Piezoelectric/electrostrictive element

• US 6,246,156 B1
• Filed: 03/25/1999
• Issued: 06/12/2001
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Takeuchi, Yukihisa, Kimura, Koji
• Primary Examiner(s): Enad, Elvin
• Assistant Examiner(s): ADDISON, KAREN B
• Application Number:
  US09/276,580
• Time in Patent Office: 810 Days
• Field of Search: 310/328
• US Class Current: 310/328
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: B32B 2311/04 Gold
• CPC Class Codes: B32B 2315/02 Ceramics
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3296 Lead oxides, plumbates or oxide forming salts thereof, e.g. silver plumbate
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/76 Crystal structural characteristics, e.g. symmetry
• CPC Class Codes: C04B 2235/762 Cubic symmetry, e.g. beta-SiC
• CPC Class Codes: C04B 2235/765 Tetragonal symmetry
• CPC Class Codes: C04B 2237/345 Refractory metal oxides
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 2237/348 Zirconia, hafnia, zirconates or hafnates
• CPC Class Codes: C04B 2237/408 Noble metals, e.g. palladium, platina or silver
• CPC Class Codes: C04B 2237/582 by joining layers or articles of the same composition but having different additives
• CPC Class Codes: C04B 35/457 based on tin oxides or stannates
• CPC Class Codes: C04B 35/486 Fine ceramics
• CPC Class Codes: C04B 35/493 : containing also other lead compounds
• CPC Class Codes: C04B 35/495 : based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
• CPC Class Codes: C04B 35/497 : based on solid solutions with lead oxides
• CPC Class Codes: G01N 11/16 : by measuring damping effect upon oscillatory body
• CPC Class Codes: H10N 30/10513 : characterised by the underlying bases, e.g. substrates
• CPC Class Codes: H10N 30/2047 : Membrane type

Abstract

A piezoelectric/electrostrictive element has at least one film-type piezoelectric/electrostrictive operating portion constituted with a first electrode film, a piezoelectric/electrostrictive film, and a second electrode film on a ceramic substrate having a material whose main component is zirconium oxide. The ceramic substrate comprises a base layer and a surface layer, the crystal phase of the zirconium oxide of the base layer is a tetragonal phase or a mixed phase of tetragonal and cubic phase, tetragonal and monoclinic phase, or tetragonal, cubic, and monoclinic phase. The crystal phase of the zirconium oxide of the surface layer is mainly a cubic phase, and the piezoelectric/electrostrictive operating portion is formed on the surface layer. So it is possible to provide a high performance piezoelectric/electrostrictive element making sure of the strength of a ceramic substrate (diaphragm) and moreover, preventing a crack from occurring due to an internal factor in the firing process of a piezoelectric/electrostrictive film.

Claims

1. A piezoelectric/electrostrictive element comprising;

a ceramic substrate having a material whose main component is zirconium oxide; and

at least one film-type piezoelectric/electrostrictive operating portion comprising a first electrode film, a piezoelectric/electrostrictive film, and a second electrode film on the ceramic substrate;

wherein the ceramic substrate comprises a base layer and a surface layer, and the crystal phase of the zirconium oxide of the base layer is a tetragonal phase or a mixed phase of tetragonal and cubic phase, tetragonal and monoclinic phase, or tetragonal, cubic, and monoclinic phase, and the crystal phase of the zirconium oxide of the surface layer is mainly cubic phase, and the piezoelectric/electrostrictive operating portion is formed on the surface layer.

2. The piezoelectric/electrostrictive element according to claim 1, wherein the zirconium oxide in the surface layer is stabilized with 6 to 20 mol % of yttrium oxide.

3. The piezoelectric/electrostrictive element according to claim 1, wherein the zirconium oxide in the base layer is stabilized with 2 to 4 mol % of yttrium oxide.

4. The piezoelectric/electrostrictive element according to claim 1, wherein the crystal grain size of the zirconium oxide in the base layer is within a range of 0.1 and 1.5 μ

m.

5. The piezoelectric/electrostrictive element according to claim 1, wherein a supporting member having at least one opening is connected to the ceramic substrate so as to close one side of the opening with the ceramic substrate.

6. A piezoelectric/electrostrictive element comprising:

a ceramic substrate having a material whose main component is zirconium oxide;

at least one film-type piezoelectric/electrostrictive operating portion comprising a first electrode film, a piezoelectric/electrostrictive film, and a second electrode film on the ceramic substrate; and

a supporting member having at least one opening, said supporting member being connected to the ceramic substrate so as to close one side of the opening with the ceramic substrate;

wherein the ceramic substrate comprises a base layer and a surface layer, and the crystal phase of the zirconium oxide of the base layer is a tetragonal phase or a mixed phase of tetragonal and cubic phase, tetragonal and monoclinic phase, or tetragonal, cubic, and monoclinic phase, and the zirconium oxide in the base layer is stabilized with 2 to 4 mol % of yttrium oxide, and the crystal grain size of the zirconium oxide in the base layer is within a range of 0.1 and 1.5 μ

m, and the crystal phase of the zirconium oxide of the surface layer is mainly cubic phase, and the piezoelectric/electrostrictive operating portion is formed on the surface layer.