Spectroscopic studies of tungsten ions in PbO-PbF2-SiO2 glasses

► Optical absorption, ESR spectra confirm W5+ oxidation state of tungsten. ► FT-IR spectrum reveals W5+ ions transformation from tetrahedral to octahedral. ► W5+ ions experiences the axial distortion stretches along the z-axis. ► Modifying glass network increased with increasing WO3.