Engineering Polymorphic Phase Boundary in Aerosol-Deposited Ba(ZrxTi1−x)O3 Thick Films for Large Transverse Piezoelectricity

Conventional deposition techniques hinder the integration of high-performance lead-free piezoelectric thick films on silicon substrates due to slow growth kinetics and complex processing. Herein, dense, crack-free Ba(Zr<i>_x</i>Ti_1-<i>_x</i>)O₃ (BZT, <i>x</i> = 0-0.10) thick films (~2 μm) were fabricated via aerosol deposition (AD) followed by annealing, forming a nanocrystalline microstructure with an average grain size of ~78 nm. Compositional tuning showed optimal electromechanical performance at <i>x</i> = 0.03, attributed to the coexistence of tetragonal and orthorhombic phases near room temperature that reduce the phase transformation energy barrier. The optimized BZT films exhibit excellent electrical properties: saturation polarization of 31.3 μC/cm², relative permittivity of 430, dielectric tunability figure of merit (FOM) of 155, and a large transverse piezoelectric coefficient |e_31,<i>_f</i>| of 1.01 C/m²-comparable to textured magnetron-sputtered BaTiO₃ films but with higher deposition efficiency. This work provides a high-throughput route for fabricating piezoelectric thick films, highlighting the potential of compositionally engineered AD-processed BZT in lead-free MEMS applications.