JP2007204346A - Piezoelectric porcelain composition and piezoelectric resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric porcelain composition having high vibration amplitude in a high frequency region, and to provide a piezoelectric resonator obtained by using the same. <P>SOLUTION: The piezoelectric porcelain composition contains a main component, expressed by compositional formula: Pb<SB>1-x</SB>(A1<SB>1/2</SB>A2<SB>1/2</SB>)<SB>x</SB>(Mn<SB>1/3</SB>M<SB>2/3</SB>)<SB>a</SB>Zr<SB>b</SB>Ti<SB>c</SB>O<SB>3</SB>, as a fundamental composition and has a perovskite type structure expressed by general formula [ABO<SB>3</SB>]. In the formula, A1 is at least one kind selected from Li, Na, K, Rb and Ce of monovalent alkali metals; A2 is at least one kind selected from Bi and rare earth elements; and M is at least one kind selected from Sb, Nb, and Ta. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a piezoelectric ceramic composition optimal for a piezoelectric device such as a piezoelectric actuator or a piezoelectric transformer, and a piezoelectric resonator using the piezoelectric ceramic composition, and is particularly high for high voltage driving in a high frequency region. The present invention relates to a device that is devised so that vibration amplitude characteristics can be obtained.

In general, piezoelectric elements are widely used as application devices such as piezoelectric actuators and piezoelectric transformers. The piezoelectric actuator is used as a motor element for precise positioning because it can control minute displacements and has high response and does not generate electromagnetic noise. The piezoelectric transformer is widely used as a backlight for an inverter for a liquid crystal display because a high step-up ratio and a high efficiency can be obtained as compared with an electromagnetic transformer.

In addition, this type of piezoelectric device utilizes the property of converting electrical energy applied to the piezoelectric element into mechanical energy. At that time, the vibration of the piezoelectric element is proportional to the magnitude of the applied AC voltage. It has the characteristic of increasing the amplitude. However, when the voltage applied to the piezoelectric element is further increased, the energy loss increases and the heat generation of the piezoelectric element itself increases. As a result, the vibration amplitude characteristic as high as expected cannot be obtained. Depending on the case, the piezoelectric element may be destroyed.

Incidentally, the maximum vibration amplitude (ξ) of the piezoelectric element, the resonance frequency (fr) at that time, and the effective vibration speed (V) of the piezoelectric element are expressed by the following equation (I).
V = √2 ・ π ・ fr ・ ξ ――― (I)
However,
V: effective vibration speed fr: resonance frequency ξ: maximum vibration amplitude

For this reason, a method is employed in which the piezoelectric element is driven with a low voltage that does not actually generate much heat, or a high voltage is intermittently applied.
However, in recent years, with higher performance of these piezoelectric devices, it is required to drive the piezoelectric element with a higher vibration amplitude.

As shown in the following formula (II), it is known that the vibration velocity (V) is proportional to the product of the piezoelectric constant (d ₃₁ ) that is the material constant of the piezoelectric element and the mechanical quality factor (Q _m ). ing. For this reason, in order to obtain a higher vibration amplitude, it is necessary to increase both the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ) of the piezoelectric element.
V = 4 / π√ (C ^E / ρ) · d ₃₁ · Q _m · E ――― (II)
However,
V: vibration velocity C ^E : Young's modulus ρ: density d ₃₁ : piezoelectric constant Q _m : mechanical quality factor E: electric field

Thus, in order to obtain a high vibration amplitude, it is necessary to increase the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ) of the piezoelectric element. However, there is no useful conventional piezoelectric element that can obtain a high vibration amplitude, and there is a problem that it cannot sufficiently cope with high voltage driving in a high frequency region.

For example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 disclose such piezoelectric elements.
JP 2003-63865 A JP 2002-362773 A JP 2002-356372 A

The present invention has been made based on such points, and the object thereof is to provide a piezoelectric ceramic composition having high vibration amplitude characteristics in a high frequency region and a piezoelectric resonator using such a piezoelectric ceramic composition. There is to do.

In order to solve the above problems, the piezoelectric ceramic composition according to claim 1 of the present invention is composed mainly of the composition formula Pb1 _-x (A11 _/ 2A21 _{/ 2} ) _x (Mn1 _/ 3M2 _{/ 3} ) _a. It is characterized by having a perovskite structure represented by Zr _b Ti _c O ₃ and having the basic composition ABO ₃ as a basic composition.
However,
A1: Lithium (Li), sodium (Na) among alkali metals (valence +1),
It contains at least one of potassium (K), rubidium (Rb), and cesium (Ce).
A2: Contains at least one of bismuth (Bi) and rare earth elements.
M: At least one of antimony (Sb), niobium (Nb), and tantalum (Ta) is included.
A piezoelectric ceramic composition according to claim 2 is the piezoelectric ceramic composition according to claim 1, wherein “x” in the composition formula is in a range of 0 <x ≦ 0.08. .
The piezoelectric ceramic composition according to claim 3 is the piezoelectric ceramic composition according to claim 1 or 2, wherein “a”, “b”, and “c” in the above composition formula are 0.01 ≦ a ≦, respectively. The range is 0.15, 0.38 ≦ b ≦ 0.60, 0.38 ≦ c ≦ 0.60, and a + b + c = 1.0.
The piezoelectric ceramic composition according to claim 4 is the piezoelectric ceramic composition according to any one of claims 1 to 3, wherein the rare earth element is lanthanum (La), neodymium (Nd), cadolinium (Gd), They are holmium (Ho) and ytterbium (Yb).
A piezoelectric ceramic composition according to claim 5 is the piezoelectric ceramic composition according to any one of claims 1 to 4, wherein a part of lead (Pb) in the composition formula is calcium (Ca), strontium ( Sr) and barium (Ba) are substituted with 5 mol% or less by any element.
According to a sixth aspect of the present invention, there is provided a piezoelectric resonator comprising the piezoelectric ceramic composition according to any one of the first to fifth aspects, wherein the average crystal grain size is 5 μm or less. It is.
According to a seventh aspect of the present invention, in the piezoelectric resonator according to the sixth aspect, the average crystal grain size is 3 μm or less.

In general, the piezoelectric material is divided into a hard material and a soft material. The hard material is a material that is hard and difficult to displace, and is a material that has a small piezoelectric constant (d ₃₁ ) and a high mechanical quality factor (Q _m ) in the formulas (I) and (II) shown in the description of the conventional example. . On the other hand, the soft material is soft and easily displaced, and has a large piezoelectric constant (d ₃₁ ) and a small mechanical quality factor (Q _m ). For example, the former is effective by adding elements such as manganese (Mn) and iron (Fe), and the latter is added with elements such as niobium (Nb), tantalum (Ta), and antimony (Sb). It is more effective.
The high power characteristic contemplated by the present invention is proportional to the product of the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ). Therefore, in order to improve the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ), the B site in the general formula “ABO ₃ ” is converted to an effective pentavalent element, that is, niobium (Nb). , Antimony (Sb), tantalum (Ta) and manganese (Mn) are combined to improve by substitution as the third component.
Also, this time, the mechanical quality factor higher the piezoelectric constant _{(d 31)} is large _{(Q m)} becomes small, the mechanical quality factor higher the piezoelectric constant _{(d 31)} is small in the reverse _{(Q m)} increases There is a relationship. That is, the relationship between the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ) is in a trade-off relationship. Therefore, it is necessary to pay attention to the balance between the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ). To achieve this balance, niobium (Nb), antimony (Sb), tantalum (Ta) and manganese The amount of (Mn) substitution must be controlled.
That is, when the substitution amount increases, Mn precipitates at the grain boundary and the piezoelectric characteristics of the piezoelectric constant (d ₃₁ ) and the mechanical quality factor (Q _m ) are greatly reduced. Therefore, the maximum amplitude is 2.0 μm. As a result, it becomes small and becomes inappropriate as a high-power piezoelectric ceramic composition. Therefore, as shown in claim 3, the amount of the third component is limited to 0.01 ≦ a ≦ 0.15.
Further, it is known that the piezoelectric constant (d ₃₁ ) is strongly influenced by the Zr / Ti ratio of the B site in the general formula “ABO ₃ ”. In particular, when the Zr / Ti ratio increases, the crystal system of the material changes from tetragonal to rhombohedral, and particularly from the region where both crystal systems exist (mixed crystal region) to rhombohedral, the piezoelectric constant ( d ₃₁ ) and the mechanical quality factor (Q _m ) show relatively large values. Therefore, as shown in claim 3, the b and c regions of the above composition are limited to 0.38 ≦ b ≦ 0.60 and 0.38 ≦ c ≦ 0.60.
On the other hand, when the A site in the general formula “ABO ₃ ” is replaced with an alkali metal, the effect of increasing the Curie temperature (when the Curie temperature is exceeded, the crystal system changes from a ferroelectric material to a paraelectric material in which piezoelectricity disappears) is effective. This makes it possible to strongly fix the domain (the region where the dipoles are aligned in a certain direction) and to greatly improve the mechanical quality factor (Q _m ). However, since the alkali metal element has a positive charge plus one valence, and the conventional A site has a positive charge plus two valences of Pb, when the element is replaced with the above element, the electric charge is reduced by one. It becomes difficult to obtain a single phase of “ABO ₃ ”.
Therefore, by combining with a trivalent lanthanoid element, an electric charge balance is maintained and a dense sintered body is obtained. However, when the substitution amount (x) at the A site exceeds 0.08, the average particle size after sintering becomes extremely large and the maximum amplitude becomes 2 μm or less, which is inappropriate as a high-power piezoelectric ceramic composition. Become. Therefore, as shown in claim 2, the A site amount (x) is limited to 0 <x ≦ 0.08.
Similarly, even when the same divalent alkaline earth element as Pb is substituted, although the mechanical quality factor (Q _m ) is slightly decreased, the piezoelectric constant (d ₃₁ ) is improved, and as a result, the vibration amplitude is similarly increased. A quantity was obtained. The substitution amount at that time was limited to 5 mol% or less as defined in claim 5.
Here, the reason why the substitution amount is limited to 5 mol% or less is as follows. That is, when substitution is performed with an alkaline earth element exceeding 5 mol%, the relative dielectric constant of the material is further increased and the piezoelectric constant (d ₃₁ ) is increased, but conversely, the mechanical quality factor (Q _m ) is decreased. As a result, the strength of the material is lowered, which makes it unsuitable as a high power material.
On the other hand, it was found that even if the material composition is the same, a high vibration amplitude can be obtained by reducing the average particle size of the sintered body. The effect was confirmed to be 5 μm or less as defined in claim 6, and in particular, a stronger effect was obtained when it was 3 μm or less as defined in claim 7.

As described above, according to the piezoelectric ceramic composition of the present invention, the main component is the composition formula Pb _1-x (A1 _1/2 A2 _1/2 ) _x (Mn _1/3 M _2/3 ) _a Zr _b Ti _{cO 3} {provided that A1 contains at least one of Li, Na, K, Rb, and Ce among alkali metals (valence + 1), A2 contains at least one of Bi and rare earth elements, M includes at least one of Sb, Nb, and Ta}, and has a basic composition and a perovskite structure represented by a general symbol “ABO ₃ ”. It has become possible to obtain a piezoelectric ceramic composition that has an amplitude, does not mechanically break even when a high voltage is applied, and can be driven stably.
Further, when x was set in the range of 0 <x ≦ 0.08, the above effect was more reliable.
In addition, when a, b and c are set as 0.01 ≦ a ≦ 0.15, 0.38 ≦ b ≦ 0.60, 0.38 ≦ c ≦ 0.60 and a + b + c = 1.0, respectively, The effect can be made more certain.
In addition, when the rare earth element is set to include at least one of La, Nd, Gd, Ho, and Yb, the above-described effect becomes more reliable.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. First, the piezoelectric ceramic composition of the present embodiment is a perovskite oxide, and the composition formula based on the molar ratio of substitutional elements is as shown in the following formula (III).
Pb _1-x (A1 _1/2 A2 _1/2 ) _x (Mn _1/3 M _2/3 ) _a Zr _b Ti _c O ₃ --- (III)

The piezoelectric ceramic composition according to the present embodiment is represented by the general symbol “ABO ₃ ” with a composition as shown in the above composition formula as a basic composition.
In the above compositional formula (III), the part of “Pb _1-x (A1 _1/2 A2 _1/2 ) _x ” corresponds to the part of “A” site in the general symbol “ABO ₃ ”. , “(Mn _1/3 M _2/3 ) _a Zr _b Ti _c ” corresponds to the “B” site in the general symbol “ABO ₃ ”.

The “A1” includes at least one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Ce) among alkali metals (valence +1). Shall be. The “A2” includes at least one kind of rare earth elements of bismuth (Bi) and lanthanum (La), neodymium (Nd), cadmium (Gd), holmium (Ho), and ytterbium (Yb). . Further, the “M” includes at least one of antimony (Sb), niobium (Nb), and tantalum (Ta).

Further, “x”, “a”, “b”, and “c” are 0.00 ≦ x ≦ 0.08, 0.01 ≦ a ≦ 0.15, 0.38 ≦ b ≦ 0.60, respectively. The range is 0.38 ≦ c ≦ 0.60, and a + b + c = 1.00. Various oxides were weighed so as to have the above stoichiometric composition, and wet-mixed with a planetary ball mill. Then, it was dried and formed into pellets, and calcined at 850 ° C. for 2 hours. Next, after pulverizing with a laika machine, the mixture was granulated by adding a binder, formed into a rectangular shape, and then fired at 1230 ° C. for 2 hours.

Then, the crystal phase of the obtained sample was identified by X-ray diffraction, and the fracture surface of the sintered body was observed with an electron microscope (SEM) to determine the average crystal grain size. Moreover, about the piezoelectric characteristic, the obtained sintered compact was processed into the test piece of 12 mm x 3 mm x 1 mm. Furthermore, electrode printing / baking, polarization treatment (2.8 at 130 ° C.)
kv / mm × 10 minutes), the frequency characteristics were measured with an impedance analyzer (HP4194A), and various piezoelectric characteristics were obtained.

On the other hand, for vibration amplitude characteristics, a test piece having an outer diameter of 15 mm × an inner diameter of φ8 mm × 3 mm was prepared, and then a Langevin type vibrator was assembled. Then, an AC voltage of 100 V near the resonance frequency was applied to the vibrator to vibrate, and the vibration amplitude was measured with a laser Doppler vibrometer (LDV).

The results of the above tests are shown in Table 1, Table 2, and Table 3.

First, Table 1 shows the results of the maximum vibration amplitude (ξ) and the average crystal grain size (μm) measured by the above method for the test pieces of sample numbers 1 to 35. Table 2 shows the results of the maximum vibration amplitude (ξ) and the average crystal grain size (μm) measured by the above method for the test pieces of sample numbers 36 to 65. Further, Table 3 shows the results of the maximum vibration amplitude (ξ) and the average crystal grain size (μm) measured by the above method for the test pieces of sample numbers 66 to 91.

In Table 1, sample number 1, sample number 5, sample number 9, sample number 23, sample number 26, sample number 27, sample number 30, sample number 31, and sample number 35 are all in the present embodiment. This is out of the range and is a comparative example (marked with * in the table). Any other sample numbers are examples in the present embodiment.
In Table 2, Sample No. 39, Sample No. 43, Sample No. 57, Sample No. 60, Sample No. 61, and Sample No. 65 are all out of the scope of the present embodiment and are comparative examples ( (* Marked in the table). All other material numbers are examples in the present embodiment.
The sample numbers shown in Table 3 are all examples in the present embodiment.

Further, for sample numbers 1 to 35 shown in Table 1, “A1” uses at least one of Li and Na, and “A2” uses La. Sample numbers 36 to 65 shown in Table 2 are those in which at least one of Li and Na is used as “A1” and Bi is used as “A2”. For sample number 66 to sample number 91 shown in Table 3, at least one of Li, Na, K, Rb, and Ce is used as “A1”, and Bi, La, and Nd are used as “A2”. , Gd, Ho, Yb at least one kind is used.

Hereinafter, each sample shown in Table 1 will be described in detail.
First, Sample No. 1 (Comparative Example) is a third component element other than Zr and Ti entering the B site position without using elements other than Pb entering the A site position in the perovskite type crystal structure of this composition. “M” does not include Ta, Nb, or Sb at all, and is outside the scope of the present embodiment. The average particle size after firing is as small as 3 μm or less, but the maximum amplitude is as low as 2.0 μm or less, which is inappropriate as a piezoelectric ceramic composition for high power.

Sample No. 5 (comparative example) is a mixed crystal region, but the third component Ta is added in a larger amount (a = 0.16) than 0.01 ≦ a ≦ It is outside the range of 0.15. The average grain size was as large as 5 μm, and abnormal grain growth was observed, and the piezoelectric characteristics were lowered. For this reason, the maximum amplitude width was 2.0 μm or less, which was inappropriate as a high-power piezoelectric ceramic composition.

Sample No. 9 (comparative example) is obtained by adding Ta as the third component within the range of the present embodiment, but Zr (= b) is as small as 0.36, and 0.38 ≦ b. Since it is outside the range of ≦ 0.60 and greatly deviates from the mixed crystal region (determined by the ratio of Zr and Ti in the region where tetragonal crystal and rhombohedral crystal coexist), the electromechanical coupling coefficient (K) and mechanical Since the piezoelectric characteristics such as the quality factor (Q _m ) are greatly reduced, the maximum amplitude is as small as 2.0 μm or less, which is inappropriate as a high-power piezoelectric ceramic composition.

Sample numbers 2, 3, 4, 6, 7, and 8 and sample numbers 10 to 18 (all examples in the present embodiment) are obtained by adding Ta as the third component. It is within the scope of the present embodiment. In any case, the maximum amplitude was 2.0 μm or more, which was useful as a high-power piezoelectric ceramic composition. In particular, when the amount of Ta of the third component is in the range of 0.07 ≦ a ≦ 0.12 and the crystal system is a mixed crystal or a rhombohedral crystal close to a mixed crystal region, the maximum amplitude amount is further increased ( Sample numbers 11, 14, 17). In particular, Sample No. 14 has a maximum amplitude of 4.4 μm. This is presumably because the value of the product of the electromechanical coupling coefficient (K) and the mechanical quality factor (Q _m ) when a high voltage is applied is maximized.

Sample Nos. 19 to 22, 28, 29, and 32 (all examples according to this embodiment) are La and Li in which part of Pb entering the A site position is part of the perovskite crystal structure of this composition. It is substituted, and is in the range of 0.01 ≦ y ≦ 0.08. These A site substitutions markedly improved the maximum amplitude.

Sample No. 23 (Comparative Example) has an A site substitution amount exceeding 0.08 and is outside the range of 0.01 ≦ x ≦ 0.08, and the average particle size after sintering becomes significantly large. The maximum amplitude was 2 μm or less, which was inappropriate as a high power piezoelectric ceramic composition.

Sample numbers 24 and 25 (both examples according to the present embodiment) are compositions substituted with La and Na, and are within the range of 0.01 ≦ y ≦ 0.08. Both the average particle diameter and the maximum amplitude were the same as those of the La and Li substitution composition.

Sample Nos. 26 and 27 (both are comparative examples) were examined for the influence of the substitution ratio of A1 and A2, and the vibration amplitude amount was not good for the composition having an A1 / A2 ratio outside 0.82 to 1.22. It became inappropriate as a small high-power material.

Sample numbers 30, 31, and 35 (comparative examples) were obtained by adding Ta and Sb at the same time. However, Zr and Ti were small, and 0.38 ≦ b ≦ 0.60 and 0.38 ≦ c ≦ 0. Outside the range of .60. Since the piezoelectric characteristics greatly deteriorated due to the large deviation from the mixed crystal region, the maximum amplitude amount was as small as 2.0 μm or less, which was inappropriate as a high-power piezoelectric ceramic composition.

Sample numbers 33 and 34 are obtained by changing the third component element to Nb, and both are within the scope of the present embodiment. In all cases, the maximum amplitude exceeds 2.0 μm, and the average particle size after sintering is extremely small, 3 μm or less, confirming that the same or better effect than the sample substituted with Ta can be obtained. did.

From the above, the main component is the composition formula Pb _1-x (A1 _1/2 A2 _1/2 ) _x (Mn _1/3 M _2/3 ) _a Zr _b Ti _c O ₃ {where A1 is an alkali metal ( Valence + 1) includes at least one of Li, Na, K, Rb, and Ce, A2 includes at least one of Bi and La, Nd, Gd, Ho, and Yb rare earth elements, and M Includes at least one of Sb, Nb, and Ta}, which has a basic composition and a perovskite structure represented by a general symbol “ABO ₃ ”, and x is 0 <x ≦ 0.08, and a, b, c are 0.01 ≦ a ≦ 0.15, 0.38 ≦ b ≦ 0.60, 0.38 ≦ c ≦ 0.60, a + b + c, respectively. Set the average particle size after sintering to 5 μm or less by setting = 1.0 Possible in which the maximum amplitude of the it is possible to obtain a piezoelectric ceramic composition for more high power 2 [mu] m.

In addition, regarding the sample numbers 10 to 18, it was examined how the vibration amplitude (ξ) changes depending on the values of “a”, “b”, and “c”. The result is shown in FIG. In FIG. 1, the horizontal axis indicates the value “b”, the vertical axis indicates the vibration amplitude (ξ), and the value “a” is 0.07, 0.10. It is a figure showing how vibration amplitude (ξ) changes when a value is changed. According to this, it can be seen that when “a” is 0.10, “b” is within a range of 0.4 <b <0.55, and a particularly high vibration amplitude (ξ) is obtained.

In addition, by preparing a plurality of types of test pieces having the values of “a”, “b”, and “c” shown in sample number 10 and different average crystal grain sizes, how the vibration amplitude (ξ) changes. I thought about what to do. The result is shown in FIG. FIG. 2 is a diagram showing the relationship between the average crystal grain size on the horizontal axis and the vibration amplitude (ξ) on the vertical axis. It can be seen that a high vibration amplitude (ξ) can be obtained when the average crystal grain size is 5 μm or less.

In particular, it can be seen that very good vibration amplitude (ξ) is obtained when the average crystal grain size is 3 μm or less.
The same can be said for the materials shown in Tables 2 and 3.

As described above, according to the present embodiment, the following effects can be obtained.
The main component is the composition formula Pb _1-x (A1 _1/2 A2 _1/2 ) _x (Mn _1/3 M _2/3 ) _a Zr _b Ti _c O ₃ (where A1 is an alkali metal (valence +1) Including at least one of Li, Na, K, Rb, and Ce, A2 including at least one of Bi and rare earth elements, and M includes at least one of Sb, Nb, and Ta} These have a basic composition and a perovskite structure represented by the general symbol ABO ₃ , so that they have a high vibration amplitude and no mechanical breakdown even when a high voltage is applied. In addition, it is possible to obtain a piezoelectric ceramic composition that can be driven stably.
Further, when x was set in the range of 0 <x ≦ 0.08, the above effect was more reliable.
In addition, when a, b and c are set as 0.01 ≦ a ≦ 0.15, 0.38 ≦ b ≦ 0.60, 0.38 ≦ c ≦ 0.60 and a + b + c = 1.0, respectively, The effect can be made more certain.
In addition, when the rare earth element is set to include at least one of La, Nd, Gd, Ho, and Yb, the above effect can be further ensured.
At the same time, by using a sintered body having an average particle size of 5 μm or less, a piezoelectric ceramic composition having a high vibration amplitude as described above can be obtained more reliably.
In particular, when the average particle size is 3 μm or less, it is more reliable.

The present invention is not limited to the one embodiment. For example, “A1” is at least one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Ce) among alkali metals (valence +1). Any two or more types may be used simultaneously.
Similarly, “A2” is at least one of bismuth (Bi), lanthanum (La) as a rare earth element, neodymium (Nd), cadolinium (Gd), holmium (Ho), and ytterbium (Yb). Any two or more of them may be used at the same time.
Similarly, since “M” is at least one of antimony (Sb), niobium (Nb), and tantalum (Ta), any two or more may be used at the same time.

The present invention relates to a piezoelectric ceramic composition and a piezoelectric resonator using the piezoelectric ceramic composition, and particularly relates to a piezoelectric resonator having a high vibration amplitude with respect to high voltage driving in a high frequency region, such as a piezoelectric actuator or a piezoelectric transformer. Most suitable for piezoelectric devices.

It is a figure which shows one embodiment of this invention, and is a characteristic view which shows the relationship between molar ratio and vibration amplitude. It is a figure which shows one embodiment of this invention, and is a characteristic view which shows the relationship between an average particle diameter and the maximum vibration amplitude.

Claims (7)

The main component is represented by the composition formula Pb _1-x (A1 _1/2 A2 _1/2 ) _x (Mn _1/3 M _2/3 ) _a Zr _b Ti _c O ₃ , and is represented by the general symbol ABO ₃ A piezoelectric ceramic composition having a perovskite structure represented by the formula:
However,
A1: Lithium (Li), sodium (Na) among alkali metals (valence +1),
It contains at least one of potassium (K), rubidium (Rb), and cesium (Ce).
A2: Contains at least one of bismuth (Bi) and rare earth elements.
M: At least one of antimony (Sb), niobium (Nb), and tantalum (Ta) is included. The piezoelectric ceramic composition according to claim 1, wherein
A piezoelectric ceramic composition, wherein “x” in the composition formula is in a range of 0 <x ≦ 0.08. In the piezoelectric ceramic composition according to claim 1 or 2,
“A”, “b”, and “c” in the above composition formula are in the range of 0.01 ≦ a ≦ 0.15, 0.38 ≦ b ≦ 0.60, and 0.38 ≦ c ≦ 0.60, respectively. And a piezoelectric ceramic composition, wherein a + b + c = 1.0. In the piezoelectric ceramic composition according to any one of claims 1 to 3,
A piezoelectric ceramic composition, wherein the rare earth element is lanthanum (La), neodymium (Nd), cadmium (Gd), holmium (Ho), or ytterbium (Yb). In the piezoelectric ceramic composition according to any one of claims 1 to 4,
A piezoelectric ceramic composition characterized in that a part of lead (Pb) in the above composition formula is substituted with 5 mol% or less by any element of calcium (Ca), strontium (Sr), and barium (Ba). A piezoelectric resonator comprising the piezoelectric ceramic composition according to any one of claims 1 to 5, wherein an average crystal grain size is 5 µm or less. The piezoelectric resonator according to claim 6, wherein
A piezoelectric resonator having an average crystal grain size of 3 μm or less.

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