Structure analysis of BaCe0.8Y0.2O3−δ in dry and wet atmospheres by high-temperature X-ray diffraction measurement

• Different structures for hydrated and dehydrated BaCe0.8Y0.2O3−δ (BCY20).
• Slow phase transition from rhombohedral to monoclinic at 300 °C in wet atmosphere.
• Chemical expansion of BCY20 in wet atmosphere.
• Importance of considering moisture when discussing phase behavior of BCY20.

High temperature X-ray diffraction measurements were performed under dry and wet atmospheres to investigate phase behavior of BaCe0.8Y0.2O3−δ (BCY20). In the temperature range of 30–400 °C, BCY20 was identified to be rhombohedral and monoclinic structures in dry and wet atmospheres, respectively. Larger lattice volumes were obtained in a wet atmosphere due to a chemical expansion induced by water incorporation. A gradual change in diffraction peak shape due to a phase transformation from rhombohedral to monoclinic was observed at 300 °C when moisture was introduced into the atmosphere. These results indicated clearly the dependence of phase behavior of BCY20 on partial pressure of water vapor in atmosphere.

A BaCe0.8Y0.2O3−δ rhombohedral phase transited to a monoclinic phase at 300 °C when moisture was introduced into the atmosphere.Figure optionsDownload as PowerPoint slide