Coexisting multi-phase and relaxation behavior in high-performance lead-free piezoceramics

Xiang Lv, Yinchang Ma, Junwei Zhang, Yao Liu, Fei Li, Xixiang Zhang, Jiagang Wu

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Phase boundary engineering (PBE) has remarkably enhanced the piezoelectric properties of potassium sodium niobate {(K, Na)NbO3, KNN} piezoceramics, yet the physical mechanisms need to be further understood. Here we outline a new physical phenomenon to describe piezoelectricity enhancement in KNN-based ceramics with PBE. We propose that the enhancement is due to the multi-phase coexistence featured with strong relaxation behavior. The strong relaxation behavior was unambiguously revealed by cryogenic experiments and originated from the polar nanoregions (PNRs) exhibiting a scale of 2.1 nm and a weak tetragonality (c/a = 1.0040). in situ temperature-dependent experiments uncovered the thermal evolution of the ferroelectric matrix and PNRs in both unpoled and poled samples, the first report in KNN-based ceramics. Our experiments combined with phenomenological theory revealed that ultra-fine nanodomains, PNRs, and easy polarization rotation together promote macro dielectric and piezoelectric properties in the relaxation-featured multi-phase coexistence. This work reveals the physical mechanism from different levels (e.g., local-mesoscopic-macroscopic), thus providing a new systematic understanding of the observed enhancement of piezoelectricity.
Original languageEnglish (US)
Pages (from-to)118221
JournalActa Materialia
StatePublished - Aug 4 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-09-14
Acknowledgements: This work is supported by the National Natural Science Foundation of China (Grant Nos. 52061130216, 52032007, and 52002252), the Central Funds Guiding the Local Science and Technology Development of Sichuan Province (2021ZYD0022), the Fundamental Research Funds for the Central Universities (YJ2021154), and Chengdu International Science and Technology Cooperation Project (2021-GH03-00003-HZ). The Royal Society is appreciated for a Newton Advanced Fellowship award (NAF\R1\201126). We thank Ms. Hui Wang (Analytical & Testing Center of Sichuan University) for measuring SEM images.

ASJC Scopus subject areas

  • Polymers and Plastics
  • Metals and Alloys
  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials


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