Diffusing behavior of MoO3 on Al2O3 and SiO2 thin films

By means of XPS, SIMS, synchrotron radiation excited total-reflection X-ray fluorescence, AES etc., the diffusion process of MoO3 on stable Al2O3 and SiO2 oxide thin films was investigated. After thermal treatment, MoO3 formed a monolayer or a submonolayer on the flat surface of the thin films. The diffusion capacity and the diffusion rate on these two kinds of films differ significantly. Besides the support used, several factors, such as the heating temperature, the heating time and the ambience influence the diffusion process. A possible explanation to all the phenomena is the combination of surface diffusion and transportation via gas phase.