Ahmad Safari

Department of Materials Science and Engineering, Rutgers University

607 Taylor Rd. Piscataway, New Jersey 08854 USA

safari@rci.rutgers.edu

 The ternary system (K,Na)NbO₃-LiTaO₃-LiSbO₃ exhibits unusually high piezoelectric properties despite being a Pb-free system, which caught great attention in recent years as there is a worldwide push for Pb-free materials technologies around the world due to environmental concerns.  In this talk, the recent advances in (K, Na) NbO₃-based ferroelectrics are reviewed, with special emphasis on the (K, Na) NbO3-LiTaO₃-LiSbO₃ system.  It will be shown that such ferroelectric ceramics are very sensitive to processing conditions such as purity of oxides used and the humidity of the ambient in which processing is accomplished.  Despite such sensitivity, it will be demonstrated that d₃₃ as high as 350 pC/N can be obtained in randomly oriented ceramics at room temperature. The origin of the high d₃₃ will be attributed to a tetragonal-orthorhombic phase transition in the vicinity of room temperature, and not to a morphotropic phase boundary.  The effects of Ba, Ag, and Cu doping on the properties of the (K, Na) NbO₃-LiTaO₃-LiSbO₃ system will also be discussed.  The properties of this system will be compared and contrasted with that of PZT in terms of phase transitions, dopants effects, and crystalloid-chemical principles. Possible venues for alleviating the strong temperature dependence of piezoelectric properties will be addressed. The acoustic properties of pure and 1 mol% Ba²⁺ doped (K,Na)NbO₃-LiTaO₃-LiSbO₃ will be compared to PZT-4 and PZT-5H, and it will be shown that one can fabricate Pb-free ultrasonic transducers with performance metrics close that of well-known PZT ceramics.

Also, Development of KNN-LT-LS thin Films by pulsed laser deposition will be discussed and the effects of dopants such as Mn and deposition conditions including temperature, oxygen pressure  on phase formation leakage currents and ferroelectric  properties will be presented.