Preparation and electrical properties of fine-scale 1–3 lead zirconic titanate∕epoxy composite thick films for high-frequency ultrasonic transducers

1–3 connectivity lead zirconic titanate (PZT)∕epoxy composite thick films containing fine-scale and high aspect ratio PZT pillars (40μm sectional width, 40μm spacing, and 5.5 aspect ratio) were obtained by a modified dice and fill method. The composite thick film works at a high frequency >7MHz with a clear and uncoupled thickness mode, together with a relatively high electromechanical coupling coefficient (kt=56.4%), low acoustic impedance (Z=7.8 Mrayls), and low mechanical Qm (3.3). High piezoelectric coefficient (d33=332pCN−1) along with reduced dielectric constant (εr=105) endowed the composite films an enhanced piezoelectric voltage coefficient g33 value of 357×10−3m2∕C, which is required to increase the receiving voltage sensitivity. The present piezocomposite thick film with microscale ordered structure is promising for high-frequency ultrasonic transducers.