Microstructural studies of PZT thick films on Cu foils

This paper explains the limits of processing conditions for Pb(Zr, Ti)O3 (PZT) thick films on Cu substrates. PZT thick films in the thickness range 5–20 μm deposited on flexible Cu foils by electrophoretic deposition showed poorer properties when compared with PZT thick films deposited on Pt foils under identical conditions. Although the density of the sintered films and the electrical properties were improved by introducing a PbO coating on the top of the films, the dielectric and ferroelectric properties of PZT thick films on Cu were still inferior to those of films deposited on Pt. Rutherford backscattering spectrometry, X-ray diffraction and transmission electron microscopy revealed the formation of a Cux–Pb alloy when sintering above 950 °C, accompanied by Ti enrichment of the PZT and the formation of ZrO2 phases. As the sintering temperature increased, the concentration of the metallic phase increased and spread throughout the film. A new Pb–Cu alloy phase was identified. The poorer electrical properties of PZT thick films on Cu were correlated with these microstructural features.