Piezoelectric thin film, piezoelectric element, and manufacturing method thereof

摘要

Provided are a piezoelectric thin film having good piezoelectricity in which a rhombohedral structure and a tetragonal structure are mixed, and a piezoelectric element using the piezoelectric thin film. The piezoelectric thin film includes a perovskite type metal oxide, in which the perovskite type metal oxide is a mixed crystal system of at least a rhombohedral structure and a tetragonal structure, and a ratio between an a-axis lattice parameter and a c-axis lattice parameter of the tetragonal structure satisfies 1.15≦c/a≦1.30. The piezoelectric element includes on a substrate: the above-mentioned piezoelectric thin film; and a pair of electrodes provided in contact with the piezoelectric thin film.

主权项

1. A piezoelectric element comprising a substrate and, on the substrate, laminated in stated order:
a first electrode; a piezoelectric thin film comprising a perovskite-type metal oxide; and a second electrode, wherein the perovskite-type metal oxide has a mixed crystal system having at least a rhombohedral structure and a tetragonal structure at 25° C., wherein the perovskite-type metal oxide contains a metal oxide represented by general formula (1):
Bix(M1-yCoy)O3  (1), where M represents at least one kind of metal selected from Fe and Al, and x and y satisfy 0.95≦x≦1.25 and 0.05≦y≦0.15, wherein a ratio between an a-axis lattice parameter and a c-axis lattice parameter of the tetragonal structure satisfies 1.15≦c/a≦1.30, and wherein the piezoelectric thin film is lead-free.