Study on the reaction mechanism between Pb 3 O 4 and Si in stored silicon delay composition

The thermogravimetric techniques and differential thermal analysis have been employed in this work to analyze the macro-reactions mechanism of the silicon delay composition. Quantum chemical calculation has been performed to study the microscopic mechanism of the main reaction (Pb3O4 + Si) at the density functional theory BPW91/6−311++G(d, p) level of theory with the SDD implicit solvent model. Our results have shown that in the silicon delay composition, the strongest reaction exothermic peak is originated from the reaction between Pb3O4 cluster and Si. For the microscopic reaction process of Pb3O4 and Si containing two reaction pathways, we found that they proceeded in this manner, Pb3O4 + Si → SiO + 3PbO and SiO + Pb3O4 → SiO2 + 3PbO, with a total of four reaction channels. In addition, we have determined the reaction sites by making use of the charge distribution from natural bonding orbital analysis and the HOMO–LUMO gap of the reactants.