“…As it was shown by Barton et al [61] and Ross-Medgaarden and Wachs [52] Eg linearly decreases with an increasing number of bridging W-O-W bonds. The band gap energy values of studied glasses are 3.6-3.7 eV and these values are compatible with the other tungstate glasses and highly disordered tungsten oxide films [66,67]. As it is seen from Fig.…”