Mixed Protonic-Electronic Conduction in "α-Al2O3": An Alternative Hypothesis

As an alternative, the voltage data of Kurita et al. recently published on galvanic cells with commercial α‐Al2O3 as a solid electrolyte and with O2, H2O/α‐Al2O3 as well as H2, H2O/α‐Al2O3 as electrodes can be quantitatively described by assuming that α‐Al2O3 represents a mixed sodium ionic–electronic conductor rather than a protonic–electronic conductor. From the evaluation of the experimental data, numerical values for the p‐type electronic conduction parameter are obtained that agree sufficiently well with the data known to date for the sodium ion conductor Na‐beta‐Al2O3.