Anisotropy Factors and Electromechanical Coupling in Lead-Free 1-3-Type Composites

Vitaly Yu Topolov, Christopher R. Bowen, Ashura N. Isaeva

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The effective electromechanical properties and anisotropy factors of novel lead-free 1-3-type composites are studied to demonstrate their large piezoelectric anisotropy and considerable level of electromechanical coupling. The composites studied contain two single-crystal (SC) components and a polymer component. The first piezoactive component is a domain-engineered [001]-poled SC based on ferroelectric alkali niobates-tantalates, and this component is in the form of a system of long rods that are parallel to the poling axis OX 3. The second SC component is a system of spheroidal piezoelectric Li 2B 4O 7 inclusions aligned in a continuous and relatively large polymer matrix. The SC rods are surrounded by an SC/polymer matrix, and the connectivity of the composite is 1-0-3. It is shown that the conditions d 33/d 31 ≥5, which indicates a large degree of anisotropy of the piezoelectric coefficients, and k 33/k 31 ≥5 and k t/k p\ ≥ 5, which indicate a large anisotropy of the electromechanical coupling factors (ECFs), can be achieved simultaneously in specific ranges of the component volume fractions and inclusion aspect ratios. Moreover, in the same volume-fraction and aspect-ratio ranges, large ECFs (k 33 k t\ ∼0.8-0.9) are also achieved. In this context, the important role of the elastic properties of the continuous anisotropic matrix is discussed. The properties and anisotropy factors of the lead-free 1-3-type composites are compared to the similar parameters of conventional lead-containing piezoelectric materials, and the advantages of the composite system studied are described.

Original languageEnglish
Pages (from-to)1278-1286
Number of pages9
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Issue number7
Early online date11 May 2018
Publication statusPublished - 1 Jul 2018


  • Ferroelectric materials
  • ferroelectric properties
  • piezoelectric and ferroelectric transducer materials

ASJC Scopus subject areas

  • Instrumentation
  • Acoustics and Ultrasonics
  • Electrical and Electronic Engineering


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