The piezo-mems act extension is not supported and developed any longer and is replaced by the below coupled field systems.
Use the coupled field modal and harmonic to analyse Piezoelectric+structure+acoustics (if needed) in 2023 R1.
In 2023 R1 there is also a small database in Engineering data on piezoelectric material (e.g., PZT 5-H).
For an example on how to use coupled field harmonic analysis see technology demo or showcase TD39: Wire Bonding with Ultrasonic Transducer
All the best