JP2006137626A - Piezoelectric ceramic and piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic and a piezoelectric element which can be improved in electric resistance. <P>SOLUTION: A piezoelectric layer 11 contains a composition expressed by (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>(1.005<a≤1.10, 0≤b≤0.1, x+y+z=1, 0.05≤x≤0.15, 0.25≤y≤0.5, 0.35≤z≤0.6, and Me is at least one kind among Sr, Ca and Ba), as the main component. Furthermore, it may contain at least one kind among Ta, Sb, Nb and W as a subcomponent within the range of 1.0 mass% or less to the main component in terms of oxide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to piezoelectric ceramics and piezoelectric elements suitable for actuators, piezoelectric transformers, ultrasonic motors, and the like.

  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).

As a multilayer actuator, there is known a multilayer actuator in which a piezoelectric layer made of these piezoelectric ceramics and an internal electrode made of a silver-palladium alloy (Ag—Pd alloy) are laminated. Furthermore, in recent years, the use of low-cost copper (Cu) for the internal electrodes has also been studied.
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, in order to use copper for the internal electrode, firing in a low oxygen reducing atmosphere is required. However, when a conventional piezoelectric ceramic is fired as it is in a low oxygen reducing atmosphere, there is a problem that electric resistance is lowered. In particular, the decrease in electrical resistance is significant at high temperatures, and improvements have been sought.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a piezoelectric ceramic and a piezoelectric element that can improve electrical resistance.

The piezoelectric ceramic according to the present invention includes a composition represented by 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 and z are 1.005 <a ≦ 1.10, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0.25 ≦ y ≦ 0.5, 0. (It is a value within a range satisfying 35 ≦ 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, and z are 1.005 <a ≦ 1.10, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0. (It is a value within the range satisfying 25 ≦ y ≦ 0.5 and 0.35 ≦ z ≦ 0.6. Me represents at least one of the group consisting of strontium, calcium and barium.)

In the piezoelectric ceramic according to the present invention, at least one selected from the group consisting of tantalum (Ta), antimony (Sb), niobium (Nb), and tungsten (W) with respect to the composition represented by chemical formula 1 or chemical formula 2. In terms of oxides (Ta ₂ O ₅ , Sb ₂ O ₃ , Nb ₂ O ₅ , WO ₃ ), each is preferably contained within a range of 1.0% by mass or less.

  The piezoelectric element according to the present invention uses the piezoelectric ceramic according to the present invention.

  According to the piezoelectric ceramic of the present invention, the composition a in Chemical Formula 1 or Chemical Formula 2 is set in the range of 1.005 <a ≦ 1.10. Therefore, even when fired in a low oxygen reducing atmosphere, high electrical resistance is achieved. In particular, a decrease in electrical resistance at high temperatures can be suppressed. Therefore, according to the piezoelectric element of the present invention, since it can be fired in a low oxygen reducing atmosphere, excellent characteristics can be obtained even when a nonmetal such as copper is used for the internal electrode, and it is used even at a high temperature. be able to.

  In particular, if a predetermined amount of at least one selected from the group consisting of tantalum, antimony, niobium, and tungsten is contained, the piezoelectric characteristics and mechanical strength can be improved.

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

  The piezoelectric ceramic according to one embodiment of the present invention contains a composition represented by Chemical Formula 3 or Chemical Formula 4 as a main component.

(Chemical formula 3)
Pb _a [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 3, a, x, y and z are 1.005 <a ≦ 1.10, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0.25 ≦ y ≦ 0.5, 0. (It is a value within a range satisfying 35 ≦ z ≦ 0.6. The composition of oxygen is determined stoichiometrically and may deviate from the stoichiometric composition.)

(Chemical formula 4)
(Pb _ab Me _b ) [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
(In the chemical formula 4, a, b, x, y and z are 1.005 <a ≦ 1.10, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0. The values are within the ranges satisfying 25 ≦ y ≦ 0.5 and 0.35 ≦ z ≦ 0.6, respectively, Me represents at least one selected from the group consisting of strontium, calcium and barium. Is determined stoichiometrically and may deviate from the stoichiometric composition.)

  These compositions have a perovskite structure, and lead, strontium, barium and calcium are located at the A site of the so-called perovskite structure and are composed of zinc (Zn), niobium (Nb), titanium (Ti) and zirconium (Zr). Is located at the B site of the so-called perovskite structure.

  In addition, the composition represented by the chemical formula 4 has more piezoelectric characteristics by substituting a part of lead in the composition represented by the chemical formula 3 with at least one selected from the group consisting of strontium, barium and calcium. It can be improved. The reason why the composition b is made 0.1 or less is that if the composition b is made too large, the sinterability is lowered, and thereby the piezoelectric characteristics are also lowered.

The composition a of lead in chemical formula 3 and the composition a of lead and at least one member selected from the group consisting of strontium, barium, and calcium in chemical formula 4 are elements located at the so-called B site, that is, [(Zn _1/3 Nb _2/3) is a composition ratio of the element that is located in a so-called a-site in the case of the 1 the composition of _x Ti _y Zr _z]. The reason why the composition a is larger than 1.005 and not larger than 1.10 is that the electric resistance can be increased within this range, and the decrease in electric resistance at high temperature is suppressed even when firing in a low oxygen reducing atmosphere. Because it can be done. A more preferable range of the composition a is 1.005 <a ≦ 1.05, and a further preferable range is 1.005 <a ≦ 1.03. This is because when the composition a is increased, the ratio of the high-temperature electric resistance to the normal-temperature electric resistance is increased, but the piezoelectric characteristics tend to be lowered.

Zinc and niobium (Zn _1/3 Nb _2/3 ) in Chemical Formula 3 and Chemical Formula 4 are for improving the piezoelectric characteristics. The reason why the composition x is 0.05 or more is that if the composition x is less than 0.05, the piezoelectric characteristics cannot be sufficiently improved. Further, the reason why the composition x is 0.15 or less is that if the composition x is too large, a large amount of expensive niobium oxide must be used, resulting in an increase in manufacturing cost and a decrease in piezoelectric characteristics. It is.

  In the chemical formulas 3 and 4, the titanium composition y is set to 0.25 to 0.5 and the zirconium composition z is set to 0.35 and 0.6 in the vicinity of the morphotropic phase boundary (MPB) within this range. This is because a high piezoelectric characteristic can be obtained.

The piezoelectric ceramic also preferably contains at least one member selected from the group consisting of tantalum, antimony, niobium and tungsten as a subcomponent. This is because the piezoelectric characteristics and mechanical strength can be improved. The contents of the subcomponents are converted to oxides (Ta ₂ O ₅ , Sb ₂ O ₃ , Nb ₂ O ₅ , WO ₃ ) with respect to the composition shown in Chemical Formula 3 or Chemical Formula 4, respectively. It is preferably within the range of 0% by mass or less. This is because if it exceeds 1.0% by mass, the sinterability is lowered and the piezoelectric properties are lowered. These subcomponents are, for example, dissolved in the main component composition, and are located at a so-called B site where titanium and zirconium can exist.

  A piezoelectric ceramic having such a configuration can be manufactured, for example, as follows.

First, for example, lead oxide (PbO) powder, zinc oxide (ZnO) powder, niobium oxide (Nb ₂ O ₅ ) powder, titanium oxide (TiO ₂ ) powder and zirconium oxide (ZrO ₂ ) powder are used as the main component raw materials. In addition to the preparation, strontium carbonate (SrCO ₃ ) powder, barium carbonate (BaCO ₃ ) powder or calcium carbonate (CaCO ₃ ) powder is prepared as necessary.

Further, for example, a tantalum oxide (Ta ₂ O ₅ ) powder, an antimony oxide (Sb ₂ O ₃ ) powder, a niobium oxide powder, or a tungsten oxide (WO ₃ ) powder is prepared as a raw material for the accessory component as necessary. The raw materials for these main components and subcomponents may not be oxides but may be those that become oxides upon firing, such as carbonates, oxalates or hydroxides. Alternatively, an oxide or another material that becomes an oxide by firing may be used.

  Next, after sufficiently drying these raw materials, the final composition is weighed so as to be in the above-mentioned range, and the raw materials of the main component and, if necessary, the raw materials of the auxiliary components are sufficiently obtained in an organic solvent or water using a ball mill or the like. And dried and calcined at 700 to 950 ° C. for 1 to 4 hours. Subsequently, for example, this calcined product is sufficiently pulverized in an organic solvent or water by a ball mill or the like, dried, and then granulated by adding a binder such as polyvinyl alcohol or acrylic resin, or a uniaxial press molding machine or Press molding using a hydrostatic pressure molding machine (CIP) or the like.

  After molding, for example, the molded body is preferably fired at 900 ° C. to 1100 ° C. for 1 hour to 8 hours in an air atmosphere or a low oxygen reduction atmosphere. Note that the firing atmosphere may be such that the oxygen partial pressure is higher than that in the air, or may be in pure oxygen, but in the present embodiment, the composition a is in the range of 1.005 <a ≦ 1.10. Therefore, even when firing in a low oxygen reducing atmosphere having a low oxygen partial pressure, high electrical resistance can be obtained. 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. After that, the above-mentioned piezoelectric ceramic is obtained by removing the electrode for polarization.

  Such a piezoelectric ceramic is preferably used as a material for piezoelectric elements such as actuators, piezoelectric transformers and ultrasonic motors.

  FIG. 1 shows a configuration example of a piezoelectric element using a piezoelectric ceramic according to the present embodiment. The piezoelectric element includes a laminated body 10 in which a plurality of internal electrodes 12 are inserted between a plurality of piezoelectric layers 11 made of the piezoelectric ceramic according to the present embodiment, for example. The thickness per layer of the piezoelectric layer 11 is, for example, about 1 μm to 100 μm, and the piezoelectric layers 11 at both ends may be formed thicker than the piezoelectric layer 11 sandwiched between the internal electrodes 12.

  The internal electrode 12 contains a conductive material. As the conductive material, for example, a noble metal such as silver (Ag), gold (Au), platinum (Pt) or palladium (Pd), or an alloy thereof can be used, but a nonmetal such as copper or an alloy thereof can be used. It is preferable to use it. This is because in the present embodiment, excellent characteristics can be obtained even if the piezoelectric layer 11 is baked in a low oxygen reducing atmosphere. The internal electrode 12 may contain about 0.1% by mass or less of various trace components such as phosphorus (P) in addition to these conductive materials.

  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 terminal electrodes 21 and 22 may be formed, for example, by sputtering a metal such as gold, or may be formed by baking a terminal electrode paste. The terminal electrode paste contains, for example, a conductive material, a glass frit, and a vehicle. As the conductive material, for example, at least one selected from the group consisting of silver, gold, copper, nickel, palladium, and platinum is used. The inclusion is preferred. Examples of the vehicle include an organic vehicle and an aqueous vehicle. The organic vehicle is obtained by dissolving a binder in an organic solvent, and the aqueous vehicle is obtained by dissolving a water-soluble binder and a dispersant in water. The thicknesses of the terminal electrodes 21 and 22 are appropriately determined according to the application and the like, but are usually about 10 μm to 50 μm.

  This piezoelectric element can be manufactured as follows, for example. First, a pre-fired powder is formed in the same manner as in the piezoelectric ceramic manufacturing method described above, and a vehicle is added thereto and kneaded to prepare a piezoelectric layer paste. Next, the above-described conductive material for forming the internal electrode 12 or various oxides, organometallic compounds, resinates, or the like that become the above-described conductive material after firing are kneaded with a vehicle 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. At that time, when a nonmetal such as copper is used as the conductive material of the internal electrode 12, the firing atmosphere is preferably a low oxygen reduction atmosphere.

  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. 1 is obtained.

  As described above, according to the present embodiment, the composition a in Chemical Formula 3 or Chemical Formula 4 is set in the range of 1.005 <a ≦ 1.10. Resistance can be obtained, and electrical resistance at high temperatures can be improved. Therefore, even if a nonmetal such as copper is used for the internal electrode 12, excellent characteristics can be obtained and the internal electrode 12 can be used even at a high temperature.

  In particular, if a predetermined amount of at least one selected from the group consisting of tantalum, antimony, niobium and tungsten is contained as a subcomponent, the piezoelectric characteristics and the mechanical strength can be improved.

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

(Examples 1-1 to 1-6)
A piezoelectric ceramic containing the composition shown in Chemical Formula 5 as a main component and tantalum as a subcomponent was produced. First, lead oxide powder, strontium carbonate powder, zinc oxide powder, niobium oxide powder, titanium oxide powder, and zirconium oxide powder were prepared as raw materials of the main components, and weighed to have the composition shown in Chemical formula 5. At that time, in Examples 1-1 to 1-6, the value of a in Chemical Formula 5 was changed as shown in Table 1. Further, tantalum oxide powder was prepared as a raw material for the auxiliary component, and weighed so that the ratio relative to the main component converted to oxide (Ta ₂ O ₅ ) was 0.4% by mass.

  Next, these raw materials were wet-mixed for 16 hours using a ball mill and then calcined at 700 ° C. to 900 ° C. for 2 hours in the air. Subsequently, the calcined product was wet pulverized for 16 hours using a ball mill, dried, granulated by adding an acrylic resin as a binder, and a diameter of 17 mm and a thickness of about 445 MPa using a uniaxial press molding machine. Molded into a 1 mm disk. After the molding, heat treatment was performed to volatilize the binder, and then it was fired at 950 ° C. for 2 to 8 hours in a low oxygen reduction atmosphere. After that, the obtained sintered body was made into a disk shape having a thickness of 0.6 mm by slicing and lapping, and silver paste was printed on both sides and baked at 350 ° C., and 3 kV / mm in 120 ° C. silicone oil. An electric field was applied for 15 minutes to perform polarization treatment. This obtained the piezoelectric ceramic of Examples 1-1 to 1-6.

  Further, as Comparative Examples 1-1 to 1-3 for the present example, the same as Example 1-1 to 1-6 except that the value of a in Chemical Formula 5 was changed as shown in Table 1. A piezoelectric ceramic was produced.

About the produced piezoelectric ceramics of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-3, after being left for 24 hours, the electrical resistance IR _{50 at 50} ° C., the electrical resistance IR _{100 at} 100 ° C., and the diameter The electromechanical coupling coefficient kr of directional vibration was measured. An impedance analyzer (HP4194A manufactured by Hewlett-Packard Company) was used to measure the electromechanical coupling coefficient kr. The results are shown in Table 1. The electrical resistance ratio is the ratio of the electrical resistance IR ₁₀₀ at 100 ° C. to the electrical resistance IR _{50 at} 50 ° C., that is, IR ₁₀₀ / IR ₅₀ .

(Chemical formula 5)
(Pb _a-0.03 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

As shown in Table 1, as the composition a was increased, IR ₁₀₀ / IR ₅₀ increased, and showed a tendency to decrease after showing a maximum value at a = 1.10. Further, the electromechanical coupling coefficient kr tended to decrease as the composition a was increased.

  That is, if the composition a is in the range of 1.005 <a ≦ 1.10, a decrease in the electrical resistance IR at high temperature can be suppressed, a high electrical resistance IR can be obtained even at a high temperature, and excellent It was also found that piezoelectric characteristics can be obtained. In particular, it was found that if the composition a is in the range of 1.005 <a ≦ 1.05, and further in the range of 1.005 <a ≦ 1.03, higher piezoelectric characteristics can be obtained. .

(Examples 2-1 to 2-6)
In Examples 2-1 to 2-4, the composition shown in Chemical Formula 6 was the main component, and in Examples 2-5 and 2-6, the composition shown in Chemical Formula 7 was the main component. A piezoelectric ceramic was produced in the same manner as in 1-2. At that time, in Examples 2-1 to 2-4, the composition b of the main component was changed as shown in Table 2, and in Examples 2-5 and 2-6, the composition Me of the main component was shown in Table 3. It was changed as follows. Moreover, as Comparative Example 2-1 with respect to Examples 2-1 to 2-4, it was the same as Examples 2-1 to 2-4, except that the composition b of the main component was changed as shown in Table 2 Thus, a piezoelectric ceramic was produced.

For the produced piezoelectric ceramics of Examples 2-1 to 2-6 and Comparative Example 2-1, the electrical resistance ratio IR ₁₀₀ / IR ₅₀ and the electromechanical coupling coefficient of radial vibration were also obtained in the same manner as in Example 1-2. kr was measured. The results are shown in Tables 2 and 3.

(Chemical formula 6)
(Pb _1.01-b Sr _b ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

(Chemical formula 7)
(Pb _1.01-0.03 Me _0.03 ) [(Zn _1/3 Nb _2/3 ) _0.1 Ti _0.43 Zr _0.47 ] O ₃

  As shown in Table 2, when the composition b of the main component was increased, the electromechanical coupling coefficient kr was improved, and a tendency to decrease after showing the maximum value was observed. That is, it was found that the composition b is preferably within the range of 0.1 or less. Further, as shown in Table 3, it was found that excellent characteristics can be obtained even if a part of lead is replaced with calcium or barium.

(Examples 3-1 to 3-17)
A piezoelectric ceramic was produced in the same manner as in Example 1-2 except that the composition shown in Chemical Formula 8 was used as the main component. At that time, in Examples 3-1 to 3-17, the composition x, y, z of the main component was changed as shown in Tables 4-6. Further, as Comparative Examples 3-1 to 3-9 with respect to Examples 3-1 to 3-17, except that the composition x, y, z of the main component was changed as shown in Tables 4 to 7, Piezoelectric ceramics were produced in the same manner as in Examples 3-1 to 3-17.

For the produced piezoelectric ceramics of Examples 3-1 to 3-17 and Comparative Examples 3-1 to 3-9, the electrical resistance ratio IR ₁₀₀ / IR ₅₀ and the radial vibrations were the same as in Example 1-2. The electromechanical coupling coefficient kr was measured. The results are shown in Tables 4-7.

(Chemical Formula 8)
(Pb _1.01-0.03 Sr _0.03 ) [(Zn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃

  As shown in Tables 4 to 7, when each of the main component compositions x, y, and z was increased, the electromechanical coupling coefficient kr was improved, and after showing the maximum value, it tended to decrease. That is, it is preferable that the compositions x, y, and z are in the ranges of 0.05 ≦ x ≦ 0.15, 0.25 ≦ y ≦ 0.5, and 0.35 ≦ z ≦ 0.6, respectively. I understood.

(Examples 4-1 to 4-9)
In Examples 4-1 to 4-4, the content of tantalum, which is a subcomponent, was changed, and in Examples 4-5 to 4-9, the type and content of the subcomponent were changed. A piezoelectric ceramic was produced in the same manner as in Example-2. At that time, in Examples 4-1 to 4-4, the content of tantalum relative to the main component was converted to oxide (Ta ₂ O ₅ ) and changed as shown in Table 8, and Examples 4-5 to 4 were changed. In -9, the types of subcomponents and the content relative to the main component were converted into oxides (Sb ₂ O ₅ , Nb ₂ O ₅ , WO ₃ ) and changed as shown in Table 9. In Table 9, the types of subcomponents are represented by oxides. The composition of the main component is as shown in Chemical formula 5. Moreover, as Comparative Example 4-1 with respect to Examples 4-1 to 4-4, the content of tantalum relative to the main component was converted to oxide (Ta ₂ O ₅ ) and changed as shown in Table 8. A piezoelectric ceramic was produced in the same manner as in Examples 4-1 to 4-4.

For the piezoelectric ceramics of Examples 4-1 to 4-9 and Comparative Example 4-1, the electrical resistance ratio IR ₁₀₀ / IR ₅₀ and the electromechanical coupling coefficient kr of radial vibration were set in the same manner as in Example 1-2. It was measured. For the piezoelectric ceramics of Examples 4-1 to 4-9 and Example 1-2, a 2 mm × 4 mm × 0.6 mm square plate was cut out from the sintered body before printing the electrodes, and a three-point bending measurement method was used. Then, the bending strength was measured. The measurement conditions were a distance between fulcrums of 2.0 mm and a load speed of 0.5 mm / min. The results are shown in Tables 8 and 9.

  As shown in Table 8, when the content of the subcomponent was increased, the electromechanical coupling coefficient kr and the bending strength were improved, and after showing the maximum value, a tendency to decrease was observed. Further, as shown in Table 9, it was found that the electromechanical coupling coefficient kr and the bending strength can be improved even when antimony, niobium or tungsten is added as a subcomponent.

That is, at least one member selected from the group consisting of tantalum, antimony, niobium and tungsten is converted into an oxide (Ta ₂ O ₅ , Sb ₂ O ₃ , Nb ₂ O ₅ , WO ₃ ) as a subcomponent, It was found that the piezoelectric characteristics and the mechanical strength can be improved by containing each in the range of 1.0% by mass or less.

  In the above-described examples, specific examples have been given. However, similar results can be obtained as long as the composition of the main component and subcomponents is within the range described in the above-described embodiment. 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 above-described embodiments and examples, the case where the main component shown in Chemical Formula 3 or Chemical Formula 4 and at least one member selected from the group consisting of tantalum, antimony, niobium, and tungsten is included as necessary is described. However, in addition to these, other components may be included. In that case, the other components may or may not be dissolved in the main component.

  In the above-described embodiment, the multilayer piezoelectric element has been described. However, the present invention can be similarly applied to a piezoelectric element having another structure such as a single plate type.

  It can be widely used in fields such as actuators, piezoelectric transformers and ultrasonic motors.

It is sectional drawing showing the example of 1 structure of the piezoelectric element using 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 (5)

A piezoelectric ceramic comprising a composition represented by 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 and z are 1.005 <a ≦ 1.10, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0.25 ≦ y ≦ 0.5, 0. (It is a value within a range satisfying 35 ≦ 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, and z are 1.005 <a ≦ 1.10, 0 <b ≦ 0.1, x + y + z = 1, 0.05 ≦ x ≦ 0.15, 0. 25 ≦ y ≦ 0.5 and 0.35 ≦ z ≦ 0.6, and Me is a value selected from the group consisting of strontium (Sr), calcium (Ca), and barium (Ba). Represents at least one). For the composition, at least one selected from the group consisting of tantalum (Ta), antimony (Sb), niobium (Nb), and tungsten (W) is used as an oxide (Ta ₂ O ₅ , Sb ₂ O ₃ , The piezoelectric ceramic according to claim 1, wherein the piezoelectric ceramic is contained in a range of 1.0% by mass or less in terms of Nb ₂ O ₅ and WO ₃ ).   A piezoelectric element using the piezoelectric ceramic according to claim 1.   4. The piezoelectric element according to claim 3, comprising a plurality of piezoelectric layers made of the piezoelectric ceramic and a plurality of internal electrodes inserted between the piezoelectric layers.   The piezoelectric element according to claim 4, wherein the internal electrode contains copper (Cu).

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