JP2001342062A - Piezoelectric ceramic, laminated piezoelectric element, and injection device - Google Patents

Abstract

(57) Abstract: piezoelectric strain constant d ₃₃ is large, the piezoelectric ceramic can be low-temperature firing, and the displacement amount is large and a large generated force, the laminated piezoelectric element capable of increasing the Ag ratio in the internal electrode And an injection device. SOLUTION: PbZrO ₃ -PbTiO ₃ is a main component,
At least _{Pb (Yb 1/2 Nb 1/2} ) O 3, Pb (Co 1/3
Nb _2/3) O ₃ and _{Pb (Zn 1/3 Nb 2/3} ) O 3 becomes a perovskite-type composite oxide as secondary components, Zr / T
The i-ratio satisfies 0.85 to 0.96 and contains 10 to 20 mol% of the subcomponent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic, a laminated piezoelectric element, and a jetting device, and more particularly to a piezoelectric ceramic suitable for a co-fired piezoelectric transformer having internal electrodes, a printer head for ink jet, a laminated piezoelectric actuator, and the like. The present invention relates to a laminated piezoelectric element and an injection device.

[0002]

2. Description of the Related Art Conventionally, co-fired laminated piezoelectric elements having internal electrodes include a piezoelectric transformer, an ink jet printer head, and a co-fired laminated piezoelectric actuator.

[0003] The simultaneous firing type laminated piezoelectric actuator is manufactured by alternately stacking piezoelectric layers and internal electrodes, integrally firing and performing electrical wiring, and utilizes a displacement amount generated through a piezoelectric phenomenon. Is what you do. A material containing Ag, Pd, Pt, or the like is used as a metal component of the internal electrode. The ratio of the metal component is such that a noble metal such as Pd or Pt is introduced into Ag having a low melting point, and the internal electrode is melted when integrally firing. The temperature is shifted to a high temperature side so that the electrode formation failure due to condensation can be avoided.

Usually, the co-fired type laminated piezoelectric actuator is set to the sintering temperature of the piezoelectric ceramic, and the sintering temperature is 1100 ° C. or higher. Therefore, the ratio of Ag in the metal component constituting the internal electrode is 70% by weight or less in the metal component so as to prevent electrode formation failure.

On the other hand, from the viewpoint of cost reduction, it is advantageous that the ratio of Ag is large.
No. 7263 discloses a piezoelectric ceramic material that can be fired at a low temperature of 1000 ° C. or less and that can reduce the manufacturing cost.

[0006]

However, in the piezoelectric material disclosed in Japanese Patent Application Laid-Open No. H11-217263,
The piezoelectric strain constant d ₃₃ which is a measure of the displacement is less than 400 pm / V, the displacement amount as a co-fired multilayer piezoelectric actuator was insufficient.

Further, in the laminated piezoelectric actuator, since there is a positive correlation between the Young's modulus and the generated force, when the piezoelectric strain constant d ₃₃ is small, Zr /
It is conceivable to increase the Young's modulus by adjusting the Ti ratio. In this case, however, the piezoelectric strain constant d ₃₃ further decreases,
There is a problem that the displacement of the laminated piezoelectric actuator is further reduced.

Further, in the case of ordinary piezoelectric ceramics, the firing temperature is 11
When the temperature is about 00 to 1300 ° C. and the Ag ratio in the metal component constituting the internal electrode is larger than 70% by weight, as described above, the internal electrode is melted during the heating process of firing,
There has been a problem in that the electrode is poorly formed due to condensation during the cooling process.

[0009] The present invention has a large piezoelectric strain constant d _33, the piezoelectric ceramic can be low-temperature firing, and the displacement amount is large and the Young's modulus is large, the laminated piezoelectric element and the injection can be increased Ag ratio in the internal electrode It is intended to provide a device.

[0010]

According to the present invention, there is provided a piezoelectric ceramic comprising:
bZrO_Three-PbTiO_Three, And at least Pb
(Yb_1/2Nb_1/2) O_Three, Pb (Co_1/3Nb_2/3) O_ThreePassing
And Pb (Zn_1/3Nb_{Two / 3}) O_ThreePerovs with as an auxiliary component
Consisting of a kite-type composite oxide and having a Zr / Ti ratio of 0.85
0.96, and the subcomponent is 10-20
%.

The piezoelectric ceramic of the present invention is made of PbZrO_Three-Pb
TiO_ThreeAnd at least Pb (Yb_1/2Nb
_1/2) O_Three, Pb (Co_1/3Nb_2/3) O_ThreeAnd Pb (Zn
_1/3Nb_{Two / 3}) O_ThreePerovskite-type composite containing
Since it is made of oxide, the pressure is maintained while keeping the Curie temperature high.
Electrostriction constant d₃₃And the firing temperature is low.
And the generated force of the laminated piezoelectric element can be increased.
In order to increase the size, the Zr / Ti ratio should be between 0.85 and 0.96.
Even if the Young's modulus is increased by changing the range, 600 pm /
Piezoelectric strain constant d above V₃₃Can be secured.

Further, the content of the auxiliary component is set to 10 to 2 in the total amount.
With 0 mol%, to further improve the piezoelectric strain constant d ₃₃ of the piezoelectric ceramic, and can ensure a high Curie temperature.

Further, the perovskite-type composite oxide A /
The B ratio is desirably 1 <A / B ≦ 1.01. For example, when the amount of Pb is excessive, the A / B ratio is set to 1 <A / B ≦
1.01 can be controlled, the porcelain can be sufficiently densified at a firing temperature of 1000 ° C. or less, and even if the Ag ratio in the metal component constituting the internal electrode is 90% by weight or more, No electrode formation failure occurs, and the cost of the internal electrode can be greatly reduced.

Further, the perovskite-type composite oxide A
It is desirable that the site contains 8 mol% or less of alkaline earth elements. This allows further improved piezoelectric strain constant d ₃₃ of the piezoelectric ceramic.

Further, the laminated piezoelectric element of the present invention is a laminated piezoelectric element in which internal electrodes and piezoelectric layers are alternately laminated, wherein the piezoelectric layer comprises the above piezoelectric ceramic, and Ag content is at least 90% by weight of the metal component.

[0016] In such a laminated piezoelectric element, as the piezoelectric porcelain described above, while maintaining a high Curie temperature can be increased piezoelectric strain constant d _33, can lower the sintering temperature, the more Zr / Ti ratio be varied greatly Young's modulus in the range of 0.85 to 0.96, it is possible to secure a 600 pm / V or more piezoelectric strain constant d _33, can the Ag amount in the internal electrode and more than 90 wt% in the metal components In addition to being able to be manufactured at low cost, the amount of displacement and the generated force can be increased.

According to a second aspect of the present invention, there is provided an injection device including a storage container having an injection hole, the above-described laminated piezoelectric element stored in the storage container, and a valve for ejecting a liquid from the injection hole by driving the multilayer piezoelectric element. It is provided with.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated piezoelectric element comprising a piezoelectric actuator according to the present invention has a laminated piezoelectric element 5 formed by alternately laminating piezoelectric ceramics 1 and internal electrodes 3a and 3b as shown in FIG. On the outer surface of the laminated piezoelectric element 5, a pair of external electrodes 7a for connecting the internal electrodes 3a and 3b alternately,
7b is formed.

A groove is formed at the end of each of the internal electrodes 3b, 3a not connected to the external electrodes 7a, 7b. By filling an insulator 8 in the groove, the external electrodes 7a, 7b are formed.
7b and the internal electrodes 3b and 3a are insulated. Lead wires 9 are connected to the external electrodes 7a and 7b, respectively.

In the present invention, the internal electrodes 3a, 3b
The metal component contains 90% by weight or more of Ag, and thus contains 90% by weight or more of Ag. Thus, the multilayer piezoelectric element 5 itself is fired at 1000 ° C. or less.

The piezoelectric ceramic 1 has a perovskite-type composite oxide as a main component, contains Pb as an A-site constituent element, and contains Zr, Ti, and B as a B-site constituent element.
It contains Yb, Nb, Co and Zn.

More specifically, the piezoelectric ceramic 1 is composed of Pb (Zr,
Ti) a main component consisting of O ₃ and Pb (Yb _1/2 Nb _1/2 )
O ₃ , Pb (Co _1/3 Nb _2/3 ) O ₃ and Pb (Zn _1/3
Nb _2/3) in which the O ₃ is a sub-component, the piezoelectric ceramic 1 is formed by these solid solution.

Pb (Zr, Ti) O ₃ (hereinafter sometimes referred to as PZT), which is widely used in perovskite-type composite oxides, is the main component, and Pb (Y
The _{b 1/2 Nb 1/2) O} 3 and Pb (Co _1/3 Nb _2/3) to cause solid solution of O _3, can increase the piezoelectric distortion constant d _33, yet maintain high Curie temperature be able to. In addition, by making Pb (Zn _1/3 Nb _2/3 ) O _{3 form} a solid solution, sintering can be performed at a temperature of 1000 ° C. or less. Be added secondary components individually, the Curie temperature, can not be sufficiently improved piezoelectric strain constant d ₃₃ and the firing temperature,
As described above, these properties can be simultaneously improved by dissolving at least _three specific perovskite-type composite oxides in Pb (Zr, Ti) O ₃ .

Incidentally, Pb (Zr, Ti) O ₃ is PbZr
It is a solid solution of O ₃ and PbTiO _3, and Pb (Yb _1/2 N
b _1/2 ) O ₃ and (Co _1/3 Nb _2/3 ) O ₃ , and Pb (Zn _1/3 Nb _2/3 ) O ₃ , so that a large Curie temperature and a large It has a piezoelectric strain constant and can realize low-temperature firing.

In particular, the content of the above subcomponents is 10 to 10% of the total amount.
Desirably, it is 20 mol%. This may, if this range, it is possible to significantly improve the piezoelectric constant d _33, since the Curie temperature can be maintained high. Conversely, when the content of the subcomponent is less than 10 mol% of the total amount, the piezoelectric strain constant d ₃₃
This is because if the ratio is small and the content is more than 20 mol%, the proportion of PZT decreases, and the high Curie temperature of PZT itself decreases. The content of the sub-components is to achieve high Curie temperature and large piezoelectric strain constant at the same time,
It is particularly desirable that the amount is 15 to 20 mol% of the total amount.

In the piezoelectric ceramic 1, Pb (Yb _1/2 N
b _1/2 ) O ₃ at 3-8 mol%, Pb (Co _1/3 Nb _2/3 ) O
₃ to 3 to 6 mol%, and Pb (Zn _1/3 Nb _2/3 ) O ₃ to ₃ to 9
Preferably, it is contained by mole%.

In the piezoelectric ceramic according to the present invention, the perovskite-type composite oxide has a Zr / Ti ratio of 0.85 to 0.9.
6 must be satisfied. Within this range, Zr / Ti
By varying the ratio, the Young's modulus of the actuator can be increased with more than 30 GPa, large generated force, it is possible to obtain a large piezoelectric device of the piezoelectric strain constant d _33.

On the other hand, the perovskite-type composite oxide Zr
If / Ti ratio is smaller than 0.85 can not be obtained a sufficient piezoelectric constant d ₃₃ to also larger than 0.96, because the Young's modulus is reduced.

Further, the perovskite-type composite oxide A /
It is desirable that the B ratio is 1 <A / B ≦ 1.01.
For example, when the amount of Pb is excessive, the A / B ratio is set to 1 <A / B ≦
1.01 can be controlled, the porcelain can be sufficiently densified at a firing temperature of 1000 ° C. or less, and even if the Ag ratio in the metal component constituting the internal electrode is 90% by weight or more, No electrode formation failure occurs, and the cost of the internal electrode can be greatly reduced.

On the other hand, when the A / B ratio is 1 or less,
Or higher sintering temperatures, or is because the piezoelectric strain constant d ₃₃ is lowered, is greater than 1.01, because the decrease in piezoelectric constant d ₃₃ becomes large. The A / B ratio of the perovskite-type composite oxide is preferably 1.005.

Further, in the present invention, as the A-site constituent element of the perovskite oxide constituting the piezoelectric ceramic 1,
In order to increase the piezoelectric strain constant of the piezoelectric ceramic, it is desirable that the alkaline site element be further contained in the A site at 8 mol% or less. Examples of the alkaline earth element include Ca, Sr, and Ba. Among them, Ba is particularly preferable as an element that partially replaces Pb at the A site.

That is, the piezoelectric strain constant d ₃₃ is expressed as d ₃₃ = K ₃₃ (ε ₃₃ ^T · S ₃₃ ^E ) ^1/2 by the electromechanical coupling coefficient K ₃₃ , the dielectric constant ε ₃₃ ^T, and the compliance S ₃₃ ^E. But A
When an alkaline earth element is contained in the site, the dielectric constant ε
_{Since the} effect of increasing ₃₃ ^T is great, as a result, the piezoelectric strain constant d
_{This is because 33} can be increased. On the other hand, if the alkaline earth element content is more than 8 mol% in the A site, the Curie temperature tends to decrease.

From the viewpoint of improving the piezoelectric distortion constant d ₃₃ and preventing the Curie temperature from lowering, the alkaline earth element
It is desirable that the content be 4 mol% or less in the site.

Further, a part of the B site of PZT is changed to N
Substituting 1 mol% or less with b is preferable because the electromechanical coupling coefficient K ₃₃ can be increased, and as a result, the piezoelectric strain constant d ₃₃ can be increased. However, when the Nb substitution amount in the B site exceeds 1 mol%, the effect is reduced, and the electromechanical coupling coefficient K ₃₃ tends to be reduced.

The subcomponent Pb (Zn_1/3Nb_2/3) O_Three
At least part of Pb (Zn_1/2W _1/2) O_ThreeAnd Pb
(Fe_2/3W_1/3) O_Three, The firing temperature decreases.
This is desirable because the effect of making it significant is significant.

According to the present invention, in particular, the piezoelectric ceramic is composed of Pb (Z
r, Ti) O _3, and Pb (Yb _1/2 Nb _1/2 ) O ₃ and Pb (Co _1/3 N)
b _2/3 ) O ₃ and Pb (Zn _1/3 Nb _2/3 ) O ₃ as a solid solution, and at least 8 mol% of Pb at the A site is substituted with Ba, and 1 mol% of part of site B with Nb
It is desirable to substitute the following.

As for the sub-component, Pb (Yb _1/2 Nb
_1/2 ) O ₃ , Pb (Co _1/3 Nb _2/3 ) O ₃ , Pb (Zn _1/3
Pb-based perovskite-type composite oxides other than Nb _2/3 ) O ₃ , such as Pb (Zn _1/3 Sb _2/3 ) O ₃ and Pb (Fe _1/3
W _1/2 ) O ₃ may be dissolved.

In particular, when the piezoelectric ceramic of the present invention has the following composition, a low firing temperature of 1000 ° C. or less can be achieved, the Curie temperature and the piezoelectric strain constant can be significantly increased, and the Zr / Ti ratio can be improved. even by increasing the Young's modulus is varied, can ensure a high piezoelectric strain constant d _33, can be increased force generated by the laminated piezoelectric element.

As the overall composition, Pb _ax Ba _x (Yb _1/2
Nb _1/2 ) _b (Zn _1/3 Nb _2/3 ) _c (Co _1/3 Nb _2/3 ) _d N
When expressed in _{b y (Zr e Ti 1-} e) 1-bcdy O 3, wherein a, b, c, d, e, x and y are, 1 <a ≦ 1.0
1, 0.03 ≦ b ≦ 0.08, 0.03 ≦ c ≦ 0.0
9, 0.03 ≦ d ≦ 0.06, 0.10 ≦ b + c + d ≦
0.2, 0.85 ≦ e / (1-e) ≦ 0.96, x ≦
0.08, y ≦ 0.01. Here,
The A / B ratio is a, the Zr / Ti ratio is e / (1-e), and b + c + d is the subcomponent amount.

The above-described laminated piezoelectric element is manufactured by the following process. First, high-purity PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ , Yb ₂
A predetermined amount of each raw material powder such as O ₃ and Co ₃ O ₄ is weighed,
The mixture is wet-mixed in a ball mill or the like for 10 to 24 hours, and then the mixture is dehydrated and dried.
3 hours calcined particle size distribution in the calcined product was again ball mill is 0.5 ± 0.2 [mu] m at D _50, wet milling so that 0.8μm less than at D _90. By using such a fine powder, firing at a lower temperature can be achieved. A slurry is prepared by mixing the obtained pulverized raw material, a binder composed of an organic polymer, and a plasticizer, and a ceramic green sheet is prepared by a slip casting method.

On one surface of the green sheet, a conductive paste having a weight ratio of Ag / noble metal (Pd, Pt, etc.) of 90/10 or more is printed as internal electrodes 3a and 3b by a screen printing method. After drying the conductive paste, a predetermined number of green sheets to which the conductive paste is applied are laminated by a predetermined number, and green sheets to which the conductive paste is not applied are provided at both ends of the laminate in the laminating direction. Are laminated.

Next, the laminate is pressurized while being heated at 50 to 200 ° C. to integrate the laminate. After the integrated laminate is cut to a predetermined size, 400 to
Debinding is performed at 800 ° C. for 5 to 40 hours, and 950
The main sintering is performed at a temperature of 〜1000 ° C. for 2 to 5 hours to obtain a laminated sintered body serving as an actuator body. The ends of the internal electrodes 3a and 3b are exposed on the side surfaces of the actuator body.

Thereafter, the piezoelectric ceramic 1 including the ends of the internal electrodes 3a and 3b is provided on two side surfaces of the actuator body.
So that the two side surfaces are alternately arranged at a depth of 50 to 500 μm every other layer and a width of 50 to 30 in the stacking direction.
A groove of 0 μm is formed, and the groove is filled with an insulator 8 such as silicone rubber. As described above, the internal electrodes 3a and 3b are alternately insulated every other layer, and are alternately connected to the same external electrodes 7a and 7b.

Thereafter, the lead wire 9 is connected to the positive electrode external electrode and the negative electrode external electrode, and the outer peripheral surface of the actuator is coated with silicone rubber by a method such as dipping, and then a polarization voltage of 0.1 to 3 kV is applied. By applying the voltage and polarizing the entire actuator, a final laminated piezoelectric actuator is obtained.

Note that the laminated piezoelectric element of the present invention has a quadrangular prism,
Any column, such as a hexagonal column or a circular column, may be used, but a quadrangular column shape is preferable from the viewpoint of easy cutting.

In the laminated piezoelectric element of the present invention, the electromechanical coupling coefficient Kr in the radial direction of the piezoelectric ceramic can be increased, so that it can be used as a filter or a piezoelectric buzzer. Although the piezoelectric ceramic according to the present invention has a perovskite crystal as a main crystal phase, a pyrochlore phase or the like may be slightly present as another crystal phase at a grain boundary. Al, S, Cl, Eu, Y, K, P, C
Although u, Mg, Si and the like may be mixed as unavoidable impurities, there is no problem in characteristics.

FIG. 2 shows an injection device of the present invention.
In the figure, reference numeral 51 indicates a storage container. An injection hole 53 is provided at one end of the storage container 51, and a needle valve 55 that can open and close the injection hole 53 is stored in the storage container 51.

A fuel passage 57 is provided in the injection hole 53 so as to be able to communicate therewith. The fuel passage 57 is connected to an external fuel supply source, and the fuel is constantly supplied to the fuel passage 57 at a constant high pressure. Therefore, when the needle valve 55 opens the injection hole 53, the fuel supplied to the fuel passage 57 is injected at a constant high pressure into a fuel chamber (not shown) of the internal combustion engine.

The upper end of the needle valve 55 has a large diameter and serves as a piston 61 slidable with a cylinder 59 formed in the storage container 51. The above-mentioned piezoelectric actuator 63 is stored in the storage container 51.

In such an injection device, when the piezoelectric actuator 63 expands by applying a voltage, the piston 61
Is pressed, the needle valve 55 closes the injection hole 53, and the supply of fuel is stopped. When the application of the voltage is stopped, the piezoelectric actuator 63 contracts, the spring 65 pushes back the piston 61, and the injection hole 53 communicates with the fuel passage 57 so that fuel is injected.

[0051]

The present invention will be described below with reference to the following examples. High purity PbO, ZrO ₂ , TiO ₂ , BaC as raw material powder
_{O 3, ZnO, Nb 2 O} 5, each raw material powder of Yb ₂ O ₃ and Co ₃ O _4, the sintered _{body, Pb ax Ba x (Yb 1/2} N
b _1/2 ) _b (Zn _1/3 Nb _2/3 ) _c (Co _1/3 Nb _2/3 ) _d Nb
_{y (Zr e Ti 1-e} ) in _1-bcdy O ₃ as a composition represented by (Table 1, x, y, a, b, c, d and e
Is a percentage converted from the atomic ratio given by the above composition formula). A predetermined amount was weighed and wet-mixed in a ball mill for 20 hours. Then, after dehydrating and drying the mixture,
Calcination was performed at 0 to 900 ° C. for 2 hours, and the calcined product was wet-pulverized again with a ball mill.

A slurry is prepared by mixing the obtained pulverized raw material, a binder composed of an organic polymer, and a plasticizer.
A ceramic green sheet having a thickness of 150 μm was prepared by a slip casting method.

On one side of this green sheet, 90
5% by weight of a conductive paste having a ratio of 10% by weight and Pd is screen-printed and dried.
Zero sheets were laminated, and ten green sheets to which no conductive paste was applied were laminated on both end faces in the laminating direction of the laminate.

Next, the laminate is pressed while being heated at 100 ° C., and the laminate is united, cut into a size of 10 mm long × 10 mm wide, and then subjected to binder removal at 800 ° C. for 10 hours. And fired for 2 hours at the temperature shown in Table 1,
On two sides of this laminated piezoelectric element, the end of the piezoelectric ceramic including the end of the internal electrode is alternately formed on the two sides so that every other layer has a depth of 100 μm and a width of 5 in the laminating direction.
A groove of 0 μm was formed, and the groove was filled with silicone rubber as an insulator.

Thereafter, a thermosetting conductor was formed in a strip shape on the other end face of the non-insulated internal electrode as an external electrode, and a heat treatment at 200 ° C. was performed. Thereafter, lead wires were connected to the positive electrode external electrode and the negative electrode external electrode, and silicone rubber was coated on the outer peripheral surface of the actuator by dipping. Then, a polarization voltage of 1 kV was applied, and the whole was subjected to a polarization treatment. 1 was obtained.

The displacement and Curie temperature of the obtained laminated piezoelectric element were measured. The measurement of the amount of displacement is performed by fixing the sample with the aluminum foil
A voltage of 200 V was applied to the sample, and evaluation was performed by using a laser displacement meter as an average value of values measured at the central portion and three peripheral portions of the element.

The piezoelectric strain constant d ₃₃ is given by:
Using the displacement amount ΔL and the applied voltage V = 200 V, d ₃₃ =
It was determined by the formula of ΔL / (n × V). Curie temperature (T
In the calculation of c), the temperature dependency of the capacitance was measured with a multimeter, and the temperature showing the maximum value was defined as the Curie temperature. The density was measured by an Archimedes method by cutting out an inactive portion of the actuator. The evaluation of the Young's modulus was obtained from the weighted displacement characteristics in a state where a voltage of 200 V was applied to the actuator. The results are shown in Table 1.

[0058]

[Table 1]

Usually, pure PZT is fired at 1000 ° C.
At the temperature, the porcelain density is 6.0 g / cm ^ThreeUse
You can't get what you can. However, the piezoelectric actuator of the present invention
In the evaporator, despite the firing temperature of 1000 ℃ or less
7.7 g / cm^ThreeIt has the above density,
It was dense. In the samples of the present invention,
A dense sintered body can be obtained at a temperature of 1000 ° C or less, and the piezoelectric strain is determined.
Number d₃₃Is 600 pm / V or more and Tc is 250 ° C. or more.
Value was obtained.

On the other hand, sample No. (Yb _1/2 Nb _1/2 ) was not substituted. 26 Although d ₃₃ and a high degree 850pm / V, Tc is as low as 195 ° C.. Also, (Co _1/3
Nb _2/3) and (not substituted with Zn _1/3 Nb _2/3) Sample No. 27, Sample No. not substituted by (Co _1/3 Nb _2/3) Sample No. 28 not substituted with (Zn _1/3 Nb _2/3 ) None of the 29, d ₃₃ is 600pm
/ V and a small displacement.

Further, when the amount of the subcomponent (b + c + d) is 10
If less than mol%, the piezoelectric strain constant d₃₃Is small,
On the other hand, when it is more than 20 mol%, the Curie temperature is low.
You can see it goes down. Further, the Zr / Ti ratio is 0.85 to 0.85.
Outside the range of 0.96, the piezoelectric strain constant d₃₃Is small
It turns out to be. Also, the piezoelectric strain constant d₃₃Is very large
Therefore, if the Zr / Ti ratio is changed to increase the Young's modulus
In any case, the piezoelectric strain constant d ₃₃Is more than 600 pm / V
You can see that it can be maintained.

In the sample of the present invention, the formation state of the internal electrodes was evaluated by observing the polished cross section of the co-fired laminated piezoelectric element by SEM, and it was confirmed that no aggregation of the internal electrodes occurred.

[0063]

As described in detail above, according to the present invention, P
bZrO ₃ -PbTiO ₃ as a main component and at least Pb
Perovskite-type composite oxide containing (Yb _1/2 Nb _1/2 ) O ₃ , Pb (Co _2/3 Nb _1/3 ) O ₃ and Pb (Zn _1/2 Nb _1/2 ) O ₃ as subcomponents since consisting, it is possible to increase the piezoelectric distortion constant d ₃₃ while maintaining a high Curie temperature,
In order to lower the firing temperature and to increase the generating force of the laminated piezoelectric element, the Zr / Ti ratio is set to 0.85
Even if the Young's modulus is increased by changing in the range of ~ 0.96,
It can be secured 600 pm / V or more piezoelectric strain constant d _33.

Further, the content of the subcomponent is set to 10 to 2 in the total amount.
By setting it to 0 mol%, the piezoelectric strain constant of the piezoelectric ceramic can be further improved, and a high Curie temperature can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piezoelectric actuator using a laminated piezoelectric element of the present invention.

FIG. 2 is a conceptual diagram showing an injection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric ceramic 3a, 3b ... Internal electrode 5 ... Multilayer piezoelectric element 7a, 7b ... External electrode 51 ... Storage container 53 ... Injection hole 55 ... Valve 63 ... Piezo actuator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 41/083 H01L 41/08 Q 41/09 U 41/187 41/18 101E 101F

Claims (5)

[Claims] (1) PbZrO_Three-PbTiO_ThreeIs the main component,
At least Pb (Yb _1/2Nb_1/2) O_Three, Pb (Co_1/3
Nb_2/3) O_ThreeAnd Pb (Zn_1/3Nb_{Two / 3}) O_ThreeThe subcomponent
Zr / T made of a perovskite-type composite oxide
i ratio satisfies 0.85 to 0.96, and the subcomponent
Characterized by containing 10 to 20 mol% of
vessel. 2. The piezoelectric ceramic according to claim 1, wherein the A / B ratio of the perovskite-type composite oxide is 1 <A / B ≦ 1.01. 3. The piezoelectric ceramic according to claim 1, wherein the A site of the perovskite-type composite oxide contains 8 mol% or less of an alkaline earth element. 4. A laminated piezoelectric element in which internal electrodes and piezoelectric layers are alternately laminated, wherein the piezoelectric layer comprises the piezoelectric ceramic according to any one of claims 1 to 3, A multilayer piezoelectric element, wherein the Ag content in the internal electrode is 90% by weight or more of the metal component. 5. A storage container having an ejection hole, a laminated piezoelectric element according to claim 4, which is accommodated in the storage container, and a valve for ejecting a liquid from the ejection hole by driving the laminated piezoelectric element. An injection device, comprising: