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

## TL;DR

This paper presents a new method to create high-performance lead-free piezoelectric thick films using aerosol deposition, suitable for MEMS applications.

## Contribution

A high-throughput aerosol deposition method for creating Ba(ZrxTi1−x)O3 thick films with large transverse piezoelectricity.

## Key findings

- Optimal electromechanical performance at x = 0.03 due to coexisting tetragonal and orthorhombic phases.
- BZT films achieved a transverse piezoelectric coefficient of 1.01 C/m2, comparable to sputtered BaTiO3 films.
- Aerosol deposition enabled dense, crack-free films with high deposition efficiency.

## Abstract

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(ZrxTi1−x)O3 (BZT, x = 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 x = 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 |e31, f| 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.