JPH057029A - Piezoelectric electrostriction ceramic laminate - Google Patents

Abstract

PURPOSE:To obtain a ceramic laminate available for piezoelectric electrostriction material wherein the distortion amount comparatively gently changes according to voltage variation, and analog control of distortion amount is possible. CONSTITUTION:By laminating repetition units of structure wherein piezoelectric ceramic materials 2a and 2b whose concentrations of constituent component are different are sandwiched between electrodes 3a and 3b and compression- bonded, a piezoelectric ceramic laminate having concentration variation of constituent component of piezoelectric ceramic material in the lamination direction is constituted. Thereby the inclination of rising part of a hysteresis curve is decreased, and analog control of distortion amount is enabled. Hysteresis can be slimmed and temperature characteristics of distortion amount can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric electrostrictive ceramic laminate, and more particularly to a piezoelectric electrostrictive ceramic laminate suitable for actuators used for positioning in precision machine tools, flow control valves, automobile braking devices and the like.

[0002]

2. Description of the Related Art A substance having a property of causing mechanical strain when an electric field is applied is generally called a piezoelectric material or a piezoelectric electrostrictive material. As an electromechanical conversion element, a bimorph, a piezoelectric ignition element, an ultrasonic vibrator, Widely used in piezoelectric buzzers, ceramic filters, etc.

Generally, when an electric field is applied to a piezoelectric material, its crystal structure changes, and it exhibits a maximum strain amount (electromechanical coupling constant) at its crystal transformation point. Since the crystal transformation point varies depending on each piezoelectric material, an appropriate piezoelectric material is selected and used according to the target operating temperature.

As such a piezoelectric material, BaTiO ₃ ,
Pb (Zr, Ti) O ₃ (generally called PZT), LiNbO ₃ ,
LiTaO _{3 and the} like are known. Further, a material in which various oxides or the like are added to the above material to improve various characteristics of the piezoelectric material is also used. Furthermore, in the above PZT material, Zr
The PNZST material in which a part of NZ is replaced by Nb and Sn causes a large strain without causing damage, so this PNZST material
The use of a material as an actuator material is under consideration.

[0005]

[Problems to be Solved by the Invention] However, PNZ
In the case of the ST material, as shown by the solid line in FIG. 15, the strain amount rapidly increases when a certain specific voltage (voltage E _q ) is applied. Only the so-called on-off digital control can be performed with respect to the maximum value (ΔL ₀ ). In addition, there is a drawback that the hysteresis of the voltage-distortion amount curve is relatively large.

In many cases, on-off digital control is also effective, but if analog strain amount control can be performed, the usefulness of the piezoelectric material as an actuator material is dramatically increased. In order to enable analog control, the amount of distortion changes relatively slowly in proportion to the change in voltage,
Moreover, it is necessary to develop a piezoelectric electrostrictive material having a hysteresis as small as possible. That is, in the case of a PZT-based piezoelectric electrostrictive material, a material having a particularly small hysteresis (a small Δx / X _max in the graph of FIG. 16) is required. Further, in the case of the PNZST-based piezoelectric electrostrictive material, a piezoelectric electrostrictive material having a characteristic of changing by a relatively small ΔL with respect to a voltage change ΔE is required, as shown in FIG.

Therefore, an object of the present invention is to provide a piezoelectric electrostrictive material in which the amount of strain changes relatively gently in response to a change in voltage, which is suitable for analog strain control and which has a relatively small hysteresis. Is.

[0008]

As a result of earnest research to achieve the above object, the present inventor has found that by stacking a plurality of piezoelectric ceramic materials having different metal component concentrations, the metal component concentration in the stacking direction is increased. The inventors have found that if the configuration is changed, the amount of strain applied by the laminated piezoelectric electrostrictive materials changes gently with a change in voltage, and the present invention has been completed.

That is, the piezoelectric electrostrictive ceramic laminate of the present invention, which is formed by laminating a plurality of piezoelectric ceramic materials, is characterized in that the concentration of the metal component forming the piezoelectric ceramic material changes in the laminating direction.

[0010]

The present invention will be described in detail below with reference to the accompanying drawings. The piezoelectric ceramic material (ceramic sheet) constituting the piezoelectric electrostrictive ceramic laminate of the present invention is not particularly limited as long as it exhibits a piezoelectric electrostrictive effect, but a preferable piezoelectric ceramic material is Pb-Nb-Zr-Sn. -Ti (PNZS
T) -based oxide, Pb (Zr, Ti) O ₃ (PZT) -based oxide, Pb-
La-Zr-Ti (PLZT) -based oxide, Pb-Mg-Nb-PbTiO
₃ (PMNPT) -based oxides and the like.

Hereinafter, Pb will be used as a laminated piezoelectric ceramic material.
The present invention will be described with reference to an example using a -Nb-Zr-Sn-Ti (PNZST) -based oxide.

In the present invention, Pb-Nb-Zr-Sn-Ti (PNZST) which can be used as a piezoelectric ceramic material
System oxide is represented by the following general formula _{Pb a Ba b Nb c [(} Zr d Sn e) 1-f Ti f] g O 3 ( however, 0.94 <a <1,0 <b <0.06,0 <
c <0.04, 0.55 <d <0.75, 0.25 <e
<0.45, 0 <f <0.08, and 0.96 <g <1
Is. ).

There are various modes for changing the concentration of a specific metal component within the above composition range. For example,
The piezoelectric electrostrictive ceramic laminate 1 shown in FIG. 1 (a) includes two piezoelectric ceramic materials 2a, 2b between a pair of electrodes 3a, 3b.
It is composed of repeating units having a structure in which b is sandwiched and crimped.

In this embodiment, the piezoelectric ceramic material 2
a and the piezoelectric ceramic material 2b have a Ti concentration (with it)
Concentrations of Zr and Sn) are different. In the example shown in FIG. 1 (b), the piezoelectric ceramic material 2a has a higher Ti concentration.

A preferable composition of the piezoelectric ceramic materials 2a and 2b is represented by the general formula: Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65
Sn _0.35 ) _1-A Ti _A ] _0.98 O ₃ (where 0 <A ≦ 0.0
8). Then, a piezoelectric ceramic material in which A is appropriately changed within the above range is used to form a laminated body. Preferable specific examples of the composition of the piezoelectric ceramic materials 2a and 2b are Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ), respectively.
_0.95 Ti _0.05 ] _0.98 O ₃ and Pb _0.96 Ba _0.03 Nb _0.02 [(Zr
_0.65 Sn _0.35 ) _0.96 Ti _0.04 ] _0.98 O ₃ .

The concentrations of Pb and Ba may be changed instead of Ti. In this case, the composition of the piezoelectric ceramic material is, for example, Pb _0.99-B Ba _B Nb _0.02 [(Zr _0.65 Sn
_0.35 ) _0.95 Ti _0.05 ] _0.98 O ₃ (provided 0 ≦ B ≦ 0.0
6) is preferred.

Further, the concentrations of Pb and Nb can be changed. In this case, for example, Pb _{0.96-C / 2} Ba _0.03 Nb _C
[(Zr _0.65 Sn _0.35 ) _0.95 Ti _0.05 ] _1-C O ₃ (where 0 <C
≦ 0.03) is preferable.

Furthermore, Zr and Sn can be used without changing the Ti concentration.
The concentration of can be changed. In this case, for example, Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _D Sn _1-D ) _0.95 Ti _0.05 ]
_It is preferably _0.98 O ₃ (however, 0.55 ≦ D ≦ 0.75).

As described above, in the present invention, the piezoelectric ceramic material is laminated by changing the concentration of any one or more of the constituent components (metal elements), but Pb-Nb-Zr-Sn-
When a laminated body is formed using a piezoelectric ceramic material made of a Ti-based oxide, it is preferable to change the Ti concentration (and the Zr and Sn concentrations accordingly) as in the present embodiment. When the piezoelectric ceramic materials with different Ti concentrations are laminated, the slope of the rising portion (S portion of the graph shown in FIG. 17) of the applied voltage / distortion curve becomes more gradual and the hysteresis curve becomes slimmer. .

The piezoelectric ceramic materials 2a, 2 to be laminated
The thickness of b is 10 to 250 μm, preferably about 100 μm.

The electrode portions 3a and 3b are formed of noble metals such as platinum, silver, palladium and silver-palladium alloy, but platinum is preferably used. As will be described later in detail, the electrode portions 3a and 3b are composed of the piezoelectric ceramic material 2a
It is formed on the surface of 2b by a screen printing method or the like. The thickness of the electrode portions 3a and 3b is 1 to 10 μm, preferably 5 μm
The degree.

When two types of piezoelectric ceramic materials having different metal component concentrations are alternately laminated and sintered, the metal component diffuses, and the concentration changes from the stepwise shape shown in FIG.
It becomes smooth as shown by curve 6 in (c). Note that FIG. 1C schematically shows the change in the Ti concentration in the stacking direction of the piezoelectric electrostrictive ceramic laminate 1 of FIG. 1A (the electrode portion 3 is omitted).

When a voltage is applied to the piezoelectric electrostrictive ceramic laminate 1 having the above-described structure, the voltage-distortion hysteresis curve has a conventional PNZST piezoelectric electrostrictive curve as schematically shown by the broken line in FIG. Compared to the laminated body (shown by the solid line), it has a gentle slope and is slim.

It is considered that the piezoelectric electrostrictive ceramic laminate of the present invention gives the above-mentioned hysteresis curve for the following reason. That is, generally, when the concentrations of the constituent components of the piezoelectric electrostrictive material are different, the phase transition electric field (the electric field corresponding to the rising portion of the hysteresis curve) shifts, but in the piezoelectric electrostrictive ceramic laminate of the present invention,
Since a plurality of types of piezoelectric ceramic materials having different concentrations of constituent components are laminated, the rising portions of a plurality of strain amount / voltage graphs are combined, which results in a gentle slope.

As a mode of changing the concentration of metal components in the stacking direction, not only two types of piezoelectric ceramic materials having different concentrations of constituent components are stacked as described above, but also three or more types of piezoelectric ceramic materials having different concentrations are stacked. It may be configured to be overlapped. For example, a configuration in which three types of piezoelectric ceramic materials having different concentrations are superposed is shown in FIGS. 2 and 3.

First, FIG. 2 shows three types of piezoelectric ceramic materials 4a, 4b and 4c having different Ti concentrations, 4a, 4b and 4c.
An example in which the layers are repeatedly laminated in the order of c, 4b, 4a ... In addition, in FIG. 2, a curve 40 shows the change in the Ti concentration after sintering.
The broken lines shown in a, 4b, and 4c show the concentration of Ti before sintering (that is, before diffusion).

Further, FIG. 3 shows the same type of piezoelectric ceramic material (for example, the piezoelectric ceramic material 4 in the example of FIG. 2).
It shows an example in which the thickness of the piezoelectric ceramic material portion having the same concentration is increased by stacking two sheets a, 4a) two by two, and it can be seen that the change in the concentration of Ti becomes more gradual. further,
If three or more piezoelectric ceramic materials of the same type are placed next to each other,
The change in the Ti concentration becomes more gradual.

As another mode of changing the metal component concentration in the stacking direction, there is a piezoelectric electrostrictive ceramic stack 7 shown in FIG. 4 (a). This piezoelectric electrostrictive ceramic laminated body 7 includes five types of piezoelectric ceramic materials 5a, 5b, 5c, 5d and 5e.
2 sheets each, 5a, 5a, 5b, 5b, 5c,
5c, 5d, 5d, 5e, 5e, 5d, 5d, 5c, 5
has a structure in which the electrodes 8, 8 ... Are sandwiched between every other piezoelectric electrostrictive ceramic material and pressure-bonded.

In the present embodiment, the piezoelectric ceramic materials 5a, 5
b, 5c, 5d, and 5e have different Ti concentrations,
As shown in FIG. 4 (b), they are arranged in such an order that the change in the Ti concentration becomes a gentle sine curve.

In this embodiment, the composition of the piezoelectric ceramic materials 5a, 5b, 5c, 5d and 5e is changed to
Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.9725 Ti _0.0275 ]
_0.98 O ₃ , Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 )
_0.96875 Ti _0.03125 ] _0.98 O ₃ , Pb _0.96 Ba _0.03 Nb
_0.02 [(Zr _0.65 Sn _0.35 ) _0.965 Ti _0.035 ] _0.98 O ₃ , Pb
_0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.96125 T
i _0.03875 ] _0.98 O ₃ and Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 S
n _0.35 ) _0.9575 Ti _0.0425 ] _0.98 O ₃ is preferable.

The change in the Ti concentration after sintering of the piezoelectric electrostrictive ceramic laminate 7 according to this embodiment has a gentler sinusoidal shape as shown by the curve 50 in FIG. 4 (c). The broken line in the figure shows the magnitude of the Ti concentration before sintering (that is, before diffusion).

Further, when the structure in which the change in the concentration of Ti is made more gradual like the piezoelectric electrostrictive ceramic laminate 7 according to this embodiment, the equipotential surface within the piezoelectric ceramic material is biased (concentration of constituent components). The equipotential surface is biased so that it is pulled in to the higher piezoelectric ceramic part), and the obtained hysteresis curve becomes smoother.

Furthermore, as a mode of changing the concentration of the metal component other than the mode described above, as shown in FIG. 5, a plurality of types of piezoelectric ceramic materials are arranged in the order of their Ti concentrations, and the change in the concentration of Ti is unidirectional. There is also a monotonically increasing configuration.

Although the Ti concentration is changed in each of the examples shown in FIGS. 2 to 5, the metal element components other than Ti may be changed as in the embodiment relating to FIG.

Next, a method for producing a piezoelectric electrostrictive ceramic laminate by laminating a plurality of types of piezoelectric ceramic materials will be described. For simplification of description, an example using two types of piezoelectric electrostrictive ceramic plates will be described below, but the case of three or more types is essentially the same.

First, a piezoelectric ceramic material having a desired composition is manufactured. In the production of piezoelectric ceramic materials, PbO, BaCO ₃ , Nb ₂ O ₅ , ZrO ₂ , Sn are used to obtain the desired composition.
O ₂ and TiO ₂ are weighed and mixed with a ball mill using a solvent such as ethanol. Mixing time is 10-5
It is about 0 hours.

Next, this is dried and further 800-900.
Calcination at 2 ° C for 2-10 hours. What was obtained by calcination,
Again using a solvent such as ethanol, use a ball mill to perform 10
Mix for ~ 50 hours, dry, then calcine a second time. This second calcination is preferably performed at 900 to 1000 ° C. for 2 to 10 hours. Furthermore, it is preferable to mix the product obtained by the second calcination again with a ball mill using a solvent such as ethanol. This mixing time is 10-100
Good time. The raw material for forming the piezoelectric ceramic material by drying the powder thus obtained (hereinafter referred to as calcined powder)
And

It is preferable that the particle size of the ceramic powder used and the particle size of the calcined powder obtained by ball mill mixing are smaller. Specifically, the average particle size is preferably about 1 μm or less. The smaller the particle size, the better the diffusion of the metal component (for example, Ti) in the piezoelectric ceramic material, and the better the characteristics of the piezoelectric electrostrictive ceramic laminate.

Next, a green sheet of a piezoelectric ceramic material is manufactured by using the above calcined powder.

First, a solvent such as ethylene glycol monoethyl ether or diethylene glycol n-butyl ether is mixed with a plasticizer such as butylphthalyl butyl glycolate, to which a dried calcined powder is added and mixed with stirring.
This stirring and mixing is preferably performed for about 5 to 60 minutes. Next, a binder component such as polyvinyl butyral is added to this mixture,
The mixture is stirred and mixed for about 20 to 120 minutes while being heated to about 80 ° C.

The obtained solution is filtered and then defoamed to obtain a slurry. Note that in filtering, 2
It is preferable to use a filter of about 00.

Using the slurry obtained above, a sheet-shaped molded body is prepared by a doctor blade method or the like. After this is dried, it is punched into a desired size to obtain a green sheet. The thickness of one green sheet is 100.
It is preferable that the thickness is about μm.

After the two types of ceramic green sheets having different Ti concentrations are manufactured in this manner, a laminated body is manufactured by the method schematically shown in FIG.

First, two kinds of ceramic green sheets t ₁ and t ₂ having different Ti concentrations are taken one by one, and both are pressure-bonded (step (a)).

One surface of the green sheet 9 obtained by pressure bonding (for example, the green sheet t ₁ surface having the higher Ti concentration)
Then, the electrode part 100 is formed by a screen printing method or the like (step (b)). Platinum is preferably used as the electrode portion 100 as described above. When it is formed by the screen printing method, it is preferable to use a mixture (platinum paste) of 60% by weight of platinum powder and 40% by weight of an organic binder such as ethylene glycol.

A plurality of green sheet laminated bodies 10 with electrodes obtained by the above-mentioned method are laminated and pressure-bonded (step (c)
).

Next, the laminated body 11 obtained in the step (c) is cut in the laminating direction, degreased and fired. Degreasing is preferably performed by setting the maximum temperature to 1000 ° C. or lower, preferably 500 ° C. or lower, and gradually increasing the temperature to the maximum temperature. For example, it is preferable to perform the heating / cooling pattern shown in FIG.

After the degreasing step, the laminated body is made 1000 to 1270.
Bake at 2 to 6 hours. In this firing step, diffusion of Ti occurs between the piezoelectric ceramic materials, and the change in Ti concentration becomes smooth from stepwise. More preferable firing temperature is 1
It is 100-1200 degreeC. The lead wires 30, 30, ... Are attached to the electrode portions 3b, 3b of the obtained piezoelectric ceramic plate laminate.
Are connected to form the target piezoelectric electrostrictive ceramic laminate 12.

When the density of the piezoelectric ceramic material of the laminated body is as low as 95 to 97% of the theoretical density, the low temperature HIP of about 1000 to 2000 atm at 850 to 1100 ° C. is 3 to 10 after the above firing. Good time to do it. This HI
P is preferably performed in an atmosphere in which the argon gas / oxygen gas is 4/1. When such low temperature HIP is performed, the density of the piezoelectric ceramic material can be set to 99% or more of the theoretical density, and the piezoelectric electrostrictive ceramic laminate having good characteristics can be obtained. In addition, HI is higher than the above temperature range.
Performing P is not preferable because Ti in the laminated piezoelectric ceramic material diffuses too much.

The present invention has been described above by taking the piezoelectric ceramic material made of Pb-Nb-Zr-Sn-Ti oxide as an example.
ZT ceramics, PLZT ceramics, PMN
PT-based ceramics can also be used.

Examples of PZT ceramics include Pb _1-A M _A [(Zr _1-B Ti _B ) _1-C (Mg _1/3 Nb _2/3 ) _C ] O ₃ (where M is Ba, Sr Or Ca, and 0 ≦ A ≦ 0.
2, 0.3 ≦ B ≦ 0.5, and 0.01 ≦ C ≦ 0.5. ) Should be used.

[0052] Incidentally, as a variation of the PZT-based ceramics, in the composition formula of the portion of the _{(Mg 1/3 Nb 2/3)} , (Cd 1/3 Nb 2/3), (Fe 1/2 Nb 1 / ₂ ), (Yb _1/2 Nb
_1/2 ), (Yb _1/2 Ta _1/2 ), (In _1/2 Nb _1/2 ), (Mn
_1/2 W _1/2 ), (Zn _1/2 W _1/2 ), (Mg _1/2 W _1/2 ),
(Co _1/2 W _1/2 ), (Ni _1/2 W _1/2 ), (Ni _1/3 N
b _2/3 ), (Mg _1/3 Ta _2/3 ), (Zn _1/3 Nb _2/3 ), (Co
It is also possible to use those substituted with _1/3 Nb _2/3 ), (Co _1/3 Ta _2/3 ), (Ni _1/3 Ta _2/3 ), etc.

As PLZT ceramics, Pb _1-A La
_A (Zr _1-B Ti _B ) O ₃ (where 0.01 ≦ A ≦ 0.1
4 and 0.3 ≦ B ≦ 0.5) can be used. A conventional piezoelectric electrostrictive material using PLZT ceramics gives a large strain with a relatively small applied electric field, but if the amount of strain is large, the piezoelectric electrostrictive material may break. However, by stacking a plurality of types of piezoelectric ceramic materials within the composition range described above, the hysteresis is slimmed down, and the piezoelectric electrostrictive ceramic multilayer body does not easily break.

As PMNPT ceramics,
Pb _1-A M _A [(Mg _1/3 Nb _2/3 ) _1-B Ti _B ] O ₃ (However,
0 ≦ A ≦ 0.2, and 0.05 ≦ B ≦ 0.15) can be used. A conventional piezoelectric electrostrictive material using PMNPT ceramics gives a small hysteresis.
As shown in (a), when the environmental temperature changes, the amount of strain changes greatly, and the temperature characteristics are poor. However, if a plurality of types of PMNPT-based ceramics within the composition range described above are appropriately laminated, the piezoelectric ceramic laminate will have the temperature characteristics (strain amount / temperature) as shown in FIG. 9 (b). Even if the temperature changes a little, it gives a substantially constant amount of strain in a fairly wide temperature range.

Also in the case of these piezoelectric ceramics, similarly, various starting materials (oxides) are mixed so as to have a desired composition, and various piezoelectric electrostrictive ceramic laminates are obtained in substantially the same manner as the above-described manufacturing method. It can be manufactured.

The present invention will be described in more detail by the following examples. Example 1 PbO, BaCO ₃ , Nb ₂ O ₅ , ZrO ₂ and SnO as starting materials
₂ and TiO ₂ , these raw material powders were composed of the following two compositions: Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.95 Ti _0.05 ] _0.98 O ₃ Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.96 Ti _0.04 ] _0.98 O ₃ was weighed and mixed in a ball mill for 24 hours. At this time, ethanol was added as a solvent.

The obtained two kinds of mixtures were each heated to 80 ° C.
After being dried under reduced pressure at 850 ° C., it was calcined at 850 to 950 ° C. for 10 hours and mixed again in a ball mill for 24 hours. Ethanol was also added to the crushed mixture at this time.

The crushed mixture obtained above was dried again, calcined at 900 to 1000 ° C. for 10 hours, ethanol was added again, and the mixture was mixed in a ball mill for 48 hours. The crushed mixture thus obtained was dried to obtain two types of calcined powder (starting material for the piezoelectric ceramic material).

The following operations were performed on each of the calcined powders. First, 48 ml of ethylene glycol monoethyl ether and 8 ml of diethylene glycol n-butyl ether as a solvent were mixed with 1 ml of butylphthalyl butyl glycolate as a plasticizer, and dried calcinated powder 1
00g was added and mixed with stirring for 5 minutes.

To this mixture, 5 g of polyvinyl butyral was added as a binder, and the mixture was heated to about 80 ° C. to give 20
Stir and mix for minutes. The solution was then filtered through 200 mesh and defoamed to give a slurry.

Using the above-mentioned slurry, a sheet-shaped molded body was prepared by the doctor blade method, and this was molded at room temperature for 50 minutes.
After drying for a time, it was punched into a desired size to obtain a green sheet. The thickness of one green sheet was about 120 μm.

One of each of the two types of green sheets thus obtained was taken, and these were placed at 100 ° C. for 40
A pressure of kg / cm ² was applied for pressure bonding. Next, one of the pressed green sheets (the green sheet with the higher Ti concentration)
60% by weight of platinum powder and 40% of organic binder on the surface of
A platinum electrode portion was formed by a screen printing method so as to have a dry thickness of 12 μm by using a platinum paste containing wt%.

Ceramic molded bodies having platinum electrode portions obtained by the above-mentioned method were laminated as shown in FIG.
At 50 ° C., pressure of 50 kg / cm ² was applied for pressure bonding. Next, this was cut in the stacking direction to obtain a stack of 5 mm length × 10 mm width × 8 mm thickness (stacking direction).

The above laminate was degreased under the conditions shown in FIG. 8 and then baked in the atmosphere at 1060 ° C. for 3 hours. A lead wire was connected to the electrode portion of the obtained fired body to obtain a desired piezoelectric electrostrictive ceramic laminate.

Regarding this piezoelectric electrostrictive ceramic laminate,
The change in Ti concentration in the stacking direction was measured by EPMA. The result is shown in FIG. A voltage was applied to the piezoelectric electrostrictive ceramic laminate to measure the amount of strain.
As a result, the hysteresis curve shown in FIG. 11 was obtained.

Example 2 By the same method as in Example 1, green sheets having the following three types of compositions were prepared. T ₁ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.95 Ti _0.05 ] _0.98 O ₃ T ₂ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.955 Ti _0.045 ] _0.98 O ₃ T ₃ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.96 Ti _0.04 ] _0.98 O ₃

The three types of green sheets are T ₁ , T ₂ , and T
_A piezoelectric electrostrictive ceramic laminate was prepared in the same manner as in Example 1, except that the laminate was repeated in the order of ₃ , T ₂ , T _1, ... The applied voltage / strain amount was measured for the obtained piezoelectric electrostrictive ceramic laminate. Results are shown in FIG.

Example 3 By the same method as in Example 1, a green sheet having the following five compositions and a thickness of about 100 μm was prepared (step (a)). T ₁ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.9725 Ti _0.0275 ] _0.98 O ₃ T ₂ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.96875 Ti _0.03125 ] _0.98 O ₃ T ₃ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.965 Ti _0.035 ] _0.98 O ₃ T ₄ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.96125 Ti _0.03875 ] _0.98 O ₃ T ₅ : Pb _0.96 Ba _0.03 Nb _0.02 [(Zr _0.65 Sn _0.35 ) _0.9575 Ti _0.0425 ] _0.98 O ₃

Each of the five types of green sheets obtained was taken and placed on one surface thereof as shown in FIG.
In the same manner as above, platinum electrode parts 8, 8, ... With a thickness (when dried) of about 6 μm were formed (step (b)). With respect to each of the same type of green sheets, a green sheet with and without an electrode portion was used, and both were pressure-bonded so that the electrode portion was sandwiched.

The five types of green sheet pairs (T ₁ + T ₁ ) obtained in this way are ... (T ₁ + T ₁ ),
(T ₂ + T ₂ ), (T ₃ + T ₃ ), (T ₄ + T ₄ ),
(T ₅ + T ₅ ), (T ₄ + T ₄ ), (T ₃ + T ₃ ),
(T ₂ + T ₂ ), (T ₁ + T ₁ ), ... are laminated in this order and pressure-bonded at 120 ° C. by applying a pressure of 160 kg / cm ² .
(Step (c)). Next, this is cut in the stacking direction and the length is 5 mm ×
A laminated body having a width of 10 mm and a thickness (laminating direction) of 8 mm was obtained.

The obtained laminate was degreased under the conditions shown in FIG. 8 in the same manner as in Example 1. Next, the degreased laminate was respectively subjected to temperatures of 1020 ° C., 1100 ° C. and 1200 ° C.
Firing was performed in the atmosphere for 3 hours. The electrode portion 8 of the obtained fired body,
The lead wires 40, 40, ... Are connected to 8, ...

With respect to these piezoelectric electrostrictive ceramic laminates, changes in Ti concentration in the laminating direction were measured by EPMA. The result is shown in FIG. 13 (a) shows the case where the firing temperature is 1020 ° C., (b) shows the case where the firing temperature is 1100 ° C., and
(c) shows the case of 1200 ° C., respectively. As is clear from FIG. 13, in the case of firing at 1200 ° C. (c), the change in the Ti concentration is closer to a sine wave shape and is smooth.

A voltage is applied to the piezoelectric electrostrictive ceramic laminate obtained above, which is fired at 1200 ° C.,
The amount of strain was measured. As a result, the hysteresis curve shown in FIG. 14 was obtained.

[0074]

As described in detail above, the piezoelectric electrostrictive ceramic laminate of the present invention gently changes the amount of strain according to the applied voltage, and its hysteresis curve is made slim. Therefore, the piezoelectric electrostrictive ceramic laminate of the present invention can be used to control the amount of distortion in an analog manner. Such a piezoelectric electrostrictive ceramic laminate is suitable for an actuator used for various controls.

[Brief description of drawings]

FIG. 1 shows a piezoelectric electrostrictive ceramic laminate according to an embodiment of the present invention, (a) is a partial schematic cross-sectional view thereof, and (b) is a schematic view showing a change in Ti concentration before firing, (c) is a schematic diagram showing a change in Ti concentration after firing.

FIG. 2 is a schematic diagram showing changes in Ti concentration (before and after firing) of a piezoelectric electrostrictive ceramic laminate according to another example of the present invention.

FIG. 3 is a schematic diagram showing changes in Ti concentration (before and after firing) of a piezoelectric electrostrictive ceramic laminate according to still another example of the present invention.

FIG. 4 shows a piezoelectric electrostrictive ceramic laminate according to still another embodiment of the present invention, (a) is a partial schematic sectional view thereof, and (b) is a schematic diagram showing a change in Ti concentration before firing. Yes,
(c) is a schematic diagram showing a change in Ti concentration after firing.

FIG. 5 is a schematic diagram showing changes in Ti concentration after firing of a piezoelectric electrostrictive ceramic laminate according to still another example of the present invention.

FIG. 6 is a schematic view showing an example of a process of manufacturing a piezoelectric electrostrictive ceramic laminate according to an embodiment of the present invention.

FIG. 7 is a schematic view showing an example of a process of manufacturing a piezoelectric electrostrictive ceramic laminate according to another embodiment of the present invention.

FIG. 8 is a graph showing an example of a heat treatment pattern in a degreasing step when manufacturing the piezoelectric electrostrictive ceramic laminate of the present invention.

FIG. 9 is a graph showing the temperature characteristics of a piezoelectric electrostrictive ceramics using PMNPT ceramics, (a) is the case of using the conventional PMNPT ceramics, (b)
Shows the case where the PMNPT-based ceramic laminate of the present invention is used.

10 is a graph showing changes in Ti concentration in the stacking direction after firing of the piezoelectric electrostrictive ceramic laminate in Example 1. FIG.

11 is a graph showing a voltage-strain amount hysteresis curve of the piezoelectric electrostrictive ceramic laminate according to Example 1. FIG.

FIG. 12 is a graph showing a voltage-strain amount hysteresis curve of the piezoelectric electrostrictive ceramic laminate of Example 2.

13 is a graph showing the Ti concentration in the stacking direction after firing of the piezoelectric electrostrictive ceramic laminate of Example 3, where (a) is a firing temperature of 1020 ° C., (b) is 1100 ° C., And (c) show the case of 1200 ° C.

14 is a graph showing a voltage-strain amount hysteresis curve of the piezoelectric electrostrictive ceramic laminate according to Example 3. FIG.

FIG. 15 is a graph schematically showing a voltage-strain amount hysteresis curve of a PNZST-based piezoelectric electrostrictive material, where a solid line indicates a case of a single piezoelectric electrostrictive material, and broken lines indicate a plurality of metal component concentrations different from each other. The case where the piezoelectric electrostrictive material of a kind is laminated (this invention) is shown.

FIG. 16 is a schematic graph showing the hysteresis of electric field-distortion amount.

FIG. 17 is a schematic graph showing the hysteresis of electric field-distortion amount.

[Explanation of symbols]

1, 7 Piezoelectric electrostrictive ceramic laminates 2a, 2b, 4a, 4b, 4c, 5a, 5b, 5c, 5
d, 5e Piezoelectric ceramic materials 3a, 3b, 8 Electrode parts 9, 10, 11 Ceramic laminated body 30, 40 Lead wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 41/24 9274-4M H01L 41/22 A

Claims (4)

[Claims] 1. A piezoelectric electrostrictive ceramic laminate obtained by laminating a plurality of piezoelectric electrostrictive ceramic materials, wherein:
A piezoelectric electrostrictive ceramic laminate, wherein the concentration of a metal component forming the piezoelectric electrostrictive ceramic material is changed. 2. The piezoelectric electrostrictive ceramic laminate according to claim 1, wherein the piezoelectric electrostrictive ceramic material is Pb-Nb-Zr.
A piezoelectric electrostrictive ceramic laminate characterized by being a -Sn-Ti-based oxide. 3. The piezoelectric electrostrictive ceramic laminate according to claim 2, wherein the concentration of Ti changes in the laminating direction. 4. The piezoelectric electrostrictive ceramic laminate according to any one of claims 1 to 3, wherein the concentration change of the metal component is sinusoidal.