Patent ID: 7348715

Claim:
A piezoelectric element comprising a layered structure in which a first electrode film, a piezoelectric thin film, and a second electrode film are layered in this order, wherein the piezoelectric thin film is made of lead zirconate titanate or lead-zirconate-titanate-based oxide, which is an oxide having a perovskite crystalline structure, the lead zirconate titanate having a chemical composition expressed by a chemical formula Pb (1-x) (Zr (1-s) Ti s )O 3 (0<s<1), the lead-zirconate-titanate-based oxide having a chemical composition expressed by a chemical formula (Pb (1-x-y) A y )(Zr (1-s-t) Ti s B t )O 3 (0<s<1, 0<t<1-s) where A is a substitutive metal ion in an A-site in the perovskite crystalline structure and B is a substitutive metal ion in a B-site in the perovskite crystalline structure, and the value of x in the chemical composition formulas of the lead zirconate titanate and the lead-zirconate-titanate-based oxide, which indicates a deficiency in Pb content in each composition that is a deviation from stoichiometric composition, is more than 0 but not more than 0.15.