Preparation and enhanced electric-field-induced strain of textured 91BNT-6BT-3KNN lead-free piezoceramics by TGG method

摘要

<001> oriented 0.91Bi_(1/2)Na_(1/2)TiO_3-0.06BaTiO_3-0.03(Na,K)NbO_3 (BNT-BT-KNN) lead-free piezoceramics were fabricated by templated grain growth method. A high grain orientation degree (Lotgering factor F is 83 %) was achieved with 5 wt% Bi_(1/2)Na_(1/2)TiO_3 (BNT) template content and a maximum strain value of 0.226 % was observed, which was 48.7 % higher than that of randomly oriented samples. However, too much BNT template will result in composition deviation from morphotropic phase boundary of BNT-BT-KNN system and disruption of the non-polar phase at zero electric field. All textured samples with 1-10 wt% template addition showed enhanced strain and large signal piezoelectric coefficient d_(33)~* without disrupting the non-polar phase at zero electric field. The enhanced electric-field-induced strain of the textured sample was primarily attributed to the facilitated phase-transition, which formed a long-range ferroelectric order along the <001> direction.