Characterization of hard piezoelectric lead-free ceramics.
K4CuNb8O23 doped K(0.45)Na(0.55)NbO3(KNNKCN) ferroelectric ceramics were found to exhibit asymmetrical polarization hysteresis loops, related to the development of an internal bias field. The internal bias field is believed to be the result of defect dipoles of acceptor ions and oxygen vacancies, which lead to piezoelectric "hardening" effect, by stabilizing and pinning of the domain wall motion. The dielectric loss for the hard lead-free piezoelectric ceramic was found to be 0.6%, with mechanical quality factors Q on the order of >1500. Furthermore, the piezoelectric properties were found to decrease and the coercive field increased, when compared with the undoped material, exhibiting a typical characteristic of "hard" behavior. The temperature usage range was limited by the polymorphic phase transition temperature, being 188 degrees C. The full set of material constants was determined for the KNN-KCN materials. Compared with conventional hard PZT ceramics, the lead-free possessed lower dielectric and piezoelectric properties; however, comparable values of mechanical Q, dielectric loss, and coercive fields were obtained, making acceptor modified KNN based lead-free piezoelectric material promising for high-power applications, where leadfree materials are desirable.
Zhang
Shujun
S
Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA. soz1@psu.edu
Lim
Jong Bong
JB
Lee
Hyeong Jae
HJ
Shrout
Thomas R
TR
Nature. 2004 Nov 4;432(7013):84-7
15516921
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Nov;52(11):2131-9
16422427
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 May;55(5):980-7
18519199
Appl Phys Lett. 2008 Apr 14;92(15):152904-1529043
19479047