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

The ceramic powders of BaCe1−xYxO3−α (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 °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 °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 °C. Ammonia was synthesized successfully from nitrogen and hydrogen at atmospheric pressure in the electrolytic cell using BaCe0.85Y0.15O3−α. The maximum rate of NH3 formation was found to be 2.1 × 10−9 mol s−1 cm−2 at 500 °C with an applied current of 0.75 mA.