Thermal oxidation of polymer-like amorphous SixCyHwOz nanoparticles

Das, Debabrata; Farjas, Jordi; Roura, P.; Viera, G.; Bertrán, E.

doi:10.1016/s0925-9635(00)00510-0

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…• C followed by the main oxidation process beginning at approximately 750 • C [10], which resulted in the weight increase. The weight loss began at approximately 600…”

Section: Characterization and Pre-treatment Of Sic Nanoparticlesmentioning

confidence: 99%

“…Therefore all SiC nanoparticles were pre-treated by vacuum baking at 200 • C for 24 h to remove the adsorbed moisture. A minor oxidation started at approximately 260 • C followed by the main oxidation process beginning at approximately 750 • C [10], which resulted in the weight increase. The weight loss began at approximately 600 • C in air and is attributed to the oxidation of carbon [11].…”

Section: Characterization and Pre-treatment Of Sic Nanoparticlesmentioning

confidence: 99%

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Processing and properties of SiC/vinyl ester nanocomposites

Yong

Hahn

2004

Nanotechnology

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The feasibility of improving polymer composites was investigated using 30 nm SiC nanoparticles in a vinyl ester resin. Even when the particle loading was less than 4% by weight, the viscosity of the nanoparticle suspension was found to increase much higher than that of microparticle suspension. This phenomenon may be the result of association between nanoparticles and polymer molecules, effectively making the nanoparticles larger. The resulting reduction in the mobility of polymer molecules also led to delayed curing. Ultrasonic mixing did not fully disperse the particles. As a result, the composite strength did not improve although the modulus increased. The use of a dispersant, methacryloxy propyl trimethoxy silane (MPS), improved the dispersion quality and hence the composite strength. The paper discusses the issues involved with processing, characterization and properties of SiC/vinyl ester nanocomposites. Methods of improving the nanocomposite quality are proposed in the paper as well.

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“…• C followed by the main oxidation process beginning at approximately 750 • C [10], which resulted in the weight increase. The weight loss began at approximately 600…”

Section: Characterization and Pre-treatment Of Sic Nanoparticlesmentioning

confidence: 99%

Section: Characterization and Pre-treatment Of Sic Nanoparticlesmentioning

confidence: 99%

Processing and properties of SiC/vinyl ester nanocomposites

Yong

Hahn

2004

Nanotechnology

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“…Therefore, they are in fact an amorphous suboxide of hydrogenated silicon. By making an elementary analysis, complemented with the mass gain measured after complete oxidation, 13 their composition was determined to be Si 1 H 0.45 O 0.15 .…”

Section: Lpicm (Umr 7647 Cnrs) Ecole Polytechnique 91128 Palaiseau Cmentioning

confidence: 99%

Anomalous crystallization of hydrogenated amorphous silicon during fast heating ramps

et al. 2005

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Thermal crystallization experiments carried out using calorimetry on several a-Si:H materials with different microstructures are reported. The samples were crystallized during heating ramps at constant heating rates up to 100 K/min. Under these conditions, crystallization takes place above 700°C and progressively deviates from the standard kinetics. In particular, two crystallization processes were detected in conventional a-Si:H, which reveal an enhancement of the crystallization rate. At 100 K/min, such enhancement is consistent with a diminution of the crystallization time by a factor of 7. In contrast, no systematic variation of the resulting grain size was observed. Similar behavior was also detected in polymorphous silicon and silicon nanoparticles, thus showing that it is characteristic of a variety of hydrogenated amorphous silicon materials.Crystallization of amorphous silicon (a-Si) is a subject that has been studied extensively during the last three decades. It improves the electrical conductivity substantially, 1 making the resulting polycrystalline silicon useful for a number of applications, such as thin film transistors (TFT), liquid crystal displays (LCD), and image sensors.2 The kinetics of this process follows the nucleation and growth steps with rate constants characterized by transmission electron microscopy. [3][4][5][6] The relative values of nucleation and growth rates determine the final grain size that can be controlled through the crystallization temperature or by ion irradiation during crystallization. 4 The temperature range in the published results seldom extends above 700°C because of the difficulty in reaching the isothermal conditions without any incipient crystallization taking place during the heating ramp. This difficulty is partially overcome by calorimetric experiments where the material is heated at a constant rate.From the heat that evolves the crystallization rate can be obtained. Kinetic studies using calorimetry have only been performed during the epitaxial crystallization of thin a-Si films obtained from rapid solidification.7 With the exception of our preliminary work, 8 no systematic studies on hydrogenated a-Si (a-Si:H) have been published. In this paper we extend the temperature range during the heating ramps above 700°C up to 100 K/min. Under these conditions, an unexpected and substantial enhancement of the crystallization rate was observed. Besides the intrinsic interest of characterizing a new phenomenon, our study can be useful to understand the crystallization that occurs during rapid thermal annealing (RTA) processes.

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“…Two exothermic peaks are resolved which are known to correspond to dehydrogenation. 13 In a recent article 14 we have reported a low-temperature oxidation process that takes place in hydrogenated SiC nanoparticles grown by PECVD. It was demonstrated that this oxidation was similar to the oxidation of polymers in the sense that it proceeded throughout the entire volume of a nanoparticle, homogeneously, without the formation of any protective layer at the surface.…”

mentioning

confidence: 99%

Enhancement of oxidation rate of a-Si nanoparticles during dehydrogenation

Das

Farjas

Roura

et al. 2001

Applied Physics Letters

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Oxidation of amorphous silicon (a-Si) nanoparticles grown by plasma-enhanced chemical vapor deposition were investigated. Their hydrogen content has a great influence on the oxidation rate at low temperature. When the mass gain is recorded during a heating ramp in dry air, an oxidation process at low temperature is identified with an onset around 250°C. This temperature onset is similar to that of hydrogen desorption. It is shown that the oxygen uptake during this process almost equals the number of hydrogen atoms present in the nanoparticles. To explain this correlation, we propose that oxidation at low temperature is triggered by the process of hydrogen desorption.

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Thermal oxidation of polymer-like amorphous SixCyHwOz nanoparticles

Cited by 5 publications

References 12 publications

Processing and properties of SiC/vinyl ester nanocomposites

Processing and properties of SiC/vinyl ester nanocomposites

Anomalous crystallization of hydrogenated amorphous silicon during fast heating ramps

Enhancement of oxidation rate of a-Si nanoparticles during dehydrogenation

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