JP3480561B2 - Piezoelectric / electrostrictive element - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a unimorph-type and bimorph-type piezoelectric / electrostrictive element used as various transducers, various actuators, and the like.

[0002]

2. Description of the Related Art Piezoelectric / electrostrictive elements are various transducers that convert electrical energy into mechanical energy, that is, mechanical displacement, force and vibration, or vice versa. It is used in various fields such as various actuators, frequency domain functional parts such as filters, various display devices such as displays, sounding bodies such as speakers, sensors such as microphones and ultrasonic sensors.

For example, a piezoelectric / electrostrictive element is shown in FIG.
As shown in, a ceramic substrate 1 that acts as a diaphragm
And a film-type piezoelectric / electrostrictive actuating portion 5 which is provided thereon and is composed of a first electrode film 2, a piezoelectric / electrostrictive film 3 and a second electrode film 4 (Japanese Patent Laid-Open No. HEI 3) 1128b), as shown in FIG. 1B, the ceramic substrate has a cavity, and the bottom of the cavity has a thin thickness portion. The piezoelectric / electrostrictive operating portion has a thin wall portion. One integrated on the outer surface is disclosed (Japanese Patent Laid-Open No. 5-4.
9270 publication).

As a ceramic substrate that constitutes such a piezoelectric / electrostrictive element 7, one using zirconium oxide partially stabilized with yttrium oxide is generally known (Japanese Patent Laid-Open No. 5-29675). , Japanese Patent Application Laid-Open Nos. 5-97437 and 5-270912).

[0005]

However, in the above-described piezoelectric / electrostrictive element, when the piezoelectric / electrostrictive operating portion 5 is formed and fired on the ceramic substrate 1 in the manufacturing process, particularly, the piezoelectric / electrostrictive film is formed. 2 (a) and (b) depending on the firing conditions by performing a heat treatment (firing) for integrating 3 with the first electrode film 2 and the ceramic substrate 1.
As shown in (1), a crack may be found in a specific portion, that is, a ceramic substrate portion in the vicinity of the peripheral edge portion of the first electrode film 2, and there is a problem that the production yield is reduced.

When the vicinity of the cracked portion was observed with an electron beam microanalyzer (EPMA), it was found that the amount of yttrium oxide, which is a stabilizer of zirconium oxide, was smaller than that of other portions. Although the cause of the decrease in yttrium oxide is not clear, the piezoelectric / electrostrictive film 3 overhangs the ceramic substrate 1 with respect to the first electrode film 2 for the purpose of preventing a short circuit between the upper and lower electrodes. Since it is a portion that directly contacts the ceramic substrate 1, it is considered that yttrium oxide may be selectively diffused into the piezoelectric / electrostrictive film 3 when the piezoelectric / electrostrictive film 3 is integrally fired. In addition, in the vicinity of the peripheral portion of the first electrode film 2 of the ceramic substrate 1, the piezoelectric / electrostrictive film 3 and the first electrode film 5 and the ceramic substrate 1 are integrated by heat treatment in terms of element structure. Since a large stress is likely to be exerted, especially when the cavity structure as shown in FIG. 1 (b) or FIG. 2 (b) is present, it becomes particularly large, so that the stress during the heat treatment is the yttrium oxide. It is possible, but not clear. However, whatever the cause, it is highly possible that the reduction of yttrium oxide induces the crystal transformation of zirconium oxide and leads to cracking.

As a means for preventing the occurrence of cracks,
Although it is conceivable to manufacture the ceramic substrate 1 from completely stabilized zirconium oxide that does not cause crystal transformation,
Since the fully stabilized zirconium oxide is inferior in mechanical strength to the partially stabilized zirconium oxide, the thickness of the ceramic substrate 1 should be reduced for the purpose of improving the displacement characteristics of the actuator and the sensitivity of the sensor according to the application. However, in some cases, there is a problem that the thickness cannot be reduced effectively and sufficiently.

As described above, the partially stabilized zirconium oxide, in particular, the zirconium oxide partially stabilized with 2 to 4 mol% of yttrium oxide has particularly excellent vibration plate characteristics, but as described above, the piezoelectric / electrostrictive When the amount of yttrium oxide, which is a stabilizer, is reduced due to some factor during firing of the film 3, there is an inherent problem that crystal transformation and further cracking are likely to occur. Such a problem is peculiar to a piezoelectric / electrostrictive film type element in which a ceramic substrate, which is a vibrating plate, and a film type piezoelectric / electrostrictive operating unit are integrated by heat treatment without using an adhesive or the like. is there.

The present invention has been made in view of such a situation, and an object of the present invention is to secure the strength as a ceramic substrate (vibration plate), and
An object of the present invention is to provide a piezoelectric / electrostrictive element having high functionality and high characteristics, in which cracks are prevented from being generated due to an internal factor in the firing process of the electrostrictive film.

[0010]

That is, according to the present invention, at least a first electrode film, a piezoelectric / electrostrictive film, and a second electrode film are formed on a ceramic substrate containing zirconium oxide as a main component. A piezoelectric / electrostrictive film type device having one film-shaped piezoelectric / electrostrictive operating part, wherein the ceramic substrate comprises a base layer and a surface layer, and the crystal phase of zirconium oxide in the base layer is a tetragonal system. Or, a tetragonal crystal and a cubic crystal, a tetragonal crystal and a monoclinic crystal, or a mixed crystal of a tetragonal crystal, a cubic crystal and a monoclinic crystal,
There is provided a piezoelectric / electrostrictive element in which the crystal phase of zirconium oxide in the surface layer is mainly composed of cubic crystals and the piezoelectric / electrostrictive operating portion is provided on the surface layer.

In the piezoelectric / electrostrictive element of the present invention, it is preferable that zirconium oxide in the surface layer is stabilized with 6 to 20 mol% of yttrium oxide.
Further, it is preferable that zirconium oxide in the base layer is partially stabilized with 2 to 4 mol% of yttrium oxide. Further, the crystal grain size of zirconium oxide in the base layer is preferably 0.1 to 1.5 μm.

Further, in the piezoelectric / electrostrictive element of the present invention, it is preferable that the ceramic substrate has a cavity structure in which only a portion forming the piezoelectric / electrostrictive operating portion is thinned. As will be described later, in the present application, the thickness of the ceramic substrate is preferably 50 μm or less, so that the portions other than the vibration plate, that is, the portions where the piezoelectric / electrostrictive operating portion is not formed, can be made thicker, which is advantageous in handling as an element substrate. Because. Further, even when the elements are arranged adjacent to each other, a thick portion can be arranged between the elements, which is advantageous in preventing mutual interference in characteristics.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the piezoelectric / electrostrictive element of the present invention, as shown in FIG. 3, a ceramic substrate 1 containing zirconium oxide as a main component is composed of a base layer 10 and a surface layer 9, and The surface layer 9 on which the electrostrictive operating portion 5 is formed is mainly composed of cubic zirconium oxide. The cubic crystal is stable in crystal and does not easily undergo crystal transformation even if yttrium oxide is reduced due to a firing atmosphere of the piezoelectric / electrostrictive operating part 5 or stress or diffusion generated during firing, so that the side of the first electrode film 2 is prevented. It is possible to effectively prevent the occurrence of cracks in the ceramic substrate 1 near the edges.

On the other hand, in the piezoelectric / electrostrictive element 7 of the present invention, the base layer 10 of the ceramic substrate 1 is tetragonal or tetragonal and cubic, tetragonal and monoclinic, or tetragonal and cubic and monoclinic. The main component is zirconium oxide which is a mixed crystal of.
A tetragonal crystal or a tetragonal crystal and a cubic crystal, a tetragonal crystal and a monoclinic crystal, or a mixed crystal of a tetragonal crystal, a cubic crystal and a monoclinic crystal has high toughness and excellent strength. You can Therefore, it is possible to realize a piezoelectric / electrostrictive element having both functionality and productivity. The main component as referred to in the present application means 85% or more by weight.

In general, the identification of various crystal phases contained in a crystal system and the calculation of the proportion thereof are performed by an X-ray diffraction method, a Raman spectroscopy method, or the like. In the present application, the X-ray diffraction method is used to represent various crystal phases. The existence ratio was obtained from the intensity ratio of the dynamic diffraction lines.

The cubic crystal abundance ratio is defined by the cubic crystal abundance ratio for each crystal phase, and the cubic crystal content ratio was determined from the intensity ratio of the main diffraction lines of each crystal phase. Then, “mainly cubic” means to satisfy the following relationship.

[0017]

[Equation 1]

When the main diffraction lines in the tetragonal crystal and the cubic crystal are close to each other and separation is difficult, a higher diffraction line may be used instead of the intensity of the main diffraction line. However, in that case, the values of the main diffraction line intensity and the high-order diffraction line intensity that are known in advance from the JCPDS card or the like are used, and the obtained high-order diffraction line intensity is standardized by the main diffraction line intensity. There is a need. For example, when the existence ratio is calculated using the diffraction lines of cubic (200) and tetragonal (002) + tetragonal (200), the JCPDS card is used to determine the intensity of each diffraction line of the main (11
1) 25, 43 ((002) for 100 diffraction intensity
And the sum of (200)),

[0019]

[Equation 2]

Is substituted for the above conditional expression. Each symbol in the mathematical formula has the following meaning.

[0021]

[Equation 3]

In the piezoelectric / electrostrictive element 7 of the present invention, the total thickness of the ceramic substrate 1 (base layer + surface layer) is piezoelectric / electrostrictive.
From the viewpoint of displacement amount, generating force or sensitivity, the high speed response of the electrostrictive element is maintained, and it is preferably 50 μm or less.
It is more preferably 0 μm or less, further preferably 15 μm or less. On the other hand, from the viewpoint of imparting sufficient strength to the piezoelectric / electrostrictive element and effectively suppressing the occurrence of cracks, the thickness ratio of the base layer 10 and the surface layer 9 is 6: 4 to.
It is preferably 8: 2.

In order to make the surface layer 9 mainly composed of cubic crystals, it is desirable to add 6 to 20 mol%, more preferably 7 to 10 mol% of yttrium oxide to the surface layer for stabilization.

On the other hand, in order for the base layer 10 to be zirconium oxide that is tetragonal or tetragonal and cubic, tetragonal and monoclinic, or a mixed crystal of tetragonal and cubic and monoclinic, the base layer 10 It is desirable to add 2 to 4 mol%, preferably 2.5 to 3.5 mol% of yttrium oxide to 10 for stabilization.

In the piezoelectric / electrostrictive element 7 of the present invention, the crystal grain size of zirconium oxide in the base layer 10 is 0.
The thickness is preferably 1 to 1.5 μm, more preferably 1.0 μm or less. This is because by setting the crystal grain diameter within the above range, it is possible to obtain a large strength even if the thickness is thin, and it is possible to stably form a predetermined crystal phase.

Aluminum oxide, titanium oxide, or a sintering aid such as viscosity may be added to the ceramic substrate 1, but silicon oxide (SiO, SiO, SiO 2) may be added to the base layer 10 and the surface layer 9 after sintering. _{When 2} ) is excessively present, the reaction with the material forming the piezoelectric / electrostrictive working part becomes large during the heat treatment with the piezoelectric / electrostrictive working part, which makes it difficult to control the composition of the piezoelectric / electrostrictive working part. Therefore, the content of silicon oxide needs to be less than 1% by weight. FIG. 4 shows an example in which a plurality of piezoelectric / electrostrictive elements (2, 3, 4) are formed on a relatively large ceramic substrate 1. As this ceramic substrate,
Of course, it is also preferable to have a cavity structure in which only the portion forming the piezoelectric / electrostrictive operating portion is thin.

The piezoelectric / electrostrictive element of the present invention is manufactured as follows. The ceramic substrate 1 is prepared by separately forming a base layer green sheet and a surface layer green sheet, each of which is made of a predetermined material, by a doctor blade method or a reverse roll coater method, and then stacking and thermocompressing them to form 1200 to 1600. It is manufactured by firing at a temperature of ° C. Or, screen printing using a slurry or paste of the surface layer material on the green sheet for the base layer,
The surface layer may be formed by a method such as spraying or coating, and the surface layer may be formed only at the portion where the piezoelectric / electrostrictive operating portion is formed. Further, the base layer may be formed on the surface layer green sheet by a method such as screen printing, spraying or coating.

When the ceramic substrate has a structure having a cavity, a green sheet provided with a cavity corresponding to the cavity is formed by using a metal mold or a machining method such as ultrasonic machining. In addition to (for substrate and surface layer), they are prepared, and similarly, they are laminated, thermocompression-bonded and fired. The cavity substrate structure may be provided with a member that closes the opening of the cavity on the side opposite to the diaphragm.

The piezoelectric / electrostrictive operating portion 5 is formed on the ceramic substrate 1 by a thick film forming method such as screen printing, spraying, dipping, coating, ion beam, sputtering, vacuum deposition, ion plating, CVD, plating. And the like. In particular, piezoelectric /
For forming the electrostrictive film, a thick film forming method such as screen printing, spraying, dipping or coating is preferably adopted. According to these thick film forming methods, the average particle diameter is 0.01 μm.
piezoelectricity of m to 5 μm, preferably 0.05 μm to 3 μm
This is because the film can be formed on the ceramic substrate by using the paste or slurry containing the ceramic particles of the electrostrictive material as the main component, and good device characteristics can be obtained.

Further, in order to form the film into a desired shape,
In addition to the method of pattern formation using screen printing method or photolithography method, laser processing method such as excimer or YAG, or mechanical processing method such as slicing or ultrasonic processing is used to remove unnecessary portions to form a pattern. A method such as forming is adopted. The heat treatment temperature for integrating the film thus formed and the ceramic substrate is generally 900 to 1400 ° C., preferably 1000.
A range of ˜1400 ° C. is advantageously chosen.

As a material of the first electrode film 2 that constitutes the piezoelectric / electrostrictive operating portion 5, a conductor that can withstand a high temperature oxidizing atmosphere such as the heat treatment temperature and the firing temperature is used.
It is not particularly limited and may be, for example, a simple metal, an alloy, a mixture of an insulating ceramic and a metal or an alloy, or a conductive ceramic. In particular, among them, platinum, palladium, high melting point noble metals such as rhodium or silver-palladium,
Electrode materials containing alloys of silver-platinum, platinum-palladium, etc. as main components, cermet materials of platinum and ceramic substrate materials, cermet materials of platinum and piezoelectric materials, cermets of platinum and substrate materials and piezoelectric materials A material is preferable, and among these, a material containing platinum as a main component is more preferable.

If glass such as silicon oxide is used as a material to be added to the electrode, a reaction is likely to occur during heat treatment with the piezoelectric / electrostrictive layer, which is likely to cause deterioration of element characteristics. Therefore, avoid its use. Is desirable. The substrate material added to the electrode is about 5 to 30% by volume,
The piezoelectric material is preferably about 5 to 20% by volume.

On the other hand, the material of the second electrode film 4 is not particularly limited, and the same material as that used for the first electrode film 2 and a sputtered film of gold, chromium, copper or the like can be used. Alternatively, a gold or silver resinate printing film or the like may be used.

As the material of the piezoelectric / electrostrictive film 3 forming the piezoelectric / electrostrictive operating portion 5, any material may be used as long as it exhibits electric field induced strain such as piezoelectric or electrostrictive effect. You can For example, even a crystalline material,
It may be an amorphous material, or a semiconductor material, a dielectric ceramic material or a ferroelectric ceramic material,
It may be an anti-ferroelectric ceramic material, or may be a material that requires polarization treatment, or it may be an unnecessary material.

The piezoelectric / electrostrictive material used in the present invention is specifically lead zirconate titanate (PZT-based).
, A material containing lead titanate as a main component,
A material containing lead zirconate as a main component, a material containing lead magnesium niobate (PMN-based) as a main component, a material containing lead nickel niobate (PNN-based) as a main component, and a material containing lead magnesium tungstate as a main component. , Lead manganese niobate-based materials, lead antimony stannate-based materials, lead zinc niobate-based materials, lead magnesium tantalate-based materials, and nickel nickel tantalate-based materials. The material which makes it a main component, Furthermore, these composite materials etc. can be mentioned.

The above-mentioned materials include lanthanum, barium, niobium, zinc, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, tungsten, nickel, manganese, lithium, strontium, magnesium, calcium, bismuth, An oxide such as tin or another compound thereof may be contained as an additive. For example, a PLZT-based material in which a lanthanum oxide or the like is added to a PZT-based material as a main component can also be used. . It should be avoided that the addition of glass such as silicon oxide easily causes a reaction with the piezoelectric / electrostrictive material and makes it difficult to maintain a predetermined material composition.

Among these piezoelectric / electrostrictive materials, a material containing lead magnesium niobate, lead zirconate, and lead titanate as a main component, lead nickel niobate, lead magnesium niobate, and zircon. Material containing lead acid and lead titanate as a main component, lead nickel tantalate, lead magnesium niobate, lead zirconate and lead titanate, or lead magnesium tantalate. It is preferable to use a material whose main component is a component of lead magnesium niobate, lead zirconate and lead titanate.

Further, among them, particularly, a material containing a component composed of lead magnesium niobate, lead zirconate, and lead titanate as a main component is preferably used. Because the above materials not only have high piezoelectric constants,
This is because the reaction with the substrate material during the heat treatment is particularly small.

In the case of a multi-component piezoelectric / electrostrictive material, the piezoelectric / electrostrictive characteristics change depending on the composition of the components. However, lead magnesium niobate preferably used in the piezoelectric / electrostrictive element of the present invention- In the case of the ternary material of lead zirconate-lead titanate, the composition in the vicinity of the phase boundary of pseudo-cubic system-tetragonal system-rhombohedral system is preferable, and particularly lead magnesium niobate: 15 mol%-
50 mol%, lead zirconate: 10 mol% to 45 mol%,
Lead titanate: A composition of 30 mol% to 45 mol% is advantageously adopted because of its high piezoelectric constant and electromechanical coupling coefficient.

The piezoelectric / electrostrictive element of the present invention converts various types of electrical energy into mechanical energy, that is, mechanical displacement, force and vibration, or vice versa. , Various actuators, frequency domain functional parts such as filters, various display devices such as displays, sounders such as transformers, microphones, speakers, transducers for communication and power, resonators or oscillators, discriminators, ultrasonic waves Sensors, acceleration sensors, angular velocity sensors, shock sensors, various sensors such as mass sensors, gyros, and Kenji Uchino (Japan Industrial Technology Center) "Piezoelectric / electrostrictive actuators from basics to applications" (Morikita Publishing) Units used for servo displacement elements, pulse drive motors, ultrasonic motors, piezoelectric fans, piezoelectric relays, etc. It is those that may be applied to Ruff element and bimorph type element, preferably various actuators, vibrators, sounding bodies, are advantageously employed in a display device or the like.

The piezoelectric / electrostrictive element of the present invention is a piezoelectric / electrostrictive element.
Since it has not only electrostrictive characteristics but also dielectric properties, it can be used as a film-shaped capacitor element.

Although the above description has been based on the unimorph structure in which the piezoelectric / electrostrictive actuating portion is formed on one side of the ceramic substrate, the piezoelectric / electrostrictive operating portion is naturally formed on both sides of the ceramic substrate. It is also applicable to a bimorph structure. In this case, the surface layer is formed on both sides of the base layer.

[0043]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A piezoelectric / electrostrictive element 7 as shown in FIG. 3B, in which a ceramic substrate is composed of a base layer and a surface layer and has a cavity, was manufactured. The substrate layer 10 was composed of tetragonal zirconium oxide containing 3 mol% of yttrium oxide, and the surface layer 9 was composed of zirconium oxide containing 7 mol% of yttrium oxide. The numerical value of the conditional expression was 0.90. The piezoelectric / electrostrictive operating part 5 was formed on the surface layer 9.

First, a surface layer was formed on the surface of the base layer green sheet by screen printing using the surface layer paste material. The thicknesses of the green sheet for the base layer and the surface layer were 6 μm and 2 μm, respectively, after firing.

Next, 0.
After providing a through hole to form a cavity of 2 mm × 4 mm, the green sheet for a base layer was laminated and thermocompression-bonded with the base layer side, and fired at 1500 ° C.

Next, the piezoelectric / electrostrictive operating portion 5 was formed on the substrate. The materials of the first electrode film 2, the piezoelectric / electrostrictive film 3, and the second electrode film 4 are platinum, lead zirconate, lead titanate, and lead magnesium niobate. And The piezoelectric / electrostrictive operating portion 5 is formed by screen printing. The first electrode film 2 is 1300 ° C. and the piezoelectric / electrostrictive film 3 is 1250 ° C.
The second electrode film 4 was baked at 600 ° C. The thicknesses of the first electrode film 2, the piezoelectric / electrostrictive film 3 and the second electrode film 4 were 3 μm, 14 μm and 0.5 μm, respectively.

1000 piezoelectric / electrostrictive elements 7 were manufactured, and whether or not cracks were generated in the ceramic substrate 1 was evaluated using a crack inspecting liquid. The results are shown in Table 1.

Example 2 Zirconium oxide containing 10 mol% of yttrium oxide added to the surface layer 9 was used.
1000 piezoelectric / electrostrictive elements similar to Example 1 were manufactured except that the numerical value of the conditional expression was 1, and the ceramic substrate 1
It was evaluated in the same manner as in Example 1 whether or not cracks had occurred. The results are shown in Table 1.

Example 3 Zirconium oxide containing 6 mol% of yttrium oxide added to the surface layer 9 was used. Except that the numerical value of the conditional expression is 0.80, 1000 piezoelectric / electrostrictive elements similar to those in Example 1 were manufactured, and it was determined whether or not cracks were generated in the ceramic substrate 1 as in Example 1. It evaluated similarly. The results are shown in Table 1.

Comparative Example 1 A piezoelectric / electrostrictive element 7 as shown in FIG. 1 (b) having a cavity in which a ceramic substrate was composed of a single layer was manufactured. The ceramic substrate was composed of tetragonal zirconium oxide to which 3 mol% of yttrium oxide was added. The piezoelectric / electrostrictive operating portion 5 was formed on the surface of the ceramic substrate 1 on the side opposite to the side where the supporting member 6 is joined.

0.2 mm on the green sheet for the supporting member
After forming a through hole to form a cavity of × 4mm,
Laminated and thermo-compressed with a green sheet for a ceramic substrate, 1
It was baked at 500 ° C. The thickness of the ceramic substrate is 8 after firing.
μm.

Next, the piezoelectric / electrostrictive operation part 5 was formed on the ceramic substrate. The material of the piezoelectric / electrostrictive operating part 5 and the thickness of each layer were the same as in the first embodiment.

The above-mentioned 1000 piezoelectric / electrostrictive elements were manufactured, and whether or not cracks were generated in the ceramic substrate 1 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0055]

[Table 1]

From Table 1, it can be seen that in the piezoelectric / electrostrictive element of the example, the crack occurrence rate is effectively lower than that of the piezoelectric / electrostrictive element of Comparative example 1.

[0057]

According to the piezoelectric / electrostrictive element of the present invention, the ceramic substrate is composed of the base layer and the surface layer, and the surface layer of the ceramic substrate on which the piezoelectric / electrostrictive operating portion is formed is mainly cubic. Since the main component is zirconium oxide, the crack is less likely to occur in the ceramic substrate in the vicinity of the peripheral portion of the first electrode film. Also, the base layer of the ceramic substrate is
Since the main component is zirconium oxide, which is tetragonal or tetragonal and cubic, tetragonal and monoclinic, or a mixture of tetragonal and cubic and monoclinic, it is possible to maintain high mechanical strength even with thin walls. Therefore, the function as a film-type piezoelectric / electrostrictive element substrate (vibration plate) member can be sufficiently exerted, and a highly functional piezoelectric / electrostrictive element can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing (a) one example and (b) another example of a conventional piezoelectric / electrostrictive element.

2A is a sectional view taken along the line AA of FIG. 1A and FIG. 2B is a sectional view taken along the line BB of FIG.

FIG. 3 is a schematic cross-sectional view showing (a) one example and (b) another example of the piezoelectric / electrostrictive element of the present invention.

FIG. 4 is a perspective view showing still another example of the piezoelectric / electrostrictive element of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate, 2 ... 1st electrode film, 3 ... Piezoelectric / electrostrictive film, 4 ... 2nd electrode film, 5 ... Piezoelectric / electrostrictive actuation part, 6 ...
Support member, 7 ... Piezoelectric / electrostrictive element, 8 ... Crack, 9 ... Surface layer, 10 ... Base layer.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 41/09

Claims (5)

(57) [Claims] 1. A ceramic substrate containing zirconium oxide as a main component, and at least one film-shaped piezoelectric / electrostrictive actuating portion comprising a first electrode film, a piezoelectric / electrostrictive film, and a second electrode film. A piezoelectric / electrostrictive film type element having, wherein the ceramic substrate comprises a base layer and a surface layer, and the crystal phase of zirconium oxide in the base layer is tetragonal or tetragonal and cubic, tetragonal and monoclinic. Or a mixed crystal of tetragonal crystal, cubic crystal and monoclinic crystal, wherein the crystal phase of zirconium oxide in the surface layer is mainly composed of cubic crystal, and the piezoelectric / electrostrictive operating portion is provided in the surface layer. Piezoelectric / electrostrictive element. 2. The piezoelectric / electrostrictive element according to claim 1, wherein zirconium oxide is stabilized with 6 to 20 mol% of yttrium oxide in the surface layer. 3. The piezoelectric / electrostrictive element according to claim 1, wherein 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 zirconium oxide in the base layer is 0.1 to 1.5 μm. 5. A support member having at least one void (cavity) bonded to the ceramic substrate so as to close one side of the void with the ceramic substrate. 4. The piezoelectric / electrostrictive element according to item 4.