Proton conduction in Gd0.1Ce0.9O1.95 was investigated, using impedance spectroscopy under various atmospheres and gas concentration cells. In an O atmosphere, the material was nearly a pure O ionic conductor. In a H atmosphere, the material behaved as a mixed conductor of O ions, electrons and protons. Depending upon the temperature, the total conductivity was usually higher by one to two orders of magnitude in H, than in air or O. This was due to mixed conduction. It was discovered that the ionic transport properties depended largely upon the ambient atmosphere, and changed from one type to the other. Proton conduction generally occurred in this material, and became significant in an H atmosphere. It could contribute between 5 and 10% of the total conductivity. A maximum contribution of 17% was detected. The reduction of Ce4+ to Ce3+ in reduced atmospheres caused the formation of additional O vacancies and electrons, and was also associated with the creation of protons.

Electrical Properties and Proton Conduction of Gadolinium-Doped Ceria. B.Zhu, I.Albinsson, B.E.Mellander: Ionics, 1998, 4[3-4], 261-6