Progress on the fabrication of lead-free textured piezoelectric ceramics: perspectives over 25 years

Further enhancement of the piezoelectric response in lead-free piezoelectric ceramics can be accomplished by inducing preferred orientation. In this paper, attempts have been made to review the progress on the fabrication of lead-free textured piezoelectric ceramics by the (reaction) templated grain growth method. The preparation (molten salt synthesis) and alignment (tape casting and extrusion molding) of anisometric template particles were introduced in detail. The texture evolution with heating was visualized by computer simulation. The review of lead-free textured piezoelectric ceramics focused on four promising systems: Na0.5Bi0.5TiO3-based, K0.5Na0.5NbO3-based, Ba(Zr0.2Ti0.8) O-3-(Ba0.7Ca0.3)TiO3 and KSr2Nb5O15. It is suggested that texturing of lead-free morphotropic phase boundary compositions will be required in order to realize viable lead-free alternatives to current lead-based materials.