Flexible electrochromics: magnetron sputtered tungsten oxide (WO_3−x) thin films on Lexan (optically transparent polycarbonate) substrates

Correlation between Thickness and Optical Properties in Nanocrystalline γ-Monoclinic WO3 Thin Films

“…Li et al [49] suggested that a broad peak centered at 262 cm −1 indicates that the sample contains W 4+ species, and the Raman band located at 322 cm −1 could be attributed to the W 5+ -O single bond which indicates the presence of W 5+ defect states [50], which induces the presence of oxygen vacancies VO. Another Raman band could be observed in Figure 6 which is centered at 435 cm −1 and is attributed to the W 5+ =O bond [51]. For Kalanur et al [27] this is attributed at the presence of oxygen vacancies accompanied by the presence of W mixed valence states (W 5+ and W 6+ ) introduced when the annealing in the air is performed and tend to modify the band gap as we will discuss in the UV-Vis characterization.…”

Catalytic and SERS activities of WO3-based nanowires: the effect of oxygen vacancies, silver nanoparticle doping, and the type of organic dye

“…For the case of WO 3 NPs, we observed two prominent peaks at 296 and 786 cm −1 which are assigned to the bending vibration of δ (O–W–O) and stretching vibrations of ν (W–O–W), respectively. 3,64 However, the emergence of oxygen vacancies in WO 3− x NPs led to peak broadening as well as a shift in peak maxima wavelengths. W 6+ –O stretching bands were shifted to wavelengths of 259 and 804 cm −1 indicating the presence of oxygen vacancies in the NP structure.…”