Mc. Bernard et al., ELECTROCHROMIC REACTIONS IN MANGANESE OXIDES .1. RAMAN ANALYSIS, Journal of the Electrochemical Society, 140(11), 1993, pp. 3065-3070
The reactions taking place during voltametric cycling of manganese oxi
des can be determined using in situ Raman spectroscopy. The main diffi
culty for the oxide identification is to obtain relevant Raman referen
ce spectra because of the many possible compounds and, for some of the
se compounds, of their instability in the laser beam. As a consequence
, several modifications of different tetra-, tri- and divalent mangane
se oxides and oxyhydroxides were carefully studied. The electrochromic
behavior of three types of manganese oxides, two prepared by thermal
oxidations and the other by electrochemical deposition, were then comp
ared. The presence of nonstoichiometry in the pristine material was ne
cessary to obtain a reversible electrochromic effect. The reaction dur
ing electrochromic cycling is more complicated than a simple passage f
rom MnO2 to MnOOH.