UFFC-S Virtual Lecturer Education Series
Piezoelectric lead zirconate titanate (PZT) in the form of bulk ceramic, single crystal, composite, and thin films have been used in sensors, actuators, and other electromechanical devices. However, the toxicity of these materials and their exposure to the environment during processing steps such as calcination, sintering, machining, as well as problems in recycling and disposal have been major concerns around the globe for the past few decades. The report of high piezoelectric activity in the ternary lead-free KNaNbO₃-LiTaO₃- LiSbO₃ and (Bi,Na)TiO₃-(Bi,K)TiO₃-BaTiO₃ /(Bi,Li)TiO₃ systems have given high hope for alternatives to PZT. Recent modifications of KNN-based compositions with BaZrO₃, NTK, and Bi₀․₅(Li 0.5 /Na₀․₅) TiO₃ results in excellent electromechanical properties increased further research and interest in Pb-free materials and brings hope for practical applications close to reality. The organization of this lecture is in the following three sections:
First, Pb-Based piezoelectric materials in view of their flexibility on a wide range of composition, processing/reproducibility, and outstanding electromechanical properties will be reviewed. Processing of piezoelectric ceramic with various densification methods as well as the development of novel design ceramic and composite by additive manufacturing will be discussed. The advantages and disadvantages of Pb-based ceramics in several applications will be emphasized.
In the second part of the talk, the latest development on KNN and BNT based composition with an emphasis on the development of reproducible BNT-based hard piezoelectric composition with high mechanical quality factor and soft piezoelectric with moderate electromechanical properties will be reviewed. The BNT-based hard composition outperformed the Pb-based piezoelectric in high power applications due to the higher coercive field and more stable Q with vibration velocity. The research study of low-temperature sintering of BNT based ceramic with Cu electrode using a combination of sintering aids and a controlled atmosphere opens an excellent opportunity for Pb-free multilayer actuators.
Lastly, the design, development, and excellent performance of piezoelectric and dielectric composite for ultrasound imaging, energy harvesting and storage, and high-power applications will be presented.
Ahmad Safari is a Distinguished Professor of the Department of Materials Science and Engineering, and Director of Glenn Howatt Electroceramic Laboratory at Rutgers University. His main field of interest includes structural property relationships in electro-ceramic materials for dielectric, piezoelectric, and ferroelectric applications, thin films, and ceramic - polymer composites for transducers, and additive manufacturing of advanced functional materials. He has published over 400 articles and book chapters and edited a book and has been granted 22 U.S. patents. He has advised over 50 senior undergraduate projects, over 30 post-doctoral research associates/visiting scientists, and graduated over 30 Ph.D. and MS students. He has presented over 600 plenaries, invited, and contributed talks at national and international conferences, workshops, universities, and industries. He is a Fellow of the IEEE UFFC-S Society, American Ceramic Society, and a member of the World Academy of Ceramics. His sustained and impactful contributions in structure-property relationships of ferroelectric and piezoelectric ceramics, composites transducers, and films have been recognized by multiple awards including IEEE-UFFC Robert E. Newnham Ferroelectrics award, IEEE UFFC-S Ferroelectrics Recognition award, the theUS-Japan scientific committee of the Dielectric and Piezoelectric Meetings US-Japan Bridge building award, and Rutgers University prestigious Donald H.Jacobs Chair in Applied Physics.
Ahmad Safari is the recipient of the IEEE UFFC-S Distinguished service award for his outstanding contribution to society for over 25 years in various capacities. He has been an active member of the AdCom for over 35 years in various positions including President, president-elect, VP of Ferroelectrics, executive member of AdCom, VP Symposia, Symposium General Chair for the Joint 2013 UFFC-EFTF and PFM Symposia, and the IEEE ISAF 96, and, TUFFC Associate Editor; member of Ferroelectrics Technical Standing Committee, and member of several UFFC-S AdCom committees including ISAF and IUS Technical Program, UFFC Bylaw, Fellow, Awards, Finance, and AdCom Emeritus. He has led the IEEE UFFC-S international delegation leader of the People-to-People Ambassador Program to China.