Low-temperature sintering and piezoelectric properties of CuO-doped (K,Na)NbO3 ceramics

• Published in: Materials research bulletin Vol. 96; pp. 121 - 125
• Main Authors: Kim, J.H., Kim, J.S., Han, S.H., Kang, H.-W., Lee, H.-G., Cheon, C.I.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2017
• Subjects: A. Ceramics; B. Microstructure; B. Piezoelectricity; D. Dielectric properties; A. Ceramics; D. Dielectric properties; B. Microstructure; B. Piezoelectricity
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2017.03.066

[Display omitted] •KNN-based lead-freepiezoelectric ceramics was fabricated at the sintering temperature below 950°C by co-doping with Na2CO3 and CuO for multilayered piezoelectric devices.•The co-doped sample has not only a high mechanical quality factor (Qm) over 900 but also excellent piezoelectric properties.•Mechanisms on micostructure development and the change in piezoelectric properties with the sintering temperature were proposed. The lead-free piezoelectric [(K0.485Na0.515)0.935Li0.065](Nb0.99Ta0.01)O3 (KNLNT) ceramics with a high mechanical quality factor (Qm) were prepared at low sintering temperature below 950°C for multilayered piezoelectric devices. Co-doping effect of 1mol% Na2CO3 and 0–1mol% CuO on the densification and piezoelectric properties were investigated. Co-doping effectively decreased the sintering temperature of KNLNT ceramics to 920°C. The co-doped KNLNT ceramics had a bimodal size distribution of large abnormal grains and small matrix grains above 900°C. When the sintering temperature increased above 900°C, a dielectric constant (εr) and loss (tan δ) decreased considerably and concurrently mechanical quality factor (Qm) greatly enhanced. The co-doped KNLNT ceramic with 1mol% Na2CO3 and 0.5mol% CuO had a high Qm and excellent piezoelectric properties when sintered at 940°C: a dielectric constant of 245 and loss (tan δ) of 0.0034, an electromechanical coupling factor (kp) of 0.449, and Qm of 904.