Surface morphology and composition of nanocrystalline MoO2 produced via the thermal decomposition of the MoO2(i-C3H7NHO)2 complex

Resumo

The surface morphology and composition of MoO₂ prepared via the low-temperature decomposition of a molybdenum(VI) isopropylhydroxylaminate complex, MoO₂(i-C₃H₇NHO)₂, have been studied by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). During the sample preparation process for XPS, the molybdenum dioxide, which has the form of nanocrystals, actively reacts with atmospheric oxygen and moisture because of the small particle size of the material. The composition of the surface layer in terms of molybdenum is 5 at % MoO₂, 10 at % Mo₂O₅, and 85 at % MoO₃, and the E_b(Mo 3d_5/2) binding energy is 230.0, 231.4, and 233.1 eV, respectively. After argon ion etching of the sample surface for 45 s, the surface composition is 52 at % MoO₂, 23 at % Mo₂O₅, and 25 at % MoO₃. In addition, there are ~3 carbon atoms per Mo atom. Based on analysis of the structure of the C 2s, 2p valence electron spectra, we assume that the carbon on the sample surface is present as amorphous or nanoparticulate carbon phases. The material studied here does not become charged when exposed to an X-ray beam, which suggests that it is a weak dielectric.