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In this work, piezoelectric PbZr0.52Ti0.48O3 (PZT) thick films were deposited onto silicon and alumina substrates using sol-gel composite slurry. Thick films prepared with rough and attrited powders are compared. A time stable polymeric PZT sol was first synthesised as the binder. It was then used as a precursor for PZT powder fabrication. Powder attrition ball milling was optimised to reduce the particles size to 200 nm. Composite slurries were obtained by mixing PZT sol with attrited or rough powders and thick films were deposited by dip-coating. The film thickness, roughness and microstructure were studied as a function of powder content, particle size, sol concentration and slurry ageing. Electromechanical measurements were performed. By strictly controlling each step of the thick film fabrication, high coupling factor (thickness mode, kt) can be obtained using both types of powder. Nevertheless, with attrited powder, better and more reproducible effective coupling coefficients in thickness mode (kt up to 46%) were reported on silicon and alumina substrates.

In this study, high performance piezoelectric thick films were prepared by depositing only a few sol–gel infiltrated composite layers on Si/SiO 2 /Ti/Pt wafers. Lead zirconate titanate (PZT) powder, binder and infiltration sol were synthesised from the same-laboratory made time-stable polymeric PZT sol. Adding coarse powder (50 wt%) to the sol precursor, crack-free coatings were prepared by dip coating in the 30–50 μm thickness range in only 3–6 layers. The results showed that good performance can be achieved by controlling sol concentration, powder charge, composite sol ageing, number of infiltrations and heat treatments. The initial results showed that only a limited number of infiltrations are needed in the final stack to obtain high piezoelectric performance. For instance, a 40 μm thick film was prepared with 6 composite layers with a 0.7 M PZT sol charged with 50 wt% PZT powder after 2 months’ ageing. Poling was performed for 5 min under 15 V/μm in an oil bath at 170 °C after 5 infiltrations and final annealing at 700 °C for 10 min in RTA. Despite substrate clamping, this coating reached an effective thickness coupling factor up of to 39% at a resonance frequency of 30 MHz. This result was obtained with a non-doped PZT powder.

High frequency piezoelectric films were prepared using the composite sol-gel technique, by mixing PZT sol and laboratory-made powders, free-cracked thick films were deposited by dip-coating on silicon, alumina and porous PZT substrates. Only 3 composite layers and few final infiltrations were used to prepare 40 mum thick films. Reproducible electromechanical properties, i.e. thickness coupling coefficients around 40%, were obtained after a poling at 15V mum in an oil bath at 170degC. A pulse echo response was measured with a 35 mum thick film deposited on a porous PZT substrate. The corresponding characteristics are an axial resolution of 45 mum (with a bandwidth at 80*%) at -6dB and a center frequency of 20 MHz. These results showed that the composite sol-gel process is a good candidate to produce piezoelectric films with a thickness of few tens of microns with a minimization of fabrication steps.

The permeability of inclusions consisting of commercially available piezoelectric disks was investigated, leading to the observation of several resonances in the 100MHz–3GHz range. This could be described through a simple analytical relation, and the inclusions were deemed attractive for manufacturing metamaterials with negative permeabilities over a significant frequency range. Moreover, they can be used as reference permeability samples.