JP2007230793A - Piezoelectric ceramic composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic composition improved in mechanical strength without being accompanied with deterioration of thermal resistance. <P>SOLUTION: This piezoelectric ceramic composition is composed of a matrix comprising a sintered compact mainly containing lead titanate zirconate having a perovskite type structure and an aluminum-containing phase existing in the matrix, and is characterized in that the aluminum-containing phase contains Al and O where the existing rate of Al is ≥98 mol% in terms of Al<SB>2</SB>O<SB>3</SB>. In this piezoelectric ceramic composition, it is preferable that the main component contains Mn and Nb, and is expressed by the compositional formula: Pb<SB>α</SB>[(Mn<SB>1/3</SB>Nb<SB>2/3</SB>)<SB>x</SB>Ti<SB>y</SB>Zr<SB>z</SB>]O<SB>3</SB>(where 0.97≤α≤1.01; 0.04≤x≤0.12; 0.48≤y≤0.58; 0.32≤z≤0.41). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric ceramic composition suitable for a resonator, a filter, a sensor and the like.

Most of the piezoelectric ceramic compositions currently in practical use have a perovskite structure such as a tetragonal or rhombohedral PZT (PbZrO ₃ —PbTiO ₃ solid solution) system or a PT (PbTiO ₃ ) system near room temperature. It is composed of a ferroelectric material. In addition, a third component such as Pb (Mg _1/3 Nb _2/3 ) O ₃ or Pb (Mn _1/3 Nb _2/3 ) O ₃ is substituted for these compositions, or various subcomponents are added. By adding, it is possible to cope with a wide variety of required characteristics.

The piezoelectric ceramic composition has a function of freely converting and extracting electric energy and mechanical energy, and is used as a resonator, a filter, an actuator, an ignition element, an ultrasonic motor, or the like. For example, when a piezoelectric ceramic composition is used as a resonator, not only is it required that Q _max (Q _max = tan θ: θ is a phase angle) as an electrical characteristic is large, but in recent years surface-mounted components have been required. It is widely spread and is required to have high heat resistance in order to pass through a solder reflow furnace when mounted on a printed circuit board. Note that high or good heat resistance means that the variation in characteristics after receiving a thermal shock is small.

Therefore, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-103684), a main component represented by the general formula Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃ (in the general formula 1.00 ≦ α ≦ 1.05, 0.07 ≦ x ≦ 0.28, 0.42 ≦ y ≦ 0.62, 0.18 ≦ z ≦ 0.45, x + y + z = 1) as subcomponents It has been proposed to improve the heat resistance of the piezoelectric ceramic composition by adding 0.3 to 0.8% by weight of Mn ₃ O ₄ with respect to 100% by weight of the main component.

JP 2000-103694 A JP 2003-128462 A

Since products equipped with a piezoelectric ceramic composition are used in various environments, mechanical strength is one of the important characteristics. Conventionally, for example, Patent Document 2 (Japanese Patent Laid-Open No. 2003-128462) reports the addition of SiO ₂ in order to increase the mechanical strength. However, it is well known that SiO ₂ improves the mechanical strength while lowering the heat resistance, and is currently used at a compromise between the properties of each other.
The present invention has been made based on such a technical problem, and an object thereof is to provide a piezoelectric ceramic composition capable of improving mechanical strength.

In the piezoelectric ceramic composition having a perovskite structure containing a lead component, the present inventors deposit an Al-containing phase on a main component composed of lead zirconate titanate (hereinafter sometimes referred to as PZT). It was confirmed that the mechanical strength was improved. The Al-containing phase contains Al and O (oxygen), and the Al content is 98 mol% or more in terms of Al ₂ O ₃ . In addition, it has been found that this piezoelectric ceramic composition is not accompanied by an increase in the optimum sintering temperature, and further, the heat resistance is improved as compared with the case where no Al-containing phase is contained. The piezoelectric ceramic composition of the present invention is based on these findings, a matrix composed of a sintered body mainly composed of lead zirconate titanate having a perovskite structure, an Al-containing phase present in the matrix, The Al-containing phase contains Al and O, and the Al content is 98 mol% or more in terms of Al ₂ O ₃ .
In the piezoelectric ceramic composition of the present invention, the main component contains Mn and Nb, and further, Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃ (however, 0.97 ≦ α ≦ 1.01, 0.04 ≦ x ≦ 0.12, 0.48 ≦ y ≦ 0.58, 0.32 ≦ z ≦ 0.41). preferable.
In the piezoelectric ceramic composition of the present invention, the triple point of grain boundaries in the sintered body contains Al and O, and the Al content is preferably 4 mol% or more in terms of Al ₂ O ₃ .

  According to the present invention, a piezoelectric ceramic composition with improved mechanical strength can be obtained without causing a decrease in heat resistance by allowing a predetermined Al-containing phase to be present in the matrix.

Hereinafter, the piezoelectric ceramic composition according to the present invention will be described in detail based on embodiments.
<Porcelain composition>
The piezoelectric ceramic composition according to the present invention contains PZT having a perovskite structure as a main component, and this main component preferably contains Mn and Nb. A more preferred main component of the present invention is represented by the following composition formula. The chemical composition here refers to the composition after sintering.

Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃
In the composition formula, 0.97 ≦ α ≦ 1.01,
0.04 ≦ x ≦ 0.12,
0.48 ≦ y ≦ 0.58,
0.32 ≦ z ≦ 0.41
In the composition formula, α, x, y, and z each represent a molar ratio, and x + y + z = 1.

The reasons for limiting α, x, y, and z in the composition formula will be described.
Α indicating the amount of Pb is preferably in the range of 0.97 ≦ α ≦ 1.01. If α is less than 0.97, it is difficult to obtain a dense sintered body. On the other hand, when α exceeds 1.01, good heat resistance cannot be obtained. Therefore, α is preferably in the range of 0.97 ≦ α ≦ 1.01, more preferably 0.98 ≦ α <1.00, and 0.99 ≦ α <1.00. Is more preferable.

X indicating the amount of Mn and the amount of Nb is preferably in the range of 0.04 ≦ x ≦ 0.12. When x is less than 0.04, Q _max is small. On the other hand, if x exceeds 0.12, good heat resistance cannot be obtained. Therefore, x is preferably in the range of 0.04 ≦ x ≦ 0.12, more preferably 0.06 ≦ x ≦ 0.12, and 0.07 ≦ x ≦ 0.11. Is more preferable.

  Y indicating the amount of Ti is in a range of 0.48 ≦ y ≦ 0.58. If y is less than 0.48, good heat resistance cannot be obtained. On the other hand, when y exceeds 0.58, it is difficult to obtain good temperature characteristics. Therefore, y is preferably in the range of 0.48 ≦ y ≦ 0.58, more preferably 0.49 ≦ y ≦ 0.57, and 0.50 ≦ y ≦ 0.55. Is more preferable.

  Z indicating the amount of Zr is in the range of 0.32 ≦ z ≦ 0.41. When z is less than 0.32 or exceeds 0.41, good temperature characteristics cannot be obtained. Therefore, z is preferably in the range of 0.32 ≦ z ≦ 0.41, more preferably 0.33 ≦ z ≦ 0.40, and 0.34 ≦ z ≦ 0.39. Is more preferable. In addition, that a temperature characteristic is favorable means that the change of the characteristic of the piezoelectric ceramic composition accompanying the temperature change in a use environment is small.

The piezoelectric ceramic composition according to the present invention having the above main components is typically composed of a sintered body. In the present invention, an Al-containing phase is present in a matrix composed of a sintered body containing the above as a main component, and the Al-containing phase can be generated by adding a predetermined amount of Al ₂ O ₃ as a raw material. It can be done. This Al-containing phase contains Al and O. The existing ratio of Al in the Al-containing phase is more than 98 mol% in terms _{of Al} 2 _{O 3.} The Al content in the Al-containing phase is preferably 99 mol% or more in terms of Al ₂ O ₃ . This Al-containing phase is understood to be that the added Al ₂ O ₃ is randomly deposited in the sintered body.

As shown in the examples described later, when the added amount of Al ₂ O ₃ is less than a predetermined amount, no Al-containing phase is generated. Further, it is possible to the addition amount of Al ₂ O ₃ even when fewer than a predetermined amount to confirm the effect of improving heat resistance. In addition, when the amount of Al ₂ O ₃ added is greater than the predetermined amount, both mechanical strength and heat resistance are improved. Presuming from the above results, Al ₂ O ₃ has the effect of improving the heat resistance of the main component, that is, PZT itself, by dissolving in the crystal grain (lattice) consisting of the main component, and in the crystal grain. Excess Al ₂ O ₃ that cannot be completely dissolved precipitates randomly at the grain boundary in the sintered body, strengthens the bond between the crystal grains, and contributes to the improvement of the mechanical strength.

A part of Al resulting from the added Al ₂ O ₃ also dissolves in the crystal grain boundary. Therefore, the piezoelectric ceramic composition according to the present invention has a large proportion of Al present at the grain boundary triple point. This abundance ratio is preferably 4 mol% or more in terms of Al ₂ O ₃ . Further, the Al content at the triple boundary of the grain boundary is preferably 5 mol% or more, and the Al content at the triple boundary of the grain boundary is more preferably 5.5 mol% or more. In the case of a preferable addition amount of Al ₂ O ₃ described below, the Al content at the grain boundary triple point is 12 mol% or less.

To produce an Al-containing phase with the effects mechanical strength improvement, the main component, especially _{Pb α [(Mn 1/3 Nb 2/3} ) x Ti y Zr z] Al 2 O 3 with respect to _{O 3} Is preferably added in an amount of 0.15 wt% or more, more preferably 0.6 wt% or more. Even if the additive amount of Al ₂ O ₃ is increased, the upper limit of the piezoelectric ceramic composition is not particularly limited because it does not impair the characteristics of the piezoelectric ceramic composition, but it is understood that the obtained effect is saturated. Is preferably 15 wt% or less, more preferably 10 wt% or less, and even more preferably 8 wt% or less.

The piezoelectric ceramic composition according to the present invention may contain SiO ₂ as another subcomponent. The inclusion of SiO ₂ is effective in improving the strength of the piezoelectric ceramic composition. In the case of containing SiO ₂ , the preferable amount of SiO ₂ is preferably 0.15 wt% or less with respect to the main component, particularly Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃ . The SiO ₂ amount is 0.07 wt% or less, and the more preferable SiO ₂ amount is 0.04 wt% or less.

The piezoelectric ceramic composition according to the present invention contains 0.01 to 1.0 wt% of at least one element selected from Ga, In, Ta and Sc as another subcomponent in terms of oxide of each element. May be. These elements can improve electrical characteristics, heat resistance, and temperature characteristics. These subcomponents are 0.01 to 15 wt%, preferably 0, in terms of oxide of the element with respect to the main component, particularly Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃ . .05 to 10 wt%, more preferably 0.2 to 8 wt%.

<Manufacturing method>
Next, a preferred method for producing the piezoelectric ceramic composition according to the present invention will be described in the order of the steps.
(Raw material powder, weighing)
As a raw material of the main component, an oxide or a powder of a compound that becomes an oxide by heating is used. Specifically, PbO powder, TiO ₂ powder, ZrO ₂ powder, MnCO ₃ powder, Nb ₂ O ₅ powder, or the like can be used. Each raw material powder is weighed so as to correspond to the composition to be finally obtained. In addition, not only the raw material powder mentioned above but it is good also considering the powder of the complex oxide containing 2 or more types of metals as raw material powder.
Next, a predetermined amount of Al ₂ O ₃ powder is added as a subcomponent to the total weight of each weighed powder. Furthermore, can be added SiO ₂ powder as the raw material powder of the auxiliary component. Furthermore, one or more of Ga ₂ O ₃ powder, Ta ₂ O ₅ powder, Sc ₂ O ₃ powder, and In ₂ O ₃ powder can be added. What is necessary is just to select suitably the average particle diameter of each raw material powder in the range of 0.1-3.0 micrometers.

(Calcination)
After the raw material powder is wet-mixed, calcination is performed in a range of 700 to 950 ° C. for a predetermined time. The atmosphere at this time may be N ₂ or air. What is necessary is just to select suitably the holding time of calcination in the range of 0.5 to 5 hours.
In addition, after mixing the raw material powder of the main component and the raw material powder of the subcomponent, both were shown to be subjected to calcining, but the timing of adding the raw material powder of the subcomponent is not limited to that described above. Absent. For example, first, only the main component powder is weighed, mixed, calcined and pulverized. And you may make it add and mix a predetermined amount of raw material powder of a subcomponent with the powder of the main component obtained after calcining pulverization.

(Granulation / molding)
The pulverized powder is granulated into granules in order to smoothly execute the subsequent molding process. At this time, a small amount of an appropriate binder such as polyvinyl alcohol (PVA) is added to the pulverized powder, and these are mixed well, and then granulated by passing through a mesh for example to obtain a granulated powder. Next, the granulated powder is pressure-molded at a pressure of 200 to 300 MPa to obtain a molded body having a desired shape.

(Baking)
After removing the binder added during molding, the molded body is heated and held for a predetermined time within a range of 1100 to 1250 ° C. to obtain a sintered body. The atmosphere at this time may be N ₂ or air. The heating and holding time may be appropriately selected within the range of 0.5 to 4 hours.

(Polarization treatment)
After the electrode for polarization treatment is formed on the sintered body, the polarization treatment is performed. In the polarization treatment, an electric field of 1.0 to 2.0 Ec (Ec is a coercive electric field) is applied to the sintered body at a temperature of 50 to 300 ° C. for 0.5 to 30 minutes.
When the polarization treatment temperature is less than 50 ° C., Ec increases, so that the polarization voltage increases and polarization becomes difficult. On the other hand, when the polarization treatment temperature exceeds 300 ° C., the insulation of the insulating oil is remarkably lowered, so that polarization becomes difficult. Therefore, the polarization treatment temperature is 50 to 300 ° C. A preferable polarization treatment temperature is 60 to 250 ° C, and a more preferable polarization treatment temperature is 80 to 200 ° C.
Moreover, if the electric field to be applied is less than 1.0 Ec, polarization does not proceed. On the other hand, when the applied electric field exceeds 2.0 Ec, the actual voltage becomes high and the sintered body tends to break, making it difficult to produce a piezoelectric ceramic composition. Therefore, the electric field applied during the polarization process is 1.0 to 2.0 Ec. A preferable applied electric field is 1.1 to 1.8 Ec, and a more preferable applied electric field is 1.2 to 1.6 Ec.

When the polarization treatment time is less than 0.5 minutes, the polarization is insufficient and sufficient characteristics cannot be obtained. On the other hand, when the polarization treatment time exceeds 30 minutes, the time required for the polarization treatment becomes long and the production efficiency is inferior. Therefore, the polarization treatment time is 0.5 to 30 minutes. A preferable polarization treatment time is 0.7 to 20 minutes, and a more preferable polarization treatment time is 0.9 to 15 minutes.
The polarization treatment is performed in an insulating oil heated to the above-described temperature, for example, a silicon oil bath. The polarization direction is determined according to a desired vibration mode. Here, when the vibration mode is to be a thickness shear vibration, the polarization direction is the direction indicated by the arrow in FIG. The thickness shear vibration is vibration in a direction indicated by an arrow in FIG.

After the piezoelectric ceramic composition is polished to a desired thickness, a vibrating electrode is formed. Next, after being cut into a desired shape by a dicing saw or the like, it functions as a piezoelectric element.
The piezoelectric ceramic composition of the present invention is suitably used as a material for piezoelectric elements such as resonators, filters, resonators, actuators, ignition elements or ultrasonic motors.

The piezoelectric ceramic composition of the present invention, three-point bending strength sigma _b3 is 160 N / mm ² or more, preferably 170N / mm ² or more, more preferably it is possible to obtain a 180 N / mm ² or more mechanical strength.
In addition, the piezoelectric ceramic composition of the present invention can have electrical characteristics having a _Qmax of 30 or more, preferably 80 or more, and more preferably 100 or more. Q _max represents the maximum value of Q (= tan θ, θ: phase angle (deg)) between the resonance frequency fr and the anti-resonance frequency fa, and is one of important characteristics as a resonator and contributes to low voltage driving. .
Furthermore, the piezoelectric ceramic composition of the present invention can have a heat resistance | ΔF ₀ | with respect to an oscillation frequency described later of 0.10% or less.

Here, the three-point bending strength σ _b3 in the present invention is obtained by the following formula (1) according to JIS R 1601. In equation (1), P: load (N), L: distance between support rolls (m), w: width of test piece (m), t: thickness of test piece (m), yb: load point The net displacement amount (m).

In the present invention, the oscillation frequency F ₀ used for the evaluation of heat resistance has a relationship represented by the following formulas (2) to (5) when equivalent circuit constants are used. In equations (2) to (5), F ₀ : oscillation frequency, Fr: resonance frequency, Fa: anti-resonance frequency, C ₁ : series capacitance, C ₀ : parallel capacitance, C _L : defined by equation (6), Cd : Free capacity, C _L1 , C _L2 : Load capacity. An equivalent circuit of the piezoelectric resonator is shown in FIG. In FIG. 2, R ₀ is resonance impedance, L ₁ is equivalent inductance, C ₁ is series capacitance, and C ₀ is parallel capacitance. As shown in the equation (2), four parameters of the resonance frequency Fr, the series capacitance C ₁ , the parallel capacitance C ₀ , and C _L influence the value of the oscillation frequency F ₀ . As shown in the equations (3) to (5), a plurality of parameters are related to the series capacitance C ₁ , the parallel capacitances C ₀ , and _CL , respectively.

In the present invention, the sample was wrapped with aluminum foil, taken out by impregnation in a solder bath at 265 ° C. for 10 seconds, and left at room temperature for 24 hours after the aluminum foil was removed. The rate of change of F ₀ before and after the test (after 24 hours) was determined based on the formula (6), and the absolute value (| ΔF ₀ |) was used as a criterion for heat resistance evaluation.

As starting materials, lead oxide (PbO) powder, titanium oxide (TiO ₂ ) powder, zirconium oxide (ZrO ₂ ) powder, manganese carbonate (MnCO ₃ ) powder, niobium oxide (Nb ₂ O ₅ ) powder, aluminum oxide (Al ₂₎ O ₃ ) powder and silicon oxide (SiO ₂ ) powder were prepared. This raw material powder was weighed so that the molar ratio was Pb _0.99 [(Mn _1/3 Nb _2/3 ) _0.10 Ti _0.53 Zr _0.37 ] O _3, and then the total weight of each powder To this, 0.02 wt% of SiO ₂ as an auxiliary component and Al ₂ O ₃ powder were added in amounts shown in Table 1, and wet mixing was performed for 10 hours using a ball mill.
The obtained slurry was sufficiently dried and press-molded, and then calcined in the air at 800 ° C. for 2 hours. After finely pulverizing with a ball mill until the calcined body had an average particle size of 0.7 μm or less, the finely pulverized powder was dried. An appropriate amount of PVA (polyvinyl alcohol) as a binder was added to the dried finely pulverized powder and granulated. About 3 g of the granulated powder was put into a mold having a cavity having a length of 20 mm and a width of 20 mm, and molded using a uniaxial press molding machine at a pressure of 245 MPa. After the binder removal treatment was performed on the obtained molded body, main firing was performed in the atmosphere at 1150 to 1250 ° C. for 2 hours to obtain a sample of a piezoelectric ceramic composition made of a sintered body.

  After both surfaces of the sample were flattened to a thickness of 0.5 mm with a lapping machine, they were cut into a length of 15 mm and a width of 5.0 mm with a dicing saw, and a temporary electrode for polarization was formed at both ends (5.0 mm direction). . Thereafter, a polarization treatment was performed by applying an electric field of 3 kV / mm for 15 minutes in a silicon oil bath at a temperature of 150 ° C. The polarization direction was the direction shown in FIG. Thereafter, the temporary electrode was removed. The sample size after removal of the temporary electrode is 15 mm long × 4.0 mm wide × 0.5 mm thick. The film was again polished to a thickness of about 0.3 mm with a lapping machine, and the vibrating electrode 2 was formed on both surfaces (polished both surfaces) of the test piece 1 as shown in FIG. The vibrating electrode 2 is composed of a Cr underlayer having a thickness of 0.01 μm and Ag having a thickness of 2 μm. The overlapping length of the vibrating electrode 2 was 1.5 mm.

Subsequently, a piezoelectric element having a length of 4 mm, a width of 0.7 mm, and a thickness of 0.3 mm was cut out from the test piece 1 described above. Thus, a sample for measuring Q _max was obtained (FIG. 3). The measurement of the Q _max using an impedance analyzer (manufactured by Agilent Technologies, Inc. 4294A), was measured in the vicinity of 4MHz. The results are shown in Table 1.

Further, both surfaces of the above sample were processed into a plane of 0.32 mm with a lapping machine and then cut into a length of 7.2 mm and a width of 2.5 mm with a dicing saw and bent at three points by an INSTRON strength tester (model 5543). The strength σ _b3 was determined by the above-described formula (1). The results are shown in Table 1.

The sample for which Q _max was measured was wrapped in aluminum foil, taken out by impregnation in a solder bath at 265 ° C. for 10 seconds, removed, and allowed to stand at room temperature for 24 hours. The absolute value | ΔF ₀ | of the change rate of the oscillation frequency F ₀ before and after the test (after 24 hours of standing) was determined. The results are shown in Table 1.

  The observation surfaces of some of the above samples were mirror-finished with diamond paste, and the element distribution was observed by EDS (energy dispersion method) of SEM (scanning electron microscope). The result is shown in FIG. FIG. 4 shows that the whiter the color, the higher the concentration of Al. Based on this measurement result, the presence or absence of an Al-containing phase was determined. The results are shown in Table 1. In Table 1, “x” indicates that no Al-containing phase is present, and “◯” indicates that an Al-containing phase is present. The Al-containing phase has a size of about 0.5 to 10 μm.

Moreover, the composition analysis of the Al-containing phase and the grain boundary triple point was performed by EDS (energy dispersion method) of STEM (scanning transmission electron microscope). As a result, it shows the amount of _Al 2 _{O 3} of Al in the amount of _Al 2 _{O 3} and a grain boundary triple point Al in Al-containing phase in Table 1. As an example, Sample No. 4 shows the result of STEM image and EDS composition analysis in the vicinity of the Al-containing phase in FIG. FIG. 6 shows the results of STEM image and EDS composition analysis in the vicinity of the grain boundary triple point.

As shown in Table 1, it can be seen that the addition of Al ₂ O ₃ as a subcomponent improves the heat resistance and also improves Q _max and mechanical strength. On the other hand, when the added amount of Al ₂ O ₃ is 0.1 wt%, an Al-containing phase is not generated. Therefore, Al ₂ O ₃ contributes to the improvement of heat resistance by being dissolved in the crystal grains (lattice) composed of the main component, and excessive Al ₂ O ₃ that cannot be completely dissolved in the crystal grains is included in the crystal grains. It is understood that it precipitates as an Al-containing phase in the boundary and strengthens the bond between the crystal grains, thereby contributing to improvement in mechanical strength. Most of the Al-containing phase is composed of Al ₂ O _3, and when the Al-containing phase is generated, the abundance of Al at the grain boundary triple point tends to increase.

When the amount of Al ₂ O ₃ added increases, Q _max tends to decrease, but mechanical strength tends to improve. Therefore, the additive amount of Al ₂ O ₃ may be set in consideration of the characteristics to be obtained.

It is a figure for demonstrating the polarization direction. It is an equivalent circuit diagram of a piezoelectric resonator. It is sectional drawing of the test piece in the state in which the vibration electrode was formed in upper and lower surfaces. It is a figure which shows the result of having observed the element distribution of the sample obtained in Example 1 by SEM-EDS. Sample No. obtained in Example 1 It is a figure which shows the result of the STEM image and EDS composition analysis of 4 Al containing phase vicinity. Sample No. obtained in Example 1 FIG. 4 is a diagram showing a result of STEM image and EDS composition analysis in the vicinity of grain boundary triple point 4.

Explanation of symbols

  1 ... Test piece, 2 ... Vibrating electrode

Claims (4)

A matrix composed of a sintered body mainly composed of lead zirconate titanate having a perovskite structure;
An Al-containing phase present in the matrix,
The piezoelectric ceramic composition characterized in that the Al-containing phase contains Al and O, and the Al content is 98 mol% or more in terms of Al ₂ O ₃ .   2. The piezoelectric ceramic composition according to claim 1, wherein the main component contains Mn and Nb. The main component is Pb _α [(Mn _1/3 Nb _2/3 ) _x Ti _y Zr _z ] O ₃ (where 0.97 ≦ α ≦ 1.01, 0.04 ≦ x ≦ 0.12, 0. The piezoelectric ceramic composition according to claim 1 or 2, represented by a composition formula of 48≤y≤0.58, 0.32≤z≤0.41). Includes a grain boundary triple point is Al and O in the sintered body, the piezoelectric according to claim 1, wherein the existence ratio of Al is not less than 4 mol% in terms of Al ₂ O ₃ Body porcelain composition.

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