Modification of the electrical and optical properties of hydrated vanadium pentoxide as a result of proton electromigration
Tóm tắt
Variation of the optical and electrical properties of films of hydrated vanadium pentoxide under the action of an applied electric field was studied. The samples exhibited an “internal” electrochromic effect caused by a redistribution of hydrogen ions in the film, rather than by their penetration from outside (electrolyte). The process of cathodic polarization at a current of I∼10−5 A for t∼10 min is accompanied by a local increase in the hydrogen concentration (confirmed by direct measurements of the ionic conductivity), leading to a change in the optical properties. This is manifested by an increase in the transmission coefficient in the longwave spectral region and by a shift of the absorption edge (at hν=2.3 eV) toward greater wavelengths. According to the IR spectroscopy data, this is also accompanied by some increase in the water content in colored regions of the V2O5·nH2O film.
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