JP2003192434A - Piezoelectric ceramic composition and piezoelectric element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic composition containing no lead and having a high electromechanical coupling coefficient compared to a conventional bismuth layered compound and to provide a piezoelectric element using the composition. <P>SOLUTION: The piezoelectric ceramic composition comprises a ceramic composition having the composition expressed by general formula of Sr<SB>1-x-y</SB>M 1<SB>x</SB>M2<SB>y</SB>Bi<SB>2</SB>(Nb<SB>1-a</SB>Ta<SB>a</SB>)<SB>2-z</SB>Ti<SB>z</SB>O<SB>9</SB>, wherein M1 is at least one element selected from Ca and Ba and M2 is at least one element selected from a group consisting of La, Y, Dy, Er, Yb, Pr, Nd, Sm, Eu and Gd, with x, y, z and a in the formula in the ranges of 0.0≤x<0.9, 0.0<y<0.3, 0.0≤z<0.3 and 0.0≤a≤1.0, respectively. The piezoelectric element 10 has a piezoelectric body 11 and electrodes 12a, 12b formed on the two principal faces of the piezoelectric body 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to Sr, Bi, Ti and Nb or T without containing lead (Pb).
The present invention relates to a piezoelectric ceramic composition containing a and a piezoelectric element using the same.

[0002]

2. Description of the Related Art A piezoelectric zirconate titanate (P) has been used as a piezoelectric ceramic composition conventionally used for piezoelectric ceramic elements such as piezoelectric ceramic oscillators and piezoelectric ceramic filters.
_{ZT: Pb (Ti x Zr 1} -x) O 3) or lead titanate (PT: PbTiO ₃₎ ceramic compositions based on have been used (for example, Patent Document 1, Patent Document 2). .

[0003]

[Patent Document 1] Japanese Unexamined Patent Publication No. 5-148016

[0004]

[Patent Document 2] Japanese Patent Application Laid-Open No. 5-139824

However, in a piezoelectric ceramic composition containing PZT or PT as a main component, a large amount of lead is contained in the composition, so that the uniformity of the product is deteriorated due to evaporation of lead oxide in the manufacturing process. was there. In addition, PZT and P
The piezoelectric ceramic composition composed of T often has a Curie point of about 200 to 300 ° C. in a practical composition, and becomes a paraelectric substance at a temperature higher than that, and the piezoelectric characteristics disappear, so that it is used at a high temperature. Difficult to apply for use. further,
In recent years, it has been required to develop a porcelain composition containing no lead in order to avoid the problem of environmental pollution.

Under these circumstances, a piezoelectric ceramic composition containing a bismuth layered compound such as SrBi ₂ Nb ₂ O ₉ as a main component is noted as a ceramic for a sensor / actuator which does not contain lead and can be used even at high temperatures. (See, for example, Patent Document 3).

[0007]

[Patent Document 3] Japanese Patent Laid-Open No. 11-322426

[0008]

However, as a material generally used for a piezoelectric ceramic element, particularly a piezoelectric ceramic oscillator, it is desirable that the electromechanical coupling coefficient, which is the efficiency of converting electric energy into mechanical energy, is large. However, the piezoelectric ceramic composition containing a bismuth layered compound as a main component, which has been reported so far, has a problem that the electromechanical coupling coefficient is not sufficiently large. Further, when a piezoelectric ceramic filter, a piezoelectric ceramic oscillator, or the like is manufactured using a piezoelectric ceramic composition containing a bismuth layer compound as a main component, the temperature change rate of the resonance frequency is higher than that in the case of using conventional PZT or PT. There is a problem that becomes large.

Due to the above problems, SrBi ₂ Nb ₂ O
_{At present} , a piezoelectric ceramic composition containing a bismuth layered compound such as ₉ as a main component has not yet been put into practical use.

[0010]

The piezoelectric ceramic composition of the present invention
Has a general formula: Sr_1-xyM1_xM2_yBi₂(Nb
_1-aTa_a)_2-zTi_zO₉(In the formula, M1 is Ca and Ba.
M2 is at least one element selected from
a, Y, Dy, Er, Yb, Pr, Nd, Sm, Eu
And at least one element selected from the group consisting of Gd
And in the general formula, x, y, z and
And a respectively 0.0 ≦ x <0.9, 0.0 <y <0.3, 0.0 ≦ z <0.3, 0.0 ≦ a ≦ 1.0, It is characterized by including a porcelain composition in the range of.

The composition of the piezoelectric element of the present invention is generally
Formula: Sr_1-xyM1_xM2_yBi₂(Nb _1-aTa_a)_2-zT
i_zO₉(In the formula, M1 is a small amount selected from Ca and Ba.
At least one element, M2 is La, Y, Dy, E
Consisting of r, Yb, Pr, Nd, Sm, Eu and Gd
Is at least one element selected from the group)
And x, y, z and a in the general formula are respectively
And 0.0 ≦ x <0.9, 0.0 <y <0.3, 0.0 ≦ z <0.3, 0.0 ≦ a ≦ 1.0, Consisting of a piezoelectric ceramic composition containing a porcelain composition in the range of
It is characterized by having a piezoelectric body.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

The composition of the piezoelectric ceramic composition of this embodiment is represented by the general formula: Sr _1-xy M _{1 x} M 2 _y Bi ₂ (Nb _1-a Ta _a ) _2-z.
It is represented by Ti _z O ₉ . In addition, x, y, and
z and a are 0.0 ≦ x <0.9 and 0.0 <, respectively.
y <0.3, 0.0 ≦ z <0.3, 0.0 ≦ a ≦ 1.0
Is in the range. Here, in the general formula, M1 is Ca
And at least one element selected from Ba,
M2 is La, Y, Dy, Er, Yb, Pr, Nd, S
It is at least one element selected from the group consisting of m, Eu and Gd. Further, the piezoelectric ceramic composition of the present embodiment may be composed only of the compound represented by the general formula, also contains the compound represented by the general formula as a main component, other than that It may contain subcomponents. When the piezoelectric ceramic composition is composed of the main component and the subcomponent, the composition ratio is as follows: main component: subcomponent = 96.0-9
The range of 9.9: 0.1-4.0 (mass%) is preferable,
More preferably 99.2 to 99.8: 0.2 to 0.8.
The range is (mass%).

As a result, a piezoelectric ceramic composition which has a larger electromechanical coupling coefficient than the conventional bismuth layered compound and does not contain lead can be obtained. By adding Ti to the conventional bismuth niobate-based compound so as to have the composition represented by the general formula of the present embodiment, the relative dielectric constant is improved, and the piezoelectric constant is also improved accordingly.

In the piezoelectric ceramic composition of the present embodiment, x, y, z and a in the general formula are 0.2 ≦ x, respectively.
≦ 0.8, 0.0 <y <0.15, 0.0 <z <0.1
5, preferably in the range of 0.0 ≦ a ≦ 0.6.
Within this range, the electromechanical coupling coefficient is larger than that of the conventional bismuth layered compound, a lead-free piezoelectric ceramic composition can be obtained, and the piezoelectric characteristics can be further improved.

The piezoelectric ceramic composition of this embodiment preferably contains MnO ₂ as an accessory component in a range of 0.8% by mass or less, more preferably 0.2% by mass to 0.1% by mass.
It is included in the range of 5% by mass. This is because the polarization process becomes easy.

Further, the piezoelectric element of the present embodiment comprises a piezoelectric body made of any one of the piezoelectric ceramic compositions described above. This makes it possible to obtain a piezoelectric element that does not contain lead and has good electrical characteristics.

Further, the piezoelectric element of this embodiment must satisfy the relationship of 22 ≦ S / t ² where S is the area of the electrode formed on the surface of the piezoelectric body and t is the thickness of the piezoelectric body. Is preferred. Furthermore, in the piezoelectric element of this embodiment, when the piezoelectric body is effectively approximated to a circle, the diameter of the effective electrode is D, and the thickness of the piezoelectric body is t, 5.3 ≦ D
It is preferable to satisfy the relationship of / t. 2 in each case
Since the size of the electrodes on the two main surfaces is larger than the thickness t, the influence of the displacement of the centers of the electrodes is small, and the piezoelectric element can be easily manufactured.

Next, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) In this embodiment, a piezoelectric ceramic composition will be described. The piezoelectric ceramic composition of the present embodiment (hereinafter, also referred to as piezoelectric ceramic composition 1) has a composition of the general formula: Sr _{1-x- y} M1 _x M2 _y Bi ₂ (Nb _1-a Ta _a ).
Including porcelain component represented by _2-z Ti _z O ₉ as a main component. Here, M1 is either Ca or Ba, and M1
2 is La, Y, Dy, Er, Yb, Pr, Nd, Sm,
It is either Eu or Gd. Further, a, x, y and z in the general formula are each 0.0 ≦ a ≦
It is in the range of 1.0, 0.0 ≦ x <0.9, 0.0 <y <0.3 and 0.0 ≦ z <0.3. In order to further increase the electromechanical coupling coefficient as compared with the conventional bismuth layered compound, a more preferably satisfies 0 ≦ a ≦ 0.6 and x satisfies 0.2 ≦ x ≦ 0.8. Is more preferable, and y and z are 0.0 <y <0.
It is more preferable to satisfy 15, 0.0 <z <0.15.

The piezoelectric ceramic composition 1 is prepared by mixing raw materials which can be main components at a predetermined ratio, and then at 1050 to 1200 ° C.
Then, it can be formed by firing for 1 to 2 hours. The firing atmosphere is the atmosphere.

As the raw material, various compounds containing the elements contained in the piezoelectric ceramic composition 1, for example, metal oxides,
Although a metal carbonate or the like can be used, a metal oxide is preferably used because the weight change before and after the calcination is small. Examples of the metal oxide include La
₂ O ₃ , Y ₂ O ₃ , Dy ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , Pr _{2
O 3, Nd 2 O 3,} Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Mn 3
O ₄ , Bi ₂ O ₃ , TiO ₂ , Nb ₂ O _5, Ta ₂ O _{5 and the} like can be mentioned. As the metal carbonate, for example, CaCO ₃ , SrCO ₃ , BaCO ₃ or the like can be used.

The piezoelectric ceramic composition 1 may be formed of only the main component, or may further contain MnO ₂ or the like as a subcomponent. When the piezoelectric ceramic composition contains subcomponents, a piezoelectric ceramic composition having excellent characteristics such as the mechanical quality factor Q _M can be obtained. As an accessory component, MnO
₂ , Cr ₂ O ₃ , CoO, Fe ₂ O ₃ , NiO and the like can be used, but MnO ₂ is particularly preferable because the mechanical quality factor Q _M can be increased. When the piezoelectric ceramic composition 1 is composed of only the main component, the piezoelectric ceramic composition 1
The composition of is, for example, when M1 is Ca and M2 is La,
It can be expressed by the following formula.

[0024]

## STR1 ## Sr _1-xy Ca _x La _y Bi ₂ (Nb _1-a Ta _a )
_2-z Ti z O ₉

When the piezoelectric ceramic composition is composed of a main component and subcomponents, the composition ratio is as follows: main component: subcomponent =
The range of 96.0 to 99.9: 0.1 to 4.0 (mass ratio) is preferable, and 99.2 to 99.8: is more preferable.
The range is 0.2 to 0.8 (mass ratio). Secondary component is Mn
In the case of O ₂ , the piezoelectric ceramic composition 1 preferably contains MnO ₂ in a range of 0.8% by mass or less, in the range of 0.2% by mass to 0.5% by mass, in order to easily perform polarization treatment. More preferably, it is included in

When the piezoelectric ceramic composition 1 contains the main component and the subcomponent, the piezoelectric ceramic composition 1 can be manufactured by mixing and firing the starting materials which can constitute both. As the firing conditions, the same conditions as in the case of producing the piezoelectric ceramic composition composed of only the above-mentioned main components can be applied.

The piezoelectric ceramic composition 1 has three times higher harmonics.
Constant N for thickness longitudinal vibration of _3tAs large as possible
It is preferable that For example, N_3tIs more than 7300Hz ・ m
Is preferred. Propagation velocity of vibration in solid (sound
So that the element thickness can be made relatively large.
Because. For example, the thickness of 36MHz element
It can be 200 μm or more. In this case, generally
Frequency constant N of the direction spread mode_pAlso 2500 Hz
Larger than m.

As described above, according to the piezoelectric ceramic composition 1 of Embodiment 1, a piezoelectric material having a relatively large electromechanical coupling coefficient is provided as compared with a lead-free bismuth layered compound based on a conventional general ceramics manufacturing method. A porcelain composition is obtained.

(Embodiment 2) In this embodiment, the first piezoelectric element will be described. The piezoelectric element of the present embodiment (hereinafter sometimes referred to as the piezoelectric element 1) is provided with a piezoelectric body made of the piezoelectric ceramic composition 1 described in the first embodiment.

The piezoelectric element 1 is specifically a piezoelectric resonator such as a piezoelectric ceramic oscillator or a piezoelectric ceramic filter, a piezoelectric vibrating body such as a buzzer or a sounder, or a displacement element such as an actuator.

FIG. 1 is a perspective view of a thickness longitudinal triple mode piezoelectric resonator as an example of the piezoelectric element of the present embodiment. Referring to FIG. 1, the piezoelectric resonator 10 includes a piezoelectric body 11 and a piezoelectric body 1.
Electrodes 12a and 12b formed on the two main surfaces of No. 1
It has and. As a material for the electrodes 12a and 12b,
Ag, Cu, Ni, Pt, Au, Ag-Pd alloy, etc. can be used. Lead wires 12c and 12d are connected to the electrodes 12a and 12b, respectively. The same material as the electrodes 12a and 12b can be used as the material of the lead wires 12c and 12d.

The electrodes 12a and 12b have a circular shape. However, the shape is not limited to a circle, and other shapes such as a square and a rectangle may be used. The electrodes 12a and 12b are formed in the same shape so as to face each other with the piezoelectric body 11 interposed therebetween.

Area S of electrodes 12a and 12b and piezoelectric body 11
It is preferable that the thickness t satisfies the relation of 22 ≦ S / t ² . That is, it is preferable that the diameter D of the electrodes 12a and 12b and the thickness t of the piezoelectric body 11 satisfy the relationship of 5.3 ≦ D / t. This is because by satisfying these relationships, the dimensional ratio can easily suppress the generation of unnecessary vibration (spurious vibration) due to the displacement of the center of the electrode.

As described above, since the piezoelectric element 1 of this embodiment uses the piezoelectric ceramic composition 1 of embodiment 1, it does not contain lead and has good electrical characteristics.

(Embodiment 3) In this embodiment, the second piezoelectric element will be described. The piezoelectric element of the present embodiment (hereinafter sometimes referred to as piezoelectric element 2) includes a piezoelectric body made of the piezoelectric ceramic composition 1 described in the first embodiment.

Specifically, the piezoelectric element 2 is, for example, a piezoelectric resonator such as a piezoelectric ceramic oscillator or a piezoelectric ceramic filter, a piezoelectric vibrating body such as a buzzer or a sounder, or a displacement element such as an actuator.

FIG. 2 shows a perspective view of a thickness shear mode piezoelectric resonator as an example of the piezoelectric element of the present embodiment. Referring to FIG. 2, the piezoelectric resonator 20 includes a piezoelectric body 21 and a piezoelectric body 2.
22a and 22b formed on the two main surfaces of
It has and. As the material of the electrodes 22a and 22b,
The same electrodes as the electrodes 12a and 12b of the second embodiment can be used. The electrodes 22a and 22b have a strip shape and are formed in the same shape so as to face each other with the piezoelectric body 21 interposed therebetween.

As described above, since the piezoelectric element 2 of this embodiment uses the piezoelectric ceramic composition 1 of embodiment 1, it does not contain lead and has good electrical characteristics.

[0039]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Example 1) In this example, an example of producing the piezoelectric ceramic composition 1 of Embodiment 1 will be described.

In this embodiment, CaCO₃, SrCO₃, B
aCO₃, La₂O₃, Y₂O₃, Dy₂O₃, Er₂O₃, Y
b₂O₃, Pr₂O₃, Nd₂O₃, Sm₂O₃, Eu₂O₃, G
d₂O ₃, Mn₃O_Four, Bi₂O₃, TiO₂, Nb₂O_FiveAnd
And Ta₂O_FiveAs a starting material, a plurality of piezoelectric ceramic compositions
Formed. Note that Mn₃O_FourIs M due to heat treatment during firing
nO₂Becomes

Specifically, the composition of the piezoelectric ceramic composition is shown in Table 1.
The starting raw materials were weighed so that the predetermined ratios shown in Table 2 and Table 2 were obtained, and these were sufficiently mixed by a ball mill so as to be uniform. This was calcined at 880 ° C. for 2 hours, then the formed compound was pulverized again by a ball mill, and polyvinyl alcohol was added to granulate. This powder was uniaxially press molded into a disk having a diameter of 13 mm at a pressure of 70 MPa, and 1100-1
It was baked at 200 ° C. for 2 hours. This disc sample is 0.3 mm
After polishing to a thickness of 0.8 mm, Ag electrodes having a thickness of 0.8 μm were applied to the upper surface and the lower surface of the disk, respectively. Then 160
Electric field of 10 kV / mm in silicon oil at ℃ 30
A polarization process was performed by applying for a minute to obtain a disk made of piezoelectric ceramics.

The composition of the main components of Samples 1 to 21 is expressed by the formula: Sr _1-xy Ca _x La _y Bi ₂ Nb _2-z Ti _z O
Is represented by _9, the composition of the main component of the sample 22 to sample 26 has the _{formula: Sr 1-xy Ca x La} y Bi 2 (Nb 1-a Ta a)
Represented by _2-z Ti z O _9, the composition of the main component of the sample 27 to sample 41 has the _{formula: Sr 1-xy M1 x M2} y Bi 2 (Nb 1-
_a Ta _a ) _2-z Ti _z O ₉ (where M1 is Ca or B
a and M2 are La, Y, Dy, Er, Yb, Pr, Nd,
It is one of Sm, Eu and Gd). In Table 1, sample No. "*" In front of indicates that it is a comparative example.

[0044]

[Table 1]

[0045]

[Table 2]

For a disk made of this piezoelectric ceramics, the capacitance C at 1 kHz, the thickness t of the disk, the diameter D of the disk, the resonance frequency F _{r of} the vibration in the thickness direction of the disk, and the vibration in the thickness direction of the disk Anti-resonance frequency F _a , the resonance frequency _{fr of} the disk radial vibration, the resistance R at the resonance point of the disk radial vibration,
The anti-resonance frequency f _a and the Poisson's ratio σ ^E of the radial vibration of the disk were measured. From these values, the IEEE standard (ANSI / IEEE Std.
6-1987), the relative permittivity ε _r , the electromechanical coupling coefficient k _{p of the} radial spreading mode, the electromechanical coupling coefficient k _{t of the} thickness extensional vibration mode, the mechanical quality factor Q _M, and The frequency constant N _p of the radial spreading mode was calculated. The calculation results are shown in Tables 3 and 4.

[0047]

[Table 3]

[0048]

[Table 4]

When the piezoelectric ceramic is used as the piezoelectric body of the piezoelectric element utilizing the thickness longitudinal vibration mode of triple harmonics, the electromechanical coupling coefficient k _t of the thickness longitudinal vibration mode is particularly important. As is clear from Table 3 and Table 4, Sample 1 known as a known porcelain composition which is a comparative example.
Compared to the electromechanical coupling coefficient k _t, the electromechanical coupling coefficient k _t porcelain composition according to the present example had. Table 1,
The electromechanical coupling coefficient k _t could be increased by substituting part of the element Sr with Ca or La and part of the element Nb with Ta or Ti in the proportions shown in Table 2. Further, the mechanical quality factor Q _M could be increased by adding MnO ₂ as a sub-component to the above main component.

In particular, 0.0≤a≤0.6, 0.2≤x≤
0.8, 0.0 <y <0.15 and 0.0 <z <0.
By using 15 piezoelectric ceramic compositions, the electromechanical coupling factor k _t and the mechanical quality factor Q _M could be increased.

Example 2 In this example, an example of producing the piezoelectric resonator 10 shown in FIG. 1 by using the ceramic composition according to Example 1 will be described.

In the piezoelectric resonator of this example, a piezoelectric body 11 was produced using the piezoelectric ceramic composition of sample 16 of Example 1. The piezoelectric body 11 was formed by dicing and polishing the polarized sample. In addition, the electrodes 12a, 12
For b, a circular electrode made of silver was used. Electrodes 12a, 1
2b was formed by vapor deposition to have a thickness of 0.8 μm.

In this embodiment, a piezoelectric body having a length of 5.1 mm, a width of 5.1 mm and a thickness t of 0.29 mm was used. Then, the diameter D of the Ag electrode was changed from about 1.2 mm to about 1.6 mm, and three types of piezoelectric resonators were produced. The impedance characteristics of these three types of piezoelectric resonators are shown in FIG. Similarly, FIG. 4 shows the results of measuring the same impedance characteristics of the piezoelectric resonator using the conventional lead-based piezoelectric ceramics (Pb _0.9 La _0.08 TiO ₃ ) as the piezoelectric body. 3 and 4 also show the relationship between the electrode area S and the thickness t of the piezoelectric body at that time.

As is apparent from FIG. 3, in any of the piezoelectric resonators of this embodiment having a resonance frequency of about 25 MHz, neither unnecessary vibration nor sub-resonance appeared between the resonance frequency and the anti-resonance frequency.

On the other hand, as is clear from FIG.
In the piezoelectric resonator using the conventional piezoelectric ceramic composition containing lead, when 22 ≦ S / t ² and 5.3 ≦ D / t, the amplitude of the sub-resonance is near the anti-resonance frequency (25.3 MHz). , And the impedance waveform near the anti-resonance frequency split greatly. Thus, in the piezoelectric resonator using the conventional piezoelectric ceramic composition, 22 ≦ S / t ² ,
When 5.3 ≦ D / t, the piezoelectric resonator could not be practically obtained.

As described above, in the piezoelectric resonator using the piezoelectric ceramic composition of Example 1, the electrode diameter D, the electrode area S,
There are few design restrictions such as the thickness t of the piezoelectric body. Also, 2
In the case of 2 ≦ S / t ² and 5.3 ≦ D / t, the size of the electrodes on the two main surfaces becomes larger than the thickness t, so that the influence of the displacement of the center of the electrodes becomes small. It turns out that it is advantageous in manufacturing.

(Embodiment 3) In this embodiment, an example in which the thickness shear mode piezoelectric resonator 20 shown in FIG. 2 is manufactured by using the ceramic composition according to Embodiment 1 will be described.

In the piezoelectric resonator of this example, a piezoelectric body 21 was produced using the piezoelectric ceramic composition of Samples 7 to 10 of Example 1. The piezoelectric body 21 was formed by dicing and polishing a sample polarized in a direction parallel to the main surface.
Further, as the electrodes 22a and 22b, strip-shaped electrodes made of silver were used. The electrodes 22a and 22b were formed by vapor deposition to have a thickness of 0.8 μm.

In this embodiment, the length L is 5.1 mm and the width W is
Was 1.0 mm and the thickness t was 0.20 mm. The size A of the overlapping portion of the electrodes was 1.2 mm.
Table 5 shows the relationship between the porcelain composition of the piezoelectric resonator and the temperature characteristic (temperature change rate) of the resonance frequency.

[0060]

[Table 5]

As is clear from Table 5, the temperature change rate of the resonance frequency of each of the samples 7 to 10 using the porcelain composition of Example 1 was 49 to 58 ppm / ° C. or less, which is comparative to the sample 1 of Comparative Example. Resonance frequency temperature change rate 80pp
It can be seen that it is smaller than m / ° C.

As described above, the piezoelectric resonator using the piezoelectric ceramic composition of Example 1 has a good temperature change rate of the resonance frequency, and is suitable as the piezoelectric ceramic composition used for the piezoelectric ceramic oscillator and the piezoelectric ceramic filter. It turns out that

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments and can be applied to other embodiments based on the technical idea of the present invention.

[0064]

As described above, according to the piezoelectric ceramic composition of the present invention, a piezoelectric ceramic composition having a larger electromechanical coupling coefficient than the conventional bismuth layered compound and containing no lead can be obtained. Further, according to the piezoelectric element of the present invention, a piezoelectric element containing no lead and having excellent electric characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a thickness longitudinal triple mode piezoelectric resonator according to a second embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a thickness shear mode piezoelectric resonator according to a third embodiment of the present invention.

FIG. 3 is a diagram showing an example of impedance characteristics of a piezoelectric resonator according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an example of impedance characteristics of a conventional piezoelectric resonator.

[Explanation of symbols]

10, 20 Piezoelectric resonator 11,21 Piezoelectric body 12a, 12b, 22a, 22b electrodes 12c, 12d lead wire D diameter t thickness L length W width Size of the overlapping part of A electrode

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Claims (8)

[Claims] 1. The composition has the general formula: Sr _1-xy M1 _x M2 _y B
i ₂ in _{(Nb 1-a Ta a)} 2- z Ti z O 9 ( wherein, M1 is at least one element selected from Ca and Ba, M
2 is La, Y, Dy, Er, Yb, Pr, Nd, Sm,
Is at least one element selected from the group consisting of Eu and Gd), and x in the above general formula,
y, z and a are in the range of 0.0 ≦ x <0.9, 0.0 <y <0.3, 0.0 ≦ z <0.3, 0.0 ≦ a ≦ 1.0, respectively. A piezoelectric ceramic composition comprising the porcelain composition according to claim 1. 2. x, y, z and a in the general formula are respectively 0.2 ≦ x ≦ 0.8, 0.0 <y <0.15, 0.0 <z <0.15, 0 The piezoelectric ceramic composition according to claim 1, wherein the range is 0.0 ≦ a ≦ 0.6. 3. The piezoelectric ceramic composition according to claim 1, further comprising MnO ₂ in a range of 0.8% by mass or less. 4. The composition has the general formula: Sr _1-xy M1 _x M2 _y B
i ₂ in _{(Nb 1-a Ta a)} 2- z Ti z O 9 ( wherein, M1 is at least one element selected from Ca and Ba, M
2 is La, Y, Dy, Er, Yb, Pr, Nd, Sm,
Is at least one element selected from the group consisting of Eu and Gd), and x in the above general formula,
y, z and a are in the range of 0.0 ≦ x <0.9, 0.0 <y <0.3, 0.0 ≦ z <0.3, 0.0 ≦ a ≦ 1.0, respectively. 2. A piezoelectric element comprising a piezoelectric body made of a piezoelectric ceramic composition containing the porcelain composition according to claim 1. 5. x, y, z and a of the general formula are respectively 0.2 ≦ x ≦ 0.8, 0.0 <y <0.15, 0.0 <z <0.15, 0. The piezoelectric element according to claim 4, wherein the range is 0.0 ≦ a ≦ 0.6. 6. The piezoelectric element according to claim 4, further comprising MnO ₂ in a range of 0.8% by mass or less. 7. When the area of the electrode formed on the surface of the piezoelectric body is S and the thickness of the piezoelectric body is t, 22 ≦ S /
The piezoelectric element according to claim 4, wherein the relationship of t ² is satisfied. 8. A relationship of 5.3 ≦ D / t is satisfied, where D is an effective electrode diameter when the piezoelectric body is effectively approximated to a circular shape, and t is a thickness of the piezoelectric body. Item 4. The piezoelectric element according to Item 4 or 5.