Hydrothermal lead zirconate titanate (Pb(Zr,Ti)O3: PZT) films with a thick of about 10 μm on both a Ti foil and a Ti layer sputtered stainless steel (SS) foil were obtained. Both PZT films showed same morphology and crystalinity. After repeating the hydrothermal process, the films were formed to cantilever shape. A tip displacement measurement of the cantilevers was carried out in order to estimate transverse piezoelectric constant (d31
). The obtained d31
value of the PZT films on Ti sputtered SS foils is -29 pm/V, which is larger than that on Ti foil (-24 pm/V). Amorphous layer consist of Pb and Ti was observed at the interfaces between the both PZT film and the Ti metals. The thickness of the layer for PZT film on Ti foil (350 nm) is thicker than that for PZT film on SS foil (200 nm). The relative permittivity of the layer is estimated to be small compared with that of PZT. Accordingly, the effective electric field for PZT layer is decreased. The deference of d31
values between the obtained PZT films is thought to be attributed to the thickness of amorphous layer.