FOURIER TRANSFORM RAMAN STUDY OF STRUCTURE REARRANGEMENT IN ELECTROCHROMIC CRYSTALLINE HYDRATE THIN FILMS $WO_{3}n(H_{2}O)$ DURING COLORATION-BLEACHING PROCESS.

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1995

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Ohio State University

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An electrochromic phenomena in transition metal oxides have been very widely studied. This unique phenomenon of electrically induced reversible coloration and charge storage in the films has many applications. It is extremely important to study colored material state for understanding of electrochromic coloration mechanism. The usual techniques are not able to be used during the polarization of a sample in an electrolyte medium for the investigation of the neighboring environment changes in the films. Fourier Transform Raman Spectroscopy gives unique possibilities to carry out in situ measurements in electrochemical cell. The electrochromic crystalline hydrate thin films $WO_{3}n(H_{2}O)$ (n=1/3: 2) have been studied to clarify the influence of injected protons and electrons on the film structure during the electrochromic coloration-bleaching process with FT Raman Spectroscopy for the first time. FT Raman spectra of thin films $WO_{3}n(H_{2}O)$ in colored and bleaching states were measured in the region $100-3500 cm^{-1}$ on a Bruker IFS 88 FT - IR spectrometer with FT Raman module using Nd : YAG laser (1.064 mkm). The $H^{+}$ and $D^{+}$ ions from aqueous electrolyte were used for the film coloration. The injected charge density varies from 1 to $30 mC/cm^{2}$. It was shown that protons and deuterons inserted into the film lattice during electrochromic coloration do not play passive role of the charge compensators as considered early but strongly interact with the films and result in structure rearrangement.

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Author Institution: Institute of Physics, pr. Nauki 46, Kiev, 252022, Ukraine

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