Ferroelectric thin film ultrasonic micromotors

Abstract

Ferroelectric thin films of lead zirconate titanate (PZT) of the morphotropic phase boundary composition have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant (1300) and breakdown strength (1 MV/cm) of the films lead to high stored energy densities. The piezoelectric coefficients d33 and d 3~ were measured to be 220 pC/N and -88 pC/N respectively; the electromechanical coupling factors calculated thereupon were k33=0.49, k31=0.22, and kp=0.32. The development of the piezoelectric ultrasonic nucromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimiwi prototype micromotors show rotational velocities of 100-300 rpm, and net normalized torques in the pN-m/vz range.

Fabrication and characterization of PZT thin-film vibrators for micromotors

“…They are between 20 % and 30 % of the bulk ceramic value of 2.0 C/m 2 . These values are quite reasonable and compare well with the piezoelectric coefficient d 33 , measured by interferometry at films on plane wafers, as described in Ref. [13].…”

Piezoelectric actuation of PZT thin-film diaphragms at static and resonant conditions

“…Standing deflection waves, travelling waves or Lamb waves have been explored for micromotors [1,2] and micro-pumps [3]. Acoustic applications have also been investigated [4].…”

Innovative materials for aircraft morphing

“…PZT-based microactuators (0.2 to 10 µm thick) have demonstrated displacements of 0.1 to 0.6 µm at 5 to 10 V operation 14 . To further develop these devices, a metalloorganic decomposition (MOD) process is being used to produce high-quality ferroelectric thin films on Si microstructures.…”