Experimental Errors in Studying the Defect Mobility in Nonstoichiometric Metal Oxides

摘要

A re-equilibration kinetic method, allowing for the determination of chemical diffusion coefficients in nonstoichiometric metal oxides in a rather simple way, has been described. This method consists in studying thermogravimetrically the mass changes of a given sample at a constant temperature when going from one thermodynamic state to another. Such process must show no hysteresis between oxidation and reduction runs, because only in this case the overall reaction rate is diffusion controlled. The sources of systematic errors and their elimination possibilities in this experimental procedure are discussed and illustrated by the results obtained on nonstoichiometric nickel and cobalt oxides.