High-temperature proton conductors for the injection of hydrogen into a vacuum

Tubes of ceramic high-temperature proton conductors (CaZr0.9In0.1O3-x, BaZr 0.9Y0.1O3-x, and Ba3Ca1.18Nb1.82 O9-x) were used to introduce hydrogen into a vacuum system. A prerequisite was a leak rate below 10(-8) mbar/s for an assembly consisting of the active tube and a 8YSZ support tube. Mass spect rometry showed that the partial pressure of hydrogen in the vacuum system, p(H2), increased linearly with the electric current flowing through the pro ton conductor. All other important partial pressures remained unaffected by this operation. Calculation of throughput during operation of the hydrogen source essentially revealed that the total current, J, is used to transpor t protons from the anode to the cathode (t(H) approximate to 1). The number of moles of H-2 transported per second is given by J/2F. In essence, the p resent proton conductor tube constitutes a precise, current-controllable de vice, with a response time of a few seconds only, that delivers ultrahigh-p urity hydrogen to a vacuum system.