Characterization of Hard Piezoelectric Lead-Free Ceramics

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 56; no. 8; pp. 1523 - 1527
• Main Authors: Shujun Zhang, Jong Bong Lim, Hyeong Jae Lee, Shrout, T.R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.08.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bias; Ceramics; Coercive force; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Constants; Dielectric loss; Dielectric losses; Dielectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Domain effects, magnetization curves, and hysteresis; Domain walls and domain structure; Environmentally friendly manufacturing techniques; Exact sciences and technology; Ferroelectric materials; Hysteresis; Lead free; Magnetic properties and materials; Niobium compounds; Phase transitions; Physics; Piezoelectric materials; Piezoelectric polarization; Piezoelectricity; Piezoelectricity and electromechanical effects; Temperature distribution; Polarization; Transition temperature; Vacancies; Dipoles; Doping; Ferroelectric ceramics; Piezoelectric properties; Piezoceramic materials; Defects; Lead free ceramic; Hysteresis loop; Ferroelectricity; Dielectric losses; Coercive force; Piezoelectricity; Oxygen ions; Mechanical loss
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2009.1215

K 4 CuNb 8 O 23 doped K 0.45 Na 0.55 NbO 3 (KNN-KCN) 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 188degC. 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.