Fabrication of Lead-Free Lithium-Doped Na 0.5 K 0.5 NbO 3 Piezoelectric Ceramics with Dense Grain Structure Using Sol–Gel Surface Coating

• Published in: Japanese Journal of Applied Physics Vol. 52; no. 10S; p. 10
• Main Authors: Lim, Sun Kyung, Han, Jeong Seon, Yoo, Ae Ri, Lee, Seong Eui, Lee, Hee Chul
• Format: Journal Article
• Language: English
• Published: 01.10.2013
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.52.10MB15

Lead-free piezoelectric 0.06(LiNbO 3 )–0.94(Na 0.5 K 0.5 )NbO 3 (LNKN) ceramics in disc form were fabricated and characterized to acquire good electromechanical properties. A molding method including cold isostatic pressing (CIP) was used to form a dense and regular microstructure and suppress the cracking problems of LNKN ceramics during the following high-temperature sintering. The LNKN ceramic sintered at 1040 °C showed a high piezoelectric constant d 33 of 170 pC/N owing to its high density. Furthermore, perovskite LNKN films with the same composition as the ceramics were fabricated using 2-methoxyethanol-based sol–gel solution. The sol–gel surface coating on the LNKN ceramics was found to be very effective for increasing the piezoelectric constant because of the interface stabilization effect leading to a uniform electric field in piezoelectric elements. As a result, we obtained the highest piezoelectric constant d 33 of 183 pC/N. The lead-free LNKN ceramics are promising for applications in eco-friendly ferroelectric and piezoelectric devices.