Hydrogen reduction properties of RuO2 electrodes

The thermodynamic stability of RuO2 under a reducing atmosphere containing hydrogen gas was investigated. The RuO2 electrode is reduced to Ru metal at 200 degrees C in 0.3% H-2 and at 300 degrees C in 0.03% H-2, even when the electrode is stacked with a (Ba, Sr)TiO3 dielectric layer. The reduction d ecreases the electrode volume. Our findings indicate that application of th e RuO2 electrode in device integration will be difficult because of the the rmodynamic instability as long as the thermal equilibrium state of reductio n is attained during hydrogen sintering.