Strong thickness dependence of aurivillius phase formation in SrBi 2Ta2O9 thin films

Yun Mo Sung, Woo Chul Kwak, Se Yeon Jung, Jung Joon Na, Sang M. Park

Research output: Contribution to journalArticle

Abstract

Sr0.7Bi2.4Ta2O9 (SBT) thin films were studied for the dependence of Aurivillius phase formation kinetics on their film thickness. SBT thin films were fabricated using a sol-gel process and spin coating, and their thickness was varied controlling the number of spin coating. The films were first heated at a low temperature for the complete crystallization of amorphous film to fluorite phase and then further heated at different elevated temperatures for the phase transformation to Aurivillius for 40 min. It was found that the phase transformation kinetics apparently increased with thickness up to ∼390 nm, and then it sharply decreased at higher values. The Aurivillius crystal size decreased and the density of crystals increased with the increase of film thickness up to ∼390 nm, implying increasing number of nuclei due to the reduced energy barrier for nucleation. Above the critical value both the size and density of crystals decreased. It is suggested that up to ∼390 nm the tensile strain energy in the films, which was stored by the shrinkage of thin films during the removal of remaining organic components from sol-gel chemistry, plays a major role for determining the phase transformation kinetics and above the critical value SBT films act as a free bulk material without substrate constraints.

Original languageEnglish
Pages (from-to)119-123
Number of pages5
JournalJournal of Electroceramics
Volume17
Issue number2-4
DOIs
Publication statusPublished - 2006 Dec 1

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Keywords

  • Ferroelectric
  • Phase transformation
  • SBT
  • Thickness
  • Thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering
  • Materials Chemistry

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