Electrochemical characteristics of grain boundaries in gadolinium and aluminum co-doped ceria and ceria-alumina composites

The influence of 1, 2, 4 and 10 cat.% Al2O3 addition on the electrochemical characteristics of commercially available 10 cat.% Gd-doped ceria and a 1:1 cat.% mixture of CeO2:Al2O3 were evaluated in our study. Analysis of the electronic conductivity and polarization-relaxation behavior of the samples showed that an Ohmic contribution to the total electronic resistance cannot only be attributed to the electrode contact resistance but is a combined contribution from the electrode interface and decreased pO(2) dependence of the grain boundary resistivity of the material. The average electrical potential barrier at the grain boundaries was calculated from impedance spectroscopy data at 50-300 degrees C. Kelvin probe force microscopy (KPFM) measurements were used to analyze the local Volta potential distribution at the grain boundaries of pure Ce0.9Gd0.1O1.95 and of samples with 4 and 10 cat.% Al addition at room temperature. KPFM measurements showed clear evidence for an increased Volta potential difference between bulk and grain boundary cores and for a considerable broadening of the Volta potential gradient at the grain boundaries with increasing Al concentration.

Automated summary

This study evaluated the influence of different concentrations of Al2O3 addition on the electrochemical characteristics of ceria and Gd-doped ceria samples. The results showed that the addition of Al2O3 altered the distribution of Volta potential at grain boundaries, leading to an increased potential difference between bulk and grain boundary cores, as well as a broadening of the potential gradient at the grain boundaries.