nm and a height of 39 nm, while at pH 8, the clusters had an average diameter of 12.8 nm and a height of 16.6 nm. At pH 5, homogeneous and dispersed Pd clusters were obtained, while at pH 8, agglomeration of Pd clusters was observed. [ABSTRACT FROM AUTHOR]

Two-dimensional silicon (silicene) and germanium (germanene) have attracted special attention from researchers in recent years. At the same time, highly oriented pyrolytic graphite (HOPG) and graphene are some of the promising substrates for growing silicene and germanene. However, to date, the processes occurring during the epitaxial growth of silicon and germanium on the surface of such substrates have been poorly studied. In this work, the epitaxial growth of silicon and germanium is studied directly during the process of the molecular beam epitaxy deposition of material onto the HOPG surface by reflection high-energy electron diffraction (RHEED). In addition, the obtained samples are studied by Raman spectroscopy and scanning electron microscopy. A wide range of deposition temperatures from 100 to 800 °C is considered and temperature intervals are determined for various growth modes of silicon and germanium on HOPG. Conditions for amorphous and polycrystalline growth are distinguished. Diffraction spots corresponding to the lattice constants of silicene and germanene are identified that may indicate the presence of areas of graphene-like 2D phases during epitaxial deposition of silicon and germanium onto the surface of highly oriented pyrolytic graphite. [ABSTRACT FROM AUTHOR]

Digital Light Processing (DLP) technology is a highly effective molding method for creating complex structural parts. However, the low solid content of SiC stereolithography slurry has been found to diminish the mechanical properties of the ceramic, regardless of whether it is sintered by Reactive Melt Infiltration (RMI) or Precursor Infiltration and Pyrolysis (PIP). This poses a significant challenge in improving the mechanical properties of SiC ceramics manufactured through DLP additive manufacturing. In response to this challenge, a novel method of RMI combined with infiltration is proposed in this study. The process involves the filling of the pores of the green body with pyrolytic carbon from PR or pyrolytic SiC from LHBPCS through circular infiltration, effectively increasing the content of SiC in the ceramics after reaction. Notably, the elastic modulus of RM-P2 and RM-L2 samples increased by 37.39% and 33.91%, respectively, demonstrating the potential of this method for preparing ceramics with high SiC content through stereolithography additive manufacturing. This innovative approach holds promise for overcoming the limitations previously associated with SiC ceramics produced through DLP additive manufacturing, opening up new possibilities for the development of high-performance SiC-based components. [ABSTRACT FROM AUTHOR]

This study presents a novel approach for investigating the shrinkage dynamics of 3D‐printed nanoarchitectures during isothermal pyrolysis, utilizing in situ electron microscopy. For the first time, the temporal evolution of 3D structures is tracked continuously until a quasi‐stationary state is reached. By subjecting the 3D objects to different temperatures and atmospheric conditions, significant changes in the resulting kinetic parameters and morphological textures of the 3D objects are observed, particularly those possessing varying surface‐to‐volume ratios. Its results reveal that the effective activation energy required for pyrolysis‐induced morphological shrinkage is approximately four times larger under vacuum conditions than in a nitrogen atmosphere (2.6 eV vs. 0.5–0.9 eV, respectively). Additionally, a subtle enrichment of oxygen on the surfaces of the structures for pyrolysis in nitrogen is found through a postmortem electron energy loss spectroscopy study, differentiating the vacuum pyrolysis. These findings are examined in the context of the underlying process parameters, and a mechanistic model is proposed. As a result, understanding and controlling pyrolysis in 3D structures of different geometrical dimensions not only enables precise modification of shrinkage and the creation of tensegrity structures, but also promotes pyrolytic carbon development with custom architectures and properties, especially in the field of carbon micro‐ and nano‐electromechanical systems. [ABSTRACT FROM AUTHOR]

Additive micro/nano‐manufacturing of polymeric precursors combining with a subsequent pyrolysis step enables the design‐controlled fabrication of micro/nano‐architected 3D pyrolytic carbon structures with complex architectural details. Pyrolysis results in a significant geometrical shrinkage of the pyrolytic carbon structure, leading to a structural dimension significantly smaller than the resolution limit of the involved additive manufacturing technology. Combining with the material properties of carbon and 3D architectures, architected 3D pyrolytic carbon exhibits exceptional properties, which are significantly superior to that of bulk carbon materials. This article presents a comprehensive review of the manufacturing processes of micro/nano‐architected pyrolytic carbon materials, their properties, and corresponding demonstrated applications. Acknowledging the "young" age of the field of micro/nano‐architected carbon, this article also addresses the current challenges and paints the future research directions of this field. [ABSTRACT FROM AUTHOR]

Featured Application: Biochars from broom and gorse presented appropriate properties for use as fuels for energy production and pose no risks from an environmental perspective due to their low PAH content. These biochars are rich in carbon and have a low ash content. However, future investigations are needed to optimize and better understand their use in energy production and other potential uses, for example, as reductant materials in carbothermic reduction processes. Biochar (BC), which can be produced from several feedstocks, has been widely studied. However, the BC derived from highly pyrolytic shrubs, such as broom and gorse, has been less frequently used and only partially characterized. These wastes, when used for the preparation of biochar, can fix carbon and contribute to environmental conservation, helping to achieve sustainable development objectives. Eight biochars from broom and gorse were produced and fully analyzed, providing a more complete and novel description, with new insights for assessing their utilization. The aims of this study were to elucidate the effects of feedstock, pyrolysis temperature, and residence time on biochar properties and to assess the adequacy of these biochars as fuel. Elemental and proximate analyses and estimations of the lower and higher heating values were performed, and physical and chemical properties, as well as several other related energy indices, were determined. The experimental results showed that the temperature was a key factor in the properties of the biochars, while residence time was less important. The BCs obtained from the two feedstocks did not show important effects on the properties, which is consistent with the fact that they are woody legumes. These biochars had a high carbon content and were thermally stable. The BCs also had a high calorific value and suitable energetic properties. Additionally, their PAH contents were low, indicating that the use of these biochars would be safe. In conclusion, broom- and gorse-derived biochars can be considered as renewable fuels for green energy production. [ABSTRACT FROM AUTHOR]

To improve the in situ soil stabilization, different chemical additives are used (ion exchange compounds, additives based on H2SO4 or vinyl polymers, and organic additives using lignosulfonates). One interesting alternative is the production of additives from various waste materials. The extensive testing of waste-based blends with soil was performed; the mechanical (unconfined compressive strength (UCS)) and hydraulic (capillary rise, water absorption, and frost resistance (FR)) soil properties were measured. The optimization process led to obtaining additive compositions ensuring high strength and sealing properties: by-pass ash from the ceramics industry, waste H2SO4, pyrolytic waxes/oils from waste mixed plastics, waste tires and HDPE, and emulsion from chewing gum waste. For sandy soil, the following additives were the most promising: emulsion from pyrolytic wax (EPW) from waste PE foil (WPEF) with the addition of waste H2SO4, pyrolytic-oil emulsion from waste tires, EPW from waste mixed plastics with the addition of "by-pass" waste ash and NaOH, EPW from WPEF with the addition of NaOH, and EPW from WPEF reaching up to 93% FR, a 79.6% 7-day UCS increase, and a 27.6% of 28-day UCS increase. For clay: EPW from WPEF with the addition of NaOH, EPW from WPEF with the addition of waste H2SO4, and solely EPW from WPEF reaching up to 7.5% FR, an 80.7% 7-day UCS increase, and a 119.1% 28-day UCS increase. [ABSTRACT FROM AUTHOR]

The formation of a diamond-like carbon coating on a substrate as a result of the action of the radiation of an industrial laser (t ~ 20 ns, λ = 1.06 μm) on a target of the highly oriented pyrolytic UPV-1 graphite in a vacuum was investigated. It is shown that by changing the power density of the laser radiation on the surface of such a target, the velocity of scanning of the laser beam over the target surface, the laser pulse repetition frequency, and the temperature of the target, one can control the ratio between the sp2- and sp3-carbon bonds in the coating applied to a substrate. It was established that a diamond-like carbon coating with a predominant content of the sp3-bonded carbon is formed at a laser power density q ≥ 5.6∙108 W/cm2. In this case, it is advisable to select the laser pulse repetition frequency and the velocity of scanning of a laser beam over the surface of a target so that 10 to 14 laser pulses fall successively into one and the same area of the target surface. It is shown that, in the case where a target has a temperature T ≥ 423 K, the content of the sp3-linked carbon in the coating applied to a substrate decreases sharply, with the result that the properties of the coating deteriorate. [ABSTRACT FROM AUTHOR]

This work assesses the failure behavior of the silicon carbide (SiC) layer in TRIstructural ISOtropic (TRISO) fuel particles with BISON during both steady-state and transient conditions for the MHTGR-350 design by General Atomics. A one-dimensional BISON model for a uranium oxycarbide–bearing TRISO is developed to simulate a power level of 50 mW/particles up to 12.4% fissions per initial metal atom (FIMA). Stress predictions for the materials of interest are presented as a function of burnup, along with the SiC failure probability computed using Weibull statistics under the assumption of realistic SiC quality. A design-basis accident (DBA) that involves control rod withdrawal is then simulated in BISON at various burnup levels. Boundary conditions during the DBA are obtained from RELAP5-3D. The predicted SiC failure probability is 3 × 10−14%. This value does not increase during the transient as a function of burnup since irradiation induces a compressive hoop stress state that reaches a maximum absolute value of around 300 MPa. This compressive stress compensates the tensile loading conditions introduced by the transient. The tensile components appear amplified at higher burnups since they increase from 100 to 140 MPa going from 6% FIMA to 12.4% FIMA. Nonetheless, burnup provides a negligible impact on the overall failure probability predictions for SiC, as transient conditions do not translate to a stress increase toward tensile values at any of the considered burnups. Additionally, a two-dimensional (2-D) exploratory BISON model is developed to determine the effects of inner pyrolytic carbon (IPyC) crack formation on SiC. IPyC failure is predicted using Weibull statistics at 105 days from the beginning of irradiation, which is set as the time for crack initiation using XFEM in the 2-D BISON model. Stress concentrations induced by the crack cause the SiC failure probability to increase with respect to the intact particle case by approximately 10 orders of magnitude. Maximum stress concentrations are found at the time of crack formation, after which stress relaxation is observed during remaining steady-state irradiations and subsequent transient simulations. Considerations are made on the results of the 2-D model being contingent on both mechanical and anisotropy properties for pyrolytic carbon. Recommendations are provided for future work involving higher dimensionality models, further investigations on uncertainties, material properties, and additional designs, such as the fluoride salt-cooled high-temperature reactor, that operate at higher burnups. [ABSTRACT FROM AUTHOR]

We have built and commissioned a novel standalone multi-crystal x-ray spectrometer (MOSARIX) in the von Hamos configuration based on highly annealed pyrolytic graphite crystals. The spectrometer is optimized for the energy range of 2–5 keV, but this range can be extended up to 20 keV by using higher reflection orders. With its nine crystals and a Pilatus detector, MOSARIX achieves exceptional detection efficiency with good resolving power (better than 4000), opening the door to study small cross section phenomena and perform fast in situ measurements. The spectrometer operates under a He atmosphere, which provides a flexible sample environment for measurements in gas, liquid, and solid phases. [ABSTRACT FROM AUTHOR]

Carbon foams with and without functional particles were prepared via a simple direct foaming process. The carbon foams were composed of pyrolytic carbon and graphite. In the foams with additional functional particles, the latter were integrated directly in the direct foaming process. These functional particles were the catalytic material Saponite and the induction heat‐able material MagSilica®. The foams were characterized including the induction heatability. The foams were also successfully tested in an induction heated lab‐scale reactor for a case study reaction, ethanol to 1,3‐butadiene. [ABSTRACT FROM AUTHOR]

Coated nuclear fuel particles, most commonly tri-structural isotropic (TRISO), are intended for use in advanced high temperature reactors. It is vital to understand the mechanical properties of each coating layer to accurately predict the performance of these fuel particles and how these might change at each stage of their lifecycle. This paper reports results of in-situ nanoindentation, with an emphasis on the structural SiC layer, along with microcantilever testing of the critical SiC-IPyC interface. At 1000 °C the hardness of the SiC layer is ∼75% lower than at room temperature implying significantly more plasticity at the reactor operating temperature. The elastic modulus was slightly lower at 1000 °C than at room temperature. Microcantilever fracture at the SiC-IPyC interface shows that failure occurs within the pyrolytic carbon layer rather than an interfacial "debonding" with a strength similar to that of bulk pyrolytic carbon. [ABSTRACT FROM AUTHOR]

Pyrolytic carbon (PyC) is widely used as the interphase in SiC f /SiC composites because of the crack deflection capability originating from its weakly bonded layered structure. However, the poor oxidation resistance limits its application in SiC f /SiC. Boron doping can improve oxidation resistance due to the crack-healing effects of boron oxide. To explore the optimal boron doping content in PyC interphase, structure characters and mechanical properties of C 128−x B x (x = 8, 20, 32, 44, 64) were simulated by ab-initio molecular dynamics. Modeling results suggest a transition of C 128−x B x from layered to amorphous accompanied by a change of its elasticity tensor from strongly anisotropic to nearly isotropic. The predicted optimal boron content is near 34 at%, at which the B-doped PyC maintains a layered structure with a high crack deflection potential according to the Cook & Gordon model while having a high crack-healing capability with a large volume expansion factor. [ABSTRACT FROM AUTHOR]

This study aimed to develop a novel electrochemical sensor using nano-gold particle modified pyrolytic graphite sheet electrodes to improve the detection and quantification of vitamin C content in sports beverages. The electrodes were fabricated by depositing 20–50 nm gold nanoparticles onto pretreated pyrolytic graphite sheets using a spontaneous adsorption technique. Square wave voltammetry served as the main analytical technique for optimizing and testing the performance of the nano-gold modified sensor. Key parameters optimized included supporting electrolyte pH, voltage scan rate and pulse frequency. The sensor gave highly linear detection across a vitamin C concentration range spanning 5–100 μg/mL, with sensitivity peaking under acidic pH 5 conditions. A limit of detection of 1.86 μg/mL was achieved. Recovery testing in spiked commercial sports drink samples yielded excellent accuracy between 97.3 and 104.2%. Additionally, vitamin C levels quantified via the sensor showed close agreement with results from a standard spectrophotometric method, confirming its reliability. This research signifies an important advancement in nutrient monitoring capabilities for the sports nutrition industry, providing a rapid, selective and cost-effective sensor for verifying vitamin contents. [ABSTRACT FROM AUTHOR]

Highly portable nanoelectronics and large-scale electronics rely on lithium-ion batteries (LIBs) as the most reliable energy storage technology. This method is thought to be both environmentally friendly and cost-effective. We provide a study of a low-cost, abundant, and renewable supply of carbon-based biomass with potential uses in LIBs. Renewable feedstocks have received significant attention in recent decades as promising tools for efficient and alternative anode materials for LIBs. Researchers can synthesise carbon-rich biochar through the pyrolytic process of biomass. Depending on the synthetic process, precise surface chemistry, and textural qualities such as specific surface area and porosity, this material can be customised to favour application-specific properties with a preferred application. In this research, we look at the performance of biochar in LIBs, its properties, and the biomass supply, and we discuss the prospects for these biomass-derived materials in energy storage devices. [ABSTRACT FROM AUTHOR]

The effects of substrate choice, substrate temperature, Se/In flux ratio, and cooling rate after deposition on the phase composition, surface morphology, and stoichiometry of indium selenide films synthesized via molecular beam epitaxy are presented. In2Se3 films were synthesized on sapphire, Si(111) and highly oriented, pyrolytic graphite (HOPG) substrates. The phase composition, stoichiometry, and surface morphology of the films were characterized via Raman spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy, respectively. Higher substrate temperature combined with higher Se/In ratio promoted formation of β-In2Se3 over γ and/or κ-In2Se3 on all substrates. Higher Se/In ratio also independently promoted β-In2Se3 over γ and/or κ-In2Se3 on all substrates at 673 K. The lateral dimensions of In2Se3 flakes increased as the substrate temperature increased on all substrates, and the largest lateral dimensions were observed for β-In2Se3 flakes on HOPG at 973 K. No evidence of α-In2Se3 was observed in the Raman spectra of any of the films at any of the synthesis conditions in this study. β-In2Se3 films on HOPG were cooled at 1200, 120, and 12 K/h and no evidence of a β to α-In2Se3 phase transition was observed. Some evidence of β to α-In2Se3 phase transition was observed in temperature-dependent XRD of In2Se3 powders, suggesting that another parameter besides cooling rate is locking the In2Se3 films into the β-phase. [ABSTRACT FROM AUTHOR]