Effect of thermal history on stability of the relaxor state in (Bi1/2K1/2)TiO3 ceramics

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Abstract

Bismuth potassium titanate (Bi1/2K1/2)TiO3 (BKT) with disordered A-site Bi3+ and K+ ions is known to undergo a spontaneous phase transition between a high-temperature relaxor R state and a low-temperature ferroelectric (FE) state at around 300 °C. Here, we demonstrate that the thermal history of BKT ceramics has a great effect on the stability of the R and FE states. To modulate the distribution of Bi3+ and K+ ions, as-sintered BKT ceramics were postannealed at 900 °C and then cooled to 500 °C at a very low cooling rate of %0.1 °C/min. The slowly cooled samples showed a normal-relaxor-like temperature dependence of dielectric permittivity without any anomaly attributed to the spontaneous R-FE transition. The slow cooling treatment changed the room-temperature crystal system of the BKT ceramics from tetragonal to cubic, although it did not induce the cationic ordering of Bi3+ and K+. It was also observed that the macroscopic domain structure disappeared after the slow cooling treatment. These observations demonstrated that the slow cooling treatment stabilized the R state in BKT to inhibit the spontaneous phase transition into the FE state. The possible reason for the stabilization of the R state in the slowly cooled BKT is discussed on the basis of the changes in cationic distribution and local compositional heterogeneity.

Original languageEnglish
Article number10PC03
JournalJapanese Journal of Applied Physics
Volume56
Issue number10
DOIs
Publication statusPublished - 2017 Oct 1

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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