Origin of colossal ionic conductivity in oxide multilayers: interface induced sublattice disorder

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Science

Background:

• Oxide ionic conductors traditionally require high operating temperatures, limiting practical applications.
• Recent discovery of colossal room-temperature ionic conductivity in yttria-stabilized zirconia (YSZ) and SrTiO3 multilayers presents a significant advancement.

Purpose of the Study:

• To investigate the fundamental mechanisms behind the colossal room-temperature ionic conductivity in YSZ/SrTiO3 multilayers.
• To elucidate the roles of lattice-mismatch strain and oxygen sublattice incompatibility in enhancing ionic mobility.

Main Methods:

• Density-functional theory (DFT) calculations were employed to model the material structures and predict ionic transport properties.
• Simulations focused on analyzing the effects of strain and sublattice structure on oxygen ion mobility in bulk YSZ and multilayered systems.

Main Results:

• Lattice-mismatch strain in bulk YSZ enhances oxygen ion mobility at elevated temperatures by inducing significant oxygen disorder.
• In multilayered YSZ/SrTiO3 structures, oxygen sublattice incompatibility, in conjunction with strain, drives extreme oxygen disorder even at room temperature.
• This combined effect is identified as the origin of colossal room-temperature ionic conductivity.

Conclusions:

• The study reveals that the combination of lattice strain and oxygen sublattice incompatibility is crucial for achieving high ionic conductivity at room temperature.
• These findings provide a mechanistic understanding for designing advanced oxide ionic conductors for energy applications.
• The results pave the way for developing novel materials that operate efficiently at ambient temperatures.