BaCeO3

BaCeO3, or barium cerate, is a ceramic oxide that crystallizes in the perovskite structure with the general formula ABO3, where on the A site sits Ba2+ and on the B site sits Ce4+. This composition forms a flexible lattice that can accommodate various dopants, creating oxygen vacancies for enhanced ionic transport. In its pure form, BaCeO3 is a wide-bandgap insulator, but its properties change markedly when doped.

Proton conductivity is a key feature of BaCeO3-based materials. When trivalent dopants such as Y3+, Gd3+, Yb3+, In3+ or Ga3+ substitute for Ce4+, oxygen vacancies are generated. In humid atmospheres, these vacancies can be hydrated to incorporate protons, enabling proton transport through the lattice via the Grotthuss mechanism. The resulting doped BaCeO3 compounds are studied as high-temperature proton conductors for electrochemical devices, particularly in intermediate-temperature solid oxide fuel cells.

Synthesis and doping are central to the material’s performance. BaCeO3 can be prepared by conventional solid-state reactions or alternative methods such as sol-gel routes, typically with dopant levels around 10–20 mol% to optimize proton conduction. The doped materials are characterized by X-ray diffraction to confirm the perovskite phase and by impedance spectroscopy to measure proton conductivity under humidified conditions.

Chemical stability presents a challenge for BaCeO3. It is susceptible to carbonation in the presence of CO2 and can be less chemically stable than some alternatives such as BaZrO3, though doping and compositional tuning can mitigate this issue. Consequently, BaCeO3-based electrolytes are most often explored in controlled environments for intermediate-temperature solid oxide fuel cells and related electrochemical applications.