Proton diffusion pathways and rates in Y-doped BaZrO3 solid oxide electrolyte from quantum mechanics

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Chemistry

Background:

• Proton conductivity in Y-doped BaZrO(3) (BYZ) is vital for solid oxide fuel cells.
• Understanding proton diffusion mechanisms at the atomic level is essential for optimizing BYZ performance.

Purpose of the Study:

• To investigate the energy barriers for intraoctahedral and interoctahedral proton transfers in BYZ.
• To elucidate the atomic-level proton diffusion mechanism and pathways in BYZ.

Main Methods:

• Quantum mechanical calculations using the Perdew-Becke-Ernzerhof flavor of density functional theory.
• Analysis of periodic structures of 12.5% Y-doped BaZrO(3) (BYZ).

Main Results:

• Calculated activation energy (E(a)) for intraoctahedral proton transfers on ZrO(6) and YO(6) octahedra are 0.48 eV and 0.49 eV, respectively.
• Calculated E(a) for interoctahedral proton transfer is 0.41 eV, consistent with the experimental value of 0.44 eV.
• Proposed atomic-level proton diffusion mechanisms and pathways, highlighting the importance of both intra- and interoctahedral transfers.

Conclusions:

• Both intraoctahedral and interoctahedral proton transfers significantly contribute to proton diffusion in BYZ.
• Thermal vibrations influence proton transfer barriers and facilitate continuous proton diffusion pathways.
• The proposed mechanisms provide a fundamental understanding of fast proton transport in BYZ electrolytes.