Preparation via microemulsion method and proton conduction at intermediate-temperature of BaCe1-xYxO3-alpha

The ceramic powders of BaCe1-xYxO3-alpha (x = 0.05, 0.10, 0.15, 0.20) have been prepared via a microemulsion method, Green compacts of the powders were sintered to densities higher than 95% of theoretical at the lower temperature (1500 degrees C). The obtained ceramics showed a single-phase of orthorhombic perovskite. The proton conduction was investigated by employing the techniques of AC impedance and electrochemical hydrogen permeation (hydrogen pumping) at 300-600 degrees C. It was found that the ceramics were almost pure proton conductors in wet hydrogen, and the highest proton conductivity was observed for x = 0.15 at 600 degrees C. Ammonia was synthesized successfully from nitrogen and hydrogen at atmospheric pressure in the electrolytic cell using BaCe1-xYxO3-alpha. The maximum rate of NH3 formation was found to be 2.1 x 10(9) mol s(-1) cm(-2) at 500 degrees C with an applied current of 0.75 mA. (c) 2008 Elsevier B.V. All rights reserved.