Ultra light tunable capacitor based on PZT thin film deposited onto aluminium foil

Lead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 57/43, elaborated by a derived sol–gel process, have been deposited onto bare and RuO2 coated aluminium substrate 16 μm thick. Commercial aluminium foil presents many advantages as ultra light weight (43 g m−2), conformability, conduction, can be easily cut, and is one of the cheapest substrates used for PZT thin films deposition (<0.1$ m-2). XRD measurements have shown a well crystallized PZT in the perovskite structure and ferroelectric behaviour has also been observed. By the use of a RuO2 film 100 nm thick at the PZT/aluminium interface, the coercive field and tunability values have been strongly improved despite an increase of the dielectric losses. The lead excess introduced in the precursor solution has been increased up to 65 % in order to lower the crystallization temperature of the PZT around 560 °C and tunability has been studied as a function of annealing time and temperature.