Proton Diffusion in Orthorhombic Perovskite Sulfides

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Proton mobility is crucial for applications like catalysis and energy storage.
• Perovskite sulfides (ABS3) offer tunable properties for such applications.
• Understanding proton diffusion mechanisms in these materials is essential.

Purpose of the Study:

• To investigate proton mobility in a wide range of perovskite sulfides (ABS3).
• To identify factors influencing proton diffusion rates and anisotropy.
• To predict potential high-mobility materials for technological applications.

Main Methods:

• Density Functional Theory (DFT) for analyzing hydrogen positions.
• Nudged Elastic Band (NEB) method for calculating activation energy barriers.
• Markovian master equation approach for diffusion rate calculations.

Main Results:

• Identified metastable hydrogen positions and calculated activation energies.
• Predicted room temperature diffusion coefficients up to 10^-6 cm^2/s in Zr-based compounds.
• Demonstrated that A- and B-site occupants significantly impact proton mobility through crystallographic effects and anisotropy.

Conclusions:

• Proton mobility in perovskite sulfides is highly dependent on structural and electronic properties.
• Symmetry-breaking distortions that shorten S-S distances are key to reducing activation energies.
• Zr-based perovskite sulfides are promising candidates for applications requiring high proton conductivity.