Conductivity behavior of BaZr0.9Dy0.1O3−δ

Dysprosium-doped barium zirconate (BaZr0.9Dy0.1O3−δ, BZDy10) was prepared by solid-state reactive sintering, and the conductivity under dry and moist (3%) conditions was studied as a function of temperature and oxygen partial pressure. In addition, the dependence of the steam partial pressure on conductivity was studied in 5%H2 and air. From this set of data, BZDy10 was found to be a pure proton conductor in moist reducing atmosphere below 600 °C, while exhibiting electronic conductivity in oxidizing atmosphere. The conductivity data were compared to values obtained on yttrium-doped barium zirconate (BaZr0.9Y0.1O3−δ, BZY10). The main difference between the two compounds is the change in conductivity between moist and dry oxidizing atmosphere. For BZY10, the conductivity is less in moist oxidizing atmosphere than under dry oxidizing conditions because the oxidation reaction is less favored than hydration. On the other hand, no difference was observed for BZDy10 under moist and dry oxidizing conditions, revealing that hydration is negligible under moist oxidizing atmosphere. Electron paramagnetic resonance (EPR) measurements were performed to determine the oxidation state of dysprosium.