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

Geun Soo Lee, Jung Soo Kim, Seung Hyun Kim, San Kwak, Bumjoo Kim, In Su Kim, Sahn Nahm

Research output: Contribution to journalReview articlepeer-review


(K0.5Na0.5)NbO3 (KNN)-based ceramics have been extensively investigated as replacements for Pb(Zr, Ti)O3-based ceramics. KNN-based ceramics exhibit an orthorhombic structure at room temperature and a rhombohedral–orthorhombic (R–O) phase transition temperature (TR–O), orthorhombic–tetragonal (O–T) phase transition temperature (TO–T), and Curie temperature of −110, 190, and 420 °C, respectively. Forming KNN-based ceramics with a multistructure that can assist in domain rotation is one technique for enhancing their piezoelectric properties. This review investigates and introduces KNN-based ceramics with various multistructures. A reactive-templated grain growth method that aligns the grains of piezoceramics in a specific orientation is another approach for improving the piezoelectric properties of KNN-modified ceramics. The piezoelectric properties of the [001]-textured KNN-based ceramics are improved because their microstructures are similar to those of the [001]-oriented single crystals. The improvement in the piezoelectric properties after [001] texturing is largely influenced by the crystal structure of the textured ceramics. In this review, [001]-textured KNN-based ceramics with different crystal structures are investigated and systematically summarized.

Original languageEnglish
Article number325
Issue number3
Publication statusPublished - 2024 Mar

Bibliographical note

Publisher Copyright:
© 2024 by the authors.


  • KNN-based piezoceramic
  • lead-free
  • phase transition
  • polymorphic phase boundary
  • reactive template grain growth

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering
  • Electrical and Electronic Engineering


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