Reactive-templated grain growth processing for lead free piezoelectric ceramics

Abstract

Texture engineering using reactive-templated grain growth (RTGG) is reviewed as a key processing technique for lead free piezoelectric ceramics. Bismuth layer structured ferroelectric ABi₄Ti₄O₁₅ (A=Na_0·5Bi_0·5, Ca, Sr) ceramics with a highly preferred {001} orientation were fabricated with enhanced piezoelectric properties using Bi₄Ti₃O₁₂ platelets. Textured simple perovskite type ceramics were also prepared in Bi_0·5Na_0·5TiO₃ (BNT), BaTiO₃ and K_0·5Na_0·5NbO₃ (KNN) based compositions with Lotgering's factor higher than 0·8. The textured BNT and KNN based ceramics exhibited enhanced electromechanical coupling coefficients and piezoelectric constants when compared with their randomly oriented counterparts. The development of microstructure and texture in the RTGG processed ceramics is dependent on the target system, starting materials and processing parameters, and optimum preparation conditions must be found by analytical investigation.

Keywords:

• LEAD FREE PIEZOELECTRIC CERAMICS
• PEROVSKITE TYPE STRUCTURE
• PREFERRED ORIENTATION
• REACTIVE-TEMPLATED GRAIN GROWTH
• TOPOTAXY