A film structure (10) includes a substrate (11), a piezoelectric film (14) formed on the substrate (11) and containing first composite oxide represented by a composition formula Pb(Zr.sub.1-xTi.sub.x)O.sub.3, and a piezoelectric film (15) formed on the piezoelectric film (14) and containing second composite oxide represented by a composition formula Pb(Zr.sub.1-yTi.sub.y)O.sub.3. In the composition formulae, x satisfies 0.10<x≤0.20, and y satisfies 0.35≤y≤0.55. The piezoelectric film (14) has tensile stress, and the piezoelectric film (15) has compressive stress.

A method for preparing a piezoelectric film includes: coating a solution containing a piezoelectric polymer and a solvent on a substrate to obtain a film, wherein the piezoelectric polymer is a copolymer of vinylidene fluoride and trifluoroethylene; and annealing the film at a temperature ranging from 122° C. to 133° C., to obtain the piezoelectric film.

A method for preparing a piezoelectric film includes: coating a solution containing a piezoelectric polymer and a solvent on a substrate to obtain a film, wherein the piezoelectric polymer is a copolymer of vinylidene fluoride and trifluoroethylene; and annealing the film at a temperature ranging from 122° C. to 133° C., to obtain the piezoelectric film.

A method of manufacturing a piezoelectric actuator includes preparing a laminate including a substrate, a first electrode layer disposed on the substrate, a piezoelectric layer disposed on the first electrode layer, and a second electrode layer disposed on the piezoelectric layer, and forming a contour shape of the piezoelectric layer. The forming of the contour shape includes dry etching the piezoelectric layer from the second electrode layer side to dig the piezoelectric layer halfway in a thickness direction, covering, with a resist film, a dry etched surface formed on a side surface of the piezoelectric layer by the dry etching, and wet etching the piezoelectric layer from the second electrode layer side to dig the piezoelectric layer until the first electrode layer is reached.

A method of manufacturing a piezoelectric actuator includes preparing a laminate including a substrate, a first electrode layer disposed on the substrate, a piezoelectric layer disposed on the first electrode layer, and a second electrode layer disposed on the piezoelectric layer, and forming a contour shape of the piezoelectric layer. The forming of the contour shape includes dry etching the piezoelectric layer from the second electrode layer side to dig the piezoelectric layer halfway in a thickness direction, covering, with a resist film, a dry etched surface formed on a side surface of the piezoelectric layer by the dry etching, and wet etching the piezoelectric layer from the second electrode layer side to dig the piezoelectric layer until the first electrode layer is reached.

Piezoelectric assembly, which comprises a substrate of Ni, Cu, or steel, a first oriented layer assembled on the substrate and a piezoelectric layer on the oriented layer. The piezoelectric layer has a degree of (100) orientation with respect to the local surface normal of 90% or more.

Piezoelectric assembly, which comprises a substrate of Ni, Cu, or steel, a first oriented layer assembled on the substrate and a piezoelectric layer on the oriented layer. The piezoelectric layer has a degree of (100) orientation with respect to the local surface normal of 90% or more.

The present disclosure provides a method for forming piezoelectric films on surfaces of arbitrary morphologies. The method includes providing a sol for forming the piezoelectric film; spraying the sol onto the surface thereby forming a liquid film containing the sol on the surface; wiping the liquid film with a flattening tool for flattening the liquid film; drying the flattened liquid film thereby forming a gel layer; and annealing the gel layer thereby forming the piezoelectric film. The piezoelectric films with high uniformity and desired thickness can be formed on curved and even wrinkled surfaces by the present method.

The present disclosure provides a method for forming piezoelectric films on surfaces of arbitrary morphologies. The method includes providing a sol for forming the piezoelectric film; spraying the sol onto the surface thereby forming a liquid film containing the sol on the surface; wiping the liquid film with a flattening tool for flattening the liquid film; drying the flattened liquid film thereby forming a gel layer; and annealing the gel layer thereby forming the piezoelectric film. The piezoelectric films with high uniformity and desired thickness can be formed on curved and even wrinkled surfaces by the present method.

A piezoelectric drive device includes a piezoelectric element, a vibrating plate with a concave portion provided in a side surface, and a projecting portion provided between two side surfaces of the concave portion and having a spherical shape, an elliptical shape, or an egg shape, wherein a plurality of the piezoelectric elements and a plurality of the vibrating plates are stacked, and the concave portion includes a bottom surface.