Molten-Salt Processed Potassium Sodium Niobate Single-Crystal Microcuboids with Dislocation-Induced Nanodomain...

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Potassium sodium niobate (KNN) ceramics exhibit normal ferroelectric properties.
• Achieving relaxor ferroelectric (RFE) properties in KNN typically requires compositional inhomogeneity or electric fields.
• Developing new synthetic strategies for functional single crystals is crucial for advanced applications.

Purpose of the Study:

• To develop a facile molten-salt synthesis for transparent, doped KNN single-crystal microcuboids.
• To investigate the ferroelectric properties and nanodomain formation mechanisms in these single crystals.
• To evaluate the potential of KNN single-crystal microcuboids in energy storage and sensing applications.

Main Methods:

• Facile molten-salt synthesis of Li, Ba-doped (K,Na)NbO3 (KNN) single-crystal microcuboids.
• Controlled supersaturation to influence crystal growth modes via island-like oriented attachment.
• Characterization of structural, ferroelectric, piezoelectric, and dielectric properties.

Main Results:

• Transparent and uniform Li, Ba-doped KNN single-crystal microcuboids (∼80 μm) were successfully synthesized.
• Distinct relaxor ferroelectric (RFE) properties were observed, differing from normal ferroelectric (FE) KNN ceramics.
• Dislocation-induced nanodomain formation during oriented attachment growth was identified as the mechanism for RFE properties.
• KNN single-crystal microcuboids showed a higher effective piezoelectric coefficient (∼459 pm/V) and high maximum polarization (69.6 μC/cm²).
• A transparent, flexible KNN-based pressure sensor demonstrated effective mechanical motion monitoring.

Conclusions:

• The molten-salt synthesis provides a novel route to KNN single-crystal microcuboids with RFE properties.
• Dislocation-induced nanodomains offer a new strategy for achieving RFE behavior in perovskite single crystals.
• KNN single-crystal microcuboids possess excellent piezoelectric and energy storage potential.
• These findings pave the way for developing advanced perovskite single crystals for flexible electronics and energy applications.