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

2 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

ASJC Scopus subject areas

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


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