Optical properties of the sodium-tungsten bronzes and tungsten trioxide

Optical properties of tungsten trioxide from first-principles calculations

“…4), which has a band structure similar to that of simple cubic WO 3 : the extra electrons from Na fill the conduction bands of the simple cubic lattice [85] without modifying its original band structure. We note that even though simple cubic WO 3 has a smaller band gap than that of the γ phase, since the energy of the Fermi level increases with increasing electron concentration from Na, and the Coulomb repulsion increases within the filled states, the onset of inter band transitions shift to higher energies as sodium is added to the system [84]. This results in a similar O2p-W5d gap in γ-WO 3 and in Na 0.65 WO 3 .…”

“…Our spectra were computed using the implementation of Refs [28,29], at the BSE level of theory, and then did not include phonon assisted transitions and it is therefore meaningful to compare them with ellipsometry data. However, the latter are limited for pure single crystal γ-WO 3 [84], and rather uncertain. To the best of our knowledge, they were reported only in Ref 84, where it was noted that the ellipsometry measurements may have been influenced by contributions from domains with different crystallographic orientations.…”

Influence of hydrogen annealing on the optoelectronic properties of WO3 thin films

“…For calculation of the relative density (r f /r b ), the value of n b was taken from Refs. [53], and the values of n were calculated using our dispersion relations. The relative density was calculated at l ¼ 500 nm.…”

Perovskite tungsten bronze-type crystals of LixWO3 grown by chemical vapour transport and their characterisation

“…On the other hand, single crystal data for this series are rather rare. A single crystal study by Sienko and Truong [15] show the metallic character of conductivity between 100 and 400 K of compositions Li x WO 3 with x of 0.39, 0.37 and 0.36 that suggests a close similarity to the metallic compositions of Na x WO 3 and their related free carrier-type optical properties [16]. The question is, however, what happens with further decrease in x concerning the optical properties.…”