US Patent No. 9,461,238

PIEZOELECTRIC THIN FILM, PIEZOELECTRIC ELEMENT, AND MANUFACTURING METHOD THEREOF


Patent No. 9,461,238
Issue Date October 04, 2016
Title Piezoelectric Thin Film, Piezoelectric Element, And Manufacturing Method Thereof
Inventorship Makoto Kubota, Yokohama (JP)
Kenichi Takeda, Yokohama (JP)
Jumpei Hayashi, Chofu (JP)
Mikio Shimada, Kawasaki (JP)
Yuichi Shimakawa, Ibaraki (JP)
Masaki Azuma, Yokohama (JP)
Yoshitaka Nakamura, Osaka (JP)
Masanori Kawai, Ikoma (JP)
Assignee CANON KABUSHIKI KAISHA, Tokyo (JP) KYOTO UNIVERSITY, Kyoto-Shi (JP)

Claim of US Patent No. 9,461,238

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.