JP2006265059A - Manufacturing method of piezoelectric material and laminated piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a piezoelectric material and a laminated piezoelectric element which can be fired at a low temperature and can exhibit an excellent displacement amount even if fired at a low temperature. <P>SOLUTION: The piezoelectric material contains 0.07 mol% or less of Sb<SB>2</SB>O<SB>3</SB>or Sb<SB>2</SB>O<SB>5</SB>against 1 mol of a compound expressed by general formula (1): (Pb<SB>1-x</SB>Ma<SB>x</SB>)(Zr<SB>1-y-z</SB>Ti<SB>y</SB>Sb<SB>z</SB>)<SB>1-p-q</SB>(Y<SB>1/2</SB>Nb<SB>1/2</SB>)<SB>p</SB>(Mn<SB>1-B1-B2</SB>W<SB>B1</SB>Sb<SB>B2</SB>)<SB>q</SB>O<SB>3</SB>(wherein Ma is one kind or more selected from the group consisting of Ba, La, Sr, and Ce). In a manufacturing method of a laminated piezoelectric element 1 which is obtained by laminating piezoelectric layer 11 and internal electrodes layers 21, 22 alternately, as a piezoelectric material there is used a material containing a compound of above general formula (1) and Sb<SB>2</SB>O<SB>3</SB>and/or Sb<SB>2</SB>O<SB>5</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric material that can be fired at a low temperature and a laminated piezoelectric element manufactured using the piezoelectric material.

Conventionally, a laminated piezoelectric element in which a piezoelectric layer and an internal electrode layer are laminated is used for an actuator such as a fuel injection device. In order to achieve a high-performance actuator, it is desired that the multilayer piezoelectric element has a high Curie point and a large amount of displacement and a small loss.
The laminated piezoelectric element can be manufactured, for example, as follows.
That is, first, a sheet of piezoelectric material is produced, and an electrode material is printed on the sheet. Next, a sheet of piezoelectric material on which the electrode material is printed is laminated to produce a laminate. Next, the multilayer body can be degreased and fired to produce the multilayer piezoelectric element.
As an example of the piezoelectric material, PZT having a composite perovskite structure represented by A (divalent) B (tetravalent) O ₃ has been used. In addition, for example, a piezoelectric material shown in Patent Document 1 below has been developed.

  By the way, in the manufacturing method of the laminated piezoelectric element, the laminated body is fired at a high temperature exceeding 1200 ° C. in order to sufficiently sinter the piezoelectric material. Therefore, as the electrode material fired simultaneously with the piezoelectric material, it is necessary to use a material that does not melt even at a temperature at which the piezoelectric material sinters, that is, a high temperature of 1200 ° C. or higher. In addition, since the laminate is usually fired in an oxidizing atmosphere, it is necessary to use an electrode material that is not easily oxidized even when fired in an oxidizing atmosphere. For this reason, it was necessary to use a noble metal as the electrode material.

However, noble metals are very expensive. Therefore, when a noble metal is used as the electrode material, the ratio of the material cost of the internal electrode layer to the manufacturing cost of the multilayer piezoelectric element becomes very large. Therefore, it has been difficult to reduce the cost of the multilayer piezoelectric element.
Therefore, development of a piezoelectric material that can be fired at a low temperature is desired so that relatively inexpensive copper, nickel, silver, or the like can be used as an electrode material. In general, it is known that the piezoelectric material can be fired at a low temperature by increasing the amount of PbO in the piezoelectric material or adding a low melting point composition such as PbO-WO ₃ .

  However, there has been a problem that an increase in PbO or a simple addition of a low-melting-point composition cannot exhibit a displacement enough to withstand practical use. Therefore, in conventional piezoelectric materials, it has been difficult to achieve both low-temperature firing and piezoelectric characteristics such as displacement.

JP 2001-322870 A

  The present invention has been made in view of such conventional problems, and can be fired at a low temperature, and can exhibit excellent displacement even when fired at a low temperature, and a method for manufacturing a multilayer piezoelectric element Is to provide.

The first invention of the general formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn 1-B1- _B2 W _B1 Sb _B2 ) A piezoelectric material containing a compound represented by _q O ₃ and Sb ₂ O ₃ and / or Sb ₂ O ₅ (where Ma is one selected from Ba, La, Sr and Ce) Above)
The piezoelectric material contains 0.7 mol% or less of Sb ₂ O ₃ and / or Sb ₂ O ₅ with respect to 1 mol of the compound represented by the general formula (1).
0.04 ≦ x ≦ 0.1
0.44 ≦ y ≦ 0.48
0 ≦ z ≦ 0.01
0 ≦ p ≦ 0.02
0.003 ≦ q ≦ 0.01
0 ≦ B1 ≦ 0.34
0 ≦ B2 ≦ 0.5
The piezoelectric material is characterized in that (Claim 1).

The piezoelectric material of the first invention contains the compound represented by the general formula (1) and Sb ₂ O ₃ and / or Sb ₂ O ₅ in the specific ratio. Therefore, the piezoelectric material can be fired at a low temperature of, for example, 1000 ° C. or less, and can exhibit a practically sufficient amount of displacement even when fired at a low temperature.
Furthermore, the piezoelectric material can exhibit a sufficiently high Curie temperature for practical use and can reduce the temperature dependence of loss. Therefore, for example, even when used in a wide temperature range of −40 ° C. to 160 ° C., stable characteristics can be exhibited.

The reason for this is estimated as follows.
That is, in the piezoelectric material, the compound represented by the general formula (1) can improve the amount of displacement to the B site in the perovskite structure compound generally represented by ABO ₃ and can be fired at a low temperature ( Mn _1-B1-B2 W _B1 Sb _B2 ) _q is incorporated. The piezoelectric material contains Sb ₂ O ₃ and / or Sb ₂ O ₅ that can improve the amount of displacement.
Therefore, the piezoelectric material can be densified and grow at low temperatures, and the amount of displacement is improved. Therefore, as described above, the piezoelectric material can be fired at a low temperature of 1000 ° C. or less, for example, and can exhibit an excellent displacement even when fired at a low temperature.

  Further, the compound represented by the general formula (1) has a structure in which part of Pb of the A site element is substituted with one or more selected from Ba, La, Sr, and Ce having different valences. ing. Therefore, in the compound represented by the general formula (1), pores are generated to maintain electrical neutrality. The charge distribution changes due to the generation of the vacancies, and the charge distribution changes more than the strain of the lattice. Therefore, the amount of displacement can be improved without substantially reducing the Curie temperature, and the piezoelectric material can exhibit both a high Curie temperature and a high amount of displacement as described above.

Further, the compound represented by the general formula (1) has a composition of (Zr _{1 -yz} Ti _y Sb _z ) _{1 -pq in} which Sb having a lower valence than Zr and Ti is injected as an acceptor. Yes. Therefore, oxygen vacancies can be formed, and defect dipoles composed of the oxygen vacancies and implanted ions for forming the vacancies can be easily oriented according to the polarization structure. Therefore, the domain wall can be pinned, and dielectric loss due to electric field application can be suppressed by this pinning effect. Therefore, in the piezoelectric material, loss can be reduced as described above.

  As described above, according to the first invention, it is possible to provide a piezoelectric material that can be fired at a low temperature and can exhibit an excellent displacement even when fired at a low temperature.

A second invention is a method for manufacturing a laminated piezoelectric element in which piezoelectric layers and internal electrode layers are alternately laminated,
A sheet-forming material containing the piezoelectric material of the first invention is prepared, the sheet-forming material is molded to produce a green sheet, and the green sheet is made of a paste containing an electrode material for an internal electrode layer Providing a printing layer,
Thereafter, a plurality of unfired sheets provided with the printed layer are laminated to form an unfired laminated body, and the unfired laminated body is fired (claim 5). .

  In the manufacturing method of the second invention, the unfired laminate is produced using the piezoelectric material of the first invention. Therefore, at the time of firing the unfired laminated body, it is possible to perform firing at a low temperature of, for example, 1000 ° C. or less, taking advantage of the characteristics of the piezoelectric material that can be fired at low temperature. Therefore, a material containing a low melting point metal having a melting point of about 1000 ° C. can be used as the electrode material fired simultaneously with the piezoelectric material. In addition, as the electrode material, a material containing copper, nickel, silver or the like that has a particularly low melting point and is relatively inexpensive can be used. As a result, the manufacturing cost of the multilayer piezoelectric element can be reduced.

  Moreover, the multilayer piezoelectric element obtained by the manufacturing method of the second invention has a piezoelectric layer made of the piezoelectric material of the first invention. Therefore, taking advantage of the excellent characteristics of the piezoelectric material described above, the multilayer piezoelectric element can exhibit a sufficient displacement amount and Curie temperature that can withstand practical use even when fired at a low temperature. Furthermore, the temperature dependency of the loss is small, and stable characteristics can be exhibited even when used in a wide temperature range of, for example, −40 ° C. to 160 ° C.

  As described above, according to the second invention, it is possible to provide a method for manufacturing a multilayer piezoelectric element that can be fired at a low temperature and can exhibit an excellent displacement even when fired at a low temperature.

Next, an embodiment of the present invention will be described.
The piezoelectric material, the general formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn 1-B1- _B2 W _B1 Sb _B2 ) _Contains a compound represented by qO ₃ .
In the general formula (1), the range of x is 0.04 ≦ x ≦ 0.1.
When x is less than 0.04, the strain of the lattice is reduced, the capacitance is decreased, and the displacement amount may be decreased. On the other hand, when it exceeds 0.1, the Curie point may be lowered to, for example, 280 ° C. or lower, and there is a possibility that the amount of displacement is lowered due to polarization deterioration at the time of use at a high temperature. Therefore, it becomes difficult to apply to a fuel injection device used at a maximum temperature of about 170 ° C., for example.

The range of y is 0.44 ≦ y ≦ 0.48.
When y is less than 0.44 or exceeds 0.48, the compound represented by the general formula (1) deviates greatly from MPB (Morphotropic Phase Boundary), and as a result, There is a possibility that the amount of displacement of the piezoelectric material is reduced.
The range of z is 0 ≦ z ≦ 0.01.
When z exceeds 0.01, defects in the B site of the perovskite structure generally represented by ABO ₃ become excessive, and the amount of displacement may be small. Further, preferably z> 0. In this case, Sb having a low valence injected as an acceptor for Zr or Ti in the general formula (1) is an essential component. Sb implanted as an acceptor can form oxygen vacancies. Since the defect dipole composed of the vacancy and the acceptor (Sb) can be easily arranged according to the molecular structure, the domain wall can be pinned. As a result, the dielectric loss of the piezoelectric material can be further reduced.

The range of p is 0 ≦ p ≦ 0.02.
When p exceeds 0.02, the Curie point is lowered, the usable temperature is lowered, and there is a possibility that the piezoelectric material lacks practicality. In this case, the amount of displacement may be small. Preferably, p> 0. In this case, (Y _1/2 Nb _1/2 ) is an essential component in the general formula (1). Therefore, in this case, the amount of displacement can be further improved.
The range of q is 0.003 ≦ q ≦ 0.01.
When q is less than 0.003, the sintering temperature becomes high, and firing at low temperature may be difficult. On the other hand, if it exceeds 0.01, the liquid phase generated by the (Mn _{1 -B1-B2} W _B1 Sb _B2 ) composition in the general formula (1) becomes excessive, and abnormal particle growth or the like may occur during sintering. There is. As a result, there is a risk of being easily broken or having a small displacement.

The range of B1 is 0 ≦ B1 ≦ 0.34, and the range of B2 is 0 ≦ B2 ≦ 0.5.
When B1 exceeds 0.34 or B2 exceeds 0.5, the charge balance tends to be lost, and the amount of displacement may be reduced.
B1> 0 is preferable. In this case, W of (Mn _1-B1-B2 W _B1 Sb _B2 ) in the general formula (1) is an essential component. Therefore, in this case, since Mn and W can coexist in the general formula (1), it becomes easier to sinter at a lower temperature, and crystal grains easily grow even when fired at a lower temperature. As a result, the amount of displacement can be further improved.
Further, B2> 0 is preferable. In this case, Sb of (Mn _{1 -B1-B2} W _B1 Sb _B2 ) in the general formula (1) is an essential component. Therefore, in this case, since Mn and Sb can coexist in the general formula (1), it becomes easier to sinter at a lower temperature, and crystal grains easily grow even when fired at a lower temperature. As a result, the amount of displacement can be further improved.

Moreover, the piezoelectric material contains 0.7 mol% or less of Sb ₂ O ₃ and / or Sb ₂ O ₅ with respect to 1 mol of the compound represented by the general formula (1).
When the content of Sb ₂ O ₃ and / or Sb ₂ O ₅ exceeds 0.7 mol%, the amount of displacement of the piezoelectric material may be reduced by excessive Sb.

Further, in the piezoelectric material, that Pb in the section relating to "Pb _1-x Ma _x" is (a perovskite structure) crystal lattice of the piezoelectric material of the general formula (1) is substituted with an element of Ma Meaning, when a plurality of elements are selected as Ma, the total mole fraction of the plurality of elements combined is x.
For example, when Ma is made of Ba, La, Sr, and Ce, “Pb _1−x BakLalSrmCen” is k + l + m + n = x.

In the general formula (1), Ma is one or more elements selected from Ba, La, Sr, and Ce.
Preferably, Ma in the general formula (1) is composed of Sr as an essential component and Ba, La, or Ce (Claim 2).
In this case, the crystal lattice of the piezoelectric material is distorted to cause polarization, and the crystal structure can be kept relatively stable. As a result, a higher displacement amount and a higher Curie temperature can be exhibited at the same time.
More preferably, in the Ma of the general formula (1), Ba, La, or Ce and Sr may have substantially the same substitution ratio with respect to Pb (Claim 3). Specifically, for example, Ma = Sr _0.045 Ba _0.045 can be set.
In this case, in the compound represented by the general formula (1), Sr having a small ionic radius and Ba, La, and Ce having a large ionic radius replace a part of Pb at the same ratio. While giving strain, the stability of the crystal structure can be further improved. Therefore, in this case, the Curie temperature can be maintained at a higher value while improving the amount of displacement of the piezoelectric material.

Next, the piezoelectric material is 0.05 to 2 parts by weight of PbO and 0.001 to 0 of WO ₃ with respect to 100 parts by weight of the compound represented by the general formula (1). It is preferable to contain 0.038 parts by weight (claim 4).
In this case, the amount of displacement can be suppressed by supplementing Pb partially evaporated during firing, and the firing temperature of the piezoelectric material can be further reduced by the liquid phase additive of PbO—WO ₃ .
If PbO is less than 0.05 parts by weight, the amount of Pb that evaporates during firing cannot be sufficiently compensated, and the amount of displacement may decrease. On the other hand, when PbO exceeds 2 parts by weight, the liquid phase is excessively formed and the amount of displacement may be small.
Moreover, when the content of WO ₃ is less than 0.001 part by weight, a liquid phase is hardly formed, and the effect of reducing the firing temperature by the liquid phase additive of PbO—WO ₃ is hardly obtained. There is a fear. On the other hand, when WO ₃ exceeds 0.038 parts by weight, the amount of displacement of the piezoelectric material may be reduced.

  Next, in the second aspect of the present invention, a multilayer piezoelectric element is manufactured in which piezoelectric layers and internal electrode layers are alternately stacked. In this manufacturing method, the piezoelectric material of the first invention is used as the piezoelectric material of the piezoelectric layer.

That is, first, the starting material is weighed so as to have a predetermined composition ratio, the starting material is calcined, and then pulverized until a predetermined BET specific surface area is obtained. Thereafter, for example, auxiliary oxides such as PbO and WO ₃ are added to form a mixture. Alternatively, the starting material can be calcined, and then an auxiliary oxide can be added and pulverized.

  In addition, since the fine powder of the piezoelectric material obtained by calcining and pulverizing the starting material has high reactivity with the auxiliary oxide, the piezoelectric oxide is used in order to suppress the solid solution of the auxiliary oxide in the piezoelectric material as much as possible. After pulverizing the material, auxiliary oxides, solvents, binders, plasticizers, and dispersants may be added to the powder obtained by pre-baking at 400 to 700 ° C. to form the material.

  Further, in the method for manufacturing a multilayer piezoelectric element according to the present invention, when adjusting the piezoelectric material to have a predetermined BET specific surface area, it is pulverized using a ball mill, a medium agitating mill, or the like to reduce the particle size. Can be done by.

Also, when preparing an unfired sheet, prepare a slurry in which a binder is added to a mixture of a piezoelectric material and an auxiliary oxide, etc., and prepare an unfired sheet by a generally known doctor blade method. Can do. Thereafter, a paste containing an electrode material is printed on the green sheet to provide a printed layer.
A desired number of unfired sheets provided with the printed layer are laminated and pressure bonded to produce an unfired laminate. This unfired laminate is degreased, fired, and then provided with side electrodes and the like that are electrically connected to the internal electrode layer, and then subjected to polarization treatment or the like, whereby a laminated piezoelectric element can be obtained.

The procedure described here is a manufacturing method well known for multilayer piezoelectric elements, and the second invention can also be applied to the case of manufacturing multilayer piezoelectric elements by other methods.
In addition to the partial electrode configuration (the area in the cross section perpendicular to the stacking direction is smaller than that of the piezoelectric layer) shown in Example 1 described later, the internal electrode layer has an entire surface electrode configuration (area substantially equal to the piezoelectric layer). Can also be prepared.

The electrode material preferably contains one or more selected from copper, nickel, and silver.
In this case, the multilayer piezoelectric element can be manufactured at low cost, and the characteristics of the piezoelectric material that can be fired at a low temperature can be exhibited to the maximum.
That is, when firing an unfired sheet in which a printed layer is formed using copper, nickel, and silver having a low melting point as an electrode material, it is necessary to perform firing at a low temperature. This is because the green sheet containing the piezoelectric material can be sintered at a low temperature of, for example, 1000 ° C. or less, and can be fired simultaneously with the electrode material.

Moreover, it is preferable to perform baking of the said unbaked laminated body at the temperature of 850 to 1000 degreeC (Claim 6).
When the firing temperature of the green laminate is less than 850 ° C., it may be difficult to sufficiently sinter. On the other hand, when the temperature exceeds 1000 ° C., the characteristics of the piezoelectric material that can be fired at a low temperature cannot be exhibited sufficiently, and copper, nickel, and silver having a relatively low melting point are used as the electrode material. The electrode material may melt.

The laminated piezoelectric element has a piezoelectric layer made of a piezoelectric material having a large amount of displacement and a small loss, and can be used for a piezoelectric actuator that can stably exhibit an excellent amount of displacement.
Such a piezoelectric actuator is suitable as a drive source for an injector for fuel injection in an internal combustion engine such as an automobile engine.

Example 1
Next, examples of the piezoelectric material of the present invention will be described.
The piezoelectric material of the present example, the general formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn 1-B1 and a compound represented by _{-B2 W B1 Sb B2) q O} 3, containing the Sb ₂ O _3, Ma is Ba, La, and one or more selected from Sr. The piezoelectric material contains 0.7 mol% or less of Sb ₂ O ₃ with respect to 1 mol of the compound represented by the general formula (1). In the general formula (1), 0.04 ≦ x ≦ 0.1, 0.44 ≦ y ≦ 0.48, 0 ≦ z ≦ 0.01, 0 ≦ p ≦ 0.02, 0.003 ≦ q ≦ The relationship of 0.01, 0 ≦ B1 ≦ 0.34, 0 ≦ B2 ≦ 0.5 is satisfied.

Hereinafter, this example will be described in detail.
In this example, piezoelectric materials (samples E1 to E12) according to examples of the present invention and comparative piezoelectric materials (samples C1 to C4) are produced, and a laminated piezoelectric material using these piezoelectric materials. An element is fabricated and its performance is evaluated.

That is, the sample E1~E12 the general formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn 1- _B1-B2 W _B1 Sb _B2 ) Add to the compound of Ma, which is a substitution element of _q O ₃ , composition ratio (x, y, z, p, q, B1, and B2), and the compound of general formula (1) It is a piezoelectric material obtained by changing the blending ratio of Sb ₂ O ₃ , PbO, and WO ₃ as shown in Table 1.
On the other hand, as shown in Table 1, the sample C1 and the sample C2 have a q value of 0 in the general formula (1) and are out of the scope of the present invention. Sample C3 and sample C4 are not added with Sb ₂ O _{3 as} shown in Table 1, and have compositions outside the scope of the present invention.

In this example, a laminated piezoelectric element 1 as shown in FIGS. 1 to 3 was produced from these piezoelectric materials, and the piezoelectric characteristics thereof were examined.
As shown in FIGS. 1 to 3, the multilayer piezoelectric element 1 is produced so that the internal electrode layers 21 and 22 are alternately positive and negative between the piezoelectric layers 11. As shown in FIG. 2 (a), one internal electrode layer 21 is disposed so as to be exposed on one side face 101 as shown in FIG. The electrode layer 22 is disposed so as to be exposed on the other side surface 102.

Further, side electrodes 31 are provided on the side surfaces 101 and 102 of the multilayer piezoelectric element 1 so as to conduct the exposed end portions of the internal electrode layers 21 and 22.
As shown in FIG. 3, the central portion of the multilayer piezoelectric element 1 in the stacking direction is a drive unit 111 that expands when the internal electrode layers 21 and 22 are energized, and the ceramic layer 12 sandwiching the drive unit 111 is At least one surface is not in contact with the internal electrode layers 21 and 22. Therefore, the ceramic layer 12 becomes a dummy portion 112 that does not expand even when the internal electrode layers 21 and 22 are energized.

Next, a specific method for manufacturing the piezoelectric material and the multilayer piezoelectric element will be described.
PbO, SrCO ₃ , BaCO ₃ , La ₂ O ₃ , ZrO ₂ , TiO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ , Sb ₂ O ₃ , WO ₃ , Mn _{2 are used} as starting materials containing each constituent atom of the piezoelectric material. O ₃ and CeO ₂ were used and weighed so that the desired composition shown in Table 1 was obtained, that is, the ratio of each constituent atom in the target composition to the same ratio in each starting material.

The weighed raw materials were wet-mixed, dried and calcined at 800 ° C. for 5 hours, and wet-pulverized with a medium stirring mill to obtain a pulverized product having a BET specific surface area of 2.5 to ³ m ² / g. A solvent, a binder, a plasticizer, and a dispersant were added to this and mixed by a ball mill to obtain a slurry.
A green sheet having a thickness of 100 μm was formed from the slurry using a doctor blade device. A conductive layer containing an electrode material made of silver / palladium = 7/3 (weight ratio) was printed on the green sheet to provide a printed layer for an internal electrode layer.

As shown in FIG. 3, 20 unfired sheets provided with the above printed layers are stacked, and a simple unfired sheet having no internal electrode layer printed layers is placed on the upper and lower ends, and thermocompression bonding is performed to perform unfired sheets. A fired laminate was produced.
Next, the green laminate was degreased in an electric furnace, then fired at 950 ° C., and polished on the entire surface to obtain a 7 × 7 × 1.8 mm laminated sintered body. In this laminated sintered body, the thickness of each piezoelectric layer was 80 μm.
Further, a pair of side electrodes were baked in order to make the internal electrode layer conductive every other side surface of the laminated sintered body, then polarized for 30 minutes at an applied electric field of 130 ° C. and 2 kV / mm, and left at room temperature for 48 hours. did.
Thus, a multilayer piezoelectric element was obtained.

Subsequently, the sintered density and the displacement amount of the piezoelectric layer were examined for the laminated piezoelectric element manufactured using each sample as the piezoelectric layer. The results are shown in Table 2.
The sintered density was calculated by polishing the piezoelectric layer to a predetermined size and measuring its weight and volume.
The amount of displacement was measured by applying a voltage of 150 V to each laminated piezoelectric element and measuring the displacement of the laminated piezoelectric element at that time with a laser displacement meter. The displacement amount was measured at room temperature, but was measured after aging for about 20 minutes in a state where the laminated piezoelectric element was driven in advance.

  Furthermore, in this example, firing was performed by changing the firing temperature of the green laminate to 1000 ° C., 1050 ° C., and 1100 ° C., and the sintered density and displacement of the piezoelectric layer at this time were examined. The results are shown in Table 2.

As known from Tables 1 and 2, the piezoelectric materials of Sample E1 to Sample E12 were sufficiently sintered even at a low temperature of 950 ° C. Then, it was found that the multilayer piezoelectric element produced using Sample E1 to Sample E12 as the material of the piezoelectric layer causes displacement by voltage application even when fired at a low temperature of 950 ° C. Samples E1 to E12 have displacement peaks at different firing temperatures at firing temperatures of 950 to 1100 ° C., and the displacement peaks are all excellent at 1.55 μm or more. It was a thing.
On the other hand, the piezoelectric materials of Sample C1 to Sample C4 could not show displacement when fired at 950 ° C. In addition, at the firing temperature of 950 to 1100 ° C., the displacement peak of sample C1 to sample C4 is sample C2 when fired at firing temperatures of 1050 ° C. and 1100 ° C., which is as low as about 1.45 μm. there were.

4 and 5 show electron microscope (SEM) photographs of these piezoelectric layers of the multilayer piezoelectric element fabricated using Sample E1 and the multilayer piezoelectric element fabricated using Sample C2.
FIG. 4 shows a piezoelectric layer of a multilayer piezoelectric element manufactured using the sample E1, (a) shows a piezoelectric layer fired at a temperature of 1000 ° C., and (b) shows a piezoelectric layer fired at 1050 ° C.
FIG. 5 shows a piezoelectric layer of a multilayer piezoelectric element manufactured using Sample C2, (a) shows a piezoelectric layer fired at a temperature of 1000 ° C., and (b) shows a piezoelectric layer fired at 1050 ° C.
As can be seen from FIGS. 4 and 5, in the piezoelectric material of the sample E1, it can be seen that the crystal grains grow at a lower temperature and the crystal grain size is larger than that of the sample C2. Due to the ease of growth at this low temperature, as shown in Table 2, it is considered that the sample E1 can exhibit a higher displacement than the sample C2.

Further, in this example, the loss was measured for the laminated piezoelectric element manufactured using the sample E7, the sample C3, and the sample C4, and the temperature dependency was examined.
Specifically, first, a load of 400 N was applied to each multilayer piezoelectric element, and a voltage of 0 to 150 V was repeatedly applied at a temperature of −40 ° C. to 160 ° C. to operate the multilayer piezoelectric element. If the input energy at this time is E1, and the energy stored in the multilayer piezoelectric element is E2, the loss L is calculated by the following equation.
L = (E1-E2) / E1 × 100
The results are shown in Table 3.

  As can be seen from Table 3, the loss at each use temperature is increased in the sample C3 and the sample C4 to which Sb is not added as compared with the sample E7 containing Sb.

According to the present embodiment as described above, the general formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn _1-B1-B2 W _B1 Sb _B2 ) _q O ₃ is contained in an amount of 0.7 mol% or less of Sb ₂ O ₃ with respect to 1 mol of the compound represented by 0.04 ≦ x ≦ 0.1, 0.44 ≦ y ≦ Piezoelectric materials with 0.48, 0 ≦ z ≦ 0.01, 0 ≦ p ≦ 0.02, 0.003 ≦ q ≦ 0.01, 0 ≦ B1 ≦ 0.34, 0 ≦ B2 ≦ 0.5 It can be seen that it can be fired at a low temperature, can exhibit a displacement that can withstand practical use even when fired at a low temperature, and its loss is small.

  In addition, as shown in Table 1, in this example, as Ma in the compound represented by the general formula (1), a combination of Sr and Ba or a combination of Sr and La was used. Although not shown in the table, it has been confirmed that the same result as this example can be obtained even when a combination of Sr and Ce is used as Ma.

(Example 2)
Next, this example is an example in which a multilayer piezoelectric element similar to that of Example 1 is manufactured using a base metal electrode material.
That is, first, the sample E1 of Example 1 was prepared as a piezoelectric material.
Using this piezoelectric material, a slurry was prepared in the same manner as in Example 1, and this slurry was molded to prepare an unfired sheet. Next, a conductive paste containing an electrode material made of an alloy of copper and nickel was printed on the green sheet, and a printed layer for internal electrodes was provided in the same manner as in Example 1. As an electrode material, copper or nickel can be used in addition to an alloy of copper and nickel.

Next, in the same manner as in Example 1, the unfired sheets provided with the printed layers were laminated, and a simple unfired sheet having no printed layers for internal electrode layers was placed on the upper and lower ends, and thermocompression bonding was performed. Thus, an unfired laminate was produced.
Next, this unfired laminated body was placed in a heating furnace, started to be heated at a temperature rising rate of 50 ° C./h, and heated at a holding temperature of 550 ° C. for 37 hours. At this time, nitrogen and water vapor were supplied as atmospheric gases from the atmospheric gas supply device into the heating furnace. Nitrogen was supplied at 10,000 ml / min, and water vapor was supplied so that the dew point temperature in the heating furnace was 70 ° C.

Thereafter, the furnace was cooled, the laminate was taken out from the heating furnace, and fired in a firing furnace.
Firing was performed by starting heating at a heating rate of 300 ° C./h and heating at a maximum holding temperature of 970 ° C. for 2 hours. Then, the temperature was lowered at the furnace cooling rate, and the laminate was taken out when the temperature in the furnace chamber was cooled to 90 ° C.
At the time of the firing, Ar ₂ -CO (CO concentration is 10% by volume) composed of CO ₂ (base gas), Ar (inert gas) and CO (reducing gas) as the atmospheric gas, and oxygen O ₂ (oxygen gas) for adjusting the partial pressure was introduced into the furnace chamber at a constant flow rate.

From room temperature to around 600 ° C., the oxygen partial pressure was controlled to be 10 ^−12.9 to 10 ^−16.0 atm by the oxygen partial pressure sensor ^outside the furnace. From 600 ° C. or higher, the oxygen partial pressure was controlled by switching to the in-furnace oxygen partial pressure sensor. The indicated value of the oxygen partial pressure sensor in the furnace at the time of switching was 10 ^−6.0 to 10 ⁻¹⁴ atm. From the switching to the maximum holding temperature, the oxygen partial pressure is increased linearly, and at the maximum holding temperature, the oxygen partial pressure is maintained in the range of 10 ^−6.0 to 10 ^−8.0 atm to control the atmosphere.
Thus, the multilayer body was fired to obtain a multilayer piezoelectric element.

In this example, as described above, a laminated piezoelectric element is produced using an alloy of Cu and Ni having a relatively low melting point as the electrode material. However, the sample E1 of Example 1 is used as the piezoelectric material. Therefore, simultaneous firing of the electrode material and the piezoelectric material was possible.
That is, in the multilayer piezoelectric element produced in this example, the piezoelectric layer was sufficiently sintered despite being fired at a low temperature of 970 ° C. Further, since Cu and Ni are relatively inexpensive, the multilayer piezoelectric element of this example can be manufactured at low cost.

1 is a perspective view of a multilayer piezoelectric element according to Example 1. FIG. 2A is a plan view of a piezoelectric layer of a multilayer piezoelectric element according to Example 1, and FIG. 2B is a plan view of a ceramic layer constituting a dummy portion. FIG. 3 is a perspective developed view showing a stacked state of piezoelectric layers according to the first embodiment. It is an electron microscope (SEM) photograph of the piezoelectric layer of the multilayer piezoelectric element manufactured using the sample E1 according to Example 1 as a piezoelectric material, (a) a photograph when fired at a firing temperature of 1000 ° C., and ( b) Explanatory drawing which shows the photograph baked with the calcination temperature of 1050 degreeC. It is an electron microscope (SEM) photograph of the piezoelectric layer of the laminated piezoelectric element produced using the sample C2 as the piezoelectric material according to Example 1, and (a) a photograph when fired at a firing temperature of 1000 ° C., and b) Explanatory drawing which shows the photograph baked with the calcination temperature of 1050 degreeC.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer piezoelectric element 11 Piezoelectric layer 21, 22 Internal electrode layer

Claims (6)

Formula _{(1) :( Pb 1-x} Ma x) (Zr 1-yz Ti y Sb z) 1-pq (Y 1/2 Nb 1/2) p (Mn 1-B1-B2 W B1 Sb B2) and a compound represented by _q O _3, Sb ₂ O ₃ and / or Sb ₂ O ₅ and the piezoelectric material containing (although, Ma is Ba, La, Sr, and one or more selected from Ce) a,
The piezoelectric material contains 0.7 mol% or less of Sb ₂ O ₃ and / or Sb ₂ O ₅ with respect to 1 mol of the compound represented by the general formula (1).
0.04 ≦ x ≦ 0.1
0.44 ≦ y ≦ 0.48
0 ≦ z ≦ 0.01
0 ≦ p ≦ 0.02
0.003 ≦ q ≦ 0.01
0 ≦ B1 ≦ 0.34
0 ≦ B2 ≦ 0.5
A piezoelectric material characterized by   2. The piezoelectric material according to claim 1, wherein Ma in the general formula (1) is composed of Sr as an essential component and Ba, La, or Ce.   3. The piezoelectric material according to claim 2, wherein in the Ma of the general formula (1), Ba, La, or Ce and Sr have substantially the same substitution ratio with respect to Pb. 4. The piezoelectric material according to claim 1, wherein the piezoelectric material has 0.05 to 2 parts by weight of PbO and 0 to ₃ of WO ₃ with respect to 100 parts by weight of the compound represented by the general formula (1). A piezoelectric material containing 0.001 to 0.038 parts by weight. A method for producing a laminated piezoelectric element in which piezoelectric layers and internal electrode layers are alternately laminated,
A sheet forming material containing the piezoelectric material according to claim 1 is prepared, and the sheet forming material is molded to produce an unfired sheet. An electrode for an internal electrode layer is formed on the unfired sheet. Provide a printing layer made of paste containing the material,
Thereafter, a plurality of unfired sheets provided with the printed layer are laminated to form an unfired laminate, and the unfired laminate is fired.   6. The method for manufacturing a multilayer piezoelectric element according to claim 5, wherein the firing of the green laminate is performed at a temperature of 850 ° C. to 1000 ° C.

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