Fabrication and characterization of PZT thick films for sensing and actuation

Lead Zirconate Titanate oxide (PZT) thick films with thicknesses of up to 10 μm were developed using a modified sol-gel technique. Usually, the film thickness is less than 1 μm by conventional sol-gel processing, while the electrical charge accumulation which reveals the direct effect of piezoelectricity is proportional to the film thickness and therefore restricted. Two approaches were adopted to conventional sol-gel processing - precursor concentration modulation and rapid thermal annealing. A 10 μm thick film was successfully fabricated by coating 16 times via this technique. The thickness of each coating layer was about 0.6 μm and the morphology of the film was dense with a crack-free area as large as 16 mm². In addition, the structure, surface morphology and physical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) and electrical performance. The dielectric constant and hysteresis loops were measured as electric characteristics. This study investigates the actuation and sensing performance of the vibrating structures with the piezoelectric thick film. The actuation tests demonstrated that a 4 mm × 4 mm × 6.5 μm PZT film drove a 40 mm × 7 mm × 0.5 mm silicon beam as an actuator. Additionally, it generated an electrical signal of 60 mV_pp as a sensor, while vibration was input by a shaker. The frequencies of the first two modes of the beam were compared with the theoretical values obtained by Euler-Bernoulli beam theory. The linearity of the actuation and sensing tests were also examined.