PROTON CONDUCTORS OF OXIDE AND THEIR APPLICATION TO RESEARCH INTO METAL-HYDROGEN SYSTEMS

Hydrogen dissolves into oxides. In some acceptor-doped perovskite-type oxides, the solubilities rise to levels as much as some mole%. In the se oxides, protonic conduction is observed within a certain temperatur e range. They may be used as proton conductive solid electrolytes at h igh temperature. In the present paper, the mechanism of hydrogen incor poration of these oxides is discussed on the basis of the thermodynami cs of crystal imperfections. Further, the following important applicat ions of these oxides to electrochemical devices for research into meta l-hydrogen systems are shown; (1) a device for the real-time determina tion of hydrogen potentials in liquid metal, (2) a device to measure h ydrogen contents in quenched metal, (3) a device to determine permeabi lities and diffusivities of hydrogen in the materials. The significanc e of the phenomenon of protonic conduction in oxide is also discussed with reference to the absorption of hydrogen by metals.