Electrochromic and ex situ IR and Raman spectroelectrochemical studies of LixInVO4 films charged/discharged in the 0 < x < 1 domain

InVO4 films were prepared using the sol-gel route from V-oxoisopropoxide an d In-nitrate precursors. Films were made by dip coating deposition techniqu e which allows the preparation of films with a thickness up to 230 nm by a single dipping cycle. The structure of crystalline InVO4 films obtained at 500 degreesC was investigated using Raman and IR spectroscopies, which were combined with X-ray diffraction. The crystalline films consist of a monocl inic InVO4-I phase with an admixed orthorhombic InVO4-III phase. Electroche mical investigations revealed that the charge capacity of the crystalline f ilms (500 degreesC) is about -40 mC cm(-2), significantly exceeding the ion storage capacity of amorphous films prepared at 300 degreesC (-20 mC cm(-2 )). In situ UV-visible spectrolectrochemical studies of amorphous and cryst alline films showed that the coloration of the films is cathodic with a cha nge in a photopic transmittance (DeltaT(vis)) from 0.034 to 0.149, respecti vely. Crystalline films exhibit higher coloring than amorphous films; this is related to their higher coloration efficiency (eta (vis) = 1.92 cm(2) C- 1). The main focus is given to IR and Raman spectroelectrochemical studies of crystalline InVO4 films (500 degreesC) galvanostatically charged in the 0 < x < 1 domain (LixInVO4). Vibrational spectra revealed that the monoclin ic InVO4-I phase remains unchanged in the 0 < x < 0.44 domain and transform s to the amorphous phase when charged in the 0.5 < x < 1 domain. Vibrationa l band changes observed in Raman and IR spectra of charged and discharged f ilms are assessed and correlated with the spectral features of CeVO4, FeVO4 , and Fe2V4O13 films studied previously. (C) 2001 The Electrochemical Socie ty.