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Journal ArticleDOI

Nanometric powder of stoichiometric silicon carbide produced in square-wave modulated RF glow discharges

01 Jan 1999-Vacuum (Pergamon)-Vol. 52, Iss: 1, pp 183-186
TL;DR: In this article, a SiC nanometric powder has been obtained in square-wave modulated radiofrequency glow discharges from CH 4 and SiH 4 gas mixtures, and the effects on the structure of the powder were examined by FTIR, EA, XPS and from optical transmittance measurements.
About: This article is published in Vacuum.The article was published on 1999-01-01. It has received 14 citations till now. The article focuses on the topics: Silicon carbide & X-ray photoelectron spectroscopy.
Citations
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Journal ArticleDOI
Limin Shi1, Hongsheng Zhao1, Yinghui Yan1, Ziqiang Li1, Chunhe Tang1 
TL;DR: In this article, a three-step process is used to fabricate submicron silicon carbide powders in the reaction of silicon with carbon during the third step of thermal treatment.

44 citations

Journal ArticleDOI
TL;DR: In this paper, a hybrid multilayer nanostructures of ceramic coatings containing Si and SiC were produced to study their structural, mechanical and surface properties, and wear properties were evaluated using an improved pin-on-disc system.

19 citations

Journal ArticleDOI
TL;DR: In this paper , a comprehensive overview on the synthesis, properties and potential applications of SiC nanoparticles is presented, with the classification of solid phase, liquid phase and vapor phase processes.

17 citations

Journal ArticleDOI
TL;DR: In this article, carbon-coated Cu nanopowders with core/shell structure have been successfully fabricated by pulsed wire evaporation (PWE) method, in which a mixed gas of Ar/ (10 vol%) was used as an ambient gas.
Abstract: Carbon-coated Cu nanopowders with core/shell structure have been successfully fabricated by pulsed wire evaporation (PWE) method, in which a mixed gas of Ar/ (10 vol.%) was used as an ambient gas. The characterization of the samples was carried out using x-ray diffraction (XRD), scanning electron microscope (SEM), and high resolution transmission electron microscope (HRTEM). It was found that the nanoparticles show a spherical morphology with the size ranging of 10-40 nm and are covered with graphite layers of 2-4 nm. When oxygen-passivated Cu nanopowders were annealed under flowing argon gas (600 and 800), the crystallinity of phase and the particle size gradually increased. On the other hand, carbon-coated Cu nanopowders remained similar to as-prepared case with no additional oxide or carbide phases even after the annealing, indicating that the metal nanoparticles are well protected by the carbon-coating layers.

8 citations

Journal ArticleDOI
TL;DR: In this article, an EG-based copper oxide nanofluids with different volume fraction were prepared by controlling explosion number of copper wire, and it was found that the copper oxide nanoparticles exhibited an average diameter about 100 nm with the oxide layer of 2~3 nm.
Abstract: 【In the present work, ethylene glycol-based (EG) copper oxide nanofluids were synthesized by pulsed wire evaporation method. In order to explode the pure copper wire, high voltage of 23 kV was applied to the both ends of wire and argon/oxygen gas mixture was used as reactant gas. EG-based copper oxide nanofluids with different volume fraction were prepared by controlling explosion number of copper wire. From the transmission electron microscope (TEM) image, it was found that the copper oxide nanoparticles exhibited an average diameter about 100 nm with the oxide layer of 2~3 nm. The synthesized copper oxide consists of CuO/ $Cu_2O$ phases and the Brunauer Emmett Teller (BET) surface area was estimated to be $6.86\;m^2\;g^{-1}$ . From the analyses of thermal properties, it is suggested that viscosity and thermal conductivity of EG-based copper oxide nanofluids do not show temperature-dependent behavior over the range of 20 to $90^{\circ}C$ . On the other hand, the viscosity and thermal conductivity of EG-based copper oxide nanofluids increase with volume fraction due to the active Brownian motion of the nanoparticles, i.e., nanoconvection.】

4 citations

References
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Journal ArticleDOI
TL;DR: In this paper, negative ions were only observed over a limited range of power modulation frequency which corresponds to particle-free plasma conditions, and the importance of negative ions regarding particulate formation was demonstrated and commented upon.
Abstract: Negative ions have been clearly identified in silane rf plasmas used for the deposition of amorphous silicon. Mass spectra were measured for monosilicon up to pentasilicon negative ion radical groups in power‐modulated plasmas by means of a mass spectrometer mounted just outside the glow region. Negative ions were only observed over a limited range of power modulation frequency which corresponds to particle‐free plasma conditions. The importance of negative ions regarding particulate formation is demonstrated and commented upon.

109 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a Brownian free molecule coagulation model to determine the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering.
Abstract: To determine self-consistently the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering was used. Cross-polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135 degrees and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross-polarization intensities is accompanied by low-frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log-normal particle size distribution. (C) 1996 American Institute of Physics.

90 citations

Journal ArticleDOI
TL;DR: In this article, different preparation methods of ultrafine powders of high melting point compounds (carbides, borides, nitrides, and oxides with melting temperatures higher than 2000 C) are reviewed and compared.
Abstract: The different preparation methods of ultrafine powders of high melting point compounds (carbides, borides, nitrides, and oxides with melting temperatures higher than 2000‡C) are reviewed. Some properties of these powders are discussed and compared. The consolidation behaviour of these compounds in the nanocrystalline (nc) state is described in detail. Compaction by hot pressing, including high pressures and high temperatures, sintering, and high-energy consolidation methods, is analysed. The microstructure, recrystallization, mechanical and physical properties of nc-carbides, nitrides, and oxides are characterized. Special attention is focused on relationships between structure and properties.

79 citations

Journal ArticleDOI
TL;DR: The rate of particle generation in a SiH4/NH3 rf discharge has been studied as a function of the discharge operating parameter space, electrode geometry, and power supply coupling mode.
Abstract: The rate of particle generation in a SiH4/NH3 rf discharge has been studied as a function of the discharge operating parameter space, electrode geometry, and power supply coupling mode. Measurements of the bulk quantity of particles produced in the discharge reveal that the mode of coupling (capacitive or dc) as well as the electrode temperature significantly affects particle generation rates. Laser light scattering measurements made as a function of the plasma power density indicate that particle generation abruptly ceases at a threshold value sufficient to induce spark breakdown at the cathode. Based on these observations, it is shown that particle growth in plasmas can be modeled entirely as a heterogeneous process. The initiation of particle growth is shown to be consistent with an electron surface desorption model involving vibrational excitation of surface clusters. Propagation of growth in the gas phase is shown to be consistent with an eliminative ion‐molecular condensation reaction, and the press...

62 citations

Journal ArticleDOI
TL;DR: In this paper, the discharge power is derived by subtracting losses from the total power reading, which can be used as an aid in the scaling of system sizes, and this discharge power exhibits interesting behavior as the pressure is varied, at constant applied rf voltage.
Abstract: Radio frequency (rf) sputtering is used for the deposition and etching of thin layers. In both cases the target etch rate must be controlled, and often power input has been used as one of the controlling parameters. An earlier paper has shown that the applied rf target voltage (V pp) was a more useful parameter, and here new data is presented which indicates that the peak‐to‐peak voltage remains the preferable parameter for both etch rate control and in transferring between machines. However, a new method is described here which obtains the discharge power by subtracting losses from the total power reading. This discharge power is shown to be related to etch rates, and can thus be used as an aid in the scaling of system sizes. In addition, this discharge power exhibits interesting behavior as the pressure is varied, at constant applied rf voltage. Three main regions are evident when etching Si with CF4: at low pressures directional ion‐induced etching is obtained; in an intermediate region the input power rises rapidly with pressure and the etching is less directional resulting in overhang profiles; and at high pressures an isotropic etching component results in undercut profiles. The two extreme regions correlate with the commonly identified regimes of: (a) low power input, low pressure reactive sputter etching, and (b) high power input, high pressure plasma etching.

51 citations