Cation environment of BaCeO3-based protonic conductors II: new computational models

Area of Science:

• Materials Science
• Quantum Chemistry
• Solid-State Chemistry

Background:

• Yttrium-doped Barium Cerate (Y:BaCeO3) is a promising material for protonic ceramic fuel cells.
• Understanding local atomic arrangements is crucial for optimizing material properties.

Purpose of the Study:

• To simulate and interpret the local structure of Y-doped BaCeO3 using quantum chemical calculations.
• To explain experimental observations, particularly the bimodal distribution in Y-O coordination shells.
• To investigate the influence of hydrogen on local environments and overall protonic conduction.

Main Methods:

• Quantum chemical calculations utilizing Hartree-Fock energy functional.
• Simulation of octahedral site environments within a Pmcn orthorhombic framework.
• Geometrical optimizations and detailed orbital analysis of structural models.
• Local charge analysis to assess the impact of hydrogen.

Main Results:

• Confirmed local arrangements including Ce-O-Ce, Ce-O-Y, and Y-O-Y configurations.
• Attributed the bimodal Y-O coordination shell distribution to local Y-atom clustering and Y-O-Y arrangements.
• Demonstrated that mobile protons dynamically alter their local environment.
• Showed that protons do not affect the global protonic conduction properties.

Conclusions:

• The study provides a theoretical basis for understanding the local structure and properties of Y:BaCeO3.
• Local Y-atom clustering is a key factor influencing the material's structure.
• Protonic dynamics are localized and do not impede overall material performance.