JP4789328B2 - Piezoelectric ceramic composition and piezoelectric resonator - Google Patents

Description

【００４６】
表１から明らかなように、本発明の範囲内の試料は、厚み滑り振動の基本波振動のＰ／Ｖ値を５５ｄＢ以上と大きくでき、且つ移相歪みの発生が起こりにくいことから安定した発振を得ることができ、さらに、発振周波数の温度変化率が±５０００ｐｐｍ以内となり小さく、しかもキュリー温度を３００℃以上とできることが判る。
【００４７】
特に、試料Ｎｏ．３〜５，１１，２４〜２６は、高いＰ／Ｖ値を維持した状態、特に６０ｄＢ以上を維持し、発振周波数の温度変化率が±３０００ｐｐｍ以内と小さくでき、キュリー温度を３５０℃以上とできることが判る。
【００４８】
また、Ｍｎを含有しない比較例の試料Ｎｏ．８の場合には焼結体の密度が低く、Ｐ／Ｖ値が３２ｄＢと小さいことが判る。一方、Ｍｎ量が１．１重量部の場合にはＰ／Ｖ値が４５ｄＢと小さいことが判る。
【００４９】
また、ｘの値が０の試料Ｎｏ．１の場合、試作した発振子１００個中５個を上回る発振子において１０゜を上回る移相歪みが発生したことから、安定した発振が得られないこと
が判る。
【００５０】
また、ＳｒとＣａを複合化した試料Ｎｏ．４の場合、ａの値が０．５でＰ／Ｖが７５ｄＢと大きな値を有しながら、−２０〜８０℃の発振周波数の温度変化率が±３０００ｐｐｍ以内と優れた温度特性を有し発振子として最も好ましい特性となる。
【００５１】
このように、本発明の圧電磁器においては、特に、厚み滑り振動の基本波振動のＰ／Ｖを大きくするとともに、共振周波数と反共振周波数の間において、１０゜を超える移相リップルの発生を著しく少なくでき、さらに、−２０℃〜８０℃での発振周波数の温度変化率を±５０００ｐｐｍ以内と小さくすることができ、安定した発振子として使用することができ、しかもキュリー温度を３００℃以上とできることが判る。
【００５２】
図３に試料Ｎｏ．４のインピーダンス特性を、図４に発振周波数の温度変化率を、図５に試料Ｎｏ．４のｘ線回折測定結果を示す。本発明の組成の圧電磁器は、図５に示すように、一般式が（Ｓｒ_1-xＣａ_x）₂Ｂｉ₄Ｔｉ₅Ｏ₁₈で表わされた結晶相からなり、Ｍｎのピークが存在しないことにより、Ｍｎが固溶した上記結晶相から構成されていることが判る。
【００５３】
【発明の効果】
以上詳述したように、本発明の圧電磁器組成物では、厚み滑り振動の基本波振動のＰ／Ｖ値を大きくしながら、共振周波数と反共振周波数の間で１０゜を超える移相歪みが発生せず、共振周波数の温度変化率が小さく、しかもキュリー温度が高く、これにより、発振子を構成した場合、発振余裕度が高まり安定した発振と、発振周波数の温度安定性に優れた高精度な発振特性が得られ、厚み滑り振動の基本波振動を用いた２〜２０ＭＨｚ発振子用素子として好適な発振子を得ることができる。
【図面の簡単な説明】
【図１】コルピッツ型発振回路を原型としたピアス発振回路を示した概略図である。
【図２】８ＭＨｚ用発振子の概略図である。
【図３】試料Ｎｏ．４のインピーダンス特性を示すグラフである。
【図４】試料Ｎｏ．４の発振周波数の温度変化率を示すグラフである。
【図５】試料Ｎｏ．４のｘ線回折測定結果を示す図である。
【符号の説明】
ｌ・・・圧電磁器
２、３・・・電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric ceramic composition and a piezoelectric resonator. For example, the present invention is suitable for a resonator, an ultrasonic vibrator, an ultrasonic motor, or a piezoelectric sensor such as an acceleration sensor, a knocking sensor, and an AE sensor. The present invention relates to a piezoelectric ceramic and a piezoelectric resonator that are suitably used for a high-frequency oscillator of an energy-confined oscillator using fundamental vibration of vibration.
[0002]
[Prior art]
Conventionally, products using a piezoelectric ceramic include, for example, a filter, a piezoelectric resonator (hereinafter, a concept including an oscillator), an ultrasonic vibrator, an ultrasonic motor, a piezoelectric sensor, and the like.
[0003]
Here, the oscillator is used by being incorporated in an oscillation circuit such as a Colpitts oscillation circuit, for example, for oscillation of a reference signal of the microcomputer. FIG. 1 shows a Pierce oscillation circuit in which the inductor L is replaced with a piezoelectric oscillator in a circuit configuration based on a Colpitts oscillation circuit. This Pierce oscillation circuit includes capacitors 11 and 12, a resistor 13, an inverter 14 and an oscillator 15. In order to generate an oscillation signal in this oscillation circuit, it is necessary to satisfy the following oscillation conditions.
[0004]
That is, the amplification factor in the amplifier circuit composed of the inverter 14 and the resistor 13 is α, the phase shift amount is θ ₁ , the feedback factor in the feedback circuit composed of the oscillator 15 and the capacitors 11 and 12 is β, and the phase shift amount is θ _{When 2} , it is necessary that the loop gain is α × β ≧ 1, and the phase shift amount is θ ₁ + θ ₂ = 360 ° × n (where n = 1, 2,...).
[0005]
In general, an amplifier circuit including a resistor 13 and an inverter 14 is built in a microcomputer. In order to obtain stable oscillation that does not cause erroneous oscillation or non-oscillation, the loop gain must be increased. To increase the loop gain determines the gain of the feedback factor beta, resonator of P / V, that is, necessary to increase the difference in resonance impedance R ₀ and anti-resonance impedance R _a. P / V is defined as a value of 20 × Log (R _a / R ₀ ).
[0006]
In order to satisfy the condition of the phase shift amount, the phase shift is reversed from about −90 ° to about + 90 ° between the resonance frequency and the anti-resonance frequency and in the vicinity thereof, and the resonance frequency is It is also important that no phase shift distortion due to spurious vibration occurs between and in the vicinity of the antiresonance frequency.
[0007]
Conventionally, PZT and PT-based materials that have high piezoelectricity and can obtain high P / V, for example, have been used. However, since PZT and PT-based materials contain lead in a proportion of about 60% of their own weight, it has been pointed out that lead may be eluted by acid rain and cause environmental pollution. Therefore, high expectations are placed on piezoelectric materials that do not contain lead. A material system mainly composed of a bismuth layered compound not containing lead has a characteristic that the mechanical quality factor (Qm) is relatively high as compared with PZT and PT materials, and is a non-lead piezoelectric material for an oscillator. Can be applied.
[0008]
[Problems to be solved by the invention]
However, the piezoelectric ceramic composition mainly comprising a bismuth layered compound containing no conventional lead, when used as resonators, sufficient P / V Do give et Lena Ibakari, processability is poor chipping (for resonator Due to the lack of porcelain edges, phase shift distortion caused by spurious vibration occurs between the resonance frequency and the antiresonance frequency, and the phase shift condition is not satisfied, so there is a problem that no oscillation or stable oscillation cannot be obtained.
[0009]
In addition, the temperature change rate of the resonance frequency is larger than ± 5000 ppm, and there is a problem that it is not possible to cope with accuracy within a frequency tolerance of ± 5000 ppm with respect to temperature characteristics required from electronic equipment.
[0010]
Therefore, the present invention does not cause phase shift distortion between the resonance frequency and the anti-resonance frequency and in the vicinity thereof, and can increase the P / V of the fundamental wave vibration such as the thickness shear vibration or the thickness longitudinal vibration. An object of the present invention is to provide a lead-free piezoelectric ceramic composition and a piezoelectric resonator that are excellent in temperature stability of oscillation frequency in a temperature range of 20 ° C. to + 80 ° C.
[0011]
[Means for Solving the Problems]
The piezoelectric ceramic composition of the present invention contains at least Bi and Ti as metal elements, and when the composition formula by molar ratio is expressed as (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O ₁₈ , 0.3 ≦ x ≦ 0.7, A1 is Sr, Ca, one of (Sr _0.5 Ca _0.5 ), A2 is (Bi _0.5 Na _0.5 ), (Bi _0.5 Li _0.5 ) And (Bi _0.5 K _0.5 ), or A1 is Sr and A2 is Ca and the main component satisfies Ca, and Mn is 0.1% in terms of MnO ₂ with respect to 100 parts by weight of the main component. It contains 4 to 0.7 parts by weight.
[0012]
When a piezoelectric resonator is manufactured using a piezoelectric ceramic composed of such a piezoelectric ceramic composition, phase shift distortion does not occur between the resonance frequency and the anti-resonance frequency and in the vicinity thereof. The P / V value at the fundamental wave and the third-order overtone vibration can be increased. For example, when the temperature change rate of the resonance frequency at −20 to 80 ° C. of the thickness-slip fundamental wave vibration is within ± 5000 ppm, and the resonance impedance R ₀ and the anti-resonance impedance _Ra are 20 × Log (R _a / R ₀ P / V represented by) can be 55 dB or more. In addition, the Curie temperature can be increased to 300 ° C. or higher.
[0013]
Conventionally, it has been known that SrBi ₄ Ti ₅ O _18- based bismuth layered compounds have low piezoelectric properties. However, in the present invention, for example, a part of Sr is replaced with a predetermined amount of Ca, and solidified in the bismuth layered compound. It has been found that excellent piezoelectric properties are exhibited by melting, and the present invention has been achieved. In particular, the SrBi ₄ Ti ₅ O _18- based bismuth layered compound has a problem that the Curie temperature is as low as 300 or less and cannot be used for electronic components corresponding to surface mounting. In the present invention, (A1 _1-x A2 _x ) When expressed as ₂ Bi ₄ Ti ₅ O ₁₈ , 0.3 ≦ x ≦ 0.7, A1 is Sr, Ca, (Sr _0.5 Ca _0.5 ), A2 is (Bi _{0. 5} Na _0.5 ), (Bi _0.5 Li _0.5 ) and (Bi _0.5 K _0.5 ), or a main component satisfying Sr and A2 satisfying Ca, It has been found that by containing 0.4 to 0.7 parts by weight of Mn in terms of MnO ₂ with respect to 100 parts by weight of the main component, the Curie temperature can be improved to a Curie temperature of 300 ° C. or higher. It has come.
[0015]
The piezoelectric resonator of the present invention is formed by forming electrodes on both main surfaces of a piezoelectric ceramic made of the above piezoelectric ceramic composition. In such a piezoelectric resonator, as described above, P / V is large in a piezoelectric resonator using a lead-free piezoelectric ceramic made of a Bi layered compound, for example, an oscillator to which a thickness shear fundamental wave vibration is applied. Stable oscillation is obtained because the oscillation margin is increased and phase shift distortion does not occur between and near the resonance frequency and antiresonance frequency, and high-precision oscillation with excellent temperature stability of the oscillation frequency Thus, an oscillator that can adapt to a frequency of 2 to 20 MHz can be obtained. Furthermore, for example, even when a surface-mounted component in which the piezoelectric resonator is built in a housing-like case is surface-mounted on a substrate with solder or the like, the characteristics of the piezoelectric resonator are not deteriorated.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The piezoelectric ceramic composition of the present invention is a Bi layered compound containing at least Bi and Ti as metal elements, and the composition formula according to the molar ratio is represented as (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O ₁₈ . When 0.3 ≦ x ≦ 0.7, A1 is one of Sr, Ca, (Sr _0.5 Ca _0.5 ) , A2 is (Bi _0.5 Na _0.5 ), (Bi _{0. 5} Li _0.5 ) and (Bi _0.5 K _0.5 ), or a main component satisfying Sr of A1 and Ca of A2 and MnMnO with respect to 100 parts by weight of the main component _It contains 0.4 to 0.7 parts by weight in terms of ₂ .
[0017]
Ru can be greater than 55dB the P / V by a said structure.
[0019]
The larger the value of x, be prone P / V of the thickness shear vibration is low, x sometimes is zero phase shift between the likely resonant frequency and the antiresonant frequency occur chipping during machining about -90 at about +90 DEG phase reversal frequency bands from DEG liable phase ripple more than 10 ° it is generated, that a easily occurs is the oscillation stop no oscillation condition is satisfied.
[0020]
_{(A1 1-x A2 x)} x when expressed as 2 Bi ₄ Ti _{5 O 18} is to increase the P / V of the thickness shear vibration, from the viewpoint of suppressing the occurrence of the phase distortion, 0. It is desirable that 3 ≦ x ≦ 0.7.
[0021]
0 Furthermore, in the present invention, with respect to the main component as 100 parts by weight, the Mn in MnO ₂ basis. It is desirable to contain 4 to 0.7 parts by weight. By incorporating the Mn, can greatly improve the P / V, MnO ₂ content often happens when the volume resistivity than 0.7 parts by weight be prone underlying that with respect to the main component of l00 parts by weight , P / V of the thickness shear vibration can not sufficiently polarized current flows during polarization, there is a fear to be low. On the other hand, 0. When less than 4 parts by weight, P / V is liable to be lowered, because the phase distortion is readily released.
[0023]
In the present invention, it is desirable that the composition formula according to the molar ratio of the main components is represented as (Sr _1-x Ca _x ) ₂ Bi ₄ Ti ₅ O ₁₈ . That, A1 is at Sr in the composition formula described above, and when A2 is Ca.
[0024]
This is because the temperature change rate of the oscillation frequency can be reduced to within ± 3000 ppm while obtaining a large value of P / V exceeding 60 dB by substituting an appropriate amount with Ca. Moreover, it is because Curie temperature can also be 300 degreeC or more.
[0027]
The piezoelectric ceramic composed of the piezoelectric ceramic composition of the present invention may contain Zr or the like from ZrO ₂ balls at the time of pulverization, but there is no problem in characteristics if the amount is small.
[0028]
The piezoelectric ceramic composed of the piezoelectric ceramic composition of the present invention has a composition formula represented by (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O ₁₈ , 0.3 ≦ x ≦ 0.7, A1 is Sr, One of Ca and (Sr _0.5 Ca _0.5 ), A2 is (Bi _0.5 Na _0.5 ), (Bi _0.5 Li _0.5 ) and (Bi _0.5 K _0.5 ) Or a crystalline phase composed of a Bi layered compound in which A1 is Sr and A2 is Ca, and Mn is almost solid-solved in the Bi layered compound. It may precipitate at the grain boundary.
[0029]
The piezoelectric ceramic composition of the present invention, although M n are desirably composed of crystal phase comprising a layered Bi compound dissolved, the other, the pyrochlore phase, perovskite phase, different Bi layered compound of structure very There may be a slight amount, but there is no problem in characteristics if the amount is small.
[0030]
The piezoelectric ceramic composed of the piezoelectric ceramic composition of the present invention includes, for example, SrCO ₃ , CaCO ₃ , Bi ₂ O ₃ , MnO ₂ , TiO ₂ , Na ₂ CO ₃ , K ₂ CO ₃ , and Li ₂ CO ₃ as raw materials. Various oxides or salts thereof can be used. A raw material is not limited to this, You may use metal salts, such as carbonate and nitrate which produce | generate an oxide by baking.
[0031]
These raw materials are weighed so as to have the above-mentioned composition, pulverized so that the average particle size distribution (D ₅₀ ) after mixing is in the range of 0.2 to 1 μm, and this mixture is calcined at 750 to 1050 ° C. Then, a predetermined organic binder is added and wet-mixed and granulated. The powder thus obtained is molded into a predetermined shape by known press molding or the like, and baked in a temperature range of 1000 to 1300 ° C. for 2 to 5 hours in an oxidizing atmosphere such as in the air to obtain a piezoelectric ceramic. .
[0032]
A piezoelectric ceramic comprising the piezoelectric ceramic composition of the present invention is optimal as a piezoelectric ceramic for an oscillator of a Pierce oscillation circuit as shown in FIG. 1, but other piezoelectric resonators, ultrasonic vibrators, ultrasonic motors, and The piezoelectric ceramic is optimal for piezoelectric sensors such as acceleration sensors, knocking sensors, and AE sensors, and is particularly suitable for high-frequency applications using the fundamental wave vibration of thickness shear vibration.
[0033]
FIG. 2 shows an oscillator using the piezoelectric resonator of the present invention. This oscillator is configured by forming electrodes 2 and 3 on both surfaces of the piezoelectric ceramic 1 described above. In such a piezoelectric resonator, the P / V of the fundamental wave in thickness-shear vibration can be increased, the oscillation margin is increased, and phase-shift distortion does not occur at frequencies between and near the resonance frequency and the anti-resonance frequency. Stable oscillation can be obtained, high-precision oscillation excellent in temperature stability of the oscillation frequency can be obtained, and in particular, a piezoelectric oscillator that can be adapted to a frequency of 2 to 20 MHz can be obtained.
[0034]
In addition, since the piezoelectric ceramic composition of the present invention has a high Curie temperature, for example, even when a surface-mounted component in which the above-described piezoelectric resonator is incorporated in a casing-like case is surface-mounted on a substrate with solder or the like, the piezoelectric resonance The characteristics of the child do not deteriorate.
[0035]
【Example】
First, SrCO ₃ powder with a purity of 99.9%, CaCO ₃ powder, Bi ₂ O ₃ powder, MnO ₂ powder, TiO ₂ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, Li ₂ CO ₃ powder as starting materials Is expressed as (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O ₁₈ in terms of the molar ratio, A1, A2, and x are the elements shown in Table 1, principal components of values, and the principal component 100 Mn is weighed and mixed so that the weight part is as shown in Table 1 in terms of MnO ₂ with respect to parts by weight, and is put into a 500 ml polypot together with zirconia balls having a purity of 99.9% and isopropyl alcohol (IPA) for 16 hours. Mix in a rotary mill.
[0036]
The slurry after mixing was dried in the atmosphere, passed through a # 40 mesh, and then calcined by holding at 950 ° C. for 3 hours in the atmosphere, and this synthetic powder was made into 99.9% pure ZrO ₂ balls and isopropyl. An alcohol (IPA) was added to a 500 ml polypot and ground for 20 hours to obtain an evaluation powder.
[0037]
An appropriate amount of an organic binder was added to the powder and granulated, and the mold was pressed at 150 MPa at a length of 25 mm, a width of 38 mm, and a thickness of l. The piezoelectric ceramic was molded into a 0 mm plate shape and subjected to main firing at a temperature of 1160 ° C. for 3 hours in the air to obtain a piezoelectric ceramic.
[0038]
When the crystal phase was confirmed by performing x-ray diffraction measurement on this piezoelectric ceramic, the general formula of the piezoelectric ceramic having the composition of the present invention was represented by (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O _18. , And was composed of a crystal phase in which Mn was dissolved.
[0039]
Then, it processed into length 6mm and width 30mm, the end surface electrode for polarizing in a length direction was formed, and the polarization process was performed. Then, the electrode for polarization was removed and processed into a thickness of 0.17 mm. Thereafter, Cr—Ag was vapor-deposited on both sides of the surface having a length of 6 mm and a width of 30 mm, and an annealing treatment was performed at 200 ° C. for 12 hours in order to increase the adhesion strength between the electrode and the porcelain.
[0040]
Thereafter, the electrode corresponding to the non-electrode is removed by etching so that the electrode structure shown in FIG. 2 is obtained, and the length is 4.45 mm (L), the width is 0.9 mm (W), and the thickness is 0.17 mm (H ) The shape was processed using a dicing saw or wire saw to obtain an oscillator for fundamental wave vibration of thickness shear vibration corresponding to 8 MHz oscillation.
[0041]
The characteristics of the oscillator were obtained by measuring the reimpedance waveform with an impedance analyzer and calculating the P / V at the fundamental wave vibration of the thickness-shear vibration by the equation P / V = 20 × Log (R _a / R ₀ ) ( Where R _{a is} anti-resonance impedance and R _{0 is} resonance impedance).
[0042]
Furthermore, from the impedance waveform, a phase shift exceeding 10 ° is achieved in a frequency band consisting of a phase shift of about + 90 ° after the phase shift is reversed from about −90 ° to about + 90 ° between the resonance frequency and the anti-resonance frequency. It was investigated whether or not distortion occurred. Phase shift distortion is evaluated by phase shift distortion = | maximum phase shift value−phase shift value locally changed from the maximum value |, and phase shift ripple exceeding 10 ° is generated in 5 or more of 100 resonators. In the case where it was done, it was marked as x, and in the case where it was less than that, it was marked as ○.
[0043]
Furthermore, the temperature change rate of the oscillation frequency was calculated by the following equation with respect to the oscillation frequency change at −20 ° C. or + 80 ° C. with reference to the oscillation frequency of 25 ° C.
[0044]
Fosc change rate (ppm) = {(Fosc (drift) -Fosc (25)) / Fosc (25)} × 100, where Fosc (drift) is an oscillation frequency at −20 ° C. or + 80 ° C. (25) is the oscillation frequency at 25 ° C. These results are shown in Table 1.
[0045]
[Table 1]

[0046]
As can be seen from Table 1, the samples within the scope of the present invention can increase the P / V value of the fundamental vibration of the thickness-shear vibration to 55 dB or more, and are less likely to cause phase-shifting distortion. can be obtained, further, small temperature coefficient of the oscillation frequency becomes within ± 5000 ppm, yet it is found and Turkey can Curie temperature and 300 ° C. or higher.
[0047]
In particular, sample no. 3 to 5 , 11 , 24 to 26 can maintain a high P / V value, particularly 60 dB or more, the temperature change rate of oscillation frequency can be as small as ± 3000 ppm , and the Curie temperature can be 350 ° C. or more. I understand that
[0048]
Moreover, sample No. of the comparative example which does not contain Mn. In the case of 8, it can be seen that the density of the sintered body is low and the P / V value is as small as 32 dB. On the other hand, when the amount of Mn is 1.1 parts by weight, it can be seen that the P / V value is as small as 45 dB.
[0049]
Sample No. with x value of 0 was used. For 1, since the phase distortion of more than 10 ° in oscillator over five hundred in oscillator the prototype has occurred, stable oscillation is seen resulting et Lena Ikoto.
[0050]
In addition, sample Nos. Obtained by combining Sr and Ca In the case of 4, the value of a is 0.5 and P / V is as large as 75 dB, and the temperature change rate of the oscillation frequency of -20 to 80 ° C. is within ± 3000 ppm and has excellent temperature characteristics. This is the most preferable characteristic as a child.
[0051]
As described above, in the piezoelectric ceramic of the present invention, in particular, the P / V of the fundamental wave vibration of the thickness shear vibration is increased, and a phase shift ripple exceeding 10 ° is generated between the resonance frequency and the anti-resonance frequency. The temperature change rate of the oscillation frequency at −20 ° C. to 80 ° C. can be reduced to within ± 5000 ppm, and it can be used as a stable oscillator, and the Curie temperature is 300 ° C. or higher. I understand that I can do it.
[0052]
In FIG. 4 shows the impedance characteristics, FIG. 4 shows the temperature change rate of the oscillation frequency, and FIG. 4 shows x-ray diffraction measurement results. As shown in FIG. 5, the piezoelectric ceramic of the composition of the present invention is composed of a crystal phase whose general formula is represented by (Sr _1-x Ca _x ) ₂ Bi ₄ Ti ₅ O ₁₈ and has no Mn peak. Thus, it can be seen that it is composed of the crystal phase in which Mn is dissolved.
[0053]
【The invention's effect】
As described in detail above, the piezoelectric ceramic composition of the present invention has a phase shift distortion exceeding 10 ° between the resonance frequency and the anti-resonance frequency while increasing the P / V value of the fundamental wave vibration of the thickness shear vibration. It does not occur, the rate of change in temperature of the resonance frequency is small, and the Curie temperature is high. As a result, when an oscillator is configured, the oscillation margin increases and stable oscillation, and high accuracy with excellent temperature stability of the oscillation frequency Thus, an oscillator suitable for a 2 to 20 MHz oscillator element using the fundamental wave vibration of thickness shear vibration can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a Pierce oscillation circuit based on a Colpitts oscillation circuit.
FIG. 2 is a schematic diagram of an oscillator for 8 MHz.
FIG. 4 is a graph showing impedance characteristics of FIG.
FIG. 4 is a graph showing a temperature change rate of an oscillation frequency of 4;
FIG. FIG. 4 is a diagram showing the result of x-ray diffraction measurement of 4;
[Explanation of symbols]
l ... Piezoelectric ceramics 2, 3 ... Electrodes

Claims (3)

While containing at least Bi and Ti as metal elements, the composition formula by molar ratio is (A1 _1-x A2 _x ) ₂ Bi ₄ Ti ₅ O _18.
When
0.3 ≦ x ≦ 0.7 ,
A1 is Sr, Ca, one of (Sr _0.5 Ca _0.5 ) ,
A2 is one of (Bi _0.5 Na _0.5 ), (Bi _0.5 Li _0.5 ) and (Bi _0.5 K _0.5 ),
Or
A1 is Sr, A2 is Ca
A piezoelectric ceramic composition comprising 0.4 to 0.7 parts by weight of Mn in terms of MnO ₂ with respect to 100 parts by weight of the main component satisfying   The P / V value of the fundamental wave vibration of thickness shear vibration is 60 dB or more, the temperature change rate at -20 ° C and + 80 ° C is 3000 ppm or less, and the Curie temperature is 350 ° C or more. The piezoelectric ceramic composition as described.   3. A piezoelectric resonator comprising electrodes formed on both principal surfaces of a piezoelectric ceramic comprising the piezoelectric ceramic composition according to claim 1.

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