Abstract

This paper presents a detailed modelling and experimental study of the piezoelectric and dielectric properties of novel ferroelectric sandwich layer BaTiO3 structures that consist of an inner porous layer and dense outer layers. The dependencies of the piezoelectric coefficients and dielectric permittivity of the sandwich structure on the bulk relative density α are analysed by taking into account an inner layer with a porosity volume fraction of 0.5-0.6. The observed changes in and are interpreted within the framework of a model of a laminar structure whereby the electromechanical interaction of the inner porous layer and outer dense layers have an important role in determining the effective properties of the system. The porous layer is represented as a piezocomposite with a 1-3-0 connectivity pattern, and the composite is considered as a system of long poled ceramic rods with 1-3 connectivity which are surrounded by an unpoled ceramic matrix that contains a system of oblate air pores (3-0 connectivity). The outer monolithic is considered as a dense poled ceramic, however its electromechanical properties differ from those of the ceramic rods in the porous layer due to different levels of mobility of 90° domain walls in ceramic grains. A large anisotropy of d3j at α = 0.64-0.86 is achieved due to the difference in the properties of the porous and monolithic layers and the presence of highly oblate air pores. As a consequence, high energy-harvesting figures of merit d3j g3j are achieved that obey the condition d33 g33 /( d31 g31) ∼ 102 at d33 g33 ∼ 10-12 Pa-1 and values of the hydrostatic piezoelectric coefficients dhz.ast; ≈ 100 pC N and ghz.ast; ≈ 20 m V m N are achieved at α= 0.64-0.70. The studied BaTiO3-based sandwich structures has advantages over highly anisotropic PbTiO3-type ceramics as a result of the higher piezoelectric activity of ceramic BaTiO3 and can be used in piezoelectric sensor, energy-harvesting and related applications.

Original languageEnglish
Article number105006
JournalSmart Materials and Structures
Volume26
Issue number10
DOIs
Publication statusPublished - 1 Sep 2017

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Keywords

  • anisotropy
  • dielectric permittivity
  • energy-harvesting figures of merit
  • piezoelectric properties
  • porous ferroelectrics

ASJC Scopus subject areas

  • Signal Processing
  • Civil and Structural Engineering
  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering

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