Effect of Na₂CO₃ Addition on the Piezoelectric and Dielectric Properties of Lead-Free (Na_0.5K_0.5)NbO₃-(Na_0.5Bi_0.5)TiO₃ Ceramics

Abstract:

Lead free piezoelectric ceramics 0.98(Na_0.5K_0.5)NbO₃-0.02(Na_0.5Bi_0.5)TiO₃ [abbreviated as 0.98NKN-0.02NB with the addition of 0~1.0 wt% Na₂CO₃ have been synthesized by the conventional mixed oxide process. The effects of amount of Na₂CO₃-content on the electrical properties and crystalline structures were investigated. The specimens of 0.98NKN-0.02NBT ceramics added with Na₂CO₃ maintain an orthorhombic phase. In the case of low Na₂CO₃ content ( 0.3 wt%), the grain growth became remarkable. The increase of grain size favors improving the piezoelectric properties, which is known as grain size effect. The grain size effect compensates the decrease of the electromechanical coupling factor due to the hard doping effect. For 0.98NKN-0.02NBT ceramics by doping 0.3 wt% Na₂CO₃, the electromechanical coupling coefficients of the thickness mode k_t and the planar mode k_p reach 0.51 and 0.33, respectively, after sintering at 1100 °C for 3 h. Moreover, the addition of excess Na₂CO₃ is a helpful method on ceramic processing to improve the dielectric tangent loss and the mechanical quality factor. Our results show that 0.98NKN-0.02NBT with the addition of 0.3 wt% Na₂CO₃ is a good lead-free piezoelectric ceramic.

• Periodical: Advanced Materials Research (Volume 716)
• Pages: 113-118
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.716.113
• Online since: July 2013
• Authors: Chun Huy Wang
• Keywords: Dielectric Property, Electromechanical Transducer, Lead-Free Piezoceramic, Piezoelectric Properties, Poling, Sintering

References

[1] S. Y. Chu, W. Water, Y.D. Juang, J. T. Liaw, and S. B. Da: Ferroelectrics, Vol. 297 (2003), p.11.

[2] M. Matsubara, T. Yamaguch, and S. Hirano: Jpn. J. Appl. Phys. Vol.44 (2005), p.6136.

[3] M. D. Maeder, D. Damjanovic and N. Setter: J. Electroceram., Vol. 13 (2004), p.385.

[4] Y. Guo, K. Kakimoto, and H. Ohsato: Jpn. J. Appl. Phys. Vol. 43, (2004), p.6662.

[5] Y. Guo, K. Kakimoto, and H. Ohsato:Solid State Commun., Vol. 129, (2004), p.279.

[6] Y. Guo, K. Kakimoto, and H. Ohsato: Appl. Phys. Lett. Vol. 85, (2004), p.4121.

[7] Y. Guo, K. Kakimoto, H. Ohsato:Mater. Lett. Vol. 59, (2005), p.241.

[8] R. C. Chang, S. Y. Chu, C. S. Hong and Y. P. Wong: J. Eur. Cerm. Soc. Vol. 27, (2007), p.4453.

[9] C. H. Wang: J. Ceram. Soc. Jpn. Vol. 117, (2009), p.680.

[10] C. H. Wang: J. Ceram. Soc. Jpn. Vol. 116, (2008), p.632.

[11] Chun-Huy Wang: J. Ceram. Soc. Jpn. Vol.117[5], (2009), p.693.

[12] Chun-Huy Wang: Advanced Materials Research, Vol. 148-149, (2011), p.232.

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

[14] T. Senda, and R. C. Bradt: J. Am. Ceram. Soc. Vol. 73 [1] (1990), p.106.

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