Recent Developments in (K, Na)NbO₃-Based Lead-Free Piezoceramics.

Area of Science:

• Materials Science
• Solid State Physics
• Ceramic Engineering

Background:

• Lead-free (Potassium Sodium Niobate) KNN-based ceramics are explored as alternatives to lead zirconate titanate (PZT).
• KNN ceramics possess specific phase transition temperatures: R-O at -110°C, O-T at 190°C, and Curie temperature at 420°C.
• Enhancing piezoelectric properties is crucial for KNN applications.

Purpose of the Study:

• To review KNN-based ceramics with various multistructures for improved piezoelectricity.
• To investigate the impact of [001] texturing on KNN ceramic properties.
• To systematically summarize [001]-textured KNN ceramics with different crystal structures.

Main Methods:

• Review of existing literature on KNN-based ceramics with multistructures.
• Analysis of the reactive-templated grain growth method for grain alignment.
• Investigation of [001]-textured KNN ceramics and their microstructural-property relationships.

Main Results:

• Multistructures in KNN ceramics can facilitate domain rotation, enhancing piezoelectric performance.
• [001]-textured KNN ceramics exhibit improved piezoelectric properties due to microstructure alignment.
• The crystal structure of textured ceramics significantly influences the enhancement of piezoelectric properties.

Conclusions:

• Multistructure engineering and [001] texturing are effective strategies to boost KNN ceramic piezoelectricity.
• The alignment of grains via texturing mimics single-crystal behavior, leading to superior properties.
• Understanding the interplay between crystal structure and texturing is key for optimizing KNN-based lead-free piezoelectric ceramics.