Initial stage sintering mechanism of NaNbO3 and implications regarding the densification of alkaline niobates

Jurij Koruza*, Barbara Malič

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The behavior of submicron- and nano-sized NaNbO3 powder compacts during conventional sintering was studied using optical dilatometry and microstructure analysis. Microstructure-development trajectories revealed the dominance of grain growth during the initial sintering stage, while densification occurred only during later stages. Surface diffusion with low activation energy in the range of 50-60kJ/mol was found to be the dominant material-transport mechanism during the initial sintering stage. The early activation of surface diffusion reduced the sintering driving force, decreased the rate of the densifying mechanisms and was thus identified as the main cause for poor densification of NaNbO3. Same explanation could be valid also for other alkaline niobate based lead-free piezoelectric ceramics. Finally, alternative sintering methods are discussed and the efficiency of the pressure-assisted sintering was demonstrated in successful production of highly-dense fine-grained NaNbO3 ceramics, with relative density and grain size of 98% and 700nm, respectively.

Original languageEnglish
Pages (from-to)1971-1979
Number of pages9
JournalJournal of the European Ceramic Society
Volume34
Issue number8
DOIs
Publication statusPublished - Aug 2014
Externally publishedYes

Keywords

  • Alkaline niobates
  • Lead-free
  • Microstructure
  • Piezoceramics
  • Sintering

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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