4f level shifts of tungsten and colouration state of a-WO3

Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these

“…The effect of proton intercalation was studied by Temmink et al for evaporated films. 291,292 The fraction of W 5+ states was linearly dependent on x, at least up to x # 0.3, as expected for low intercalation levels. In addition, W 4+ states were detected for x .…”

“…0.25; however, they could not be reliably quantified due to uncertainties in the deconvolution. 291,292 The latter type of species was also observed by Henningsson 293 in deeply coloured polycrystalline films. Stolze et al 280 studied W 4f states in sub-stoichiometric sputter deposited W oxide films.…”

Unprecedented Electrochromic Stability of a-WO3–x Thin Films Achieved by Using a Hybrid-Cationic Electrolyte

“…In amorphous tungsten trioxide, the band gap between the filled O 2p orbitals (valence band) and the empty W 5d orbitals (conduction band, consisting of degenerate t2g/eg levels) can reach higher than 3.5 eV with reducing grain size, therefore, the a-WO 3– x film is generally optical transparency in a broad spectral range . The O 2p and W 5d orbitals are strongly hybridized with each other, and thus, the t2g/eg levels are partially delocalized .…”

“…In amorphous tungsten trioxide, the band gap between the filled O 2p orbitals (valence band) and the empty W 5d orbitals (conduction band, consisting of degenerate t2g/eg levels) can reach higher than 3.5 eV with reducing grain size, therefore, the a-WO 3−x film is generally optical transparency in a broad spectral range. 53 The O 2p and W 5d orbitals are strongly hybridized with each other, and thus, the t2g/eg levels are partially delocalized. 54 The electrochromic absorption can be rationalized in terms of either interband transitions or intervalence transfers in different W ionic states, and both models rely on the broken octahedral symmetry but associate with the excess electrons in different bound states.…”

Reactive Evaporation of Metal Wire and Microdeposition of Metal Oxide Using Atmospheric Pressure Reactive Microplasma Jet

“…This spectrum was deconvoluted into three sets of doublet peaks (W 4 f 7=2 and W 4 f 5=2 ), corresponding to metal tungsten (W 4 f 7=2 : 31.2 eV, W 4 f 5=2 : 33.3 eV), W 5þ (35.0 and 37.1 eV), and W 6þ (35.4 and 37.5 eV). 12,13) Thus, the spectrum in Fig. 3(b) clearly indicated that some oxide and metallic phases were mixed in the deposits prepared at the flow rate of 20 ccm or above.…”