Effects of LiF on the Structure and Electrical Properties of (Na_0.52K_0.435Li_0.045)Nb_0.87Sb_0.08Ta_0.05O₃ Lead-Free Piezoelectric Ceramics Sintered at Low Temperatures

P. D. Gio^*, N. D. Phong

Department of Physics, College of Sciences, Hue University, Hue, Vietnam.

DOI: 10.4236/msce.2015.311003                

Abstract

The (Na_0.52K_0.435 Li_0.045)Nb_0.87Sb_0.08Ta_0.05O₃ (KNNLST) + x wt% LiF piezoelectric ceramics, where x = 0, 2, 4, and 6, have been fabricated successfully by the conventional solid-state reaction method. The effect of LiF on the sintering temperature, the structure and electrical properties of KNNLST ceramics was systematically studied. The LiF addition significantly reduced the sintering temperature of the ceramics from 1100℃ to 930℃. Experimental results showed that with the doping of LiF, all the ceramic samples could be well sintered and exhibit a dense, pure perovskite structure. With increasing LiF content, the tetragonal-orthorhombic transition point (T_O-T) and the Curie temperature (T_c) of the ceramics shifted to the lower and higher temperatures, respectively. The specimens containing 4 wt% LiF sintered at 930℃ showed the good electrical properties: the density of 4.26 g/cm³; the electromechanical coupling factor, k_p = 0.27 and k_t = 0.40; the dielectric constant, ε = 744; the piezoelectric constant (d₃₁) of 41 pC/N.

Keywords

Lead-Free, Crystal Structure, Piezoelectric Properties, Electromechanical Coupling Factor

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Xu, Y. (1991) Ferroelctric Materials and Their Applications. North-Holland, Amsterdam, London, New York and Tokyo.
[2]	Hou, Y.D., Zhu, M.K., Tian, C.S. and Yan, H. (2004) Structure and Electrical Properties of PMZN-PZT Quaternary Ceramics for Piezoelectric Transformers. Sensors and Actuators A: Physical, 116, 455-460. http://dx.doi.org/10.1016/j.sna.2004.05.012
[3]	Gao, F., Cheng, L., Hong, R., Liu, J., Wang, C. and Tian, C. (2009) Crystal Structure and Piezoelectric Properties of xPb(Mn1/3Nb2/3)O3-(0.2-x)Pb(Zn1/3Nb2/3)O3-0.8Pb(Zr0.52Ti0.48)O3 Ceramics. Ceramics International, 35, 1719-1723. http://dx.doi.org/10.1016/j.ceramint.2008.09.001
[4]	Hou, Y.D., Chang, L.M., Zhu, M.K., Song, X.M. and Yan, H. (2007) Effect of Li2CO3 Addition on the Dielectric and Piezoelectric Responses in the Low-Temperature Sintered 0.5PZN-0.5PZT Systems. Journal of Applied Physics, 102, Article ID: 084507. http://dx.doi.org/10.1063/1.2800264
[5]	Jin, B.M., Lee, D.S., Kimb, I.W., Kwon, J.H., Lee, J.S., Song, J.S. and Jeong, S.J. (2004) The Additives for Improving Piezoelectric and Ferroelectric Properties of 0.2Pb(Mg1/3Nb2/3)O3-0.8[PbZrO3-PbTiO3] Ceramics. Ceramics International, 30, 1449-1451. http://dx.doi.org/10.1016/j.ceramint.2003.12.070
[6]	Lee, J.S., Choi, M.S., Hung, N.V., Kim, Y.S., Kim, I.W., Park, E.C., Jeong, S.J. and Song, J.S. (2007) Effects of High Energy Ball-Milling on the Sintering Behavior and Piezoelectric Properties of PZT-Based Ceramics. Ceramics International, 33, 1283-1286. http://dx.doi.org/10.1016/j.ceramint.2006.04.017
[7]	Saito, Y., Takao, H., Tani, T., Nonoyama, T., Takatori, K., Homma, T., Nagaya, T. and Nakamura, M. (2004) Lead- Free Piezoceramics. Nature, 432, 84-87. http://dx.doi.org/10.1038/nature03028
[8]	Yeo, H.G., Sung, Y.S., Song, T.K., Cho, J.H., Kim, M.H. and Park, T.G. (2009) Donor Doping Effects on the Ferroelectric and the Piezoelectric Properties of Pb-Free (Bi0.5Na0.5)TiO3 Ceramics. Journal of Korean Physical Society, 54, 896-900. http://dx.doi.org/10.3938/jkps.54.896
[9]	Abe, J., Kobune, M., Kitada, K., Yazawa, T., Masumoto, H. and Goto, T. (2007) Effects of Spark-Plasma Sintering on the Piezoelectric Properties of High-Density (1-x)(Na0.5K0.5)NbO3-xLiTaO3 Ceramics. Journal of Korean Physical Society, 51, 810-814. http://dx.doi.org/10.3938/jkps.51.810
[10]	Song, T.K., Kim, M.-H., Sung, Y.-S., Yeo, H.-G., Lee, S.H., Jeong, S.-J. and Song, J.-S. (2007) Depolarization Temperatures in Pb-Free Piezoelectric Materials. Journal of Korean Physical Society, 51, 697-700. http://dx.doi.org/10.3938/jkps.51.697
[11]	Karaki, T., Yan, K. and Adachi, M. (2007) Barium Titanate Piezoelectric Ceramics Manufactured by Two-Step Sintering. Japanese Journal of Applied Physics, 46, 7035. http://dx.doi.org/10.1143/JJAP.46.7035
[12]	Karaki, T., Adachi, M. and Yan, K. (2008) High-Performance Lead-Free Barium Titanate Piezoelectric Ceramics. Advances in Science and Technology, 54, 7-12. http://dx.doi.org/10.4028/www.scientific.net/AST.54.7
[13]	Wang, K., Li, J.-F. and Liu, N. (2008) Piezoelectric Properties of Low-Temperature Sintered Li-Modified (Na, K)NbO3 Lead-Free Ceramics. Applied Physics Letters, 93, Article ID: 092904. http://dx.doi.org/10.1063/1.2977551
[14]	Li, J.-F., Wang, K., Zhu, F.-Y., Cheng, L.-Q. and Yao, F.-Z. (2013), (K, Na)NbO3-Based Lead-Free Piezoceramics: Fundamental Aspects, Processing Technologies, and Remaining Challenges. Journal of the American Ceramic Society, 96, 3677-3696. http://dx.doi.org/10.1111/jace.12715
[15]	Eriksson, M., Yan, H.X., Nygren, M., Reece, M.J. and Shen, Z.J. (2010) Low Temperature Consolidated Lead-Free Ferroelectric Niobate Ceramics with Improved Electrical Properties. Journal of Materials Research, 25, 240-247. http://dx.doi.org/10.1557/JMR.2010.0034
[16]	Wongsaenmai, S., Ananta, S. and Yimnirun, R. (2012) Effect of Li Addition on Phase Formation Behavior and Electrical Properties of (K0.5Na0.5)NbO3 Lead Free Ceramics. Ceramics International, 38, 147-152. http://dx.doi.org/10.1016/j.ceramint.2011.06.049
[17]	Zhou, J.-J., Cheng, L.-Q., Wang, K., Zhang, X.-W., Li, J.-F., Liu, H. and Fang, J.-Z. (2014) Low-Temperature Singtering of (K, Na)NbO3-Based Lead-Free Piezoceramics with Addition of LiF. Journal of the European Ceramics Society, 34, 1161-1167. http://dx.doi.org/10.1016/j.jeurceramsoc.2013.11.029
[18]	Zhang, Y.J., Chu, R.Q., Xu, Z.J., Chen, Q., Liu, Y. and Zhang, G.C. (2012) Effects of Li2CO3 on the Sintering Behavior and Piezoelectric Properties of Bi2O3-Excess (Bi0.5Na0.5)0.96Ba0.06TiO3 Ceramics. Current Applied Physics, 12, 204-209. http://dx.doi.org/10.1016/j.cap.2011.06.002
[19]	Matsubara, M., Toshiakiamaguchi, Sakamoto, W., Kikuta, K., Yogo, T. and Hirano, S.-I. (2005) Processing and Piezoelectric Properties of Lead-Free (K, Na)(Nb, Ta)O3 Ceramics. Journal of the American Ceramic Society, 88, 1190-1196. http://dx.doi.org/10.1111/j.1551-2916.2005.00229.x
[20]	Park, H.-Y., Seo, I.-T., Choi, J.H., Nahm, S. and Lee, H.-G. (2010) Low-Temperature Sintering and Piezoelectric Properties of (Na0.5K0.5)NbO5 Lead-Free Piezoelectric Ceramics. Journal of the American Ceramic Society, 93, 36-39. http://dx.doi.org/10.1111/j.1551-2916.2009.03359.x
[21]	Park, H.-Y., Choi, J.-Y., Choi, M.-K., Cho, K.-H., Nahm, S., Lee, H.-G. and Kang, H.-W. (2008) Effect of CuO on the Sintering Temperature and Piezoelectric Properties of (Na0.5K0.5)NbO3 Lead-Free Piezoelectric Ceramics. Journal of the American Ceramic Society, 91, 2374-2377. http://dx.doi.org/10.1111/j.1551-2916.2008.02408.x
[22]	Zhou, J.-J., Cheng, L.-Q., Wang, K., Zhang, X.-W., Li, J.-F., Liu, H. and Fang, J.-F. (2014) The Phase Structure and Electric Properties of Low-Temperature Singtered (K, Na)NbO3-Based Piezoceramics Modified by CuO. Ceramics Inernational, 40, 2927-2931. http://dx.doi.org/10.1016/j.ceramint.2013.10.019
[23]	Zhou, J.-J., Li, J.-F., Cheng, L.-Q., Wang, K., Zhang, X.-W. and Wang, Q.-M. (2012) Addition of Small Amounts of BiFeO3 to (Li, K, Na)(Nb,Ta)O3 lead-Free Ceramics: Influence on Phase Structure, Microstructure and Piezoelectric Properties. Journal of the European Ceramic Society, 32, 3575-3582. http://dx.doi.org/10.1016/j.jeurceramsoc.2012.05.019