Mechanical failure dependence on the electrical history of lead zirconate titanate thin films

Piezoelectric micromechanical systems (piezoMEMS) are often subjected to harsh mechanical and electrical loads during operation. This study evaluates the effects of the electrical history of a lead zirconate titanate (PZT) layer on the electro-mechanical response and structural limits of multilayer stacks. Electro-mechanical characterization was performed under biaxial bending employing the Ball-on-three Balls (B3B) test on virgin, poled, and DC biased (80 kV/cm) samples. No significant effect on the characteristic strength or Weibull modulus of the stack was observed. However, the crack initiation stress was highest for the virgin samples (σ₀ ∼ 485 ± 30 MPa); this decreased for both poled samples (σ₀ ∼ 410 ± 30 MPa), and samples measured under 80 kV/cm (σ₀ ∼ 433 ± 30 MPa). in situ ε_r and loss tangent measurements suggested electromechanical loading conditions can destabilize the domain structure. Overall, the electrical history and electromechanical loading conditions can reduce the PZT film's fracture resistance.