Effect of Reoriented Nanodomains on Crystal Structure and Piezoelectric Properties of Polycrystalline Ferroelectric Ceramics

It has been widely accepted that electric fields induce a reversible structural phase transition and thus yield giant piezoelectric responses in ferroelectric ceramics. Based on detailed measurements of polycrystalline (Li 0.5 Nd 0.5 ) 2+ -modified 0.95Bi 0.5 Na 0.5 TiO 3 -0.05BaTiO 3 ceramics, we demonstrate in this study that coherent diffraction from nanodomains in ferroelectric ceramics masks the real crystal structure. The observed electric-field-induced phase transformation behavior is a consequence of relaxor-to-ferroelectric transformation caused by changes in the coherence length of the nanodomains. A driving mechanism of the structure–property relationship in which high piezoelectric properties originate from correlated ordering of nanodomains during poling is proposed.