Domain Wall Engineering in Lead-Free Piezoelectric Crystals

For [111] poled barium titanate (BaTiO3) single crystals, piezoelectric properties increased with decreasing domain sizes. To explain the phenomenon, the multidomain crystals were regarded as composite of (a) a distorted 90° domain wall region with ultrahigh piezoelectric property and (b) a normal tetragonal domain region. This model suggested that the d 31 of the lead-free piezoelectric crystals with domain sizes below 1 μ m can be over 1,000 pC/N. Thus, to induce the finer engineered domain configurations, a patterning electrode was used. As the results, the domain size of 3 μm was successfully induced, and the d31 was obtained at −243.2 pC/N.