Evaluation of vapor pressure of MoO2Cl2 and its initial chemical reaction on a SiO2 surface by ab initio thermodynamics

The vapor pressure of MoO2Cl2 and its initial chemical reaction on a SiO2 surface were evaluated and analyzed using ab initio thermodynamics. The vapor pressure of MoO2Cl2 was calculated using the Gibbs free energy, while considering the zero-point energy, temperature-dependent enthalpy change, and entropy. The initial surface reaction was also studied as functions of temperature and partial pressure. The calculated sublimation temperature of MoO2Cl2 was 410 K, and its vapor pressure at 350 K was 8.2 torr. The partial pressure calculated for MoO2Cl2 agreed reasonably well with the experimentally measured value. The surface reaction energy barrier between MoO2Cl2 and SiO2 was 0.8 eV.