Synthesis Of Silicon Carbide Nanowires Research Articles

Thermal Radiation Shielding and Mechanical Strengthening of Mullite Fiber/SiC Nanowire Aerogels Using In Situ Synthesized SiC Nanowires.

Traditional solid nanoparticle aerogels have been unable to meet the requirements of practical application due to their inherent brittleness and poor infrared shielding performance. Herein, combining vacuum impregnation and high-temperature pyrolysis, a novel micro/nano-composite fibrous aerogel was prepared via in situ synthesis of silicon carbide nanowires (SiC NWS) in mullite fiber (MF) preform. During this process, uniformly distributed SiC NWS in the MF preform serve as an enhancement phase and also act as an infrared shielding agent to reduce radiation heat transfer, which can significantly improve the mechanical properties of the mullite fiber/silicon carbide nanowire composite aerogels (MF/SiC NWS). The fabricated MF/SiC NWS exhibited excellent thermal stability (1400 °C), high compressive strength (~0.47 MPa), and outstanding infrared shielding performance (infrared transmittance reduced by ~70%). These superior properties make them appealing for their potential in practical application as high-temperature thermal insulators.

Low temperature synthesis of silicon carbide nanowires on cathode for thermionic energy converter

Surface nanostructuring on cathode of thermionic energy converter (TEC) has been researched aggressively throughout recent decades. In this paper, we report a simple approach of low temperature synthesis (600 °C) of silicon carbide nanowires (SiCNWs) by liquid phase source chemical vapor deposition (CVD). These as-synthesized nanowires grown on silicon substrate are utilized as cathode or emitter in the application of thermionic energy converter (TEC) system. The thickness of catalyst (magnesium) coated on silicon substrate should be at least 100 nm for the growth of SiCNWs. By controlling the thickness of catalyst, different size (diameter) of nanowires were obtained.

Novel Synthesis of Silicon Carbide Nanowires from e-Waste

In this study a novel new process for the synthesis of silicon carbide nanowires from a voluminous and problematic waste stream, e-waste, is verified. Silicon carbide nanowires (SiC NWs) with diameters of 30–200 nm and length up to 10 μm were synthesized via the carbothermal reduction of two electronic waste (e-waste) components. The glass fraction of an obsolete computer monitor (GCM) was used as a source of silica and the computer’s plastic shell (CPS) as a carbon source. After identifying the composition of the GCM and the CPS, a stoichiometric mixture of both components was prepared and subsequently heat-treated at 1550 °C in an inert atmosphere. The resulting product was characterized, and results confirmed the formation of three distinct morphologies of SiC NWs; smooth surface NWs, bamboo-like NWs, and hexagonal prism NWs with high-density stacking faults (SF). According to the N2 physisorption analysis, the SiC NWs showed mesoporous characteristics with a specific surface area of 51.4 m2/g and pore...

Toward green chemistry: A new approach to the synthesis of semiconducting SiC nanowires

In recent years, the synthesis of silicon carbide nanowires (NWSiC) has been extensively studied and a fast, simple one-step chemical method of branched one-dimensional SiC nanostructure formation from Si/PTFE mixture via a thermolysis route (SHS) has been proposed. The aim of this study is to further develop the production protocol by decreasing the cost of starting reactants and environmental impact of the synthesis. Thus, recycled grinded solar panels were tested as a silicon source. Furthermore, technical PTFE powder (the industrial by-product) has been proposed instead of the pure commercially available one to further decrease the final cost of the process. The parametric optimization of the process was carried out as well as in situ diagnostics based on the analysis of light emitted during the combustion. The possibility of scaling up the production of NWSiCs was confirmed. The products were characterized using XRD, SEM, and Raman spectroscopy and used as fillers in nanocomposites. Reactors used for the combustion synthesis (left) and the substrate: recycled grinded solar panels as the Si source (right).

High-yield synthesis of silicon carbide nanowires by solar and lamp ablation

We report a reasonably high yield (∼50%) synthesis of silicon carbide (SiC) nanowires from silicon oxides and carbon in vacuum, by novel solar and lamp photothermal ablation methods that obviate the need for catalysis, and allow relatively short reaction times (∼10 min) in a nominally one-step process that does not involve toxic reagents. The one-dimensional core/shell β-SiC/SiOx nanostructures—characterized by SEM, TEM, HRTEM, SAED, XRD and EDS—are typically several microns long, with core and outer diameters of about 10 and 30 nm, respectively. HRTEM revealed additional distinctive nanoscale structures that also shed light on the formation pathways.

Synthesis of Silicon Carbide Nanowires from a Hybrid of Amorphous Biopolymer and Sol–Gel‐Derived Silica

We report here the formation of silicon carbide (SiC) nanowires from inorganic–organic hybrid of sol–gel‐derived silica and the commercially available lignin that is naturally abundant amorphous biopolymer. This organic–inorganic hybrid material in the absence of catalyst was carbothermally reduced for a period of 1 h at 1400°C in inert atmosphere followed by oxidization. The nanostructures were characterized by scanning electron microscopy and high resolution scanning electron microscopy, which show the continuous formation of β‐SiC nanowires in the range of 50–200 nm diameter and length of few micrometers. Transmission electron microscopy revealed Y‐shaped structures (branched) of the nanowires grown in the direction of parallel to the [100] plane having two heads and one leg. The nanowires were formed with joints that were formed at regular intervals as circular rings. The deposition of silica layer on the outer surface of the nanowires was also observed. According to the X‐ray diffraction pattern, peaks at 2θ=35.9° and 59.8° indicate the formation of β‐SiC and a sharp peak at 2θ=22.1° suggests the presence of unreacted crystalline silica (crystoballite). The Raman shifts for β‐SiC appeared as small peaks at 795.6 and 983.1 cm−1, respectively. The characteristic vibration of SiC at 795 cm−1in Fourier transform infrared spectroscopy was also observed.

Synthesis of Silicon Carbide Nanowires Doped with Al<sub>2</sub>O<sub>3</sub>

Synthesis of silicon carbide nanowires (SiC NWs) from an alumina doped silica-graphite rod is reported. The rod was gradually heated up to a growth temperature by passing current through it under constant flowing argon at atmospheric pressure. The as-grown layers, deposited on the rod surface were separated from the inner core and characterized using scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, selected area electron diffraction, X-ray diffraction and Raman spectroscopy. A non-uniform layer thickness of alumina coating on SiC NWs was clearly observed when the doping was increased from 1 to 2 and 3 wt.%.

An Approach to the Synthesis of Silicon Carbide Nanowires by Simple Thermal Evaporation of Ferrocene onto Silicon Wafers

AbstractScales of silicon carbide nanowires (SiC‐NWs) with high quality were synthesized by direct thermal evaporation of ferrocene onto silicon wafers at high temperature. Ferrocene decomposed into iron and carbon, which was subsequently treated with silicon to form SiC‐NWs at high temperature. The SiC‐NWs possess small diameters of ≈ 20 nm and lengths of several μms. Furthermore, the samples show a uniform morphology, crystalline structure, and a very thin oxide layer. The main crystal direction of [111] was confirmed by high‐resolution field‐emission‐transmission electron microscopy (HR‐FETEM). The Raman scattering spectra showed two peaks at ≈ 796 (TO) and ≈ 980 cm–1 (LO) with varying intensity ratios at different positions. The band line fluctuation was contributed to the Raman selection rules. With reference to the experimental results, we suggested a tentative growth model according to the vapor–liquid–solid (VLS) mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis of silicon carbide nanowires by CVD without using a metallic catalyst

Using CH 3SiCl 3 (MTS) and H 2 as the precursors, large quantities of SiC nanowires with homogeneous diameter have been fabricated by a simple chemical vapor deposition process without using a metallic catalyst. The as-grown SiC nanowires were identified by TEM and XRD as single crystal β-SiC structure, with diameters of about 70 nm. As the increasing of deposition temperature, or as the decreasing of H 2/MTS mol ratio, the SiC crystal dimensions increase and the morphologies of the as-grown SiC crystal change from nanowires to grains. β-SiC coaxial nanocables with a amorphous wrapping layer have also been obtained by the oxidation of SiC nanowires.

Novel method for synthesis of silicon carbide nanowires

Novel method for synthesis of silicon carbide nanowires

Synthesis of silicon carbide nanowires in a catalyst-assisted process

At elevated temperatures, silicon carbide nanowires were synthesized in a catalyst-assisted process using aluminum as a catalyst. Transmission electron microscopy shows that the nanowires are around 20 nm in diameter and around 2 μm in length. High resolution transmission electron microscopy shows that the nanowires are crystalline β-SiC. Raman spectra show the typical features of nano-SiC. A model based on vapor–liquid–solid process is proposed to explain our finding.