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 BaTiO 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(MgNb)O-PbTiO ceramic with an average grain size of 7.8 μm, being significantly smaller than previously reported textured Pb(MgNb)O-PbTiO ceramics ( 20 μm), while achieving a high piezoelectric coefficient d of 1330 pC N. 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.