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In situ UV-Vis and ex situ IR spectroelectrochemical investigations of amorphous and crystalline electrochromic Nb 2 O 5 films in charged/discharged states

Authors :
Anton Meden
Jože Grdadolnik
Boris Orel
Marjeta Maček
Source :
Journal of Solid State Electrochemistry. 2:221-236
Publication Year :
1998
Publisher :
Springer Science and Business Media LLC, 1998.

Abstract

Niobium oxide (Nb2O5) films and powders have been obtained via the sol-gel route from an NbCl5 precursor. XRD spectra revealed that films with pseudohexagonal (TT-phase) and orthorhombic (T-phase) structure were formed at 500 °C and 800 °C, respectively, while at 300 °C films were amorphous. Infrared (IR) and Raman spectra of powders and films of Nb2O5 in different polymorphic forms were detected, and vibrational band assignments were made. Electrochromic properties of amorphous films and films with the TT-phase were established from in situ ultraviolet visible (UV-Vis) spectroelectrochemical measurements and correlated with ex situ IR transmission spectra of charged films. Ex situ IR spectra revealed that charging of amorphous films is accompanied by variations of the Nb-O stretching mode intensity, while, for films with the TT- and T-phase, splitting of the Nb3-O stretching modes and the appearance of polaron absorption were noted with Li+ ion insertion. Ex situ X-ray diffraction (XRD) spectra of charged films with the TT-phase showed changes of the unit cell dimensions with charging. The influence of the polaron absorption on the ex situ near-grazing incidence angle (NGIA) IR reflection-absorption spectra of charged/discharged films is discussed in detail.

Details

ISSN :
14330768 and 14328488
Volume :
2
Database :
OpenAIRE
Journal :
Journal of Solid State Electrochemistry
Accession number :
edsair.doi...........2ed9c794c9131995044491b8e5965f59
Full Text :
https://doi.org/10.1007/s100080050092