Formation of the core-shell microstructure in lead-free Bi1/2Na1/2TiO3-SrTiO3 piezoceramics and its influence on the electromechanical properties

Jurij Koruza*, Virginia Rojas, Leopoldo Molina-Luna, Ulrike Kunz, Michael Duerrschnabel, Hans Joachim Kleebe, Matias Acosta

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The Bi1/2Na1/2TiO3-based materials exhibit the largest electric-field-induced strains among lead-free piezoceramics and are considered as promising candidates for actuation applications. A typical representative of this group is (1-x)Bi1/2Na1/2TiO3-xSrTiO3, where its excellent electromechanical properties were recently related to the existence of a core-shell microstructure. Although the latter was also reported in other Bi1/2Na1/2TiO3-based ceramics, the formation mechanism remains unknown. In the present work we therefore first investigated the solid-state reaction occurring during calcination using simultaneous thermogravimetric analysis, X-ray diffraction, scanning and transmission electron microscopy. The reaction occurred in two steps, whereby the cores and shells had different formation reaction temperatures, which resulted in a metastable heterogeneous microstructure. Furthermore, a series of sintered samples with different relative densities, grain sizes, and core densities was prepared. Modifications of these microstructural parameters resulted in variation of the maximal strain by 17% and in the electric-field required to trigger the phase transitions by 38%.

Original languageEnglish
Pages (from-to)1009-1016
Number of pages8
JournalJournal of the European Ceramic Society
Issue number4
Publication statusPublished - 1 Mar 2016
Externally publishedYes


  • Core-shell
  • Electromechanical properties
  • Lead-free
  • Piezoelectricity
  • Relaxor

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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