Textured piezoelectric ceramics with reduced grain size for high-frequency transducer applications

Textured piezoelectric ceramics are considered promising next-generation piezoelectric materials, offering single-crystal-like high piezoelectric performance and low production cost. However, the large grain size of textured ceramics (15 ~ 40 μm) lead to significant decrease in piezoelectricity as the thickness of samples approaches the scale of grain size, limiting their application in high-frequency transducers (>20 MHz, corresponding thickness <100 μm). Here, we address this issue by reducing the grain size through template shortening. A modified topochemical microcrystal conversion method was developed to fabricate BaTiO₃ templates with a much smaller length of 2.7 μm, compared with conventional templates (>7 μm). Using these reduced-size developed templates, we obtained <001 > -textured Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ ceramic with an average grain size of 7.8 μm, being significantly smaller than previously reported textured Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ ceramics (~20 μm), while achieving a high piezoelectric coefficient d₃₃ of 1330 pC N^-1. Notably, the adverse thickness scaling effect on piezoelectric performance was greatly mitigated: at a thickness of 100 μm, the piezoelectric response was found to reduce only 8% for our textured ceramics with reduced grain size, compared with almost 30% in conventional-grain-size textured ceramics. This strategy provides a practical route to high-performance textured ceramics suited for next-generation high-frequency ultrasonic transducers.