Theoretical Study of the Thermochemistry of Molecules in the Si-O-H-C System

Ho, Pauline; Melius, Carl F.

doi:10.1021/j100007a056

Cited by 87 publications

(76 citation statements)

References 10 publications

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“…The thermodynamic data for these compounds were obtained from theoretical studies of the literature. [38,39] It was found that the only species that may be present at equilibrium in relatively high mole fractions at temperatures above 1300 K are Si(OH) 4 , SiH(OH) 3 , and SiOSiO. When these three species were not considered, the results were found to be almost identical to those shown in Figure 1 (for SiO 2 deposition) and Figures 3 and 4 (for co-deposition) over the whole temperature range.…”

Section: Gas Phase Equilibrium Resultsmentioning

confidence: 99%

Co-deposition of Silica, Alumina, and Aluminosilicates from Mixtures of CH3SiCl3, AlCl3, CO2, and H2. Thermodynamic Analysis and Experimental Kinetics Investigation

Nitodas

Sotirchos

1999

Chem. Vap. Deposition

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The co-deposition of silica, alumina, and aluminosilicates from mixtures of methyltrichlorosilane, aluminum trichloride, carbon dioxide, and hydrogen was investigated in this study. In order to elucidate some aspects of the co-deposition process, the deposition of pure silica and pure alumina from mixtures of methyltrichlorosilane and aluminum trichloride, respectively, with CO 2 and H 2 was also investigated. Kinetic data were obtained by carrying out CVD experiments on SiC substrates in a hot-wall reactor of tubular geometry, which permitted continuous monitoring of the deposition rate through the use of a microbalance. Reaction rate data are presented for temperatures between 1073 and 1373 K (800±1100 C) at 13.3 kPa (100 torr) pressure for various feed compositions and various positions along the axis of the deposition reactor. Thermodynamic equilibrium computations were performed on the Al/Si/Cl/C/O/H, Al/Cl/C/O/H, and Si/Cl/C/O/H systems at the conditions used in the deposition experiments. The experimental observations are discussed in the context of the results of the equilibrium analysis and of past studies. Among the most interesting findings of this study is that the presence of AlCl 3 has a catalytic effect on the incorporation of silica in the deposit, leading to co-deposition rates that are a factor of 2±3 higher than the deposition rates that are obtained when only one of the two chlorides (CH 3 SiCl 3 or AlCl 3 ) is present in the feed.

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Section: Gas Phase Equilibrium Resultsmentioning

confidence: 99%

Co-deposition of Silica, Alumina, and Aluminosilicates from Mixtures of CH3SiCl3, AlCl3, CO2, and H2. Thermodynamic Analysis and Experimental Kinetics Investigation

Nitodas

Sotirchos

1999

Chem. Vap. Deposition

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“…However, oxygen loss and excessive carbon loss, while not unprecedented20212223, are not common. Previous studies on the bond dissociation energies of TEOS and similar compounds reveal that the dissociation of organometallic compounds to form oxygen containing gases requires higher energy than simply breaking C-H bonds242526. This may explain the higher oxygen and carbon loss as a result of increasing ion energy and fluence, and thus an increase in the total deposited energy.…”

Section: Resultsmentioning

confidence: 98%

Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

Shojaee

Wang

et al. 2017

Sci Rep

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Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. In this study, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. The results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. It was found that carbon was present in a non-graphitic sp2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. A combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films.

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“…In the Supporting Information (Tables S7 -S11), we also provide raw electronic energies at the G2 level, atomic coordinates, vibrational frequencies, moments of inertia, and polynomial fits of the thermodynamic data suitable for use with the CHEMKIN software. 17 As has been typical in previous publications involving the BAC-MP4 series, 15,16,[18][19][20][21][22][23][24][25] we focus our discussion on the predicted thermochemical parameters, rather than on the ab initio calucations themselves. .…”

Section: Amentioning

confidence: 99%

BAC-G2 Predictions of Thermochemistry for Gas-Phase Aluminum Compounds

Allendorf¹

2001

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A self-consistent set of thermochemical data for 55 molecules in the Al-H-C-O-F-Cl system are obtained from ab initio quantum-chemistry calculations using the BAC-G2 method. Calculations were performed for both stable and radical species. Good agreement is found between the calculations and experimental heats of formation in most cases where data are available for comparison. Electronic energies, molecular geometries, moments of inertia, and vibrational frequencies are provided in the Supporting Information, as are polynomial fits of the thermodynamic data (heat of formation, entropy, and heat capacity) over the 300-3000 K temperature range. (This page intentionally left blank)5

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Theoretical Study of the Thermochemistry of Molecules in the Si-O-H-C System

Cited by 87 publications

References 10 publications

Co-deposition of Silica, Alumina, and Aluminosilicates from Mixtures of CH3SiCl3, AlCl3, CO2, and H2. Thermodynamic Analysis and Experimental Kinetics Investigation

Co-deposition of Silica, Alumina, and Aluminosilicates from Mixtures of CH3SiCl3, AlCl3, CO2, and H2. Thermodynamic Analysis and Experimental Kinetics Investigation

Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

BAC-G2 Predictions of Thermochemistry for Gas-Phase Aluminum Compounds

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