JP4671522B2 - Piezoelectric ceramic, multilayer piezoelectric element, and injection device - Google Patents

Description

【００５９】
【表２】

【００６０】
【表３】

【００６１】
【表４】

【００６２】
表１から、（Ｃｏ_1/3Ｎｂ_2/3）を含まない比較例Ｎｏ．１の場合には、機械的品質係数Ｑｍが６０と低く、発熱温度が１２０℃と高いことが判る。これに対して、本発明の実施例では、圧電歪定数ｄ₃₃が５０５ｐＣ／Ｎ以上、キュリー温度が２９５℃以上、機械的品質係数Ｑｍが１００以上で発熱温度が８０℃以下であることが判る。また、希土類元素の中でもＹｂが最も特性が良好であること判る。
【００６３】
また、表２から、Ｂサイトの（Ｙｂ_2/3Ｗ_1/3）、（Ｃｒ_1/2Ｎｂ_1/2）による置換量の合計が１０モル％以下である場合にはキュリー温度が２９０℃以上、圧電歪定数が４７０ｐＣ／Ｎ以上であるが、１０モル％よりも多い場合には、圧電歪定数、キュリー温度が低下することが判る。
【００６４】
さらに、表３から、ＡサイトのＢａ、Ｃａ、Ｓｒによる置換量が０の場合には、圧電歪定数が小さく、１０モル％を越えるとキュリー温度が低下することが判る。
【００６５】
【発明の効果】
以上詳述した通り、本発明によれば、Ｂサイトの一部を、Ｗと、Ｙ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｌｕ及びＹｂのうち少なくとも１種とで置換することにより、ジルコン酸チタン酸鉛が本来有している高いキュリー温度をほとんど低下させることなく圧電性を高めることができ、また、Ｂサイトの一部を、さらにＮｂおよびＣｏで置換することにより、金属元素Ｗ、Ｙｂなどの固溶効果による大きな圧電歪定数と高いキュリー温度をほとんど低下させることなく、機械品質係数Ｑｍを向上させることができ、自己発熱温度を低下でき、さらに、Ａサイトの一部をＣａ、Ｓｒ、Ｂａで総量１０モル％以下置換することにより、キュリー温度を非常に高くすることができるとともに、高いキュリー温度を保持したまま、圧電歪定数を向上させることができる。
【図面の簡単な説明】
【図１】本発明の積層型圧電アクチュエータを示す斜視図である。
【図２】本発明の噴射装置の説明図である。
【符号の説明】
１・・・圧電体
２・・・内部電極
３１・・・収納容器
３３・・・噴射孔
３５・・・バルブ
４３・・・積層型圧電素子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric ceramic and a laminated piezoelectric element and ejecting apparatus, for example, a ceramic filter, ultrasonic applications transducer, piezoelectric buzzer, piezoelectric ignition unit, ultrasonic motor, a piezoelectric fan, a piezoelectric actuator, and an acceleration sensor, knocking sensor, related to the piezoelectric ceramic and the laminated piezoelectric element and ejecting device suitable AE sensor.
[0002]
[Prior art]
Conventionally, products using piezoelectric ceramics include ceramic filters, ultrasonic applied vibrators, piezoelectric buzzers, piezoelectric ignition units, ultrasonic motors, piezoelectric fans, piezoelectric actuators, acceleration sensors, knocking sensors, AE sensors, etc. Piezoelectric sensors are known.
[0003]
Here, the piezoelectric actuator uses an inverse piezoelectric effect of a piezoelectric body, and conventionally, a stacked piezoelectric actuator using a piezoelectric longitudinal effect by alternately laminating piezoelectric ceramics and internal electrodes is known. Piezoelectric actuators with large piezoelectric strain constants are suitable for use when large displacements are required, and piezoelectric ceramics with a high Curie temperature are required when operation in a high temperature atmosphere is required. Necessary. Generally, there is a negative correlation between the piezoelectric strain constant and the Curie temperature, and there is also a negative correlation between the mechanical quality factor Qm of the piezoelectric ceramic and the piezoelectric strain constant.
[0004]
Therefore, conventionally, a ceramic composition having a large piezoelectric strain constant and a high Curie temperature has been searched for in a composition system in which the mechanical quality factor Qm is kept low. As such a piezoelectric ceramic, for example, a system in which Pb (Ni, Nb) O ₃ or Pb (Mg, Nb) O ₃ or the like is dissolved as a third component in lead zirconate titanate is known. It has been used as a piezoelectric ceramic for piezoelectric actuators.
[0005]
[Problems to be solved by the invention]
However, when a voltage is repeatedly applied to the multilayer piezoelectric actuator and continuously driven, self-heating increases in a piezoelectric ceramic in which the mechanical quality factor Qm is kept low. Therefore, a piezoelectric ceramic used for the actuator needs to have a high Curie temperature in consideration of the fact that the temperature of the piezoelectric ceramic self-heating is added to the ambient temperature. In a conventional piezoelectric ceramic having a low Curie temperature, the dielectric constant changes abruptly near the Curie temperature, the amount of supplied charge necessary to sufficiently displace the actuator increases, and it becomes difficult to sufficiently displace the actuator. There was a problem.
[0006]
In general, in piezoelectric ceramics, the Curie temperature tends to decrease as the piezoelectric strain constant increases. Therefore, in high temperature applications, the piezoelectric ceramics that make up the multilayer piezoelectric actuator use a material with a high Curie temperature to increase the number of layers. The required amount of displacement has been secured by doing so. However, easily increasing the amount of displacement depending on the number of stacked layers has a problem of reducing reliability and increasing product cost.
[0007]
Nowadays, a piezoelectric ceramic having a high Curie temperature and a large piezoelectric strain constant has been eagerly desired in order to realize a multilayer piezoelectric actuator that can be driven at high reliability, low cost, and high temperature.
[0008]
An object of the present invention is to provide a piezoelectric ceramic, a laminated piezoelectric element, and an injection device that have a high Curie temperature, a large mechanical quality factor, a small self-heat generation amount, and a large piezoelectric strain constant.
[0009]
[Means for Solving the Problems]
The piezoelectric ceramic according to the present invention is a perovskite complex oxide mainly composed of Pb, Zr, and Ti, and the A site of the perovskite complex oxide is 10 mol% at least one of Ca, Sr, and Ba. In addition to the following substitution, the B site is substituted with W, Nb, Co, and at least one of Y, Dy, Ho, Er, Tm, Lu, and Yb for a total of 10 mol% or less. .
[0010]
By substituting a part of the B site with W and at least one of Y, Dy, Ho, Er, Tm, Lu and Yb, lead zirconate titanate can be obtained in a relatively small amount of solid solution. Piezoelectricity can be increased without substantially lowering the inherently high Curie temperature.
[0011]
Further, by substituting part of the B site with Nb and Co, the mechanical quality factor Qm can be reduced without substantially lowering the large piezoelectric strain constant and the high Curie temperature due to the solid solution effect of the metal elements W and Yb. It can be improved and the self-heating temperature can be lowered.
[0012]
Furthermore, by replacing part of the A site with Ca, Sr, or Ba in a total amount of 10 mol% or less, the Curie temperature can be made extremely high, and the piezoelectric strain constant is improved while maintaining the high Curie temperature. be able to.
[0013]
The piezoelectric ceramic according to the present invention, a general _{formula, Pb 1-a M a (} Yb 2/3 W 1/3) x (Co 1/3 Nb 2/3) y (Zr 1-z Ti z) 1-xy When expressed as O ₃ , the x, y, z, and a are 0.01 ≦ x ≦ 0.05, 0.005 ≦ y ≦ 0.03, 0.48 ≦ z ≦ 0.50, 0.03. ≦ a ≦ 0.10, M satisfies at least one relationship among Ca, Sr and Ba.
[0014]
In a piezoelectric ceramic having such a composition, the Curie temperature can be set to 270 ° C. or higher, the piezoelectric strain constant d ₃₃ can be set to 485 pC / N or higher, and the mechanical quality factor Qm of the piezoelectric ceramic can be increased to 100 or higher. Can reduce the self-heating temperature by about 40 ° C. or more. Furthermore, when the piezoelectric strain constant obtained from the resonance / antiresonance method is defined as the resonance piezoelectric strain constant and the effective piezoelectric strain constant calculated from the actual displacement is defined as the effective piezoelectric strain constant, the piezoelectric strain constant ratio (effective piezoelectric strain constant) Strain constant / resonance piezoelectric strain constant) is approximately 1.5 times that of general PZT. However, in the piezoelectric ceramic of the present invention, since the piezoelectric strain constant ratio is large, the effective piezoelectric strain constant can be increased. A multilayer piezoelectric actuator that can be driven at high reliability, low cost, and high temperature can be realized.
[0015]
The multilayer piezoelectric element of the present invention is formed by alternately laminating piezoelectric bodies and electrodes, and the piezoelectric body is composed of the piezoelectric ceramic. In such a multilayer piezoelectric element, which has a good displacement characteristics for the piezoelectric strain constant d ₃₃ of the piezoelectric ceramic is large, mechanical quality factor Qm of the piezoelectric ceramic is large can reduce the self-heating temperature, further the Curie temperature Since it is high, it can be driven even if the ambient temperature becomes high.
[0016]
In addition, the injection device of the present invention includes a storage container having an injection hole, the stacked piezoelectric element stored in the storage container, and a valve that ejects liquid from the injection hole by driving the stacked piezoelectric element. It comprises.
[0017]
As described above, the multilayer piezoelectric element has a high piezoelectric strain constant, so that the amount of displacement can be increased, the self-heating temperature can be lowered because the mechanical quality factor Qm of the piezoelectric ceramic is large, and the Curie temperature is high. It is possible to provide an injection device that can be used in an excellent high temperature atmosphere.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a multilayer piezoelectric actuator which is a multilayer piezoelectric element of the present invention. This multilayer piezoelectric actuator includes an active body 3a formed by alternately laminating a plurality of piezoelectric bodies 1 and a plurality of internal electrodes 2. The insulator 4 is formed on every other layer at the end of the internal electrode 2 on the opposite side surface of the columnar laminate 3 made of the inert body 3b formed on both end faces of the active body 3a. An end portion of the internal electrode 2 that is not formed is connected to the same external electrode 5.
[0019]
The active body 3a and the inactive body 3b are simultaneously fired to form the columnar laminate 3, and the piezoelectric body 1 and the inactive body 3b of the active body 3a are made of the same piezoelectric ceramic material. This is desirable from the viewpoint of reducing the shrinkage difference. The active body 3a is a part that generates displacement, and the inactive body 3b has a function of mechanically holding the columnar laminate 3 and transmitting the generated force to the outside.
[0020]
The internal electrodes 2 are exposed on all the side surfaces of the columnar laminate 3 at the time of simultaneous firing, and grooves are formed on every opposite side surface of the piezoelectric body 1 including the end portions of the internal electrodes 2 on the opposite side surfaces. The groove is filled with an insulator 4 such as glass, epoxy resin, polyimide resin, polyamideimide resin, or silicone rubber, whereby one end of the internal electrode 2 is insulated.
[0021]
The insulator 4 is preferably made of a material having a low Young's modulus, such as silicone rubber. Thus, the internal electrodes 2 are alternately insulated every other layer, and the other end face of the non-insulated internal electrode 2 is formed by, for example, applying the conductive member 5b to the conductive heat-resistant adhesive 5a previously applied. The external electrode 5 is formed by heat-curing the conductive heat-resistant adhesive 5a in the state of being adhered. A lead wire 6 is attached to the lower end of the external electrode 5.
[0022]
The thickness of the piezoelectric body 1 of the active body 3a is 0.05 to 0.25 mm, the thickness of the internal electrode 2 is 0.003 to 0.01 mm, and the thickness of the inactive body 3b is 0.5 to 3.0 mm. The number of layers of the piezoelectric body 1 and the internal electrode 2 is 100 to 400 layers in order to obtain desired characteristics.
[0023]
Furthermore, in order to prevent creeping discharge between the internal electrodes 2 and to apply a large voltage, the side surface of the columnar laminate 3 is covered with a coating layer (not shown) made of a stretchable insulator such as silicone rubber. ing.
[0024]
The internal electrode 2 is made of Ag and a noble metal (Pd, Pt, etc.). It is desirable to perform low-temperature firing so that the amount of noble metal can be reduced. The internal electrode may contain glass.
[0025]
The piezoelectric body 1 composed of the piezoelectric ceramic of the present invention is a perovskite complex oxide mainly composed of Pb, Zr, and Ti, and the A site of the perovskite complex oxide is Ca, Sr, and Ba. 10 mol% or less is substituted with at least one species, and the B site is a total of 10 mol% or less with W, Nb, Co, and at least one of Y, Dy, Ho, Er, Tm, Lu and Yb. It is a replacement.
[0026]
In the present invention, by selecting and combining the metal element W and at least one metal element selected from the group consisting of Y, Dy, Ho, Er, Tm, Lu and Yb, in a relatively small amount of solid solution, Piezoelectricity can be enhanced without substantially reducing the high Curie temperature inherent to lead zirconate titanate.
[0027]
Further, by substituting a part of the B site with a small amount of Nb and Co, the mechanical quality factor Qm is reduced to 100 with almost no decrease in the large piezoelectric strain constant and the high Curie temperature due to the solid solution effect of the metal elements W, Yb and the like. The self-heating temperature can be reduced by about 40 ° C. or more by the solid solution effect of the metal components Nb and Co.
[0028]
In this case, the total amount of sub-components contained in the B site, i.e., a W, and Nb, and Co, Y, Dy, Ho, Er, Tm, the substitution of B site by at least one of Lu, and Yb It is important to make it 10 mol% or less. As a result, the Curie temperature can be kept very high at 270 ° C. or higher. On the other hand, when the substitution amount by the subcomponent is more than 10 mol%, the decrease in the Curie temperature and the piezoelectric strain constant is increased. In particular, the total amount of subcomponents contained in the B site is desirably 2 to 5 mol%.
[0029]
In addition, it is important that a part of the A site is substituted by 10 mol% or less (a ≦ 0.1) with at least one metal element selected from the group consisting of Ca, Sr, and Ba. Thereby, the piezoelectric strain constant can be further improved while maintaining a high Curie temperature. When the amount of the subcomponent contained in the A site is more than 10 mol%, the Curie temperature decreases greatly. Therefore, the amount of the subcomponent contained in the A site is preferably 10 mol% or less. In particular, the amount of subcomponents contained in the A site is desirably 4 to 7 mol% from the viewpoint of maintaining a high piezoelectric strain constant and a Curie temperature.
[0030]
The piezoelectric ceramic according to the present invention, a general _{formula, Pb 1-a M a (} Yb 2/3 W 1/3) x (Co 1/3 Nb 2/3) y (Zr 1-z Ti z) 1-xy When expressed as O ₃ , the x, y, z, and a are 0.01 ≦ x ≦ 0.05, 0.005 ≦ y ≦ 0.03, 0.48 ≦ z ≦ 0.5, 0.03. ≦ a ≦ 0.10, M satisfies at least one relationship among Ca, Sr and Ba.
[0031]
In a piezoelectric ceramic having such a composition, the Curie temperature can be set to 270 ° C. or higher, the piezoelectric strain constant d ₃₃ can be set to 485 pC / N or higher, and the mechanical quality factor Qm of the piezoelectric ceramic can be increased to 100 or higher. Can reduce the self-heating temperature by about 40 ° C. or more.
[0032]
In the general formula, a indicating the substitution amount by at least one of Ca, Sr, and Ba at the A site is set to 0.03 to 0.1. If this range is satisfied, the Curie temperature can be increased to 275 ° C. or higher. Because. On the other hand, when a is smaller than 0.03, the piezoelectric strain constant tends to decrease, and when it exceeds 0.10, the Curie temperature tends to decrease greatly. a is preferably 0.04 to 0.07 from the viewpoint of maintaining a high Curie temperature and improving the piezoelectric strain constant.
[0033]
The substitution of the A site is preferably a combination of Sr and Ba among Ca, Sr, and Ba. In this case, it is desirable that the substitution amount a with Sr at the A site is 0.03 and the substitution amount a with Ba is 0.04.
[0034]
Furthermore, x indicating the amount of substitution by at least one of W, Y, Dy, Ho, Er, Tm, Lu and Yb at the B site is preferably 0.01 to 0.05. As a result, the piezoelectricity can be increased while maintaining a high Curie temperature. However, when the substitution amount x is smaller than 0.01, the firing temperature tends to be higher, and the substitution is more than 0.05. When the amount is large, the Curie temperature tends to decrease. The amount x of substitution at the B site by W, Y or the like is preferably 0.015 to 0.03 from the viewpoint of lowering the firing temperature and raising the Curie temperature.
[0035]
Substitution of at least one of Y, Dy, Ho, Er, Tm, Lu and Yb at the B site is preferably Yb or Y from the viewpoint of high Curie temperature.
[0036]
Further, when y indicating the substitution amount of (Co _1/3 Nb _2/3 ) at the B site satisfies 0.005 to 0.03, a large piezoelectric strain constant and a high Curie temperature are hardly lowered. The mechanical quality factor Qm can be improved. However, when y is smaller than 0.005, the improvement effect of the mechanical quality factor Qm is small. On the other hand, when y is larger than 0.03, the piezoelectric strain constant is There is a tendency for the Curie temperature to decrease. y is preferably 0.01 to 0.02.
[0037]
Z indicating the amount of substitution of Zr by Ti has an optimum value for increasing the piezoelectric strain constant in the range of 0.48 ≦ z ≦ 0.5, and is larger than 0.53 when z is smaller than 0.48. In some cases, the piezoelectric strain constant tends to be small.
[0038]
The co-fired multilayer piezoelectric actuator configured as described above is manufactured by the following process. First, a predetermined amount of each raw material powder such as high-purity PbO, ZrO ₂ , TiO ₂ , Co ₂ O ₃ , Nb ₂ O ₅ , WO ₃ , BaCO ₃ , SrCO ₃ , CaCO ₃ and Yb ₂ O _{3 is used} as the raw material powder. Weigh and wet mix for 10 to 24 hours with a ball mill, etc., then dehydrate and dry the mixture, then calcine at 800 to 900 ° C. for 1 to 3 hours. The calcined product has a particle size distribution of D again with a ball mill or the like. Wet pulverize so that ₅₀ is 0.5 ± 0.2 μm and D ₉₀ is less than 0.8 μm.
[0039]
A slurry in which the obtained pulverized raw material, a binder made of an organic polymer, and a plasticizer are mixed is prepared, and a ceramic green sheet is prepared by a slip casting method.
[0040]
A conductive paste having a predetermined Ag / Pt ratio is printed on one side of the green sheet by a screen printing method. After the conductive paste is dried, a predetermined number of green sheets coated with the conductive paste are stacked, and the green sheets are not coated with the conductive paste at both ends in the stacking direction of the laminate. Are laminated.
[0041]
Next, pressure is applied while heating the laminated body at 50 to 200 ° C. to integrate the laminated body. After integrated laminate which is cut to a predetermined size, 5-40 hours at 400 to 800 ° C., the binder removal chromatography was performed, the sintering is performed in 2-5 hours at 950 to 1150 ° C., A laminated sintered body serving as the actuator body is obtained. The end of the internal electrode 2 is exposed on the side surface of the actuator body.
[0042]
After that, on the two side surfaces of the actuator body, the depth is 50 to 500 μm every other layer and the width 50 in the stacking direction so that the two side surfaces alternate with the end portions of the piezoelectric ceramic 1 including the end portions of the internal electrodes 2. A groove of ˜300 μm is formed, and the groove 4 is filled with an insulator 4 such as silicone rubber. As described above, the internal electrodes 2 are alternately insulated every other layer and are alternately connected to the same external electrode 5.
[0043]
Thereafter, the lead wire 6 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 polarizing the entire actuator, a final stacked piezoelectric actuator is obtained.
[0044]
The laminated piezoelectric actuator of the present invention may be any columnar body such as a quadrangular column, a hexagonal column, or a cylinder, but a quadrangular columnar shape is desirable for ease of cutting.
[0045]
The piezoelectric body comprising the piezoelectric ceramic of the present invention has a perovskite crystal as the main crystal phase, and it is desirable that there is almost no heterogeneous phase. Further, Ag, Al, Fe, S, Cl, Eu, K, P, Cu, Mg, Si and the like may be mixed as inevitable impurities, but there is no problem in characteristics.
[0046]
In addition, subcomponents other than W, Nb, and Co dissolved in the B site are particularly limited to one type as long as they are metal elements selected from the group consisting of Y, Dy, Ho, Er, Tm, Lu, and Yb. Even if selected in combination, the effect is the same and there is no problem in characteristics.
[0047]
FIG. 2 shows an injection device 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.
[0048]
A fuel passage 37 is provided in the injection hole 33 so as to be able to communicate. 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.
[0049]
The upper end of the needle valve 35 has a large diameter, and has a cylinder 39 formed in the storage container 31 and a piston 41 that can slide. In the storage container 31, the laminated piezoelectric element 43 described above is stored.
[0050]
In such an injection device, when the laminated piezoelectric element 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 voltage application is stopped, the laminated piezoelectric element 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. .
[0051]
【Example】
As raw material powder of high purity _{PbO, ZrO 2, TiO 2,} BaCO 3, SrCo 3, CaCO 3, WO 3, Yb 2 O 3, Y 2 O 3, Dy 2 O 3, Ho 2 O 3, Er 2 O 3 , Tm ₂ O ₃ , Lu ₂ O ₃ , Nb ₂ O ₅ and Co ₃ O ₄ raw material powders were weighed in predetermined amounts and wet mixed in a ball mill for 20 hours. Next, this mixture was dehydrated and dried, and then calcined at 900 ° C. for 3 hours. The calcined product was wet pulverized again with a ball mill, dehydrated and dried to obtain a pulverized raw material.
[0052]
Next, an organic binder (PVA) was mixed with the pulverized raw material and granulated. The obtained powder was press-molded at a pressure of 1500 kgf / cm ² to obtain a cylindrical shaped body. Furthermore, these compacts were sealed in a container made of MgO or the like and fired at 1100 to 1200 ° C. for 2 hours in the atmosphere. An electrode was formed by baking Ag paste on both main surfaces of the obtained cylindrical sintered body, and a polarization treatment was performed by applying a direct voltage of 2 kV / mm for 30 minutes in silicon oil at 80 ° C. using the measured values obtained by measurement by a resonance-antiresonance method using an impedance analyzer, to evaluate the piezoelectric strain constant d ₃₃ according to Japan electronic materials Manufacturers Association standard EMAS-6100.
[0053]
The mechanical quality factor Qm was calculated by 1 / Qm = 2πC _F R ₀ F _r [1− (F _r / F _a ) ² ]. Here, C _F is a capacitance, R ₀ is a resonance resistance, F _r is a resonance frequency, and F _a is an anti-resonance frequency. Further, the temperature at which the relative dielectric constant reaches a maximum value from the temperature characteristics of the relative dielectric constant was defined as the Curie temperature. Furthermore, in the evaluation of self-heating, an AC voltage with a frequency of 1 kHz with a maximum amplitude voltage of 600 V was added to a disk-shaped piezoelectric ceramic having a diameter of 13 mm and a thickness of 0.3 mm, and the center of the surface of the piezoelectric ceramic after 15 minutes was measured. The temperature rise from room temperature was defined as the exothermic temperature.
[0054]
In Table 1, the composition formula is Pb _0.93 Ba _0.04 Sr _0.03 (R _2/3 W _1/3 ) _0.015 (Co _1/3 Nb _2/3 ) _y (Zr _0.52 Ti _0.48 ) _1-y O ₃ The piezoelectric strain constant d ₃₃ , Curie temperature, mechanical quality factor Qm, and exothermic temperature when the element and y of the rare earth element R were fixed were determined and described.
[0055]
Further, in Table 2, the composition formula, a _{Pb 0.96 Ba 0.04 (Yb 2/3 W} 1/3) x (Co 1/3 Nb 2/3) y (Zr 1-z Ti z) 1-xy O 3 The piezoelectric strain constant d ₃₃ , the Curie temperature, the mechanical quality factor Qm, and the heat generation temperature when x, y, and z were fixed and obtained were described.
[0056]
In Table 3, the composition _{formula, Pb 1-efg Ba e Sr} f Ca g (Yb 2/3 W 1/3) 0.015 (Co 1/3 Nb 2/3) 0.02 (Zr 1-z Ti z) 0.965 O ₃ and fixed and determined e, f, g, the piezoelectric strain constant d ₃₃ in the case of changing the z, Curie temperature, the mechanical quality factor Qm, the exothermic temperature has been described.
[0057]
In Table 4, the composition formula, a _{Pb 0.93 Ba 0.04 Sr 0.03 (Yb} 2/3 W 1/3) x (Co 1/3 Nb 2/3) y (Zr 1-z Ti z) 1-xy O 3 The piezoelectric strain constant d ₃₃ , the Curie temperature, the mechanical quality factor Qm, and the heat generation temperature when x, y, and z were fixed and obtained were described.
[0058]
[Table 1]

[0059]
[Table 2]

[0060]
[Table 3]

[0061]
[Table 4]

[0062]
From Table 1, Comparative Example No. which does not contain (Co _1/3 Nb _2/3 ). In the case of 1, the mechanical quality factor Qm is as low as 60 and the exothermic temperature is as high as 120 ° C. In contrast, in the example of the present invention, it can be seen that the piezoelectric strain constant d ₃₃ is 505 pC / N or more, the Curie temperature is 295 ° C. or more, the mechanical quality factor Qm is 100 or more, and the heat generation temperature is 80 ° C. or less. . Moreover, it turns out that Yb has the best characteristic among rare earth elements.
[0063]
Also, from Table 2, when the total amount of substitution by (Yb _2/3 W _1/3 ) and (Cr _1/2 Nb _1/2 ) at the B site is 10 mol% or less, the Curie temperature is 290 ° C. As described above, the piezoelectric strain constant is 470 pC / N or more, but when it is more than 10 mol%, it can be seen that the piezoelectric strain constant and the Curie temperature are lowered.
[0064]
Furthermore, it can be seen from Table 3 that when the substitution amount of Ba, Ca, and Sr at the A site is 0, the piezoelectric strain constant is small and the Curie temperature is lowered when it exceeds 10 mol%.
[0065]
【The invention's effect】
As described above in detail, according to the present invention, a part of the B site is replaced with W and at least one of Y, Dy, Ho, Er, Tm, Lu, and Yb, thereby obtaining titanium zirconate. Piezoelectricity can be increased with almost no decrease in the high Curie temperature inherent to lead acid, and metal elements W, Yb, etc. can be obtained by substituting part of the B site with Nb and Co. The mechanical quality factor Qm can be improved without substantially lowering the large piezoelectric strain constant and the high Curie temperature due to the solid solution effect, and the self-heating temperature can be lowered. Further, a part of the A site is Ca, Sr, By substituting Ba for a total amount of 10 mol% or less, the Curie temperature can be made very high, and the piezoelectric strain constant can be improved while maintaining the high Curie temperature. It can be.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a multilayer piezoelectric actuator of the present invention.
FIG. 2 is an explanatory diagram of an injection device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 2 ... Internal electrode 31 ... Storage container 33 ... Injection hole 35 ... Valve 43 ... Multilayer piezoelectric element

Claims (3)

The general formula is
Pb _1-a M _a (Yb _2/3 W _1/3 ) _x (Co _1/3 Nb _2/3 ) _y (Zr _1-z T i _z
) When expressed as _1-xy O ₃ , the x, y, z, and a are
0.01 ≦ x ≦ 0.05
0.005 ≦ y ≦ 0.03
0.48 ≦ z ≦ 0.50
0.03 ≦ a ≦ 0.10
M is, Ca, pressure electromagnetic device you and satisfies at least one relationship selected from Sr and Ba. A multilayer piezoelectric element comprising piezoelectric bodies and electrodes alternately stacked, and wherein the piezoelectric body comprises the piezoelectric ceramic according to claim 1 . A storage container having an injection hole, the multilayer piezoelectric element according to claim 2 accommodated in the storage container, and a valve for ejecting liquid from the injection hole by driving the multilayer piezoelectric element. An injection device characterized by comprising:

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