Patent ID: 8114307

Claim:
A piezoelectric element comprising: a piezoelectric body comprising a piezoelectric film and a pair of electrodes in contact with the piezoelectric film, the piezoelectric film being interposed between the pair of electrodes; and a substrate on which the piezoelectric body is formed, wherein the piezoelectric film is an ABO 3 perovskite oxide in which an A-site atom consists of Bi and a B-site atom is composed of atoms of at least two types of elements, wherein the piezoelectric film includes at least two crystal phases, one of which is a tetragonal structure and another of which is selected from the group consisting of rhombohedral, pseudo-cubic, orthorhombic, and monoclinic structures, and wherein the ratio of the tetragonal structure is larger on the surface of the piezoelectric film at the side of the substrate than on the surface of the piezoelectric film at the other side.