JP2006193414A - Method for producing piezoelectric ceramic and method for producing piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic capable of being fired at a low temperature and capable of being fired in a low-oxygen reducing atmosphere. <P>SOLUTION: The piezoelectric ceramic is prepared by adding 0.01 to 1.5 mass% PbO and not more than 1.0 mass% CuO to a calcined powder containing a composition (Pb<SB>a-b</SB>Me<SB>b</SB>) [(Zn<SB>1/3</SB>Nb<SB>2/3</SB>)<SB>x</SB>Ti<SB>y</SB>Zr<SB>z</SB>]O<SB>3</SB>(wherein 0.96≤a≤1.03; 0≤b≤0.1; x+y+z=1; 0.05≤x≤0.40; 0.1≤y≤0.5; 0.2≤z≤0.6; and Me is Sr, Ca, or Ba) and firing the resulting mixture. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a piezoelectric ceramic suitable for a piezoelectric vibrator such as a piezoelectric sounding body, a piezoelectric actuator, and a sensor, and a method for manufacturing a piezoelectric element.

  2. Description of the Related Art Conventionally, there is an actuator that uses a displacement generated by a piezoelectric effect as a mechanical drive source. In particular, multilayer actuators in which a piezoelectric layer and internal electrodes are laminated have lower power consumption and heat generation than electromagnetic actuators, have good responsiveness, and can be reduced in size and weight. Is used in various fields such as needle selection control of textile knitting machines.

Piezoelectric ceramics used in these actuators are required to have a large piezoelectric characteristic, particularly a piezoelectric strain constant. Examples of piezoelectric ceramics capable of obtaining a large piezoelectric strain constant include lead titanate (PbTiO ₃ ; PT), lead zirconate (PbZrO ₃ ; PZ), and lead zinc niobate (Pb (Zn _1/3 Nb _2/3). ) O ₃ ) ternary system (see Patent Document 1 and Patent Document 2), or a part of its lead (Pb) is replaced with strontium (Sr), barium (Ba), calcium (Ca), etc. (See Patent Literature 3, Patent Literature 4 and Patent Literature 5).
Japanese Examined Patent Publication No. 44-17344 JP 2001-181035 A Japanese Patent Publication No. 45-39977 JP 61-129888 A JP 2001-181036 A

  However, since the firing temperature of conventional piezoelectric ceramics is as high as about 1200 ° C., an expensive noble metal such as platinum (Pt) or palladium (Pd) is used for the internal electrode when a multilayer piezoelectric element is manufactured. There was a problem that manufacturing cost was high. Therefore, in order to use a cheaper material for the internal electrode, it has been desired to lower the firing temperature.

  For example, when an inexpensive silver-palladium (Ag—Pd) alloy is used for the internal electrode, palladium causes an oxidation-reduction reaction during firing, causing cracks and peeling in the multilayer piezoelectric element. Needs to be 30% by mass or less, and for that purpose, based on the silver-palladium phase diagram, the firing temperature must be 1150 ° C. or less, preferably 1120 ° C. or less. In order to further reduce the production cost, it is preferable to reduce the palladium content. For example, in order to reduce the palladium content to 20% by mass or less, it is necessary to set the firing temperature to 1050 ° C. or less. In order to make the amount 15% by mass or less, it is necessary to set the firing temperature to 1000 ° C. or less. Furthermore, in order to set the palladium content to 10% by mass or less, it is necessary to set the firing temperature to 980 ° C. or lower. To further reduce the palladium content to 5% by mass or lower, the firing temperature is set to 950 ° C. or lower. There is a need.

  More recently, the use of inexpensive copper (Cu) for internal electrodes has also been studied, but since the melting point of copper is 1085 ° C., the firing temperature must be 1050 ° C. or lower in order to use copper. . However, since copper begins to sinter from a lower temperature, it is necessary to make the firing temperature as low as possible. In addition, since copper is a base metal, it is oxidized when fired in an air atmosphere and cannot be used as an electrode. Therefore, firing in a low oxygen reducing atmosphere is necessary.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a piezoelectric ceramic manufacturing method and a piezoelectric element manufacturing method capable of obtaining high piezoelectric characteristics even when fired at a low temperature in a low oxygen reducing atmosphere. It is to provide.

The piezoelectric ceramic manufacturing method according to the present invention has a ratio of 0.01 to the composition in which the raw material of lead is converted to oxide (PbO) with respect to the calcined powder containing the composition represented by chemical formula 1 or chemical formula 2. A step of adding within a range of not less than 1.5% by mass and not more than 1.5% by mass, and adding and firing a copper raw material within a range of not more than 1% by mass with respect to the composition in terms of oxide (CuO). It is a waste. (Chemical formula 1)
Pb _a [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 1, a, x, y and z are 0.96 ≦ a ≦ 1.03, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0.1 ≦ y ≦ 0.5, 0. (It is a value within the range satisfying 2 ≦ z ≦ 0.6.)
(Chemical formula 2)
(Pb _ab Me _b ) [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 2, a, b, x, y, z are 0.96 ≦ a ≦ 1.03, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0. (It is a value within the range satisfying 1 ≦ y ≦ 0.5 and 0.2 ≦ z ≦ 0.6. Me represents at least one of the group consisting of strontium, calcium and barium.)

The lead raw material and the copper raw material are preferably added after calcining. Further, at least one raw material selected from the group consisting of tantalum (Ta), antimony (Sb), niobium (Nb), tungsten (W), and molybdenum (Mo) is used as an oxide (Ta ₂ O ₅ , Sb ₂ O). ₃ , Nb ₂ O ₅ , WO ₃ , MoO ₃ ) and may be added within a range of 1.0% by mass or less in proportion to the composition. In that case, it is preferable to calcine a mixture containing the composition raw material and at least one raw material selected from the group consisting of tantalum, antimony, niobium, tungsten, and molybdenum into a calcined powder.

  The method for manufacturing a piezoelectric element according to the present invention is a method for manufacturing a piezoelectric element including a laminate in which piezoelectric layers and internal electrodes are alternately stacked, and the piezoelectric element according to any one of claims 1 to 4. A piezoelectric layer is formed using a porcelain manufacturing method.

  According to the method for manufacturing a piezoelectric ceramic of the present invention, lead and copper raw materials are added within a predetermined range and calcined to a calcined powder containing the composition shown in chemical formula 1 or chemical formula 2. Therefore, even if the firing temperature is lowered or firing is performed in a low oxygen reducing atmosphere, high piezoelectric characteristics can be obtained. Therefore, according to the piezoelectric element manufacturing method of the present invention, since this piezoelectric ceramic manufacturing method is used, an inexpensive silver-palladium alloy or copper can be used for the internal electrode, and the manufacturing cost can be reduced. Can do. Further, a larger displacement amount can be obtained.

  In addition, if a predetermined amount of at least one selected from the group consisting of tantalum, antimony, niobium, tungsten and molybdenum is added, the piezoelectric characteristics can be further improved.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 shows a method for manufacturing a piezoelectric ceramic according to an embodiment of the present invention. First, raw materials for the composition shown in Chemical Formula 1 or Chemical Formula 2 are prepared and weighed so as to have the composition shown in Chemical Formula 1 or Chemical Formula 2. This is because high piezoelectric characteristics can be obtained by using the composition shown in Chemical Formula 1 or Chemical Formula 2.

(Chemical formula 1)
Pb _a [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
In the chemical formula 1, a, x, y, z are 0.96 ≦ a ≦ 1.03, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0.1 ≦ y ≦ 0.5, 0.2 It is a value within a range satisfying ≦ z ≦ 0.6. The composition of oxygen is determined stoichiometrically and may deviate from the stoichiometric composition.

(Chemical formula 2)
(Pb _ab Me _b ) [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
In the chemical formula 2, a, b, x, y and z are 0.96 ≦ a ≦ 1.03, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0.1 ≦ y ≦ 0.5 and 0.2 ≦ z ≦ 0.6. Me represents at least one member selected from the group consisting of strontium, calcium and barium. The composition of oxygen is determined stoichiometrically and may deviate from the stoichiometric composition.

The raw materials for the composition shown in Chemical Formula 1 or Chemical Formula 2 are specifically the raw materials for lead, zinc, niobium, titanium, and zirconium, and, if necessary, the raw materials for strontium, calcium, and barium. is there. These raw materials may be any materials as long as they become oxides upon firing, such as oxides, carbonates, oxalates or hydroxides. For example, lead oxide (PbO) powder, zinc oxide (ZnO) powder, niobium oxide (Nb ₂ O ₅ ) powder, titanium oxide (TiO ₂ ) powder, zirconium oxide (ZrO ₂ ) powder, strontium carbonate (SrCO ₃ ) powder, Examples thereof include barium carbonate (BaCO ₃ ) powder and calcium carbonate (CaCO ₃ ) powder.

If necessary, at least one raw material of the group consisting of tantalum, antimony, niobium, tungsten and molybdenum is prepared as an additive component. This is because the piezoelectric characteristics can be further improved by adding these. These raw materials may be any materials that can be converted into oxides upon firing. For example, tantalum oxide (Ta ₂ O ₅ ) powder, antimony oxide (Sb ₂ O ₃ ) powder, niobium oxide (Nb ₂ O). ₅ ) Powder, tungsten oxide (WO ₃ ) powder or molybdenum oxide (MoO ₃ ) powder. Next, these raw materials are converted into oxides (Ta ₂ O ₅ , Sb ₂ O ₃ , Nb ₂ O ₅ , WO ₃ , MoO ₃ ), respectively, for the compositions shown in Chemical Formula 1 or Chemical Formula 2, respectively. Weigh so that it is within the range of 1.0 mass% or less. This is because high piezoelectric characteristics can be obtained within this range.

  Subsequently, these raw materials are mixed by a ball mill or the like, and then calcined at a temperature lower than the firing temperature, for example, 700 ° C. to 900 ° C. for 1 hour to 4 hours to obtain calcined powder (step S101).

  After that, a lead raw material is prepared as another additive component, and is converted to oxide (PbO) and is 0.01% by mass or more and 1.5% by mass or less based on the composition shown in Chemical Formula 1 or Chemical Formula 2. Weigh so that it is within the range. Further, a copper raw material is prepared as another additive component, and is weighed so as to be within a range of 1% by mass or less with respect to the composition shown in Chemical Formula 1 or Chemical Formula 2 in terms of copper oxide (CuO). To do. This is because by adding these, firing can be performed at a low temperature even in a low oxygen reducing atmosphere, and variation in characteristics can be reduced. Any of these raw materials may be used as long as it becomes an oxide by firing, and examples thereof include lead oxide (PbO) and copper oxide (CuO).

  A more preferable range of the lead raw material is 0.01% by mass or more and 1% by mass or less in terms of oxide (PbO) with respect to the composition shown in chemical formula 1 or chemical formula 2, and the copper raw material. A more preferable range is 0.005% by mass or more and 0.1% by mass or less in terms of oxide (CuO) with respect to the composition shown in Chemical Formula 1 or Chemical Formula 2. This is because higher piezoelectric characteristics can be obtained within these ranges.

  Next, it is preferable that the lead raw material and the copper raw material are calcined at a temperature lower than the firing temperature, for example, 500 ° C. to 700 ° C. for 1 hour to 4 hours to obtain an additive powder (step S102). This is because a compound having a melting point lower than that of a single compound can be produced, so that a liquid phase is generated and sintering can be promoted even if the firing temperature is lowered.

  Subsequently, the prepared calcined powder and the additive powder are mixed and pulverized by a ball mill or the like, then added with a binder, granulated, and press-molded using a uniaxial press molding machine or a hydrostatic pressure molding machine (CIP) (step) S103). After that, for example, the molded body is fired at 950 ° C. to 1050 ° C. for 2 hours to 8 hours in an air atmosphere or a low oxygen reduction atmosphere (step S104). Note that the firing atmosphere may be such that the oxygen partial pressure is higher than that in the air or in pure oxygen. After firing, the obtained sintered body is polished as necessary, provided with a polarization electrode, and subjected to polarization treatment by applying an electric field in heated silicone oil (step S105). After that, the piezoelectric ceramic is obtained by removing the polarization electrode as necessary.

  In the manufacturing method described above, the raw material of tantalum, antimony, niobium, tungsten, or molybdenum is mixed with the raw material of the composition shown in Chemical Formula 1 or Chemical Formula 2 and calcined. After calcining the raw material of the composition shown in (5), it may be added to the calcined powder. However, it is preferable to add it before calcination because higher characteristics can be obtained.

  Thus, according to the method for manufacturing a piezoelectric ceramic according to the present embodiment, lead and copper raw materials are added within a predetermined range to the calcined powder containing the composition shown in Chemical Formula 1 or Chemical Formula 2. Therefore, even if the firing temperature is lowered or the firing is performed in a low oxygen reducing atmosphere, high piezoelectric characteristics can be obtained.

  In particular, if the lead raw material and the copper raw material are added after calcining, the firing temperature can be lowered.

  In addition, if a predetermined amount of at least one selected from the group consisting of tantalum, antimony, niobium, tungsten and molybdenum is added, the piezoelectric characteristics can be further improved.

  This method of manufacturing a piezoelectric ceramic is preferably used when manufacturing piezoelectric elements such as actuators, piezoelectric buzzers, piezoelectric sounding bodies and sensors.

  FIG. 2 shows a configuration example of the piezoelectric element. The piezoelectric element includes, for example, a stacked body 10 in which a plurality of piezoelectric layers 11 and a plurality of internal electrodes 12 are alternately stacked. For example, the internal electrodes 12 are alternately extended in opposite directions, and a pair of terminal electrodes 21 and 22 electrically connected to the internal electrode 12 are provided in the extending direction. The piezoelectric layer 11 is formed by the method for manufacturing a piezoelectric ceramic according to the present embodiment, and the internal electrode 12 is a conductive material such as silver (Ag), gold (Au), copper, platinum, palladium, or an alloy thereof. Contains. Among these, a silver-palladium alloy or copper is preferable as the conductive material.

  Specifically, this piezoelectric element can be manufactured as follows, for example.

  First, a calcined powder is formed in the same manner as in the piezoelectric ceramic manufacturing method described above, and a lead raw material and a copper raw material are added as additive components thereto, and a binder and a solvent are added and kneaded to obtain a piezoelectric layer. Make a paste. At that time, it is preferable that the additive component is calcined and added in the same manner as in the piezoelectric ceramic manufacturing method described above. Next, the above-described conductive material for forming the internal electrode 12 or various oxides, organometallic compounds, or resinates that become the above-described conductive material after firing are kneaded with a binder and a solvent to prepare an internal electrode paste. Note that additives such as a dispersant, a plasticizer, a dielectric material, and an insulator material may be added to the internal electrode paste as necessary.

  Subsequently, using these piezoelectric layer paste and internal electrode paste, a green chip which is a precursor of the laminate 10 is manufactured by, for example, a printing method or a sheet method. After that, a binder removal process is performed, and the laminate 10 is formed by firing. The firing temperature is preferably 950 ° C. to 1050 ° C. as described above. When copper is used as the conductive material for the internal electrode 12, the firing atmosphere is preferably a low oxygen reduction atmosphere. This is because copper oxidation can be suppressed and reduction of lead oxide can be suppressed.

  After the laminated body 10 is formed, terminal polishing is performed by, for example, barrel polishing or sand blasting and sputtering of a metal such as gold, or printing or transferring a terminal electrode paste produced in the same manner as the internal electrode paste. Then, terminal electrodes 21 and 22 are formed by baking. Thereby, the piezoelectric element shown in FIG. 2 is obtained.

  As described above, according to the method for manufacturing a piezoelectric element according to the present embodiment, since the above-described method for manufacturing a piezoelectric ceramic is used, even if the firing temperature is lowered or the material is fired in a low oxygen reducing atmosphere. However, high piezoelectric characteristics can be obtained. Therefore, an inexpensive silver-palladium alloy, copper, or the like can be used for the internal electrode 12, so that the manufacturing cost can be reduced and a larger displacement can be obtained.

  Furthermore, specific examples of the present invention will be described.

(Examples 1-1 to 1-3)
First, lead oxide powder, strontium carbonate powder, titanium oxide powder, zirconium oxide powder, zinc oxide powder and niobium oxide powder are weighed to have the composition shown in Chemical Formula 3, and the tantalum oxide powder has the composition shown in Chemical Formula 3. These were weighed so as to be 0.2% by mass with respect to the product, and these were wet mixed using a ball mill for 16 hours, and then calcined in the atmosphere at 700 ° C. to 900 ° C. for 2 hours to obtain calcined powder ( FIG. 1; see step S101).

  Subsequently, the lead oxide powder and the copper oxide powder were weighed and calcined at 500 ° C. to 700 ° C. for 2 hours to obtain an additive powder (see FIG. 1; step S102). At that time, the addition amount of the lead oxide powder is 0.3% by mass, 0.05% by mass or 0.5% by mass with respect to the composition shown in Chemical Formula 3, and the addition amount of the copper oxide powder is With respect to the composition shown in No. 3, the content was 0.01% by mass or 0.05% by mass.

Subsequently, the calcined powder and the additive powder were mixed and pulverized for 16 hours using a ball mill and dried, and then granulated by adding polyvinyl alcohol as a binder, and at a pressure of about 245 MPa using a uniaxial press molding machine. It was formed into a disk shape having a diameter of 17 mm and a thickness of 1 mm (see FIG. 1; step S103). After forming, heat treatment was performed to volatilize the binder, and then the mixture was fired at 950 ° C. for 2 hours in a low oxygen reducing atmosphere having an oxygen partial pressure of 1 × 10 ⁻⁵ Pa to 1 × 10 ⁻¹ Pa (FIG. 1; (See step S104). After that, the obtained sintered body was formed into a disk shape having a thickness of 0.6 mm by slicing and lapping, silver paste was printed on both sides and baked at 300 ° C., and 3 kV / mm in 120 ° C. silicone oil. An electric field was applied for 15 minutes to perform polarization treatment (see FIG. 1; step S105). Thereby, the piezoelectric ceramics of Examples 1-1 to 1-3 were obtained.

  As comparative examples 1-1 to 1-3 for this example, except that lead oxide powder and copper oxide powder were added to the composition shown in chemical formula 3 when producing calcined powder, Piezoelectric ceramics were produced in the same manner as in Examples 1-1 to 1-3. That is, Comparative Examples 1-1 to 1-3 do not add lead oxide powder and copper oxide powder to the calcined powder but add them before calcining.

  10 pieces of each of the produced piezoelectric ceramics of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 were prepared and allowed to stand for 24 hours, and then the density, the electromechanical coupling coefficient kr of radial vibration, and The relative dielectric constant εr was measured. For these measurements, an impedance analyzer (HP4194A manufactured by Hewlett-Packard Company) was used, and the frequency when measuring the relative dielectric constant εr was 1 kHz. Table 1 shows the average value and the variation width. The variation width is obtained by dividing the difference between the highest value and the lowest value in each embodiment by the average value and multiplying by 100.

(Chemical formula 3)
(Pb _0.965 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

  As shown in Table 1, according to Examples 1-1 to 1-3 in which lead oxide and copper oxide were added to the calcined powder, compared with Comparative Examples 1-1 to 1-3 added at the time of calcining. The piezoelectric characteristic kr × √εr was improved and the variation width was small. That is, by adding lead and copper raw materials to the calcined powder and firing it, high piezoelectric characteristics can be obtained even when firing temperature is lowered or firing in a low oxygen reducing atmosphere. It was found that variation in characteristics can be reduced.

(Examples 2-1 to 2-44)
Piezoelectric ceramics were produced in the same manner as in Examples 1-1 to 1-3, except that the amounts of lead oxide powder and copper oxide powder added to the calcined powder were changed. The addition amount of the lead oxide powder and the copper oxide powder was changed as shown in Tables 2 to 10 with respect to the composition shown in Chemical formula 3. Further, as Comparative Example 2-1 for this example, a piezoelectric ceramic was produced in the same manner as in Examples 2-1 to 2-44, except that the lead oxide powder and the copper oxide powder as additive components were not added. .

  For the produced piezoelectric ceramics of Examples 2-1 to 2-44 and Comparative Example 2-1, the density, the electromechanical coupling coefficient kr of the radial vibration, and the relative dielectric were the same as in Examples 1-1 to 1-3. The rate εr was measured. The results are shown in Tables 2-10.

  As shown in Tables 2 to 10, according to Examples 2-1 to 2-44 to which lead oxide and copper oxide were added, piezoelectric characteristics kr × √εr compared to Comparative Example 2-1 to which lead oxide and copper oxide were not added. Was able to improve. That is, the lead material is added in the range of 0.01% by mass to 1.5% by mass in terms of oxide (PbO) with respect to the composition, and the copper material is oxidized with respect to the composition. If it is added within the range of 1% by mass or less in terms of the product (CuO), high piezoelectric characteristics can be obtained even if the firing temperature is lowered or firing in a low oxygen reducing atmosphere. I understood that I could do it.

  If the lead content is within the range of 0.01% by mass or more and 1% by mass or less in terms of oxide (PbO) with respect to the composition shown in Chemical Formula 3, or It is more preferable that the copper content is within the range of 0.005 mass% or more and 0.1 mass% or less in terms of oxide (CuO) with respect to the composition shown in Chemical formula 3. I also understood that.

(Examples 3-1 to 3-6, 4-1 to 4-4)
In Examples 3-1 to 3-6, except that tantalum oxide, lead oxide, and copper oxide were added to the composition shown in Chemical Formula 4, in Examples 4-1 to 4-4, Chemical Formula 5 Piezoelectric ceramics were fabricated in the same manner as in Examples 1-1 to 1-3 except that tantalum oxide, lead oxide, and copper oxide were added to the composition shown. At that time, the addition amounts of the lead oxide powder and the copper oxide powder were changed as shown in Tables 11 and 12 with respect to the composition shown in Chemical Formula 4 or Chemical Formula 5. Further, as Comparative Example 3-1 with respect to Examples 3-1 to 3-6 and Comparative Example 4-1 with respect to Examples 4-1 to 4-4, the addition of lead oxide and copper oxide as additive components was not added. Except for the above, piezoelectric ceramics were produced in the same manner as in Examples 3-1 to 3-6 or Examples 4-1 to 4-4.

  For the produced Examples 3-1 to 3-6, 4-1 to 4-4 and Comparative Examples 3-1 and 4-1, the density and radial direction were also the same as in Examples 1-1 to 1-3. The electromechanical coupling coefficient kr and the relative dielectric constant εr of vibration were measured. The results are shown in Tables 11 and 12.

(Chemical formula 4)
(Pb _0.95 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.42 Zr _0.48 ] O ₃

(Chemical formula 5)
(Pb _0.98 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

  As shown in Tables 11 and 12, according to Examples 3-1 to 3-6 and 4-1 to 4-4 to which lead oxide and copper oxide were added, Comparative Examples 3-1 and 4 without addition Compared to −1, the piezoelectric characteristic kr × √εr could be improved. That is, even if the composition of the composition is changed, if firing is performed by adding lead and copper raw materials to the calcined powder, the firing temperature is lowered or the firing is performed in a low oxygen reducing atmosphere. Even so, it was found that high piezoelectric characteristics can be obtained.

(Examples 5-1 to 5-12)
A piezoelectric ceramic was produced in the same manner as in Example 1-1 except that the type and amount of the additive component were changed as shown in Table 13. The amount of lead oxide added was 0.3% by mass with respect to the composition shown in Chemical Formula 3, and the amount of copper oxide added was 0.01% by mass with respect to the composition shown in Chemical Formula 3. In addition, as Comparative Examples 5-1 to 5-12 with respect to Examples 5-1 to 5-12, Examples 5-1 to 5-12 and A piezoelectric ceramic was produced in the same manner.

  For the produced Examples 5-1 to 5-12 and Comparative Examples 5-1 to 5-12, as in Example 1-1, the density, the electromechanical coupling coefficient kr of the radial vibration, and the relative dielectric constant εr Was measured. The results are shown in Table 13. In addition, content of the additive component shown in Table 13 is the value converted into the oxide with respect to the composition shown in Chemical formula 3.

  As shown in Table 13, according to Examples 5-1 to 5-12, kr × √εr could be increased as compared with Comparative Examples 5-1 to 5-12. In addition, kr × √εr is further improved in Examples 5-2 to 5-12 to which an additive component such as tantalum is added, compared to Example 5-1 in which an additive component such as tantalum is not added. I was able to. That is, it has been found that it is more preferable to add at least one member selected from the group consisting of tantalum, antimony, niobium, tungsten and molybdenum as an additive component.

(Examples 6-1 to 6-3)
A piezoelectric ceramic was produced in the same manner as in Example 1-1 except that strontium carbonate powder was not added, or that barium carbonate powder or calcium carbonate powder was added instead of strontium carbonate powder. . That is, instead of the composition shown in Chemical Formula 3, the raw materials were mixed so that the composition shown in Chemical Formula 6 or Chemical Formula 7 was obtained. In addition, as Comparative Examples 6-1 to 6-3 with respect to Examples 6-1 to 6-3, Examples 6-1 to 6-3 were used except that the additive components lead oxide and copper oxide were not added. A piezoelectric ceramic was produced in the same manner.

  Also in Examples 6-1 to 6-3 and Comparative Examples 6-1 to 6-3, the density, the electromechanical coupling coefficient kr of the radial vibration, and the relative dielectric constant εr were set in the same manner as in Example 1-1. It was measured. The results are shown in Table 14. In addition, the addition amount of the additive component shown in Table 14 is a value converted into an oxide with respect to the composition shown in Chemical Formula 6 or Chemical Formula 7.

(Chemical formula 6)
Pb _0.995 [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

(Chemical formula 7)
(Pb _0.965 Me _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

  As shown in Table 14, according to Examples 6-1 to 6-3, kr × √εr could be increased as compared with Comparative Examples 6-1 to 6-3. Moreover, compared with Example 6-1 in which a part of lead is not substituted with other elements, the substituted Examples 6-2, 6-3, and 1-1 further improve kr × √εr. I was able to. That is, it has been found that it is more preferable if a part of lead is substituted with at least one member selected from the group consisting of strontium, calcium and barium.

(Examples 7-1 and 7-2)
In the same manner as in Example 1-1 or Example 5-1, additive powder was added to the calcined powder to produce a multilayer piezoelectric element as shown in FIG. Copper was used for the internal electrode 12, the thickness of the piezoelectric layer 11 sandwiched between the internal electrodes 12 was 20 μm, the number of layers was 15 layers, and the vertical and horizontal dimensions were 4 mm × 4 mm. In Example 7-1, lead oxide and copper oxide were added to the calcined powder obtained by adding tantalum oxide to the composition shown in Chemical formula 3. In Example 7-2, lead oxide and copper oxide were added to the calcined powder of the composition shown in Chemical formula 3. The amount of lead oxide added is 0.3 mass% with respect to the composition shown in Chemical Formula 3, the amount of copper oxide added is 0.01 mass% with respect to the composition shown in Chemical Formula 3, and the amount of tantalum oxide added is It is 0.2 mass% with respect to the composition shown in Chemical formula 3. The firing atmosphere was a low oxygen reducing atmosphere with an oxygen partial pressure of 1 × 10 ⁻⁵ Pa to 1 × 10 ⁻¹ Pa, the firing temperature was 950 ° C., and the firing time was 2 hours.

(Chemical formula 3)
(Pb _0.965 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

  Further, as Comparative Example 7-1 with respect to Examples 7-1 and 7-2, except that lead oxide, zinc oxide and tantalum oxide were not added to the composition shown in Chemical Formula 3, other examples were used. Piezoelectric elements were fabricated in the same manner as in 7-1 and 7-2.

  With respect to the produced piezoelectric elements of Examples 7-1 and 7-2 and Comparative Example 7-1, the displacement amount when a voltage of 30 V was applied was measured. The results obtained are shown in Table 15.

As shown in Table 15, according to Examples 7-1 and 7-2, a displacement larger than that of Comparative Example 7-1 could be obtained. That is, it has been found that if lead and copper are added as additive components to the calcined powder, the generated displacement can be increased even if the firing temperature is lowered and firing is performed in a low oxygen reducing atmosphere.
It has also been found that the firing temperature can be further lowered by further adding copper as an additive component.

  In the above examples, some examples have been specifically described. However, even if the composition and the composition of the additive components are changed, the same results are obtained as long as they are within the range described in the above embodiments. Can be obtained.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the embodiments and examples described above, the case where at least one of the group consisting of antimony, tantalum, niobium, tungsten, and molybdenum is added as necessary as an additive component has been described. Other components may be added. In that case, other components may be dissolved in the main component or may not be dissolved.

  It can be widely used in the fields of actuators, piezoelectric buzzers, sounding bodies and sensors.

It is a flowchart showing the manufacturing method of the piezoelectric ceramic which concerns on one embodiment of this invention. It is sectional drawing showing the example of 1 structure of the piezoelectric element manufactured using the manufacturing method of the piezoelectric ceramic which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Laminated body, 11 ... Piezoelectric layer, 12 ... Internal electrode, 21, 22 ... Terminal electrode.

Claims (6)

With respect to the calcined powder containing the composition represented by Chemical Formula 1 or Chemical Formula 2, 0.01% by mass or more and 1.5% in terms of the ratio of the lead (Pb) raw material to the oxide (PbO) Adding within a range of less than or equal to mass% and adding and firing a copper (Cu) raw material within a range of less than or equal to 1 mass% at a ratio to the composition in terms of oxide (CuO). A method of manufacturing a piezoelectric ceramic.
(Chemical formula 1)
Pb _a [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 1, a, x, y and z are 0.96 ≦ a ≦ 1.03, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0.1 ≦ y ≦ 0.5, 0. (It is a value within the range satisfying 2 ≦ z ≦ 0.6.)
(Chemical formula 2)
(Pb _ab Me _b ) [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 2, a, b, x, y, z are 0.96 ≦ a ≦ 1.03, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.40, 0. 1 ≦ y ≦ 0.5 and 0.2 ≦ z ≦ 0.6, Me is a value selected from the group consisting of strontium (Sr), calcium (Ca) and barium (Ba). Represents at least one).   2. The method for manufacturing a piezoelectric ceramic according to claim 1, wherein the lead raw material and the copper raw material are added after calcining. Furthermore, at least one raw material selected from the group consisting of tantalum (Ta), antimony (Sb), niobium (Nb), tungsten (W), and molybdenum (Mo) is used as an oxide (Ta ₂ O ₅ , Sb ₂ O). ₃ , Nb ₂ O ₅ , WO ₃ , MoO ₃ ), each of which is added within a range of 1.0% by mass or less in proportion to the composition. Item 3. A method for manufacturing a piezoelectric ceramic according to Item 2.   The mixture containing the raw material of the composition and at least one raw material in the group consisting of tantalum, antimony, niobium, tungsten and molybdenum is calcined to obtain a calcined powder. The manufacturing method of the piezoelectric ceramic described. A method of manufacturing a piezoelectric element comprising a laminate in which piezoelectric layers and internal electrodes are alternately laminated,
A method for manufacturing a piezoelectric element, comprising: forming a piezoelectric layer using the method for manufacturing a piezoelectric ceramic according to any one of claims 1 to 4. 6. The method of manufacturing a piezoelectric element according to claim 5, wherein copper is used as the conductive material of the internal electrode.

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