JP4992796B2 - Oscillator - Google Patents

Description

The present invention relates to a calling pendulum.

A piezoelectric ceramic composition has a piezoelectric effect that causes electrical polarization when subjected to pressure from the outside, and an inverse piezoelectric effect that causes distortion when an electric field is applied from the outside, so that mutual conversion between electrical energy and mechanical energy is achieved. It is used as a material for performing. Such piezoelectric ceramic compositions are used in a wide variety of products such as resonators, filters, sensors, actuators, ignition elements or ultrasonic motors (see Patent Documents 1 to 3 below).
JP-A-5-139824 JP 10-330156 A JP 2000-1367 A

When using an oscillator comprising a piezoelectric element oscillating circuit, Q _max of the piezoelectric element in order to ensure the oscillation characteristics be large. In recent years, it is also required that the temperature characteristic of the oscillation frequency F ₀ is good. Note that Q _max is tan θ _max when the maximum value of the phase angle is θ _max (unit: deg). In other words, the resonance frequency fr and anti-resonance when X is reactance and R is resistance This is the maximum value of Q (= | X | / R) between the frequency fa. Further, “the temperature characteristic of the oscillation frequency F ₀ is good” means that when the temperature of the oscillator or the oscillation circuit including the oscillator changes, the ratio of the change amount of the oscillation frequency F _{0 to} the change amount of the temperature is small. This means that the oscillation frequency F ₀ is stable with respect to temperature change.

However, in the case of an oscillator that uses the third harmonic of the thickness longitudinal vibration (third harmonic mode of the thickness longitudinal vibration), the frequency band used is high compared to an oscillator that uses the bending vibration mode. A conventional piezoelectric ceramic composition has not been sufficiently satisfactory in terms of temperature characteristics of Q _max and oscillation frequency F ₀ . An oscillator that uses the third harmonic of the thickness longitudinal vibration can be applied to, for example, a resonator that is an element that generates a reference clock for controlling a microcomputer, and is also intended to replace an expensive crystal resonator. There is a need for a piezoelectric ceramic composition that exhibits sufficient performance when used in an oscillator that uses a third harmonic of thickness longitudinal vibration.

Of the oscillator with high _{Q max} as described above and good temperature characteristic of the oscillation frequency _{F 0} is requested, the oscillation frequency _{F 0} is the product is 16～60MHz, piezoelectric ceramics mainly composed of PbTiO ₃ It is common to use the third harmonic mode of thickness longitudinal vibration. In such an oscillator, since the thickness of the substrate (piezoelectric element) is reduced particularly at a frequency of 30 MHz or more, there is a possibility that the piezoelectric element is cracked in a lapping process or the like. Therefore, in order to avoid cracking of the piezoelectric element, it is also required to increase the frequency constant Fr · t of the piezoelectric element.

The frequency constant Fr · t is a product of the resonance frequency Fr (Hz) of the piezoelectric element and the thickness t (m) of the piezoelectric element, and is a substantially constant value. The frequency constant Fr · t is a specific value determined by the composition of the piezoelectric ceramic composition, but the firing temperature of the piezoelectric ceramic composition, the shape of the piezoelectric element, the size of the vibrating electrode of the oscillator, or the vibrating electrode If the thickness is changed, it will fluctuate to some extent. The resonance frequency Fr is the resonance frequency in the third harmonic mode of thickness longitudinal vibration. For example, when a 40 MHz oscillator is manufactured using a piezoelectric element having a frequency constant of 7000 Hz · m, the piezoelectric element needs to be thinned to about 175 μm, so that the piezoelectric element is easily broken. Therefore, in particular, in an oscillator that requires an oscillation frequency F _{0 of} 30 MHz or more, it is required to increase the frequency constant of the piezoelectric element to prevent cracking of the piezoelectric element during processing.

Therefore, the present invention provides a sufficiently high Q _max , good temperature characteristics of the oscillation frequency F ₀ , and a high frequency constant when used in an oscillator that uses the third harmonic mode of thickness longitudinal vibration. An object of the present invention is to provide a piezoelectric ceramic composition that enables the piezoelectric ceramic element, a piezoelectric element made of the piezoelectric ceramic composition, and an oscillator using the piezoelectric element.

An oscillator according to the present invention includes a piezoelectric element made of a piezoelectric ceramic composition and a pair of electrodes facing each other with the piezoelectric element interposed therebetween, and the piezoelectric ceramic composition contains a complex oxide having a perovskite structure. The composite oxide
_{(Pb α La β Sr γ)} (Ti 1- (x + y + z) Zr x Mn y Nb z) O 3
Has a composition represented in, 0.87 ≦ α ≦ 0.98,0 <β ≦ 0.08, 0.005 ≦ γ ≦ 0.05,0.125 ≦ x ≦ 0.300,0.020 ≦ y ≦ 0.050 and 0.040 ≦ z ≦ 0.070 are satisfied.

In the resonator according to the present invention, since the piezoelectric element is composed of a piezoelectric ceramic composition having the composition represented by the above formula, even when used as an oscillator utilizing the third harmonic mode of thickness longitudinal vibration. A sufficiently high Q _max , a good temperature characteristic of the oscillation frequency F ₀ , and a high frequency constant can be obtained.

According to the present invention, when used in an oscillator that uses the third harmonic mode of thickness longitudinal vibration, it is possible to obtain a sufficiently high Q _max , good temperature characteristics of the oscillation frequency F ₀ , and a high frequency constant. Provided are a piezoelectric ceramic composition, a piezoelectric element comprising the piezoelectric ceramic composition, and an oscillator using the piezoelectric element. In addition, according to the present invention, since the piezoelectric ceramic composition has a high Curie temperature, it is possible to obtain a piezoelectric element that is not easily depolarized even at a high temperature.

  Hereinafter, preferred embodiments of an oscillator using the piezoelectric ceramic composition of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a perspective view showing an embodiment of an oscillator, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 and 2 includes a rectangular parallelepiped piezoelectric element 2 and a pair of vibrating electrodes 3 facing each other with the piezoelectric element 2 interposed therebetween. One vibration electrode 3 is formed at the center of the upper surface of the piezoelectric element 2, and another vibration electrode 3 is formed at the center of the lower surface of the piezoelectric element 2. The piezoelectric element 2 is made of the piezoelectric ceramic composition of the present embodiment. The vibrating electrode 3 is made of a conductive material such as Ag.

  The size of the piezoelectric element 2 may be an appropriate size depending on the application, and is, for example, about 1.0 to 4.0 mm in length, 0.5 to 4.0 mm in width, and about 50 to 300 μm in thickness. The shape of the vibrating electrode 3 is usually circular, and its dimensions are, for example, a diameter of 0.5 to 3.0 mm and a thickness of about 0.5 to 5 μm.

The piezoelectric ceramic composition contains a composite oxide having a perovskite structure as a main component. This composite oxide has a composition represented by the following chemical formula (1).
_{(Pb α La β Sr γ)} (Ti 1- (x + y + z) Zr x Mn y Nb z) O 3 ··· Equation (1)

The composite oxide satisfies 0.87 ≦ α ≦ 0.98. When α is less than 0.87, the resistivity of the piezoelectric ceramic composition is likely to decrease, and thus there is a tendency that the polarization treatment for imparting piezoelectricity to the piezoelectric ceramic composition is difficult at the time of manufacturing the piezoelectric element 2. . When α exceeds 0.98, Q _max tends to be small. By setting α within the above range, these tendencies can be suppressed. From the same viewpoint, it is preferable that 0.88 ≦ α ≦ 0.97.

The composite oxide satisfies 0 <β ≦ 0.08. When the composite oxide constituting the piezoelectric ceramic composition contains La within the range of 0 <β ≦ 0.08, Q _max is improved. If β is 0, the sinterability of the piezoelectric element 2 tends to deteriorate, and piezoelectric characteristics may not be obtained appropriately. On the other hand, if β exceeds 0.08, the Curie temperature decreases, and the piezoelectric element 2 tends to be easily depolarized when heated. By setting β within the above range, these tendencies can be suppressed. From the same viewpoint, it is preferable that 0.02 ≦ β ≦ 0.06.

The composite oxide satisfies 0.005 ≦ γ ≦ 0.05. When γ is 0, the frequency constant tends to be small. On the other hand, when γ exceeds 0.05, the Curie temperature is lowered, and when the piezoelectric element 2 is heated, it tends to be easily depolarized. By setting γ within the above range, these tendencies can be suppressed. From the same viewpoint, it is preferable that 0.005 ≦≦ γ ≦ 0.045.

The composite oxide satisfies 0.125 ≦ x ≦ 0.300. If x is less than 0.125, the temperature characteristic of the oscillation frequency F ₀ tends to be lowered. Moreover, when x exceeds 0.300, the Curie temperature decreases, and when the piezoelectric element 2 is heated, it tends to be easily depolarized. By setting x within the above range, these tendencies can be suppressed. From the same viewpoint, 0.13 ≦ x ≦ 0.25 is preferable, 0.13 ≦ x ≦ 0.20 is more preferable, and 0.13 ≦ x ≦ 0.16 is particularly preferable. preferable. If x ≧ 0.125, the ratio of ZrO _{2 to} the weight of the portion derived from the oxides of Pb, La and Ti in the composite oxide of the chemical formula (1) exceeds 5 wt%. , ZrO ₂ is relatively contained in the composite oxide.

The composite oxide satisfies 0.020 ≦ y ≦ 0.050. If y is less than 0.020, Q _max tends to be small. On the other hand, if y exceeds 0.050, the resistivity of the piezoelectric ceramic composition is likely to decrease, and therefore, it is difficult to perform a polarization treatment for imparting piezoelectricity to the piezoelectric ceramic composition during the manufacture of the piezoelectric element 2. Tend. By setting y within the above range, these tendencies can be suppressed. From the same viewpoint, it is preferable that 0.030 ≦ y ≦ 0.045.

  The composite oxide satisfies 0.040 ≦ z ≦ 0.070. If z is less than 0.040, the sinterability of the piezoelectric element 2 tends to deteriorate. When z exceeds 0.070, the resistivity becomes too high, and the characteristic deterioration due to the thermal shock test tends to increase. By setting z within the above range, these tendencies can be suppressed.

  The piezoelectric ceramic composition may contain a compound other than the complex oxide having the composition represented by the chemical formula (1) as an impurity or a trace additive. Such compounds include, for example, oxides of Na, Al, Si, P, K, Fe, Cu, Zn, Hf, Ta or W. In addition, when the said piezoelectric ceramic composition contains these oxides etc., the total value of the content rate of each oxide in a piezoelectric ceramic composition is 0. 0 of the whole piezoelectric ceramic composition in conversion of the oxide of each element. It is preferable that it is 3 weight% or less. In other words, it is preferable that 99.7% by weight or more of the piezoelectric ceramic composition is an oxide represented by the chemical formula (1). In this case, the piezoelectric ceramic composition itself has a composition represented by the chemical formula (1).

In this embodiment, since the piezoelectric element 2 included in the oscillator 1 is formed of the piezoelectric ceramic composition, the oscillator 1 is used in an oscillation circuit as an oscillator using a third harmonic mode of thickness longitudinal vibration. Sometimes a sufficiently high Q _max , a good temperature characteristic of the oscillation frequency F ₀ , and a high frequency constant are achieved. In addition, the Curie temperature of the piezoelectric ceramic composition can be set to a desired value.

  The above-described method for manufacturing the oscillator 1 according to the present embodiment mainly includes a step of granulating the raw material powder of the piezoelectric element 2, a step of pressing the raw material powder to form a formed body, and firing the formed body. A step of forming the sintered body, a step of polarizing the sintered body to form the piezoelectric element 2, and a step of forming the vibrating electrode 3 on the piezoelectric element 2. Hereinafter, a method for manufacturing the oscillator 1 will be specifically described.

First, a starting material for preparing a piezoelectric ceramic composition is prepared. As the starting material, oxides of each element constituting the composite oxide having the perovskite structure represented by the above chemical formula (1) and / or compounds that become these oxides after firing (carbonate, hydroxide, oxalic acid) Salt, nitrate, etc.). Specific starting _{materials, PbO, L a 2 O 3} , La (OH) 3 , etc., _3, etc. SrCO, may be used to _{TiO 2,} ZrO _2, MnO 2 or MnCO _{3, Nb} 2 _{O 5} or the like. Each of these starting materials is blended in a weight ratio such that a composite oxide having a composition represented by the above chemical formula (1) is formed after firing.

  Next, the blended starting materials are wet mixed by a ball mill or the like. The wet-mixed starting material is temporarily molded to form a temporary molded body, and the temporary molded body is temporarily fired. By this temporary baking, the temporary baking body containing the piezoelectric ceramic composition of this embodiment mentioned above is obtained. The calcination temperature is preferably 700 to 1050 ° C., and the calcination time is preferably about 1 to 3 hours. If the pre-baking temperature is too low, the chemical reaction tends not to proceed sufficiently in the temporary molded body. If the temporary baking temperature is too high, the temporary molded body starts to sinter, and the subsequent pulverization tends to be difficult. is there. The pre-baking may be performed in the air, or may be performed in an atmosphere having a higher oxygen partial pressure or in a pure oxygen atmosphere than in the air. Further, the wet-mixed starting material may be temporarily fired as it is without being temporarily formed.

  The obtained calcined product is slurried and finely pulverized (wet pulverized) with a ball mill or the like, and then dried to obtain a fine powder. If necessary, a binder is added to the obtained fine powder to granulate the raw material powder. In addition, it is preferable to use alcohol, such as water and ethanol, or a mixed solvent of water and ethanol, as a solvent for slurrying the calcined body. Examples of the binder added to the fine powder include commonly used organic binders such as polyvinyl alcohol, polyvinyl alcohol added with a dispersant, and ethyl cellulose.

  Next, a compact is formed by press molding the raw material powder. What is necessary is just to set the load at the time of press molding to 100-400 Mpa, for example.

  The resulting molded body is subjected to binder removal treatment. The binder removal treatment is preferably performed at a temperature of 300 to 700 ° C. for about 0.5 to 5 hours. The binder removal treatment may be performed in the air, or may be performed in an atmosphere having a higher oxygen partial pressure than the air or a pure oxygen atmosphere.

  After the binder removal treatment, the compact is fired to obtain a sintered body (piezoelectric ceramic composition). The firing temperature may be about 1050 to 1250 ° C., and the firing time may be about 1 to 8 hours. In addition, the binder removal treatment and firing of the molded body may be performed continuously or separately.

  Next, the sintered body is cut into a thin plate, and this is lapped and surface-treated. When the sintered body is cut, a cutting machine such as a cutter, a slicer, or a dicing saw can be used. After the surface processing, provisional electrodes for polarization treatment are formed on both surfaces of the thin plate-like sintered body. As the conductive material constituting the temporary electrode, Cu is preferable because it can be easily removed by etching with a ferric chloride solution. For forming the temporary electrode, it is preferable to use a vacuum deposition method or sputtering.

  A polarization electric field is applied to a thin plate-like sintered body on which a temporary electrode for polarization treatment is formed, and polarization treatment is performed. The conditions for the polarization treatment may be appropriately determined according to the composition of the piezoelectric ceramic composition contained in the sintered body. Usually, the temperature of the sintered body subjected to the polarization treatment is 150 to 300 ° C., and a polarization electric field is applied. The time may be 1 to 30 minutes, and the magnitude of the polarization electric field may be 0.9 times or more the coercive electric field of the sintered body.

  After the polarization treatment, the temporary electrode is removed from the sintered body by etching or the like. Then, the sintered body is cut into a desired element shape to form the piezoelectric element 2. By forming the vibrating electrode 3 on the piezoelectric element 2, the resonator 1 of the present embodiment is completed. For the formation of the vibrating electrode 3, it is preferable to use a vacuum deposition method or sputtering.

  The preferred embodiments of the piezoelectric ceramic composition and the oscillator according to the present invention have been described above, but the present invention is not necessarily limited to the above-described embodiments.

  For example, the piezoelectric ceramic composition of the present invention includes a filter, an actuator, an ultrasonic cleaner, an ultrasonic motor, a vibrator for an atomizer, a fish detector, a shock sensor, an ultrasonic diagnostic device, and a waste toner sensor in addition to an oscillator. It may be used for a gyro sensor, a buzzer, a transformer or a lighter.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

As starting materials for Sample 2, lead oxide (PbO), lanthanum hydroxide (La (OH) ₃ ), strontium carbonate (SrCO ₃ ), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), manganese carbonate (MnCO ₃₎ ) And niobium oxide (Nb ₂ O ₅ ) powder raw materials were prepared. These powder raw materials were weighed and blended so that the piezoelectric ceramic composition constituting the ceramic sample (sintered body) after the main firing had the composition of “Sample 2” in Table 1. Next, the blended powder raw material mixture and pure water were mixed with a Zr ball by a ball mill for 10 hours to obtain a slurry. This slurry was sufficiently dried and then press-molded, and this was temporarily fired at 900 ° C. to obtain a temporarily fired body. Next, the calcined product was finely pulverized with a ball mill, and then dried and granulated by adding an appropriate amount of PVA (polyvinyl alcohol) as a binder. About 3 g of the obtained granulated powder was placed in a 20 mm long × 20 mm wide mold and molded using a uniaxial press molding machine with a load of 245 MPa. The molded sample was heat treated to remove the binder, and then fired at 1150 to 1250 ° C. for 2 hours to obtain a porcelain sample (sample 2) that was a sintered body composed of the piezoelectric ceramic composition. A plurality of porcelain samples as “Sample 2” were prepared by the same operation.

One of the obtained porcelain samples was flattened to a thickness of 0.4 mm with a double-sided lapping machine, and then cut into a size of 6 mm length × 6 mm width with a dicing saw. A pair of Ag electrodes having a size of 5 mm × 5 mm was formed by vacuum-depositing an Ag paste on both ends of the cut ceramic sample. After installing the porcelain sample on which the Ag electrode is formed in the electric furnace, the LCR meter is used to measure the temperature at which the capacitance of the porcelain sample reaches the maximum value in the temperature raising process and the temperature lowering process. The Curie temperature _Tc was determined from the average value. The results are shown in Table 1. In order for the oscillator to function normally even at a high temperature, the piezoelectric element needs to maintain piezoelectricity even at a high temperature, and therefore the higher the Curie temperature _Tc is preferable.

A porcelain sample (sample 2) different from that for measuring the Curie temperature _Tc was flattened to a thickness of 0.4 mm with a double-sided lapping machine, and then cut into a size of 16 mm long × 16 mm wide with a dicing saw. A pair of temporary electrodes for polarization treatment having a size of 15 mm × 15 mm was formed by applying an Ag paste to both ends of the cut ceramic sample. The porcelain sample on which the temporary electrode was formed was subjected to polarization treatment by applying a polarization electric field twice the coercive electric field for 15 minutes in a silicon oil bath at a temperature of 120 ° C. After the polarization treatment, the porcelain sample from which the temporary electrode was removed was again polished with a lapping machine to a thickness of about 0.25 mm. The polished porcelain sample was held in a thermostatic bath at 200 ° C. to 300 ° C. for 5 minutes to 1 hour to stabilize the characteristics. The porcelain sample after being held in the thermostat was processed into a 7 mm × 4.5 mm piezoelectric element 2 with a dicing saw. Next, the vibrating electrodes 3 were formed on both surfaces of the piezoelectric element 2 using a vacuum vapor deposition apparatus, and the oscillator 1 having the same configuration as that shown in FIGS. The vibrating electrode 3 was composed of a 1.5 μm Ag layer.

Using an impedance analyzer (Agilent Technology 4294A), the Q _max of the resonator 1 in the third harmonic mode of thickness longitudinal vibration near 30 MHz was measured. The results are shown in Table 1. Q _max contributes to stable oscillation and is preferably as large as possible.

Next, using an impedance analyzer (4294A manufactured by Agilent Technologies), the resonance frequency Fr (Hz) of the oscillator 1 at room temperature is measured, and the resonance frequency Fr and the thickness t (m) of the piezoelectric element = 2.5 ×. The frequency constant Fr · t (Hz · m) was determined from the product of 10 ⁻⁴ (m). The results are shown in Table 1.

Next, as shown in FIG. 3, parallel capacitors C _L1 and C _L2 having a predetermined capacitance were connected to the oscillator 1 to form a Colpitts oscillation circuit 20 together with the IC. In the Colpitts oscillation circuit 20, Rf is a feedback resistor and Rd is a limiting resistor. The Colpitts oscillation circuit 20 was connected to a predetermined DC power source (not shown). The Colpitts oscillation circuit 20 was placed in a constant temperature bath at 25 ° C., and the oscillation frequency (hereinafter referred to as F ₀ (25 ° C.)) when the temperature in the bath was stabilized at 25 ° C. was measured. Moreover, the temperature of the thermostatic chamber containing the Colpitts oscillation circuit 20 is set to −40 ° C., and the oscillation frequency when the temperature in the bath is stabilized at −40 ° C. (hereinafter referred to as F ₀ (−40 ° C.)). , And the temperature of the constant temperature bath containing the Colpitts oscillation circuit 20 is set to 85 ° C., and the oscillation frequency (hereinafter referred to as F ₀ (85 ° C.)) when the temperature in the bath is stabilized at 85 ° C. is measured. did. Oscillation frequencies F ₀ (25 ° C.), F ₀ (−40 ° C.), and F ₀ (85 ° C.) were measured using a frequency counter (53181A manufactured by Agilent Technologies).

Based on the measured oscillation frequencies F ₀ (25 ° C.), F ₀ (−40 ° C.), and F ₀ (85 ° C.), the temperature characteristics of the oscillation frequency F ₀ are calculated using the following equations (2) and (3). Values F ₀ TC1 and F ₀ TC2 (unit: ppm / ° C.) were determined. The results are shown in Table 1. The smaller F ₀ TC1 and F ₀ TC2 are, the more stable the oscillation frequency F ₀ is with respect to the temperature change, which means that the temperature characteristic of F ₀ is better. Therefore, F ₀ TC1 and F ₀ TC2 are preferably as small as possible.

F ₀ TC1 (ppm / ° C.) = {F ₀ (25 ° C.) − F ₀ (−40 ° C.)} / [{25 ° C .− (− 40 ° C.)} × F ₀ (25 ° C.)] × 10 ^6.・ Formula (2)

F ₀ TC2 (ppm / ° C.) = {F ₀ (85 ° C.) − F ₀ (25 ° C.)} / {(85 ° C.−25 ° C.) × F ₀ (25 ° C.)} × 10 ⁶ Formula (3 )

Except that each powder raw material was blended so that the piezoelectric ceramic composition constituting the ceramic sample (sintered body) after the main firing would have the compositions of Samples 1 and 3 to 8 shown in Table 1. In the same manner as in No. 2, porcelain samples of Samples 1 and 3 to 8 were produced. Further, the Curie temperature T _{c of} the samples 1 and _{3 to 8} and Q _max , Fr · t, F ₀ TC1 and F ₀ TC2 of the piezoelectric element manufactured using the samples 1 and 3 to 8 in the same manner as the sample 2 I asked for each. The results are shown in Table 1. Of samples 1 to 8 shown in Table 1, Curie temperature _Tc is 300 ° C. or higher, Q _max is 10 or higher, Fr · t is 7100 or higher, and absolute values of F ₀ TC1 and F ₀ TC2 A sample having a value of 10 ppm / ° C. or less is preferred.

As shown in Table 1, the piezoelectric ceramic composition constituting the porcelain sample was 0.87 ≦ α ≦ 0.98, 0 <β ≦ 0.08, 0 <γ ≦ 0.05, 0.125 ≦ x ≦. In Samples 2 to 7, which satisfy 0.300, 0.020 ≦ y ≦ 0.050, and 0.040 ≦ z ≦ 0.070, T _c is 300 ° C. or higher, Q _max is 10 or higher, and Fr T was 7100 or more, and it was confirmed that the absolute values of F ₀ TC1 and F ₀ TC2 were both 10 ppm / ° C. or less.

  In Sample 1 where γ is 0.000, Fr · t was confirmed to be less than 7100.

In Sample 8 where γ is greater than 0.050, it was confirmed that T _c was less than 300 ° C.

From the above experimental results, according to the present invention, when used for an oscillator using the third harmonic mode of thickness longitudinal vibration, sufficiently high Q _max , good temperature characteristics of the oscillation frequency F ₀ , and high It has been found that a piezoelectric ceramic composition is provided that makes it possible to obtain a frequency constant.

1 is a perspective view showing an oscillator according to an embodiment of the present invention. It is sectional drawing along the II-II line of FIG. It is. It is a Colpitts oscillation circuit diagram provided with an oscillator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Oscillator, 2 ... Piezoelectric element, 3 ... Vibrating electrode.

Claims (1)

A piezoelectric element made of a piezoelectric ceramic composition, and a pair of electrodes facing each other with the piezoelectric element interposed therebetween,
The piezoelectric ceramic composition contains a complex oxide having a perovskite structure,
The composite oxide is
_{(Pb α La β Sr γ)} (Ti 1- (x + y + z) Zr x Mn y Nb z) O 3
In represented has a composition,
0.87 ≦ α ≦ 0.98,
0 <β ≦ 0.08,
0.005 ≦ γ ≦ 0.05,
0.125 ≦ x ≦ 0.300,
0.020 ≦ y ≦ 0.050, and 0.040 ≦ z ≦ 0.070
Satisfies the resonator.

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