JP2011082534A - Laminated piezoelectric element and injection device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated piezoelectric element with good durability that is free of breaking of wires of an external electrode and an internal electrode even when driven continuously for a long period in a high-electric-field and high-pressure environment, and an injection device. <P>SOLUTION: The laminated piezoelectric element is constituted by coating ends of every other layer of a plurality of internal electrodes 2 with insulators 3 on a side face of a square pole type pillar laminate 1a formed by alternately laminating a plurality of piezoelectric bodies 1 and the plurality of internal electrodes 2, joining external electrodes 4 to ends of the internal electrodes 2 which are not covered with the insulators 3, and connecting and fixing lead wires 5 to the respective external electrodes 4, wherein a piezoelectric layer 1 contains Si, which is segregated at a crystal grain boundary and not present in the form of a definite glass layer to be present as SiO<SB>2</SB>which is substantially monomolecular. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to piezoelectric ceramics and laminated piezoelectric elements and injection devices using the same, and is used for, for example, piezoelectric transformers, precision positioning devices such as automobile fuel injection devices and optical devices, and drive elements for vibration prevention. The present invention relates to a multilayer piezoelectric element such as a multilayer piezoelectric actuator and an ejection device.

Conventionally, as a ferroelectric ceramic or a piezoelectric ceramic, there is a composite perovskite compound mainly composed of PbTiO ₃ —PbZrO ₃ (hereinafter abbreviated as PZT). These materials are almost entirely composed of ceramics, and are produced by forming a raw material or calcined powder into a predetermined shape and then firing it at a high temperature. In these conventional piezoelectric ceramics, piezoelectric ceramics having various characteristics are produced according to the application by selecting the composition ratio of the components and used for applications such as actuators, ceramic filters, and piezoelectric buzzers. For example, the piezoelectric actuator has excellent features such as low power consumption and heat generation, excellent response speed, large displacement, and small dimensions and weight compared to a conventional electromagnetic actuator in which a coil is wound around a magnetic material. have. However, PZT ceramics have the disadvantages that the four-point bending strength is about 101 MPa and that cracks and chips are likely to occur during processing.

Therefore, Patent Document 1 discloses P containing 0.01 to 0.3% by weight of Fe, 0.01 to 0.04% by weight of Al, and 0.01 to 0.04% by weight of Si for the purpose of suppressing chipping and cracking during grinding.
ZT piezoelectric ceramics are disclosed.

In the PZT-based piezoelectric ceramic disclosed in Patent Document 1, Al and Si contained as subcomponents easily form a liquid phase in the sintering stage, and PbO—Al ₂ is formed at the crystal grain boundary of the sintered body after the sintering. A glass phase mainly composed of O ₃ —SiO ₂ is formed. Thereby, the sintered body can be densified at a temperature lower than that of the piezoelectric ceramic not containing these subcomponents, and crystals can be grown. For this reason, cracking and chipping during grinding can be suppressed, and the fracture toughness value of the sintered body can be increased because the glass phase has a higher fracture toughness value than the perovskite type compound.

  As a multilayer piezoelectric element, a multilayer piezoelectric actuator in which piezoelectric bodies and internal electrodes are alternately stacked is known. Multilayer piezoelectric actuators are classified into two types: simultaneous firing types and stack types in which piezoelectric ceramics and internal electrode plates are alternately stacked. Simultaneous firing is considered in terms of lowering the voltage and reducing manufacturing costs. Since the multilayer piezoelectric actuator of the type is advantageous for thinning, its superiority is being shown.

JP2002-220281

  However, the piezoelectric ceramic disclosed in Patent Document 1 has a problem that it is inferior in terms of reliability and durability, such as a change in volume resistivity over time. For example, when piezoelectric ceramics are used as an in-vehicle piezoelectric actuator, reliability and durability are very important factors.

In addition, when processing piezoelectric ceramics or ultrasonic cleaning, the surface roughness decreases because of the occurrence of grain loss, and not only the porcelain surface but also the internal crystal grains are damaged, resulting in a decrease in durability. There is a problem.

  In addition, the present invention provides a piezoelectric ceramic having excellent durability without causing dielectric breakdown even when driven continuously for a long time under a high electric field and high pressure, and a laminated piezoelectric element and an injection device using the same. For the purpose.

The multilayer piezoelectric element of the present invention is a multilayer piezoelectric element formed by alternately laminating piezoelectric layers made of piezoelectric ceramics and internal electrode layers, and Si is contained in the piezoelectric layer. Si is segregated at the crystal grain boundaries of the piezoelectric ceramics, and the Si does not exist as a clear glass layer but exists as SiO ₂ of about a single molecule.

  In the multilayer piezoelectric element of the present invention, the crystal grain boundary has a thickness of 1 nm or less in the above configuration.

  Furthermore, the multilayer piezoelectric element of the present invention is characterized in that, in each of the above-described configurations, the metal composition of the internal electrode layer is composed of a Group 8 metal and a Group 1b metal of the periodic table.

  In the multilayer piezoelectric element of the present invention, when the content of the Group 8 metal in the internal electrode is M1 (wt%) and the content of the Group 1b metal is M2 (wt%) in each of the above configurations. 0 <M1 <15 and 85 <M2 <100.

  Furthermore, the multilayer piezoelectric element of the present invention is characterized in that, in each of the above structures, the Group 8 metal is at least one of Pt and Pd, and the Group 1b metal is at least one of Au and Ag. To do.

  An injection device according to the present invention includes a storage container having an injection hole, a laminated piezoelectric element having the above-described configuration housed in the storage container, and a valve for ejecting liquid from the injection hole by driving the laminated piezoelectric element. It is characterized by comprising.

According to the multi-layer piezoelectric element of the present invention, the piezoelectric ceramic constituting the same contains 5 ppm or more and less than 100 ppm of Si, so that the glass phase is not formed at the grain boundary and the change in volume resistivity with time can be reduced. Therefore, even when a multilayer piezoelectric element and an injection device using the same are driven continuously for a long time under a high electric field and high pressure, the external electrode and the internal electrode are not disconnected and excellent in durability. It is possible to provide a laminated piezoelectric element and an injection device.

1 illustrates a multilayer piezoelectric element according to the present invention, in which (a) is a perspective view and (b) is a cross-sectional view taken along line A-A ′. It is a schematic sectional drawing which shows the injection apparatus of this invention.

  FIG. 1 shows a multilayer piezoelectric actuator which is an embodiment of the multilayer piezoelectric element of the present invention. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a longitudinal section along the line AA 'in FIG. FIG.

As shown in FIG. 1, the multilayer piezoelectric actuator has an end portion of the internal electrode 2 on the side surface of a quadrangular columnar stacked body 1a in which a plurality of piezoelectric bodies 1 and a plurality of internal electrodes 2 are alternately stacked. A porous conductor that is covered with an insulator 3 every other layer and is made of a conductive material and glass mainly composed of silver and has a three-dimensional network structure at the end of the internal electrode 2 that is not covered with the insulator 3 The external electrodes 4 are joined and lead wires 5 are connected and fixed to the external electrodes 4. Reference numeral 6 denotes an inactive layer.

The piezoelectric body 1 is formed of a PZT-based piezoelectric ceramic material whose details will be described later. The piezoelectric ceramics are those piezoelectric strain constant d ₃₃ indicating the piezoelectric characteristic is high is preferable.

The thickness of the piezoelectric body 1, that is, the distance between the internal electrodes 2 is preferably 50 to 250 μm. As a result, even if the laminated piezoelectric actuator applies a voltage and increases the number of laminated layers in order to obtain a larger displacement, the actuator can be reduced in size and height and the dielectric breakdown of the piezoelectric body 1 can be reduced. Can be prevented.

  An internal electrode 2 is disposed between the piezoelectric bodies 1, and the metal composition of the internal electrode 2 is composed of a group 8 metal and a group 1b metal of the periodic table. Preferably, the Group 8 metal is at least one of Pt and Pd, and the Group 1b metal is at least one of Au and Ag. An example is an Ag-Pd alloy.

When the content of the Group 8 metal is M1 (wt%) and the content of the Group 1b metal is M2 (wt%), if 0 <M1 <15, 85 <M2 <100, Since the content of a certain Group 1b metal can be reduced, an inexpensive stacked piezoelectric element can be provided. However, if the content of the Group 1b metal is reduced, the melting point of the alloy metal is lowered, so that it cannot be used unless it is sintered at a low temperature of 1000 ° C. or lower. Si is 5ppm or more and 100pp in the porcelain composition
When the content is less than m, porcelain crystals tend to grow, and it becomes easier to sinter at lower temperatures. Further, when the Si content is in the above range, the piezoelectric characteristics are not adversely affected.

  In addition, a groove having a depth of 30 to 500 μm and a width in the stacking direction of 30 to 200 μm is formed on the side surface of the columnar laminated body 1a. An insulator 3 is formed by filling an epoxy resin, a polyimide resin, a polyamideimide resin, a silicone rubber, or the like. The insulator 3 is preferably made of a material having a low elastic modulus that follows the displacement of the columnar laminate 1a, particularly silicone rubber, in order to strengthen the bonding with the columnar laminate 1a.

  External electrodes 4 are joined to opposite side surfaces of the columnar laminate 1a, and the laminated internal electrodes 2 are electrically connected to the external electrodes 4 every other layer. The external electrode 4 serves to commonly supply a voltage necessary for displacing the piezoelectric body 1 to each connected internal electrode 2 by the inverse piezoelectric effect.

  Furthermore, lead wires 5 are connected and fixed to the external electrodes 4 by soldering. The lead wire 5 serves to connect the external electrode 4 to an external voltage supply unit.

In the present invention, the piezoelectric ceramic is characterized in that the piezoelectric ceramic constituting the piezoelectric body 1 has PbTiO ₃ —PbZrO ₃ as a main component and an Si content of 5 ppm or more and less than 100 ppm. Si has the effect of improving the strength of porcelain. If the Si content is in the above range, Si segregates at the grain boundary and the bond between crystal grains becomes strong, so during processing, ultrasonic cleaning, etc. It becomes difficult to shatter. Further, it is known that the grain boundary degradation induced by the DC electric field corresponds to the degradation of the porcelain by the degradation mechanism of the volume resistivity. In piezoelectric ceramics, the grain boundaries are known to have a higher resistivity than the interior of the grains, and when a DC electric field is applied, Maxwell-Wagner type polarization generates a strong electric field at the grain boundaries. . It is considered that the volume resistivity of the porcelain is deteriorated by this electric field causing local breakdown. From the above points, when the Si content is 100 ppm or more, a glass phase is formed at the grain boundary, so the resistivity at the grain boundary is increased, a strong electric field is generated at the grain boundary, and local dielectric breakdown occurs. Deterioration of volume resistivity tends to occur. If it is less than 100 ppm, a clear glass phase is not formed at the grain boundary, and exists as SiO ₂ of about a single molecule. Therefore, the resistivity at the grain boundary is lowered, and local dielectric breakdown can be made difficult to occur. On the other hand, when the Si content is less than 5 ppm, the effect of improving the bonding force between the crystal grains is small, so that the grains are easily shed during processing or ultrasonic cleaning.

In addition, the piezoelectric ceramic of the present invention is a sintered body substantially composed of a perovskite type compound except for the component composed of Si. However, the fact that the remainder is composed essentially of a perovskite type compound is positively This means that it is a perovskite type compound other than impurities, and components contained as impurities (excluding Si) may be contained within a range of less than 100 ppm.

Further, in the present invention, it is preferable that Si is segregated at the crystal grain boundary and the thickness of the crystal grain boundary layer of the porcelain is 1 nm or less. If the Si content is less than 100 ppm, Si segregates at the crystal grain boundary, and the thickness of the grain boundary layer is 1 nm or less. As a result, while increasing the strength of the porcelain, it is possible to reduce the time-dependent change of the volume resistivity while hardly affecting the characteristics such as the piezoelectric strain constant. This is because, when Si is dissolved in crystal grains, the piezoelectric characteristics are remarkably reduced, but if segregated at the crystal grain boundaries, the influence on the piezoelectric strain characteristics can be reduced. When the thickness of the crystal grain boundary layer exceeds 1 nm, a clear glass phase is formed at the crystal grain boundary. If there is a glass phase at the grain boundary, the resistivity of the grain boundary becomes high, so that it becomes easy to cause a minute dielectric breakdown at the crystal grain boundary. Therefore, it is better for Si to be present at the monomolecular level than at the crystal grain boundary as a glass phase.

Preferably, the average crystal grain size A of the piezoelectric ceramic is 0.5 to 0.5 in order to improve the mechanical strength.
When the standard deviation is B, the B / A is 0.5 or less when the standard deviation is B, the average void diameter C is 0.5 to 5 μm, the D / C is 0.25 or less when the standard deviation is D, and the void ratio Is 5% or less, it becomes strong against external impact and repeated fatigue. In addition, the destruction mode that suddenly increases the leakage current and leads to destruction is known as the avalanche mode, but this cause is caused by structural defects such as cracks and voids, so if the microstructure of the porcelain is uniform, For example, when used as an actuator, a change in volume specific resistance with time during continuous driving is small, and thus high reliability can be obtained.

As the grain size of porcelain increases, the bending strength tends to decrease. When the average crystal grain size A of porcelain exceeds 5 μm, it tends to be broken by external impact and repeated fatigue, and the volume resistivity deteriorates. Easier to use and less reliable. On the contrary, it is difficult to make the average crystal grain size of the porcelain less than 0.5 μm because of the problem of atomization of raw materials and firing temperature. Therefore, the average crystal grain size of the porcelain is preferably 1 to 3 μm.

If the ratio B / A between the average crystal grain size A and the standard deviation B of the porcelain exceeds 0.5, the fine structure of the porcelain is not uniform and large defects and crystal grains are present. Therefore, it becomes easy to be destroyed by an external impact or repeated fatigue, and the volume resistivity is liable to deteriorate and the reliability is lowered.

Since the average crystal grain size of the porcelain is 0.5 to 5 μm, the average diameter C of the voids in the porcelain is about 0.5 to 5 μm. The smaller the defect, the stronger the resistance to external impact and repeated fatigue, and the lower the volume resistivity, thereby improving the reliability. If the average diameter of the voids exceeds 5 μm, the void is likely to be broken by external impact or repeated fatigue, and the volume resistivity is easily deteriorated, so that the reliability is lowered. On the other hand, making the average diameter of voids less than 0.5 μm is difficult to produce at low cost due to problems of atomization of raw materials and firing temperature.

  Further, when the ratio D / C between the average diameter C of the voids in the porcelain and the standard deviation D thereof exceeds 0.25, there is a large defect in the porcelain, which is easily broken due to external impact or repeated fatigue. Further, if the void ratio exceeds 5%, there are too many defects, so that it tends to be destroyed by external impact or repeated fatigue, and the volume resistivity tends to deteriorate, so the reliability is lowered. Moreover, although it is preferable from the surface of a characteristic or reliability that a void does not exist, it is difficult on a manufacturing method.

A method for producing the multilayer piezoelectric element of the present invention will be described. First, the columnar laminate 1a is produced. First, as a raw material powder of PZT, a predetermined amount of high-purity PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ , WO ₃ , BaCO ₃ , SrCO ₃ , Yb ₂ O ₃ and SiO ₂ is weighed in a predetermined amount. Then, the mixture is wet-mixed for 10 to 24 hours using a ball mill, etc., and then the mixture is dehydrated and dried, and then calcined at 800 to 900 ° C. for 1 to 3 hours. Wet pulverize so that ₅₀ is 0.5 ± 0.2 μm and D ₉₀ is less than 0.8 μm. Mixing the calcined powder of pulverized piezoelectric ceramics such as PZT, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer such as DBP (diethyl phthalate) or DOP (dibutyl phthalate) A slurry is prepared, and a ceramic green sheet to be the piezoelectric body 1 is prepared from the slurry by a tape molding method such as a well-known doctor blade method or calendar roll method.

  Next, a conductive paste is prepared by adding a binder, a plasticizer, and the like to Ag—Pd or Pt powder, and this is printed on the upper surface of each green sheet to a thickness of 1 to 40 μm by screen printing or the like.

And the green sheet | seat with which the electrically conductive paste was printed on the upper surface is laminated | stacked, and after removing a binder about this laminated body at predetermined temperature, the columnar laminated body 1a is produced by baking at 900-1200 degreeC.

  The columnar laminate 1a is not limited to the one produced by the above-described manufacturing method, and any method can be used as long as the columnar laminate 1a formed by alternately laminating a plurality of piezoelectric bodies and a plurality of internal electrodes can be produced. It may be formed by any manufacturing method.

  Thereafter, grooves are formed in every other side surface of the columnar laminate 1a by a dicing apparatus or the like.

  Thereafter, a silver glass conductive paste or the like can be baked at 550 to 700 ° C. to form the external electrode 4.

  Next, the columnar laminate 1a on which the external electrode 4 is formed is immersed in a silicone rubber solution, and the silicone rubber solution is vacuum degassed to fill the groove of the columnar laminate 1a with silicone rubber. The columnar laminate 1a is pulled up from the solution, and the side surface of the columnar laminate 1a is coated with silicone rubber. Thereafter, the silicone rubber filled in the groove and coated on the side surface of the columnar laminate 1a is cured.

  Thereafter, the lead wire 6 is connected to the external electrode 4 to complete the multilayer piezoelectric element of the present invention.

Then, a direct current voltage of 0.1 to 3 kV / mm is applied to the pair of external electrodes 4 via the lead wires 5 to polarize the columnar laminated body 1a, thereby completing a laminated piezoelectric actuator as a product. 5 is connected to an external voltage supply unit, and a voltage is applied to the internal electrode 2 via the lead wire 5 and the external electrode 4, the piezoelectric bodies 1 are greatly displaced by the inverse piezoelectric effect. It functions as an automobile fuel injection valve that injects and supplies fuel.

FIG. 2 shows an injection apparatus according to the present invention. In the figure, reference numeral 31 denotes a storage container.
An injection hole 33 is provided at one end of the storage container 31, and a needle valve 35 that can open and close the injection hole 33 is stored in the storage container 31.

  A fuel passage 37 is provided in the injection hole 33 so as to communicate therewith, and the fuel passage 37 is connected to an external fuel supply source, and fuel is always supplied to the fuel passage 37 at a constant high pressure. Therefore, when the needle valve 35 opens the injection hole 33, the fuel supplied to the fuel passage 37 is formed to be injected into a fuel chamber (not shown) of the internal combustion engine at a constant high pressure.

  Further, the upper end portion of the needle valve 35 has a large diameter, and serves as a piston 41 slidable with a cylinder 39 formed in the storage container 31. In the storage container 31, the above-described piezoelectric actuator 43 is stored.

  In such an injection device, when the piezoelectric actuator 43 is extended by applying a voltage, the piston 41 is pressed, the needle valve 35 closes the injection hole 33, and the fuel supply is stopped. When the application of voltage is stopped, the piezoelectric actuator 43 contracts, the disc spring 45 pushes back the piston 41, and the injection hole 33 communicates with the fuel passage 37 so that fuel is injected.

Example 1
The sintered body is Pb _1-x Ba _x (Zn _1/3 Nb _2/3 ) _a (Yb _1/2 Nb _1/2 ) _b (Co _1/3 Nb _2/3 ) _c (Fe _2/3 W _{1 / 3) d Nb e [Zr} 0.48 Ti 0.52] 1-a-b-c-d-e O 3 ( wherein, x, a, b, c , d, e is a value smaller than 1) A predetermined amount is weighed so that the composition becomes, and a predetermined amount of SiO ₂ is weighed. The raw material contains SiO ₂ as an impurity, but a raw material with as little content as possible is used. After wet-mixing for 18 hours with a ball mill, the mixture is then calcined at 900 ° C. for 2 hours, and the calcined product is wet-pulverized again with a ball mill or the like.

Thereafter, an organic binder and a plasticizer were mixed with the pulverized product to prepare a slurry, and a green sheet having a thickness of 150 μm was prepared by a slip casting method. On this green sheet, a conductive paste having a ratio of 90% by weight of Ag and 10% by weight of Pd was screen-printed to a thickness of 4 μm and dried, and then 20 sheets of green sheets on which electrode films were formed (piezoelectric) the strain constant d ₃₃ 200 layers) was stacked when measuring, the green sheet a conductive paste on both ends of the stacking direction is not applied to the laminate by laminating 10 sheets.

Next, this laminate is heated while being heated at 100 ° C., and the laminate is integrated to obtain a vertical 10
After cutting to mm × width 10 mm, the binder was removed at 800 ° C. for 10 hours and baked at 1000 ° C. to prepare the columnar laminate shown in 1a. Thereafter, grooves having a depth of 100 μm and a width of 50 μm in the stacking direction are formed on the two side surfaces of the multilayer piezoelectric element so that the two side surfaces alternate with each other at the end portions of the piezoelectric ceramic including the electrode end portions. The groove was filled with silicone rubber as an insulator.

Thereafter, a thermosetting conductor was formed in a strip shape as an external electrode on the other end face of the non-insulated electrode, and a heat treatment at 200 ° C. was performed. Thereafter, lead wires are connected to the positive electrode external electrode and the negative electrode external electrode, and the outer peripheral surface of the multilayer piezoelectric element is coated with silicone rubber, and then a polarization voltage of 1 kV is applied to the entire multilayer piezoelectric element. Was subjected to polarization treatment to obtain a laminated piezoelectric element of the present invention as shown in FIG. The obtained laminated piezoelectric element was measured for the amount of displacement when a voltage of 0 to 200 V was applied, and the piezoelectric strain constant d ₃₃ was measured. The amount of displacement was measured by fixing a sample with aluminum foil on the top surface on a vibration isolation table, applying a voltage of 0 to 200 V to the sample, and measuring it at the center of the element and at three locations around the element with a laser displacement meter. The average value was evaluated. The piezoelectric strain constant d ₃₃ was calculated from the equation: d ₃₃ = ΔL / n · V using the number of layers n = 200, the displacement ΔL, and the applied voltage V = 200V.

  Further, the Si content was quantified by ICP mass spectrometry capable of quantification on the order of ppm. Further, the thickness of the grain boundary layer was calculated from a TEM image.

  For ease of grain removal, ultrasonic cleaning was performed in pure water for 10 minutes, and the subsequent surface was observed with a metallographic microscope.

HALT (Highly Accelerated Life Testing)
) A test was conducted. The time until the leakage current increased and the dielectric breakdown occurred was measured. The test was conducted under the conditions of an atmospheric temperature of 300 ° C. and an electric field of 2 kV / mm.

  The results are shown in Table 1.

As can be seen from Table 1, Samples 1, 10, and 11 having a Si content of 100 ppm or more have a grain boundary layer thickness exceeding 1 nm, and the time until dielectric breakdown is fast. On the other hand, Samples 8, 9, and 15 having a Si content of less than 5 ppm had low resistance to degranulation, and degranulation was observed after processing and after ultrasonic cleaning. It can be seen that when the Si content of the present invention is in the range of 5 ppm or more and less than 100 ppm, the grain boundary layer is 1 nm or less, the volume resistivity does not change for a long time even when a voltage is applied, and dielectric breakdown hardly occurs.

Further, in the above-described manufacturing method, the composition is easily controlled, so that a predetermined amount of SiO ₂ is added. However, if the Si content of the fired piezoelectric ceramic can be in the range of 5 ppm or more and less than 100 ppm, the SiO _{2 is} positively added. A starting material containing a large amount of SiO ₂ as an impurity may be used without adding.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 1a ... Columnar laminated body 2 ... Internal electrode 3 ... Insulator 4 ... External electrode 5 ... Lead wire 6 .... Inactive part 7 ... Conductive auxiliary member 31 ... Storage container 33 ... Injection hole 35 ... Needle valve 37 ... Fuel passage 39 ... Cylinder 41 ... Piston 43 ... Piezo actuator 45 ... Disc spring

Claims (6)

A multilayer piezoelectric element comprising piezoelectric layers made of piezoelectric ceramics and internal electrode layers alternately stacked, wherein Si is contained in the piezoelectric layer, and the Si is a crystal grain boundary of the piezoelectric ceramics. A laminated piezoelectric element characterized in that the Si is not segregated as a clear glass layer but is present as monomolecular SiO ₂ .   The multilayer piezoelectric element according to claim 1, wherein a thickness of the crystal grain boundary is 1 nm or less.   3. The multilayer piezoelectric element according to claim 1, wherein the metal composition of the internal electrode layer comprises a Group 8 metal and a Group 1b metal of the periodic table.   When the content of the Group 8 metal in the internal electrode is M1 (wt%) and the content of the Group 1b metal is M2 (wt%), 0 <M1 <15, 85 <M2 <100 The multilayer piezoelectric element according to claim 3, wherein   The multilayer piezoelectric element according to claim 3 or 4, wherein the Group 8 metal is at least one of Pt and Pd, and the Group 1b metal is at least one of Au and Ag.   A storage container having an injection hole, the stacked piezoelectric element according to any one of claims 1 to 5 stored in the storage container, and a valve for ejecting liquid from the injection hole by driving the stacked piezoelectric element An injection device comprising:

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