Synthesis of Single-Crystalline Plate-Shaped K_0.5Na_0.5NbO₃ Particles by Multi-Step Molten Salt Method

Abstract:

In this study, single-crystalline plate-shaped KNN particles were successfully synthesized by a multi-step molten salt method (MMSM). First, precursor particles K₄Nb₆O₁₇ (K4N6) with layer-structure was synthesized at 1050 °C in molten KCl-salt (MMSM-1) by starting materials of Nb₂O₅ and K₂CO₃. Second, plate-shaped KNN was synthesized at 1000 °C in molten KCl-NaCl-salt (MMSM-2) from K4N6 particles and K₂CO₃ powders. X-ray diffraction (XRD) analysis revealed that the crystallographic {010} plane of K4N6 was converted into the pseudo-cubic {001} plane of KNN. SEM images showed that MMSM-synthesized KNN particles preserved the shape of K4N6 precursor particles, and had a thickness of about 3 ~ 5 μm, a width of 10 ~ 15 μm and a length of 15 ~ 20 μm. EDX spectrum proved that the K:Na mole ratio was 0.6:0.4. These plate-shaped KNN particles were very promising templates to fabricating textured KNN-based ceramics.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 1395-1398
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.1395
• Online since: June 2012
• Authors: Zhi Liu, Yue Ming Li, Zong Yang Shen, Zhu Mei Wang
• Keywords: Multi-Step Molten Salt Method, Perovskite, Piezoelectric Ceramic (PZT)

References

[1] EU-Directive 2002/96/EC: Waste electrical and electronic equipment (WEEE): Off. J. Eur. Union 46 (2003) 24–38.

[2] EU-Directive 2002/95/EC: Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS): Off. J. Eur. Union 46 (2003) 19–23.

[3] J. Rödel, W. Jo, K.T.P. Seifert, E.M. Anton, T. Granzow and D. Damjanovic, Perspective on the Development of Lead-free Piezoceramics, J. Am. Ceram. Soc. 92 (2009) 1153-1176.

DOI: 10.1111/j.1551-2916.2009.03061.x

[4] Y. Saito, H. Takao, T. Tani, et al, Lead-free piezoceramics, Nature 432 (2004) 84-87.

DOI: 10.1038/nature03028

[5] Y.M. Li, Z.Y. Shen, L. Jiang, et al., Phase transition and electrical properties of LiNbO3-modified K0.49Na0.51NbO3 lead-free piezoceramics, J Mater Sci: Mater Electron. 22 (2011) 1071-1075.

DOI: 10.1007/s10854-010-0261-1

[6] Y.M. Li, Z.Y. Shen, L. Jiang, et al., Microstructure, phase transition and electrical properties of LiSbO3-doped (K0.49Na0.51)NbO3 lead-free piezoelectric ceramics, J Mater Sci: Mater Electron. 22 (2011) 1409-1414.

DOI: 10.1007/s10854-011-0322-0

[7] L. Zhao, F. Gao, C. Zhang, M. Zhao, C. Tian, Molten salt synthesis of anisometric KSr2Nb5O15 particles, J. Cryst. Growth. 276 (2005) 446-452.

DOI: 10.1016/j.jcrysgro.2004.11.388

[8] Y. Saito, H. Takao, Synthesis of polycrystalline platelike NaNbO3 particles by the topochemical micro-crystal conversion from K4Nb6O17 and fabrication of grain-oriented (K0.5Na0.5)NbO3, J Electroceram. 24 (2010) 39-45.

DOI: 10.1007/s10832-008-9557-4

[9] Y. Saito, H. Takao, Synthesis of polycrystalline platelike KNbO3 particles by the topochemical micro-crystal conversion method and fabrication of grain-oriented (K0.5Na0.5)NbO3 ceramics, Journal of the European Ceramic Society. 27 (2007) 4085-4092.

DOI: 10.1016/j.jeurceramsoc.2007.02.099

[10] C. Sun, X. Xing, J. Chen, J. Deng, L. Li, R. Yu, L. Qiao, G.Liu, Hydrothermal Synthesis of Single Crystalline (K,Na)NbO3 Powders, Eur. J. Inorg. Chem. 2007 (2007) 1884-1888.

DOI: 10.1002/ejic.200601131

[11] J.T. Zeng, K.W. Kwok, H.L. C. Chan, KxNa1-xNbO3 powder synthesized by molten-salt process, Mater. Lett..61 (2007) 409-411.

DOI: 10.1016/j.matlet.2006.04.083

[12] F. Zhang, L. Han, S. Bai, T.D. Sun, K. Tomoaki, A. Masatoshi, Hydrothermal Synthesis of (K,Na)NbO3 Particles, Jpn. J. Appl. Phys. 47 (2008) 7685-7688.

[13] L.H. Li, J. Chen, J.X. Deng, R.B. Yu, L.J. Qiao, G.R. Liu, X.R. Xing, Topochemical Synthesis of Micron-Platelet (Na0.5K0.5)NbO3 Particles, Eur. J. Inorg. Chem. 2008 (2008) 2186-2190.

DOI: 10.1002/ejic.200701263