NEW REACTION PATHWAYS OF PROPENE + BCl3 DECOMPOSITION IN CHEMICAL VAPOR DEPOSITION PROCESS

Abstract

More reaction pathways in the CVD process of preparing boron-carbides with BCl3-C3H6(propene)-H2 precursors were examined in addition to the "lowest" path proposed by Jiang et al. in Theor Chem Acc127:519–538, 2010. The new pathways investigated in this work involve 81 new transition states and 79 new intermediates. Geometries of the species were optimized with the density functional theory at B3PW91/6-311G(d,p) level. Intrinsic reaction coordinates were analyzed to confirm the correct reaction linkages. Energy barriers and reaction energies were calculated with the accurate model chemistry method G3(MP2) after a non-dynamical electronic correlation detection using CASSCF method. Heat capacities and entropies were obtained with the statistical thermodynamics and fitted as a function of temperature. Gibbs free energies at 298.15 K and 1200 K were used to examine the reaction paths. It was found that some steps in the new paths at both 298.15 K and 1200 K are different from the "lowest" path obtained previously and the pathways for the new products CB and C2B were obtained.