Study of monolayer dispersion of MoO3 on muscovite powder and diffusing behavior of MoO3 on muscovite wafer by SR-TXRF

Abstract

The dispersion capacity of MoO₃ on the surface of muscovite powder was studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. The results indicated that MoO₃ can disperse onto the surface of a support as a sub-monolayer. The dispersion capacity was 5.88 mg MoO₃ (g muscovite)⁻¹, or 3.24 Mo atoms nm⁻². The diffusing process of MoO₃ on muscovite wafer was investigated by means of Synchrotron Radiation excited Total-reflection X-Ray Fluorescence spectroscopy (SR-TXRF). A stripe of MoO₃ on the muscovite wafer was used as the diffusion source. After thermal treatment in air or dry N₂, MoO₃ diffuses onto the surface of muscovite and forms a sub-monolayer. Sublimation of MoO₃ was also detected during the diffusion process. The diffusion rate in two heating atmospheres differed significantly. The diffusion rate of MoO₃ on muscovite in dry N₂ was greater than that in air. A possible explanation of the phenomena is that surface diffusion onto the muscovite surface plays a more important role in the process than transportation via gas phase during the diffusion of MoO₃.