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Compositional Dependence of Piezoelectric Properties in NaxK1−xNbO3 Lead-Free Ceramics Prepared by Spark Plasma Sintering

Authors

  • Bo-Ping Zhang,

    1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
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    • §University of Science and Technology, Beijing.

  • Jing-Feng Li,

    Corresponding author
    1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
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    • *Member, American Ceramic Society.

    • Tsinghua University.

  • Ke Wang,

    1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
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    • Tsinghua University.

  • Hailong Zhang

    1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
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    • §University of Science and Technology, Beijing.


  • S. Trolier-McKinstry—contributing editor

  • This work was financially supported by the Toyota Motor Corporation in the Tsinghua-Toyota collaborative research project on lead-free piezoelectric ceramics and also partly supported by National Natural Science Foundation of China under Grant No. 50325207.

†Author to whom correspondence should be addressed. e-mail: jingfeng@mail.tsinghua.edu.cn

Abstract

Lead-free piezoelectric NaxK1−xNbO3 (x=20–80 mol%) ceramics were fabricated using spark plasma sintering at a low temperature (920°C). All the NaxK1−xNbO3 ceramics showed a similar orthorhombic phase structure, while the corresponding lattice parameters decreased from the KNbO3 side to the NaNbO3 side with increasing Na content. A discontinuous change in lattice parameter close to composition of 60 mol% Na indicated the presence of a transitional area that is similar to the morphotropic phase boundary (MPB) in NaxK1−xNbO3 ceramics. The sintered density of the NaxK1−xNbO3 ceramics decreased with increasing Na content, from a relative density of 99% for the K-rich side to 92% for the Na-rich side. The piezoelectric constant d33 and planar mode electromechanical coupling coefficient kp showed a maximum value of 148 pC/N and 38.9%, respectively, due to the similar MPB effects in the PZT system.

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