Microstructure and electrical properties of NaNbO₃-BaTiO₃ lead-free piezoelectric ceramics

Abstract

Lead-free piezoelectric ceramics (1-x)NaNbO₃-xBaTiO₃ have been fabricated by a traditional ceramic sintering technique. The effects of BaTiO₃ (BT) synthesized by hydrothermal method on crystal structure, density, dielectric, piezoelectric, and electromechanical properties were investigated. Results show that the phase structure transforms from the orthorhombic phase to the tetragonal phase with the increase of the content of BT, and the two phases co-exist when 0.08<x≤0.10. However, the optimum composition for (1-x)NaNbO₃-xBaTiO₃ ceramics is 0.90NaNbO₃-0.10BaTiO₃. The 0.90NaNbO₃-0.10BaTiO₃ ceramics sintered at 1250°C have higher properties: piezoelectric constant d₃₃ of 120 pC/N, dielectric constant ϵ_r of 718, planar electromechanical coupling factor k_p of 24%, planar frequency N_d of 3 MHz·mm, and the mechanical quality factor Q_m of 138, respectively. The results show that the (1-x)NaNbO₃-xBaTiO₃ ceramics is one of the promising lead-free materials for high-frequency applications.

Keywords

Lead-free piezoelectric ceramics / NaNbO₃-BaTiO₃ / piezoelectricity / ceramics / crystal structure / microstructure

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Acknowledgements

The authors would like to thank the financial support from the Fostering Fund of the Ministry of Education (No. 707031) and the National 863 Foundation Program (No. 2007AA03Z104).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg