02295nas a2200217   4500008004100000050001500041245013600056210006900192260001200261300001200273490000800285520157600293653002101869653001801890653002301908653003701931100001901968700001801987700002102005856005102026       1995                        eng d  aLBNL-3900800aPreparation and Properties of Spin-Coated Nb<sub>2</sub>O<sub>5</sub> Films by the Sol-Gel Process for Electrochemical Applications0 aPreparation and Properties of SpinCoated Nbsub2subOsub5sub Films  c05/1996  a162-1680 v2773 a<p>The preparation and properties of Nb<sub>2</sub>O<sub>5</sub> coatings made by the sol-gel process were investigated. The films were deposited by spin coating on In<sub>2</sub>O<sub>3</sub>:Sn/glass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized by investigation of the stoichiometry, refractive index, optical transmission, electrochemical behavior, and the microstructure. X-ray diffraction studies showed the films to be amorphous for heat treatments below 450 °C. X-ray photoelectron spectroscopy (XPS) measurement revealed the O:Nb atomic stoichiometry to be 5:2. Cyclic voltammetric measurements showed that the Nb<sub>2</sub>O<sub>5</sub>/1 M LiClO<sub>4</sub>-propylene carbonate system exhibits electrochemical reversibility beyond 1200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb<sub>2</sub>O<sub>5</sub> films exhibit an electrochromic effect in the spectral range 300&lt;λ&lt;2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for a 250 nm thick electrode. XPS spectra indicate that Nb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li<sup>+</sup>. The bronze coloration is due to a simultaneous injection of electrons and Li<sup>+</sup> ions into Nb<sub>2</sub>O<sub>5</sub>. The sol-gel-deposited&nbsp;Nb<sub>2</sub>O<sub>5</sub> films are useful for cathodically coloring electrochromic electrodes in electrochromic devices.</p>10aElectrochemistry10aNiobium oxide10aoptical properties10aX-ray photoelectron spectroscopy1 aÖzer, Nilgün1 aChen, Din-Guo1 aLampert, Carl, M  uhttp://dx.doi.org/10.1016/0040-6090(95)08011-2