Prediction of Thermodynamic and Kinetic Parameters for Interfacial Reactions of the SIO₂ System by Quantum Chemistry Methods

Abstract

With the help of Quantum Chemistry methods, this study analyzed gas/solid chemical reactions, as well as weak interaction reactions of the SiO₂ system with the surface. Requirements are for the prior calculation of thermodynamic properties of the partner reactions and the determination of all transition states products, which occur during the complicated reaction processes and between the precursors and the surface. A molecule model or molecule cluster will represent the surface of the solid particles. The final target for this study was to derive and develop new reaction paths for the development of a mechanism to describe the formation and growth of SiO₂ in gas phase synthesis from SiH₄ through flame synthesis.

After validation of the accuracy of the Density Functional Theory (DFT), enthalpies, , of a series of stable molecules, radicals, and transition state structures are calculated using ab initio and (DFT) calculations. The ab initio and Density Functional calculations were combined with isodesmic reaction analysis, whenever possible, in order to improve the accuracy of the enthalpy values. Entropies, , and heat capacities, Cp_f298 (T) were calculated using Density Functional (DFT) calculation results. Kinetic parameters for new reaction paths were estimated as well for 500 K to 1800 K temperature range and 0.001 to 300 atm pressure range.

Keywords:

• SiO₂
• Thermachemistry
• Kinetics
• Interfacial relations

ACKNOWLEDGMENT

The authors thank The “Deutsche Forschungsgemeinschaft” for support of this work. This study is a part of the “Schwerpunktprogramm 1155: Molekulare Modellierung und Simulation in der Verfahrenstechnik.”