Mechanisms and Kinetics of Electrochemical Intercalation of Oxygen into Nd2NiO4+δ

Abstract

ABSTRACTOverstoichiometric insertion of oxygen into thin films of Nd2NiO4+δwas performed electrochemically at room temperature (RT) in order to obtain an in-situ compositional analysis of the process. Thin Nd2NiO4+δlayers were deposited onto resonators of a Quartz Crystal Microbalance (QCM) by Pulsed Laser Deposition (PLD). Cyclic voltammograms showed oxidation and reduction peaks typical for these oxides. The change in oxygen stoichiometry was determined by in-situ QCM measurements during potential step experiments. The resulting maximum mass change was on the order of 50 ng and corresponded to a maximum excess oxygen content of δ = 0.12 in Nd2NiO4+δ. The time dependence of the mass change was described by a transport model which leads to oxygen diffusion coefficients in the range from 2.10−12 to 10−11 cm2/s depending on δ and the direction of the reaction.