SiC Sheet Research Articles

A novel siloxene@MoS2 heterostructure for improving the wear and corrosion resistance performance of epoxy coatings

Siloxene (Sic) flakes are two-dimensional silicon-based materials that have been extensively investigated in the domains of batteries, supercapacitors, and electrocatalysis, with essentially no research in the domain of corrosion and wear resistance performance of metal coatings. In this study, Sic sheets were prepared through topological chemical exfoliation and applied to epoxy (EP) resin systems for the first time. The effects of Sic sheets on the corrosion and wear resistance performance of the composite coatings were explored. To improve the enhancement effect of Sic on the tribological properties and corrosion resistance of the composite coatings, molybdenum disulfide (MoS2), which exerts a self-lubricating effect and an enhanced interfacial effect, was grown on the surface of Sic using a hydrothermal method. The corrosion resistance and tribological properties of the prepared composite coatings were characterized through electrochemical impedance spectroscopy, polarization curve analysis, and friction and wear tests. The results indicated that the composite coating containing 0.75 wt% siloxene@MoS2 (Sic@MS) has the best corrosion resistance and tribological properties. Compared with the pure EP coating, the wear rate of the Sic@MS coating with the aforementioned concentration was reduced by 67 %. Furthermore, the impedance module value at 0.01 Hz was increased by three orders of magnitude and the corrosion current density was reduced by three orders of magnitude after 60 days of immersion in NaCl solution. The above results provide a new idea for the application of Sic materials.

Synergetic effect of milling speed and duration on particle morphology and mechanical properties of nanocrystalline Al matrix containing SiC

ABSTRACT In the present study, the composite sheets were produced by powder rolling the ball-milled Al/SiC mixture. The effect of milling speed (350–550 rev min–1) and milling duration (8 and 12 h) on the Al particle morphology and subsequent mechanical properties were examined for composites with different volume fractions of SiC. From the microstructural investigation, SiC particles are evenly distributed and well dispersed in the Al matrix; those are prepared under higher milling speed (550 rev min–1) and higher milling time (12 h). Furthermore, the flattened-shaped particle morphology was obtained under lower milling conditions, whereas the reduced-granule shape was obtained under higher milling conditions (550 rev min–1, 12 h). Consequently, the Al/SiC composite sheets made from a granule-shaped Al/SiC mixture show higher density, microhardness, and tensile strength due to significant consolidation and SiC uniformity. In addition, the tensile strength of 430.26 MPa has been achieved for the Al/2vol.-%SiC sheet compared to pure Al (393.49 MPa) under similar processing conditions.

Quantum effects in two-dimensional silicon carbide

Two-dimensional (2D) silicon carbide is an emergent direct band-gap semiconductor, recently synthesized, with potential applications in electronic devices and optoelectronics. Here, we study nuclear quantum effects in this 2D material by means of path-integral molecular dynamics (PIMD) simulations in the temperature range from 25 to 1500 K. Interatomic interactions are modeled by a tight-binding Hamiltonian fitted to density-functional calculations. Quantum atomic delocalization combined with anharmonicity of the vibrational modes cause changes in structural and thermal properties of 2D SiC, which we quantify by comparison of PIMD results with those derived from classical molecular dynamics simulations, as well as with those given by a quantum harmonic approximation. Nuclear quantum effects are found to be appreciable in structural properties such as the layer area and interatomic distances. Moreover, we consider a real area for the SiC sheet, which takes into account bending and rippling at finite temperatures. Differences between this area and the in-plane area are discussed in the context of quantum atomic dynamics. The bending constant (κ=1.0eV) and the 2D modulus of hydrostatic compression (Bxy = 5.5 eV/Å 2) are clearly lower than the corresponding values for graphene. This study paves the way for a deeper understanding of the elastic and mechanical properties of 2D SiC.

Activation of h‐BN and SiC monolayer sheets through foreign atom substitution; a comparative study based on ab‐initio method

AbstractHere, we studied two different 2D monolayer systems (i.e., h‐BN and SiC), which exhibit unique electronic and magnetic properties. We analyzed the effects of Transition Methods (TM) doped atoms (i.e., Mn, Ni, and Sc) on the single vacancy (SV) h‐BN and SiC systems using first principles calculations. Through comparison we found that Mn substitution in SV h‐BN and SiC can modify their electronic and magnetic properties having larger magnetic moment as compared to other dopants (i.e., Ni and Sc.). Band structure and PDOS plots confirmed that TM doping in SV h‐BN can convert the pure h‐BN (insulator) to semiconductor, metal, or semi‐metal, it is also observed from the results that Mn‐doped h‐BN has higher band gap approximately equal to Eg ~ 2.7 eV during the negative spin and has smaller band gap, that is, (Eg ~ 1.1 eV) during the positive spin. Similarly doping with the TM atoms on the SV SiC monolayer system can convert pure SiC to metal or half metal. In addition, Mn‐doped SiC showed semimetal property having 0 eV band gap. These finding will help us to vary the electronic and magnetic properties of the pure h‐BN and SiC sheets which can be used for the opto‐electronic and spintronic applications.

Application of siligraphene sheets to detect COVID-19 through volatile organic biomarkers in exhaled breath of humans: A first-principles study

The possibility of using siligraphene sheets to detect volatile organic biomarkers in the exhaled breath of humans with COVID-19 is studied. Heptanal, octanal, and nonanal are identified as the prominent biomarkers of COVID-19. Adsorption of these molecules on SiC and SiC7 sheets is examined by density functional theory. The adsorption energies indicate that the considered sheets could be proper materials to use as reusable sensors. SiC and SiC7 exhibit semiconductor properties. The energy bandgap of SiC7 reduces more drastically than that of SiC with heptanal, octanal, and nonanal adsorption. Thus, the electronic properties of SiC7 are sensitive to the adsorption of the considered molecules. It is also shown that physisorption of the water molecule has no considerable effect on the bandgap of SiC7. Thus, SiC7 is a suitable sensor for use in humid conditions like an exhaled breath of humans to diagnose COVID-19.

The role of defects presenting in graphitic SiC sheets and their consequences in the exfoliation of layers – a first principles approach

First principles calculations are employed to understand the effect of single and divacancy defects in the exfoliation process of 2D SiC sheets and their influence over the structural stability and electronic properties.

First-principle investigation of silicon carbide nanosheets fluorination: Stability trends, electronic, optical and magnetic properties

We employed first-principles calculations to investigate the fluorination of silicon carbide nanosheets. We found that the Si atoms are the energetically favorable adsorption sites for F atoms in silicon carbide nanosheets in all studied cases. The strain caused by the fourfold coordinated Si atoms in the flat SiC nanosheet determines the relative position of the adsorbed F atoms: occupying nearest-neighbor Si sites if they bound sheet’s opposing sides or away from each other if they are on the same side of the sheet. The fluorinated nanosheets’ electronic and magnetic properties are weakly dependent on which side of the sheet the F atoms bind; however, they are strongly dependent on the relative distance between them. For F atoms adsorbed on nearest-neighbor Si sites, the system is a small gap p-type semiconductor with 1 μB per adsorbed atom. On the other hand, if F atoms do not occupy nearest-neighbor Si sites, the system is a metal with 1/2 μB per adsorbed atom. The adsorption of F atoms strongly affects the optical properties of SiC sheets inducing optical anisotropy regarding the direction of the incidence of light.

Engineering the electronic properties of siligraphene sheets by organic molecules: a density functional theory investigation

The effect of molecular adsorption on the electronic properties of siligraphene sheets is investigated through density functional theory (DFT) calculations. Adsorption of the organic molecules tetracyanoethylene (TCNE), tetrathiafulvalene (TTF), as well as tetracyanoquinodimethane (TCNQ) on siligraphene (SiC x with x = 1, 2, 3, 5 and 7) is studied. The three types of SiC x : SiC, SiC2 and SiC7 have semiconductor properties, while SiC3 and SiC5 are semimetals. P-type and n-type semiconductors are obtained via charge transfer between the organic molecules and SiCx sheets. The SiC, SiC2 and SiC7 sheets exhibit p-type semiconductor behaviour after TCNE and TCNQ adsorption, while they exhibit n-type semiconductor behaviour due to TTF adsorption. The adsorbed molecules have no significant effect on the band gap energy of SiC3 and SiC5. The results provide an effective method to model the electronic properties of siligraphene sheets.

Controlled growth of SiC crystals in combustion synthesis

Abstractβ‐SiC powders with different particle morphologies were prepared by combustion synthesis in an N2 atmosphere, with carbon black, carbon fiber, graphene, and graphite as carbon sources. With carbon black as the carbon source, single‐phase β‐SiC nanopowder with an average particle size around 20 nm was obtained. From carbon fiber and graphene, SiC fibers and sheets were produced, which were polycrystalline and consisted of lots of nanocrystals with random orientations. It was proposed that the synthesis of SiC occurs by gas–solid reaction and the growth of SiC is confined to the carbon particles. In the controlled growth of SiC, the morphology of the precursor carbon is preserved, offering an opportunity to control the particle morphology of SiC by changing carbon sources.

γ-Hydroxybutyric acid drug recognition by palladium decorated silicon carbide monolayer

γ-Hydroxybutyric acid (HBA) is the most frequently used drug to carry out drug-facilitated sexual assault, banned for sale by FDA. Thus, its recognition in the biological samples is of great importance for drug communities and the police. Two-dimensional nanomaterials have attracted considerable attention as chemical sensors for different biological and gas molecules. Here, we inspected the sensing properties of the pristine SiC sheet (SiCS) and its Pd-decorated form (Pd@SiCS) toward the HBA drug by the TPSS density functional computations. We uncovered that the sensing response of SiCS to the HBA drug is very small (~4.8 at 298 K) because it interacts weakly with the pristine SiCS with the binding energy (BE) of –0.28 eV. When a Pd atom was decorated on the SiCS, it was preferentially adsorbed onto an Si-C of the SiCS with BE of –2.28 eV. We found that the Pd@SiCS adsorbed the HBA drug strongly with BE of − 1.15 eV. Thus, the Pd decoration amplified the sensing response of SiCS to the HBA drug from 6.3 to 485.3, which is high. We predicted a short recovery time of 2.8 s for the HBA desorption from the Pd@SiCS surface. Our study suggested that the Pd-decoration makes SiCS a promising candidate for the HBA drug detection.

High Thermal Conductivity Enhancement of Polymer Composites with Vertically Aligned Silicon Carbide Sheet Scaffolds.

Owing to the growth of demand for highly integrated electronic devices, high heat dissipation of thermal management materials is essential. Epoxy composites have been prepared with vertically aligned (VA) three-dimensional (3D)-structured SiC sheet scaffolds. The required VA-SiC sheet scaffolds were prepared by a novel approach starting with a graphene oxide (GO) scaffold. The VA-GO scaffolds were reduced to VA-graphene scaffolds in an argon environment, and the latter were subsequently transformed into VA-SiC sheet scaffolds by a template-assisted chemical vapor deposition method. Epoxy resin was filled in the empty spaces of the 3D scaffold of SiC sheets to prepare the composite mass. The material so prepared shows anisotropic thermal property with ultrahigh through-plane conductivity of 14.32 W·m-1·K-1 at a SiC sheet content of 3.71 vol %. A thermal percolation is observed at 1.78 vol % SiC filler. The SiC sheet scaffold of covalently interconnected SiC nanoparticles plays a vital role in the formation of the thermal conductive network to significantly enhance the thermal conductivity of epoxy composites. The application of the VA-SiC/epoxy composite as an efficient thermal dissipating material has also been presented. The VA-SiC/epoxy composites have a strong potential for preparing heat-dissipating components in integrated microelectronics.

Spectrometry studies of Ag implanted silicon carbide thin films for application as a diffusion barrier against transition metals

A diffusion kinetics study of implanted silver (Ag) ions into SiC films is conducted. SiC thin films have been processed on Si (1 0 0) substrates by electron beam deposition from a commercial high purity hot-pressed SiC sheet. The as-deposited films were thereafter implanted with Ag+ ions. Realtime Rutherford backscattering spectrometry experiments showed that Ag+ is stable until 600 °C, which is the highest temperature that the heater in the system used could achieve. Conventional RBS studies on isochronally annealed films at higher temperatures in the range between 650 °C and 950 °C reveal that there is no significant change in the spectra up to a temperature of ∼ 750 °C. At 850 °C a change in the Ag implantation profile was observed, suggesting that Ag is mobile at that temperature. The corresponding depth profile at 850 °C suggests that there is significant Ag in- diffusion, however the overall integrated intensity data indicate that most of the Ag+ is escaping out of the films. Upon annealing for one hour at 950 °C, all the Ag ions have essentially escaped out of the films and/or spread throughout the layer below the detection limit of RBS. Isothermal annealing studies over varied duration times at 850 °C confirm Ag in-diffusion, but at the same time there is evidence of depletion of Ag near-surface regions as the annealing time increases; the overall out-diffusion of the implanted metal, although steady, is found to be slow in an isothermal process. FTIR investigations point to a diffusion model through pores and grain boundaries.

Effects of biaxial strain and functional groups on SiC/ti3C2 heterostructure: a first principle calculation

MXene-bonded heterostructure has been demonstrated as an effective strategy to prevent the face-to-face stacking of MXene and improve the performance of MXene anode for metal-ion batteries. However, the understanding of the interfacial electronic properties of MXene-bonded heterostructure is still a little clear. In this paper, the effects of biaxial strain and functional groups on the structure and electronic properties of SiC/Ti3C2 heterostructure have been investigated using the first-principles method. We found that there exists a strong interfacial coupling between the SiC and Ti3C2 sheet because of the chemical activity of Ti surface, and the carrier mobility of heterostructure can be further tuned by biaxial strain, which decreases with tensile strain and increases with compressive strain. Furthermore, it has been demonstrated that the surface functionalization of F and OH could reconcile the strong interlayer interaction between the bilayer, and the type of Schottky barrier can be tuned by functional groups. More notably, there exists a transition from metal to semiconductor when SiC/Ti3C2O2 is under the tensile strain of 6%, and the band gap can be opened with a larger strain. Taken together, these results indicate intriguing electronic properties of the SiC/Ti3C2 heterostructure, which could pave the way for MXene-based nanodevice applications.

New highly efficient 2D SiC UV-absorbing material with plasmonic light trapping

The present paper is a systematic analysis of the thermoelectric and optical properties of the SiC monolayer. Based on the density functional theory (DFT) combined with the Boltzmann transport theory, the thermal conductivity, the electrical conductivity and the figures of merit are all determined and discussed for the SiC hybrid. At room temperature, it is found that SiC shows interesting values with respect to its counterparts graphene and silicene. To improve the absorption of the SiC sheet, a strategy is proposed using finite-difference time-domain (FDTD) combing with PSO-based approach. The absorbance of the UV-photodector with SiC monolayer and the SiC-based photodector with Au plasmonic grating are studied. Among our findings, the Au plasmonic grating enhances the absorbance of SiC to reach a maximum absorbance of 99.6% at the resonance wavelength of ( nm), which significantly improves the performance of UV-sensors. Therefore, by combining optical DFT analysis with FDTD simulation supported by global PSO optimization, we have been able to develop a new SiC monolayer high performance UV photodetector suitable for advanced optoelectronic applications.

Adsorption of O2 on the M doped (M=Fe, Co, Al, Cu, and Zn) SiC sheets: DFT study

Adsorption of O2 on the M doped SiC sheets (M = Fe, Co, Al, Cu, and Zn) have been studied by density functional theory. We found that MSi doped SiC sheets have the higher structural stability than Mc doped SiC sheets. Compared with pure SiC sheet, MC doped SiC sheets have the larger adsorption energy to O2. When O2 molecule is adsorbed away from and on M site, the most stable adsorption structures are the CoC and CuC doped SiC sheets respectively. Density of state (DOS) of the most stable structures are calculated to investigate the adsorption process. Based on calculated results, the MC doped SiC sheets are more suitable for adsorption of O2.

Metallized siligraphene nanosheets (SiC7) as high capacity hydrogen storage materials

A planar honeycomb monolayer of siligraphene (SiC7) could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van der Waals-induced first principles calculations based on density functional theory (DFT), we have explored the structural, electronic, and hydrogen (H-2) storage characteristics of SiC7 sheets decorated with various light metals. The binding energies of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca),scandium (Sc), and titanium (Ti) dopants on a SiC7 monolayer were studied at various doping concentrations, and found to be strong enough to counteract the metal clustering effect. We further verified the stabilities of the metallized SiC7 sheets at room temperature using ab initio molecular dynamics (MD) simulations. Bader charge analysis revealed that upon adsorption, due to the difference in electronegativity, all the metal adatoms donated a fraction of their electronic charges to the SiC7 sheet. Each partially charged metal center on the SiC(7)sheets could bind a maximum of 4 to 5 H-2 molecules. A high H-2 gravimetric density was achieved for several dopants at a doping concentration of 12.50%. The H-2 binding energies were found to fall within the ideal range of 0.2-0.6 eV. Based on these findings, we propose that metal-doped SiC7 sheets can operate as efficient H-2 storage media under ambient conditions.

Tuning Optoelectronic Properties of the Graphene-Based Quantum Dots C16- xSi xH10 Family.

The electronic and optical properties of graphene-based quantum dots (QDs) are investigated using DFT and many-body perturbation theory. Formation energy, hardeness and electrophilicity show that all structures, from pyrene to silicene QD passing through 15 CSi QD configurations, are energetically and chemically stable. It is also found that they are reactive which implies their favorable character for the possible electronic transport and conductivity. The electronic and optical properties are very sensitive to the number and position of the substituted silicon atoms as well as the directions of the light polarization. Moreover, quantum confinement effects make the exciton binding energy of CSi quantum dots larger than those of their higher dimensional allotropes such as silicene, graphene, and SiC sheet and nanotube. It is also higher those of other shapes of quantum dots like hexagonal graphene QDs and can be tailored from the ultraviolet region to the visible one. The values of the singlet-triplet splitting determined for the X- and Y-light polarized indicate that all configurations have a high fluorescence quantum yield compared to the yield of typical semiconductors, which makes them very promising for various applications such as the light-emitting diode material and nanomedicine.

Study on Debris Behavior and Its Influence on EDM Characteristics in Deep Micro-hole Machining

The micro EDM is widely utilized to drill micro hole in many metallic materials regardless of its hardness such as the inkjet printer nozzle and diesel fuel injection nozzle. Although the drilling micro hole by micro EDM has been well developed and many methods have been put forward to improve the machining efficiency and accuracy, the problem of decrease in machining speed has not been solved completely. In most cases, the reason for the decrease of drilling speed was thought to be the accumulation of debris and bubble in the gap area. However, the assumption has not been confirmed directly so far. Hence, in this research, in order to find out the debris and bubble behavior and its influence in micro EDM, a high speed camera was utilized to observe the gap area during drilling micro-hole in SiC and stainless steel SUS304 sheet workpieces by using the sandwich workpiece. The diameter of micro tool was equal to the thickness of workpiece, which made it possible to directly observe the gap area through the glass plates. It was found that a bubble grows up alone or merges with other bubbles to become a big bubble with the increase of feed depth, then overflows out of gap area slowly. When a micro hole is drilled into a certain depth, debris is accumulated in the bottom of gap area and the occurrence of abnormal discharge becomes more frequent. Hence, the workpiece material is difficult to be removed and the machining speed decreases seriously.

Stability, magnetic and electronic properties of SiC sheet doped with B, N, Al and P

Using DFT-based calculations, we study chemical doping of silicene–graphene hybrid with (B, N, Al and P). Planar structure of SiC sheet remains unaffected on doping and all the systems are stable. P and N dopants are strongly bonded to the hybrid compared with Al and N. Charge transfer calculations show that (B, N)/(Al, P) behave like acceptors/donors, respectively. All configurations retain the semi-conductor character of pure SiC and show magnetic order. Curie temperature is determined for the ferromagnetic structures. These results provide the possibility of tuning the gap and inducing magnetism in SiC as required for future applications.

Mechanical response of SiC sheet under strain

The effect of biaxial strain on crystallographic structure, band gap, polarization, linear and non linear elastic properties of 2D SiC hybrid are studied using ab-initio calculations. The determination of the two critical strain points reveals an elastic region just a little smaller than that of graphene. With load, charge distributions vary and electronic states CBM and VBM undergo a location change. Consequently, enlarging strain reduces the band gap monotonically leading to a semiconductor–metal transition. Debye temperature 407.81K intermediates between the ones of silicene and germanene. Planar SiC shows a piezoelectric response comparable to 2D buckled compounds materials. The negative sign of the effective non linear modulus reveals an hyperelastic softening behavior of SiC. Under pressure, second order elastic constants show a small anisotropie. The results show that tailoring physical properties of SiC under strain reveals its great potential in the electronic and mechanical devices.