Physical and Electrical Properties of Lead-Free (Bi_0.5Na_0.5)TiO₃-(Na_0.5K_0.5)NbO₃ Ceramics

Abstract:

Lead-free (1-x)(Bi_0.5Na_0.5)TiO₃–x(Na_0.5K_0.5)NbO₃ (x<0.1) ceramics have been prepared by the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na_0.5K_0.5)NbO₃ diffuse into the lattice of (Bi_0.5Na_0.5)TiO₃ to form a solid solution and the hexagonal phase with a perovskite structure. The samples with a low content of (Na_0.5K_0.5) NbO₃ exhibit relatively good physical and electrical properties. For 0.96(Bi_0.5Na_0.5) TiO₃–0.04 (Na_0.5K_0.5) NbO₃ ceramics, the electromechanical coupling coefficients of the planar mode k_p and the thickness mode k_t reach 0.25 and 0.52, respectively, after sintering at 1100 °C for 5 h. The ratio of the thickness coupling coefficient to the planar coupling coefficient is 2.08. With suitable (Na_0.5K_0.5)NbO₃ concentration and sintering conditions, a dense microstructure and good electrical properties are obtained. Our results show that 0.96(Bi_0.5Na_0.5)TiO₃–0.04(Na_0.5K_0.5)NbO₃ solid solution ceramics are promising lead-free ceramics for high-frequency electromechanical transducer applications.

• Periodical: Materials Science Forum (Volume 687)
• Pages: 348-353
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.687.348
• Online since: June 2011
• Authors: Chun Huy Wang
• Keywords: Dielectric Property, Piezoelectric Properties, Poling, Sintering

References

[1] T. Takenaka, K. Maruyama and K. Sakata: Jpn. J. Appl. Phys., Vol. 30 (1991), p.2236.

[2] T. Takenaka, K. Sakata and K. Toda: Ferroelectric Vol. 106 (1990), p.375.

[3] T. Takenaka, and H. Nagata: Jpn. J. Appl. Phys. Vol. 36 (1997), p.6055.

[4] A. Herabut, and A. Safari: J. Am. Ceram. Soc. Vol. 80 (1997), p.2954.

[5] A. Sasa, T. Chiba, Y. Mamiya and E. Otsuki: Jpn. J. Appl. Phys. Vol. 38 (1999), p.5546.

[6] N. Ichinose, and K. Udagawa: Ferroelectric Vol. 169 (1995), p.317.

[7] C. H. Wang: J. Ceram. Soc. Jap., Vol. 116.

[5] (2008), p.632.

[8] V. Mueller, A. Kouvatov, R. Steinhausen, H. Beige, and H. P. Abicht: Integrat. Ferroelectrics Vol. 63 (2004), p.593.

[9] Anon. : Proc. IRE., Vol. 49 (1961), p.1161.

[10] T. Senda, and R. C. Bradt: J. Am. Ceram. Soc. Vol. 73.

[1] (1990), p.106.

[11] K. Okazaki and K. Nagata: J. Am. Ceram. Soc. Vol. 56(2) (1973), p.82.

[12] K. H. Hartal: Ferroelectrics, Vol. 12 (1976), p.9.

[13] R. L. Coble: J. Appl. Phys. Vol. 56 (1985), p.131.