Electrochemistry of solid-phase reactions: Phase formation in the In2O3-WO3 system. Processes at the WO3|In2O3 and WO3|In6WO12 interfaces

Reactions of interactions at the WO3|In2O3 and WO3|In6WO12 heterophase reaction interfaces, whose main product is In2(WO4)3, are studied by electrochemical methods for the first time ever. Due to a far greater n type conductance inherent in the initial substances, the reactions are a model object for the development of methodology of the electrochemical approach. Both reactions are discovered to proceed at the expense of the transport of components of WO3 and no evidence is discovered for the contribution of In3+ into diffusion and migration. Consisted data are obtained between the polarity of a spontaneously generated reaction difference of potentials and the direction of the field that accelerates the reaction: the current that is passed through electrochemical cells accelerates the reactions exclusively at the (−)-potential of a brick of WO3. A difference is discovered between the charge and mass transport paths—spontaneous and field-induced mass transport of WO3 or its components occurs via heterophase interfaces and adjacent areas and does not touch upon the In2(WO4)3 grains. Shown is the antibatic character of the behavior exhibited by dependences of identical properties of cells (potential drop across a cell) following a change in the dc polarity. A possible role of a reactionless electrosurface transport of WO3 in the mechanism of reaction and evolution of electrochemical properties of model electrochemical cells is demonstrated. The obtained data may or may not testify in favor of a hypothesis that presumes a prevailing role of the {WO4}2− mobility in the In2(WO4)3 structure.