Study of solid state kinetics using voltammetry of immobilized particles. Application to tetragonal to monoclinic transition in nanoparticulate zirconia and praseodymia-doped zirconia

摘要

The voltammetry of immobilized particles methodology is applied to study solid state reaction kinetics on the basis of the electrocatalytic ability of solids toward selected electrochemical processes. Measurement of the time variation of catalytic current for oxygen evolution reaction in aqueous alkaline media provides a direct estimate of fractional conversion of the reactant in the course of the reaction for testing different reaction kinetic models. This methodology is applied to analyze the formation of monoclinic zirconia and praseodymia-doped zirconia from tetragonal precursors. Discrimination between competing and successive reactions mechanisms is obtained for reactions involving specimens with high praseodymium loadings, where a secondary pyrochlore phase is formed, combining the above data with those for the electrochemical reduction of dissolved oxygen.