X-ray photoelectron spectroscopic studies of glasses in the MoO3-Bi2O3 and MoO3-Bi2O3-CuO systems

Abstract The local structure and the connectivity in the amorphous network of glasses from MoO3-Bi2O3 and MoO3-Bi2O3-CuO systems have been studied by comparative analysis of crystalline and amorphous phases using X-ray photoelectron spectroscopy. According to the XPS data the amorphous networks of both glass systems consist mainly of MoO4 tetrahedra as well as of small amounts of MoO6 octahedra. Based on the O1s spectra analysis it was suggested that the MoO6 octahedra are connected by bridging Mo O Mo bonds, while the MoO4 tetrahedra participate in the formation of mixed type Bi O Mo bonds. The presence of mixed Bi O Mo bonds with a relatively significant covalent character is crucial for the glass formation. Mainly Mo6 + and Bi3 + ions were detected in MoO3-Bi2O3 glasses and additionally Cu+ and Cu2 + ions were observed in MoO3-Bi2O3-CuO amorphous samples. UV-visible diffuse reflectance analysis confirmed the XPS data, revealing the presence of Mo6 +, Bi3 + and Cu2 + ions in the glasses. Formation of MoO4 tetrahedral units (absorption band at 260 nm) in the amorphous network was also found by optical absorption spectra. The role of MoO3 as glass former was confirmed.