Strain-Enhanced Low-Temperature High Ionic Conductivity in Perovskite Nanopillar-Array Films.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• High ionic conductivity is crucial for solid oxide electrochemical devices like fuel cells.
• Achieving high ionic conductivity at low temperatures, especially for out-of-plane transport, remains a significant challenge.

Purpose of the Study:

• To enhance low-temperature out-of-plane ionic conductivity in Na0.5Bi0.5TiO3 (NBT) films.
• To explore the role of interphase strain in improving ionic transport and material stability.

Main Methods:

• Utilized the emergent interphase strain methodology.
• Fabricated Na0.5Bi0.5TiO3 (NBT)-MgO nanopillar-array films.
• Employed atomic-scale electron microscopy and first-principles calculations.

Main Results:

• Achieved exceptional low-temperature out-of-plane ionic conductivity (0.003 S cm-1 at 400 °C) in NBT-MgO films, over an order of magnitude higher than pure NBT.
• Demonstrated that interphase tensile strain (+2%) expands the c-lattice and weakens oxygen bonding, reducing ion migration energy.
• Enhanced the thermal stability of NBT up to 600 °C, significantly above its bulk transition temperature.

Conclusions:

• Established a clear relationship between strain, material structure, and ionic conductivity.
• Strain engineering offers a promising pathway for designing high-performance ionic conductors for energy applications.
• The NBT-MgO nanopillar system provides a model for developing advanced solid oxide ionic conductors.