Thermochemistry of molecules in the B/F/H/N system

摘要

A self-consistent set of thermochemical data for 88 chemical species in the B/F/H/N system is obtained from ab initio electronic structure calculation. Calculations were performed for both stable and radical species. The quantities calculated include the atomization energy (Sigma D-0), heat of formation (Delta H-f) at 0 K and 298.15 K, and bond dissociation energies (BDE) for all species. Good agreement is found between the calculation data and experimental or theoretical reference data for the quantities analyzed in this work for several species containing B, F, H, and N atoms. We also present a compilation of experimental and theoretical atomization energies (16 experimental X 26 theoretical data), heat of formation at 0 K (25 experimental X 26 theoretical data), heat of formation at 298 K (29 experimental X 36 theoretical data), and bond dissociation energy for several species. Polynomial fits of the predicted thermodynamic data (heat capacity, entropy, and enthalpy) over the 200-6000 K temperature range are also included, for the 88 species. The species analyzed in this study are important in a kinetic mechanism for growth boron nitride films in a Chemical Vapour Deposition (CVD) reactor. It is generally difficult to optimize conditions in a CVD reactor because films properties depend on complex interactions involving heat and mass transport, chemical kinetics, and thermochemistry. Developing a reliable set of thermodynamic data is a necessary first step for system optimization, since it provides important constraints on the possible reaction mechanism. (c) 2005 Wiley Periodicals, Inc.