Processing and Piezoelectric Properties of Lead-Free (K,Na) (Nb,Ta) O3 Ceramics
The preparations of (K0.5Na0.5)NbO3 (KNN)-based ceramics were studied as lead-free piezoelectric materials. The authors found that the addition of CuO greatly enhanced the sinterability of the KNN-based ceramics. The sinterability and piezoelectric properties of these ceramics were dependent upon the A/B ratio, CuO doping, and the formation of a solid solution with KTaO3. Perovskite (K0.5Na0.5)xNbO3 (x=A/B ratio) was synthesized with A/B ratios of 1.00 and 1.05 by CuO doping, while (K0.5Na0.5)NbO3 contained K4CuNb8O23 as a second phase with A/B ratios below 0.98. Although the A site-rich (K0.5Na0.5)NbO3 (x=1.00 and 1.05) ceramics exhibited deliquescence, the A site-poor (K0.5Na0.5)NbO3 (x≤0.98) ceramics with K4CuNb8O23 had higher densities without deliquescence. K4CuNb8O23 also improved Qm, which reached 1400 for the (K0.5Na0.5)1.0NbO3 doped with 0.5 mol% K4CuNb8O23. The formation of a solid solution with KTaO3 raised the melting point of the system and also improved its sinterability. The kp and Qm of (K0.5Na0.5)0.97(Nb0.95Ta0.05)O3 with CuO were 0.41 and 1400, respectively.
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Document Type: Research Article
Affiliations: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
Publication date: May 1, 2005