Preparation and enhanced electrical properties of grain-oriented (Bi1/2Na1/2)TiO3-based lead-free incipient piezoceramics

(Bi1/2Na1/2)TiO3 (BNT) based lead-free incipient piezoceramics are promising candidates for actuator applications due to their giant electromechanical strains originating from the reversible relaxor-ferroelectric phase transition. To decrease the electric field required for this large strain, the templated grain growth method was employed to prepare < 100 > oriented 0.91Bi(1/2)Na(1/2)TiO(3)-0.06BaTiO(3)-0.03AgNbO(3) piezoceramics using plate-like BNT templates. Textured samples provided a high unipolar strain of 0.38% and a corresponding large signal piezoelectric coefficient, d(33)* of 766 pm/V at 5 kV/mm, which are 78% higher than the values of the randomly oriented ones. The enhanced electric-field-induced strain at relatively lower field was attributed primarily to the facilitated phase-transition to form a long range ferroelectric order along the < 100 > direction. It was also found that the textured piezoceramics exhibited significantly reduced frequency dependence in the unipolar strain behavior at room temperature, resulting from the decreased electric field required for the relaxor-ferroelectric phase transition. (C) 2015 Elsevier Ltd. All rights reserved.