Piezoelectric/electrostrictive film element and method of producing the same

• US 5,600,197 A
• Filed: 12/28/1994
• Issued: 02/04/1997
• Est. Priority Date: 02/14/1994
• Status: Expired due to Term

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Takeuchi, Yukihisa, Nanataki, Tsutomu
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/365,129
• Time in Patent Office: 769 Days
• Field of Search: 310/324, 310/328, 310/330, 310/358
• US Class Current: 310/328
• CPC Class Codes: B41J 2/161 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1637 molding
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1643 thin film formation by plating
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: B41J 2002/14387 Front shooter
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: H10N 30/074 by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
• CPC Class Codes: H10N 30/097 by sintering
• CPC Class Codes: H10N 30/2048 having non-planar shape
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A piezoelectric/electrostrictive film element which includes a ceramic substrate having at least one window and an integrally formed diaphragm portion for closing each window, and a piezoelectric/electrostrictive unit including a lower electrode, a piezoelectric/electrostrictive layer and an upper electrode, which are formed in this order on the diaphragm portion. The piezoelectric/electrostrictive layer consists of a dense body having a crystal grain size of not smaller than 0.7 μm, and a porosity (x) of not greater than 15%, and the diaphragm portion has a deflection percentage (y) of 0-8%, which is a percentage of an amount of deflection of a central part of the diaphragm portion, with respect to a length of a shortest line which extends across the corresponding window and passes a center of the window. Further, the porosity (x) and the deflection percentage (y) satisfies the following formula: y≦0.1167x² -3.317x+25.5. Also disclosed are three methods for producing the piezoelectric/electrostrictive film element as described above.

Claims

1. A piezoelectric/electrostrictive film element comprising:

a ceramic substrate having at least one window, and a diaphragm portion closing each of said at least one window, said diaphragm portion being formed as an integral part of said ceramic substrate; and

a piezoelectric/electrostrictive unit including a lower electrode, a piezoelectric/electrostrictive layer and an upper electrode, which are formed in the order of description on an outer surface of said diaphragm portion by a film-forming method, to provide a laminar structure, said piezoelectric/electrostrictive layer consisting of a dense body having a crystal grain size of not smaller than 0.7 μ

m, and a porosity (x) of not greater than 15%, said diaphragm portion having a deflection percentage (y) of 0-8%, which is a percentage of an amount of deflection of a central part of said diaphragm portion into the window in an unbiased state, with respect to a length of a shortest line which extends across a corresponding one of said at least one window and passes through a center of the window, said porosity (x) and said deflection percentage (y) satisfying the following formula;

space="preserve" listing-type="equation">y≦

0.1167x.sup.2 -3.317x+25.5.

2. A piezoelectric/electrostrictive film element as defined in claim 1, wherein said crystal grain size of said dense body for said piezoelectric/electrostrictive layer is not smaller than 1.5 μ

m.

3. A Piezoelectric/electrostrictive film element as defined in claim 2, wherein said crystal grain size is not smaller than 2.0 μ

m.

4. A Piezoelectric/electrostrictive film element as defined in claim 1, wherein said porosity (x) and said deflection percentage (y) satisfy the following formula:

space="preserve" listing-type="equation">y≦

0.2x.sup.2 -3.9x+20.5

where x≦

10, 0≦

y≦

6.

5. A Piezoelectric/electrostrictive film element as defined in claim 4, wherein said porosity (x) and said deflection percentage (y) satisfy the following formula:

space="preserve" listing-type="equation">y≦

-x+7

where x≦

6, 0≦

y≦

3.

6. A piezoelectric/electrostrictive film element as defined in claim 1, wherein said diaphragm portion of said ceramic substrate has a thickness of 1 μ

m-30 μ

m.

7. A piezoelectric/electrostrictive film element as defined in claim 6, wherein said diaphragm portion of said ceramic substrate has a thickness of 3 μ

m-15 μ

m.