Grain oriented Na0.5Bi0.5TiO3-BaTiO3 ceramics with giant strain response derived from single-crystalline Na0.5Bi0.5TiO3-BaTiO3 templates

Grain oriented lead-free piezoelectric 0.93Na0.5Bi0.5TiO3-0.07BaTiO3 (NBT-7BT) were fabricated by templated grain growth (TGG) method using single-crystalline NBT-7BT platelets with a morphotropical phase boundary (MPB) as templates. The NBT-7BT templates were synthesized by the topochemical technique, using Na0.5Bi4.5Ti4O15 (NBIT) platelets as precursors. The grain oriented NBT-7BT ceramics were textured with 10 wt% of NBT-7BT templates and sintered at 1175 °C for 5-50 h. The microstructure, strain behavior and temperature-dependent permittivity of lead-free NBT-7BT ceramics were systematically investigated. The strain responses of the grain oriented NBT-7BT ceramics were found to increase monotonously with the increase of the grain orientation degree. The NBT-7BT ceramic with 89% degree of grain orientation had an excellent actuating performance with up to 0.7% free strain at 7 kV/mm at room temperature, corresponding to a field-induced Smax/Emax of as high as 1000 pm/V.