Synthesis of Fe–SiC Nanowires via Precursor Route (original) (raw)
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SiC nanowires grown on activated carbon in a polymer pyrolysis route
Materials Science and Engineering: B, 2010
a b s t r a c t -SiC nanowires are a novel type of photocatalysts. However, they tend to be entangled together especially at high concentrations when dispersed in water, which may reduce the photocatalytic activity. It is reasonable to expect that -SiC nanowires would provide better photocatalytic activity if they are grown on activated carbon. In the letter we report the successful synthesis of quantities of -SiC nanowires grown on the surfaces of the activated carbon by pyrolysis of polycarbosilane at 1300 • C. The nanowires, with the diameters of 50-100 nm and the length of tens of micrometers, are composed of single crystal -SiC along the 1 1 1 direction. Both the VLS and the VS mechanisms were employed to interpret the nanowires growth.
Synthesis and characterization of 3C–SiC nanowires
Journal of Non-Crystalline Solids, 2008
Silicon carbide nanowires have been synthesized by carbothermal reduction, from carbon monoxide and single crystal silicon. Transmission electron microscopy and cathodoluminescence studies confirm the growth of a cubic b-SiC core, coated with an amorphous oxide shell. Planar defects, as stacking faults and rotational twins, are present on (1 1 1) planes. The formation of short thick rods or long thin wires, depending on the growth temperature and time, is discussed.
Direct synthesis of β-SiC and h-BN coated β-SiC nanowires
Solid State Communications, 2002
b-Silicon carbide (b-SiC) nanowires (NWs) have been grown by thermal treatment of commercial silicon particles disposed in a graphite crucible under nitrogen atmosphere. By the same way, treatment under argon of a mixture of a boron nitride (BN) based powder and silicon particles led to h-BN coated b-SiC nanowires. The structures of both nanoobjects have been investigated by HRTEM, EDX and EELS. q
Journal of the Ceramic Society of Japan, 2009
High-yield SiC/SiO2 core-shell nanowires were synthesized without adding metal catalysts from outside through a simple thermal evaporation of silicon powders during decomposition of methane gas. The influence of three parameters, size of Si raw powder (50 nm and 5 μ m), reaction temperature (1573, 1623 and 1673 K), and soaking time (1, 3 and 6 h), was investigated. The typical synthesized nanowires from different conditions possess the diameter of no thicker than 100 nm with several tens micrometers in length. It was addressed that the condition using the smaller size Si powder, which contained the highest amount of oxygen, at higher temperature lead to more complete reaction to obtain a large quantity of nanowires. The synthesized nanowires at higher reaction temperature and longer soaking time possessed larger core than those nanowires prepared at lower reaction temperature and shorter soaking time. Oxidation of larger size Si powder improved yield of nanowires. Based on these results, it was suggested that the typical nanowires should be grown via the oxide-assisted growth mechanism.
SiC nanowires (NWs) with diameters of 20-200 nm and lengths from tens to hundreds of micrometers have been synthesized by the carbothermal reduction of colloidal silica. The morphology and microstructure of NWs have been studied in detail by electron microscopy techniques. SiC NWs have been found to be hexagonal prisms, ''bamboo-like'' nanorods and nanobelts. The NWs with a [111] growth axis are hexagonal prism nanorods, while the nanobelts have growth directions varying from [110] to [113]. It has been found that NW growth proceeds in two stages. Initially, SiC crystallites grow on the carbon fiber surface. These crystallites serve as seeds, on which the SiC NWs nucleate and grow. The crystallites containing microtwins and stacking faults (SFs) with a preferential [111] growth direction give rise to the growth of nanorods, while the nanobelts start growing on the (111) facets of relatively perfect crystallites. Wires with core (SiC)-shell (SiO 2) structure have been obtained under special temperature treatment in air. The core-shell structure has been confirmed by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) mapping techniques.
Catalyst-Free Chemical Vapor Deposition for Synthesis of SiC Nanowires with Controlled Morphology
Springer Series in Materials Science, 2013
SiC wires of different morphology were grown using methyltrichlorosilane (MTS) and hydrogen by chemical vapor deposition under ambient pressure. Taguchi method has been used to design experiments to get the optimum parameters for growing SiC wires of diameter in nanometer range. Results from XRD and SEM analyses showed the growth of -SiC wires having different morphology. At higher temperature (1500 °C), the growth of SiC grains was observed rather than wires. The optimum deposition conditions for uniform diameter growth of SiC nano wires, smoothness of the surface and homogeneous growth of SiC on the surface have been obtained. The hydrogen to MTS flow rate ratio should be above 20 for the growth of SiC wires of nanometer diameter. The deposition temperature for the growth of crystalline SiC wires should be 1100-1300 °C. The total flow rate of carrier gas comprising of argon and hydrogen for a particular H2/MTS flow rate ratio is critical for morphological outcome of SiC. In the present study it was 2 lpm for H2/MTS flow rate ratio 14 to obtain wire morphology. When the total gas flow rate was increased to 6 lpm for the same H2/MTS flow rate ratio 14, the wire morphology of SiC disappeared and the formation of grains occurred. The optimum deposition temperature i.e. 1300 °C was kept constant and further experiments were conducted by changing H2/MTS mole ratio to verify morphological outcome of SiC. A plausible mechanism has been suggested for the above observations using vapor-solid mechanism. . TEM images of the SiC nanowires grown at H2/MTS = 70 and T = 1300 °C.
Cubic SiC Nanowires: Growth, Characterization and Applications
2010
Functionalized 3C-silicon carbide NW have the potential to act as highly sensitive detector elements in biochemical field (Yakimova et al., 2007). Many methods are currently being used to prepare SiC-NW (pure or with a SiO 2 shell) on silicon substrates using a catalyst, including chemical vapour deposition, vacuum evaporation of SiC, direct synthesis from Si and C powders. In this paper we will present a brief review of growth methods used to obtain cubic silicon carbide NW, both with and without SiO 2 shell, and our results on the NW growth and characterization of morphological, structural and optical properties by SEM, TEM, CL and Raman. Finally we will review some of the possible applications for nanodevices.
SiC nanowires: material and devices
Journal of Physics D: Applied Physics, 2011
SiC nanowires are of high interest since they combine the physical properties of SiC with those induced by their low dimensionality. For this reason, a large number of scientific studies have been dedicated to their fabrication and characterization as well as to their application in devices. SiC nanowires growth involving different growth mechanisms and configurations was the main theme for the large majority of these studies. Various physical characterization methods have been employed for evaluating SiC nanowire quality. Very low diameter (<10 nm) nanowires as well as nanowires free of planar defects have not been demonstrated and these are some of the main challenges. Another issue is the high unintentional doping of the nanowires that does not allow the demonstration of high performance field effect transistors using SiC nanowires as channel material. On the other hand, the grown nanowires are suitable for field emission applications and to be used as reinforcing material in composite structures as well as for increasing the hydrophobicity of Si surfaces. All these aspects are examined in detail in the different sections of the present paper.
Synthesis of .BETA.-SiC/SiO2 core-shell nanowires by simple thermal evaporation
Journal of the Ceramic Society of Japan, 2009
Beta-SiC/SiO2 core-shell nanowires were obtained in a mullite boat after the reaction between silicon nanopowder and CH4 gas at 1623 K (1350°C), without adding metal catalysts from outside. The as-grown nanowires were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, scanning TEM, and infrared-ray spectroscopy. The results showed that the typical nanowires consisted of single crystalline β-phase SiC core of 50-70 nm in diameter and a uniform wrapping layer of low crystallinity SiO2 of ~15 nm in thickness, and their lengths were up to several tens of micrometers. The nanowires axes lay along the [111] direction of β-SiC. Oxygen from the experimental setup or the raw powder should be a key factor to synthesize the core/shell nanowires.
β-SiC nanowires were successfully fabricated on pare Si (100) substrate using simple carbo-thermal evaporation of graphite at 1200˚C. The obtained β-SiC nanowires were aligned with diameters ranged between 40 to 500 nm. The majority of crystal planes were β-SiC (111) with other less intensity of (200), (220) and (311). The silicon substrate location inside the furnace found to be critical in the formation of the β-SiC nanowires. Also, FTIR absorption peaks for β-SiC nanowires found at higher frequency side of 1110 cm-1 which is pointed to Si–O asymmetric stretching mode.