Influence of powder preparation process on piezoelectric properties of PZT sol-gel composite thick films

In this work, piezoelectric PbZr_0.52Ti_0.48O₃ (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, k_t) can be obtained using both types of powder. Nevertheless, with attrited powder, better and more reproducible effective coupling coefficients in thickness mode (k_t up to 46%) were reported on silicon and alumina substrates.