Abnormal electrocaloric effect of Na0.5Bi0.5TiO3-BaTiO3lead-free ferroelectric ceramics above room temperature

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Abstract

We demonstrate the electrocaloric effect (ECE) of Na0.5Bi0.5TiO3-BaTiO3(NBT-BT) lead-free ferroelectric ceramics, which were fabricated by the solid-state reaction method. Based on a Maxwell relation, the ECE was characterized via P-T curves under different electric fields. The polarization of NBT increases monotonically within the temperature range of 25-145 °C. It indicates that the NBT has an abnormal ECE with a negative temperature change (ΔT140= -0.33 K at E = 50 kV/cm) opposite to that of the normal ferroelectrics. The 0.92NBT-0.08BT composition near the morphotropic phase boundary has a normal ECE under low electric fields and an abnormal ECE under high electric fields. The abnormal ECE character originates from the relaxor characteristic between ferroelectric and antiferroelectric phases, while the common ECE is always related to the normal ferroelectric-paraelectric phase transition.
Original languageEnglish
Pages (from-to)1866-1869
Number of pages4
JournalMaterials Research Bulletin
Volume46
Issue number11
DOIs
Publication statusPublished - 1 Nov 2011

Keywords

  • A. Ceramics
  • C. Differential scanning calorimetry
  • C. X-ray diffraction
  • D. Dielectric properties
  • D. Ferroelectricity

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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