Microstructural engineering of crystallographically textured BiScO₃-PbTiO₃-based piezoceramics with improved high-temperature stability

Ferroelectric materials with outstanding thermal stability are extremely essential for high-performance electromechanical device applications operating at elevated temperatures. In this study, templated grain growth (TGG) method was utilized as a microstructural engineering strategy to fabricate textured polycrystalline high-temperature piezoceramics with a ternary composition of 2.5Bi(Zn0.5Zr0.5)O-3-37.5BiScO(3)-60PbTiO(3) (BZZ-BS-PT). 1, 3, 5 and 7 vol% of < 001 > -oriented BaTiO3 (BT) plate-like template particles were aligned in the BZZ-BS-PT matrix powder via tape casting and then sintered in air at 1100 degrees C for 3 h. A high crystallographic orientation (similar to 90 %) in the [001] was successfully achieved for dense textured ceramics. Microstructure analyses revealed chemically stable BT templates in matrix with minor Bi-rich or Sc-rich secondary phases. Interestingly, the TGG process induced an extraordinary microstructural phenomenon in all textured ceramics, characterized by multiple matrix grains in contact with a single template particle, along with typical oriented block-like grain structures. Significant texturing in BZZ-BS-PT ceramics led to dramatic increases in electrical and electromechanical properties (in between 24 % and 87 %) in comparison to those of random ones. Enhanced piezoelectric and electromechanical performance of textured ceramics exhibited excellent thermal stability at high temperatures due to their high Curie temperature (T-C > 400 degrees C) and depolarization temperature (T-d > 380 degrees C). These findings point out that the highly textured BZZ-BS-PT piezoceramics can be potential candidates for high-temperature applications with a safety operating temperature as high as 350 degrees C.