Lead-free piezoelectric ceramics: Alternatives for PZT?

Abstract

Investigations in the development of lead-free piezoelectric ceramics have recently claimed comparable properties to the lead-based ferroelectric perovskites, represented by Pb(Zr,Ti)O 3 , or PZT. In this work, the scientific and technical impact of these materials is contrasted with the various families of "soft" and "hard" PZTs. On the scientific front, the intrinsic nature of the dielectric and piezoelectric properties are presented in relation to their respective Curie temperatures (T C ) and the existence of a morphotropic phase boundary (MPB). Analogous to PZT, enhanced properties are noted for MPB compositions in the (Na,Bi)TiO 3 -BaTiO 3 and ternary system with (K,Bi)TiO 3 , but offer properties significantly lower. The consequences of a ferroelectric to antiferroelectric transition well below T C further limits their usefulness. Though comparable with respect to T C , the high levels of piezoelectricity reported in the (K,Na)NbO 3 family are the result of enhanced polarizability associated with the orthorhombic-tetragonal polymorphic phase transition being compositionally shifted downward. As expected, the properties are strongly temperature dependent, while degradation occurs through the thermal cycling between the two distinct ferroelectric domain states. Extrinsic contributions arising from domains and domain wall mobility were determined using high field strain and polarization measurements. The concept of "soft" and "hard" lead-free piezoelectrics were discussed in relation to donor and acceptor modified PZTs, respectively. Technologically, the lead-free materials are discussed in relation to general applications, including sensors, actuators and ultrasound transducers.

Microstructure effects on BaTiO3/BaTi0.8Zr0.2O3 composites properties

“…Barium titanate (BaTiO3) is a perovskite type (ABO3) ferroelectric material [1] employed as main component in a variety of environmentall-friendly electronic devices such as memory storage systems, piezoelectric transducers, pyroelectric detectors and multi-layer ceramic capacitors [2][3][4][5]. However, in order to meet the technological requirements that these devices must satisfy, i.e.…”

First-principles studies of lone-pair-induced distortions in epitaxial phases of perovskiteSnTiO3andPbTiO3

“…[9][10][11][12][13][14] However, developing suitable replacements remains a great challenge, as, paraphrasing the authors of Ref. 12, when performance, cost, ease of preparation and precursors availability are taken into account, PZT still remains the almost perfect all-around piezoelectric material.…”

Effect of Nb-donor and Fe-acceptor dopants in (Bi1/2Na1/2)TiO3–BaTiO3–(K0.5Na0.5)NbO3 lead-free piezoceramics

“…3 A second system that has received much attention is ͓K 0.5 Na 0.5 ͔NbO 3 ͑KNN͒, 3,5 although the phase boundary in this system was eventually shown to be a polymorphic phase boundary instead of an MPB. 3,6 One reason for the versatility of PZT is the possibility to fine-tune its properties by doping with different elements. In the literature there are comparably few reports on the isovalent doping of PZT ͑Refs.…”