JP2001316182A - Piezoelectric ceramic and piezoelectric resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic capable of being improved in strength, together with to provide a piezoelectric ceramic having high mechanical quality modulus (Qm) and high frequency constant when used in thickness slipping oscillation mode. SOLUTION: This ceramic consists of perovskite compound oxide grain as a principal ingredient containing Na and Nb, and contains partially stabilized zirconia grain and/or contains stabilized zirconia by 0.3-3 wt.% to whole amount, and when representing it by a formula (1-y) NaxNbO3-y (M1-aBia) (Li1-bM2b)Of, M1 is at least one kind among K, Na, Li, Ba, Sr, Ca, and Mg, and M2 is at least one kind among Ti, V, Nb, Ta and Sb, and x, y, a, b, f, respectively satisfy the conditions 0.95<=x<=1.02, y<=0.08, 0<=a<=1, 0<b<=1, f is arbitrary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic and a piezoelectric resonator, and more particularly, to a piezoelectric ceramic and a piezoelectric resonator suitably used in a high frequency range.

[0002]

2. Description of the Related Art In recent years, the frequency used for wireless communication and electric circuits has been increasing, and accordingly, a piezoelectric resonator (used for a concept including an oscillator) used for these electric signals has been developed. A device that can handle a high frequency range is required and is being developed. In recent years, particularly, a resonator utilizing a thickness longitudinal vibration mode or a thickness shear vibration mode capable of coping with a high frequency region, and a piezoelectric material having a high frequency constant have been developed.

[0003] In a resonator using a thickness longitudinal vibration mode or a thickness shear vibration mode, the resonance frequency is determined by the thickness of the piezoelectric element. In a lead titanate-based oscillator that has been widely known, when the third harmonic of the thickness longitudinal vibration is used, the element thickness is about 230 μm when the oscillation frequency is 33.86 MHz.
m, when the fundamental wave of thickness-shear vibration was used, the element thickness was about 180 μm when the oscillation frequency was 8.0 MHz.

As described above, when the third harmonic of the thickness longitudinal vibration is used, the frequency constant is about five times larger than the frequency constant of the fundamental wave of the thickness shear vibration. However, thickness longitudinal vibration 3
When harmonics are used, the oscillation conditions are satisfied by the fundamental vibration in the thickness longitudinal vibration mode existing in the low-frequency region and the fifth harmonic vibration existing in the high-frequency region. There was a problem that it would.

In this phenomenon, the oscillation condition is determined by the gain and phase of the oscillator and the IC, and the oscillation circuit IC
Since the gain decreases as the frequency increases, erroneous oscillation is suppressed by optimizing the circuit constants of the oscillation circuit.

However, when the temperature changes, the circuit constant also changes, which may cause erroneous oscillation. Therefore, even when used in a high frequency region, it is desirable to use the fundamental wave oscillation, and therefore, it has a high frequency constant. Piezoelectric materials have been desired. Further, in order to obtain a piezoelectric element in a higher frequency range, a piezoelectric ceramic having a high processing yield when thinning is desired.

In recent years, alkali niobate-based piezoelectric ceramics have attracted attention as a ceramic material having a high frequency constant and high piezoelectricity.

Among the alkali-based niobate-based oxides, sodium niobate (NaNbO ₃ ) is a perovskite (ABO ₃ ) -type oxide. For example, Japan
Journal of Applied Physi
cs, p. 322, vol. As described in U.S. Pat. No. 31,1992, it exhibits ferroelectricity only at a temperature lower than around -183 [deg.] C., which is a common operating temperature of -20 for piezoelectric resonators and oscillators. In the range of up to 80 ° C., it does not show piezoelectricity and cannot be used as a piezoelectric material.

However, the main component is NaNbO ₃ , and the subcomponents are A _0.5 BO ₃ type compounds such as Ba _0.5 NbO ₃ and Sr
_{When 0.5} NbO ₃ is contained, piezoelectricity can be exhibited in a specific temperature range.
No. 5262. Such a piezoelectric ceramic has a relative dielectric constant of 1060 or less, a mechanical quality factor of 40 to 660, a frequency constant of 2680 to 3560 KHz · mm in a fundamental wave in a radially expanding vibration mode, and a resonance frequency used in a high frequency region. It has good characteristics as a resonator and an oscillator.

On the other hand, sodium lithium niobate (N
a _x Li _y NbO ₃ ) -based ceramics contain NaNbO ₃ as a main component and LiNbO ₃ as an auxiliary component, and have a low relative dielectric constant and are suitable for high-frequency filters. No. 56-29396. Japanese Patent Publication No. 56-29396 describes that the electromechanical coupling coefficient is about 56% and the bending strength is 160 MPa.

[0011] In the K _x Na _y Li _z NbO ₃ ceramics, in order to obtain high piezoelectric _properties, K x Na _y Li _z Nb
The proportion of NaNbO ₃ occupied by the O ₃ ceramics is preferably set to a proportion of about 0.9 or less in terms of mole fraction in the total amount. For example, the piezoelectric material described in Japanese Patent Application Laid-Open No. 11-228226 Of about 0.75-0.
The K _x Na _y Li _z NbO ₃ based ceramic containing NaNbO ₃ of 9 was achieved, as a main component.

[0012]

In recent years, the frequency of electronic equipment has been increased, and piezoelectric ceramics have been reduced in thickness. However, Japanese Patent Application Laid-Open Nos. Hei 9-165262 and Hei 11
In the piezoelectric ceramic disclosed in JP-A-228226, the thickness of the ceramic is 100% due to the low density and the existence of giant crystal grains.
When a piezoelectric element having a thickness of not more than μm was obtained, it was damaged during processing, and the processing yield was as low as 50% or less.

Further, NaNb disclosed in these publications
O ₃ -based ceramics exhibit good piezoelectric properties when added with an auxiliary component, but as the added amount increases, Tc decreases, so that the piezoelectricity decreases. For example, the temperature during reflow soldering (about 250 ° C.) C.), there is a problem that the mechanical quality factor is deteriorated and cannot be used as a piezoelectric resonator.

An object of the present invention is to provide a piezoelectric ceramic and a piezoelectric resonator that can improve the strength. Further, the present invention can improve the strength, and when the thickness sliding mode is used, has a high mechanical quality factor. An object is to provide a piezoelectric ceramic and a piezoelectric resonator having a high frequency constant.

[0015]

According to the piezoelectric ceramic of the present invention, a partially stabilized zirconia particle and / or a stabilized zirconia particle is mainly composed of a perovskite-type composite oxide containing at least Na and Nb as metal elements. 0.3 to 3% by weight of the total amount.

In such a piezoelectric ceramic, for example, Y ₂ O ₃
The stabilized zirconia particles and / or the stabilized zirconia particles containing 4 to 12% of
Since there is almost no solid solution reaction with a perovskite-type composite oxide containing Na and Nb, for example, Na _x NbO ₃ (where 0.95 ≦ x ≦ 1.02) and it is present at the grain boundary, it is perovskite. It can suppress the grain growth of the type composite oxide, refine the structure, and improve the bending strength.

On the other hand, partially stabilized zirconia particles and / or
Alternatively, the stabilized zirconia particles do not exhibit abnormal expansion due to martensitic transformation around 1100 ° C., unlike zirconia that is not stabilized, so that the electrical characteristics deteriorate inside the porcelain mainly composed of a perovskite-type composite oxide. Since a large number of micro-cracks causing the occurrence are not generated, even if the added amount is increased, the electrical characteristics are not significantly reduced.

In particular, the moles of the perovskite-type composite oxide
The composition formula based on the ratio is expressed as (1-y) Na _xNbO_Three−y (M1
_1-aBi_a) (Li_1-bM2_b) O_fWhen expressed as above,
1 is K, Na, Li, Ba, Sr, Ca and Mg
And at least one of M2 is Ti, V, Nb, Ta and
At least one of Sb, x, y, a,
b and f are 0.95 ≦ x ≦ 1.02, y ≦ 0.08, 0
≦ a ≦ 1, 0 <b ≦ 1, f is arbitrary.
Especially when using the thickness slip mode.
Number (Q_m) Is 500 or more and the frequency constant is 1700 KHz
・ It has excellent characteristics of not less than mm and the bending strength is 18
A piezoelectric ceramic having a pressure of 0 MPa or more can be obtained.

Further, the secondary components _{(M1 1-a Bi a)} (Li
_1-b M2 b) at O _f, some or all of the Li Na
And / or substitution with K can increase the frequency constant.

Further, a first transition metal (element from Sc of atomic number 21 to Zn of 29) is applied to the piezoelectric ceramic described above.
Of at least one of 0.01 to 3 of the total amount in terms of oxides.
Desirably, it is contained by weight. By containing these elements, the mechanical quality factor can be increased.

The piezoelectric resonator of the present invention is a piezoelectric resonator having a pair of electrodes formed on opposing surfaces of a piezoelectric substrate,
The piezoelectric substrate is made of the piezoelectric ceramic. As described above, since the bending strength of the piezoelectric substrate can be improved, a piezoelectric ceramic having a small thickness can be manufactured with a high yield. For example, even when a piezoelectric resonator that operates at a high frequency using thickness sliding vibration is manufactured. In addition, the piezoelectric ceramic is not damaged, and the production yield of the piezoelectric resonator can be improved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION A piezoelectric ceramic according to the present invention comprises a perovskite-type composite oxide containing at least Na and Nb as metal elements as a main component, and contains partially stabilized zirconia particles and / or stabilized zirconia particles in the whole amount. 0.
It is necessary to contain 3 to 3% by weight.

This is because when 0.3% to 3% by weight of the partially stabilized zirconia particles and / or the stabilized zirconia particles is contained in the total amount, the transverse rupture strength can be improved. When the content of the particles and / or the stabilized zirconia particles is less than 0.3% by weight, the effect of improving the bending strength is small, and when the content exceeds 3% by weight, the sinterability is reduced and the bending strength is reduced. This is because not only does the electrical property deteriorate, but also the electrical characteristics deteriorate.

The amount of the partially stabilized zirconia particles and / or the stabilized zirconia particles in the piezoelectric ceramic is 0.7 to 2% by weight based on the total amount in view of improving the transverse rupture strength and the electric characteristics. It is desirable.

The partially stabilized zirconia particles and / or the stabilized zirconia particles may be those which do not cause martensitic transformation within the firing temperature range. For example,
Zirconia containing at least 16 mol% of a stabilizer composed of CaO and MgO, and zirconia containing at least 8 mol% of a stabilizer composed of Y ₂ O ₃ are generally stabilized zirconia, and include CaO, MgO and Y _2. The case where the content of O ₃ is lower than the above is partially stabilized zirconia.

[0026] As the stabilizer of partially stabilized zirconia and / or stabilized zirconia, from the viewpoint of improvement in mechanical quality factor in the electrical characteristics, Y ₂ O ₃ is desirable, especially a Y ₂ O ₃ 4 to 12 Molar content is desirable because it improves the mechanical quality factor.

The average crystal grain size of the partially stabilized zirconia particles and / or the crystal particles of the stabilized zirconia particles is such that the proportion of solid solution in the perovskite-type composite oxide is reduced,
From the viewpoint of preventing the deterioration of the electrical characteristics, 0.5 to
Desirably, it is 1.0 μm.

As the perovskite-type composite oxide containing Na and Nb, the perovskite-type composite oxide particles are Na _x NbO ₃ (provided that 0.95 ≦ x ≦ 1.0
2) is desirable from the viewpoint of increasing the mechanical quality factor (Qm).

As the perovskite oxide, in particular,
The composition formula based on the molar ratio is represented by (1-y) Na _x NbO ₃ -y
(M1 _1-a Bi _a) when expressed as _{(Li 1-b M2 b)} O f,
M1 is at least one of K, Na, Li, Ba, Sr, Ca and Mg, M2 is at least one of Ti, V, Nb, Ta and Sb, and the x, y, a,
b and f are 0.95 ≦ x ≦ 1.02, y ≦ 0.08, 0
≦ a ≦ 1, 0 <b ≦ 1, f is arbitrary,
In particular, when using the thickness-shear vibration mode, the mechanical quality factor (Q _m ) is 500 or more, and the frequency constant is 1700 kHz.
mm or more, and the bending strength is desirably 180 MPa or more.

Na _x NbO _{3, which} is a main component, increases the value of x to 0.95 in order to increase the mechanical quality factor (Qm) to 500 or more.
It is desirable to set it to 1.02. Further, it is desirable that y, which is a mole fraction between the main component and the subcomponent, be contained at most 0.08 from the viewpoint of increasing the mechanical quality factor (Qm). That is, it is desirable that Na _x NbO _{3 as} a main component be present at 0.92 or more.

Further, the sub-component is a compound represented by ABO _f, A is _{(M1 1-a Bi a)} , B is (Li _1-b M
_2b ). However, M1 is K, Na, Li, Ba,
At least one of Sr, Ca and Mg, and M2 is T
It is at least one of i, V, Nb, Ta and Sb. A is a number in the range of 0 ≦ a ≦ 1, b is a number in the range of 0 <b ≦ 1, and f is an arbitrary number. Here, f is a typical value of 3, but varies depending on the valence and combination of the contained elements.

Here, as for the particles composed of perovskite-type composite oxides containing at least Na and Nb, when the average particle diameter is smaller than 0.5 μm, the electrical properties are greatly reduced, and when the average particle diameter is larger than 4 μm, the transverse rupture strength is obtained. Therefore, it is desirable to have an average particle size of 0.5 to 4 μm.

Further, sub-component _{(M1 1-a Bi a)} (Li 1-b
In M2 _b) O _f, some or all of the Li be substituted with Na and / or K, preferably in terms of the frequency constant of the porcelain can be maintained high.

Further, at least one of the first transition metals
It is desirable from the viewpoint of improving the mechanical quality factor (Q _m) containing 0.01 to 3 wt% in total volume species in terms of oxide. In particular, it is desirable to contain 0.2 to 1% by weight.

As the first transition metal, a mechanical quality factor (Q
_m ), at least one of V, Cr, Mn, Fe, Co, and Ni, especially Mn, as a first transition metal is 0.0% of the total amount in terms of oxide.
It is desirable to contain 1 to 3% by weight. When the content of the first transition metal increases, some of those metal elements
A phase may be formed and may be present at the grain boundaries of the crystal grains, but may be any as long as the porcelain composition is within the range of the present invention.

It should be noted that at least one of the first transition metals to be added is dissolved in the crystal grains of the perovskite-type composite oxide because the effect of improving the mechanical quality factor (Qm) is large. preferable.

The piezoelectric ceramic of the present invention has crystal grains of perovskite-type composite oxide as a main component, and has a structure in which partially stabilized zirconia particles and / or stabilized zirconia particles are dispersed at the grain boundaries of the main crystal particles. However, zirconia may be slightly dissolved in the main crystal grains.

The piezoelectric ceramic of the present invention can be manufactured, for example, as follows. First, Na ₂ CO ₃ and Nb ₂ O ₅ as main components in the starting material, and K as a subcomponent.
₂ CO ₃ , Na ₂ CO ₃ , Li ₂ CO ₃ , BaCO ₃ , SrC
O ₃ , CaCO ₃ , MgCO ₃ , Bi ₂ O ₃ , Nb ₂ O ₅ , T
iO ₂ , V ₂ O ₅ , Ta ₂ O ₅ , Sb ₂ O ₅ , and further, as oxides of the first transition metal, Sc ₂ O ₃ , V ₂ O ₅ , Cr ₂ O ₃ , M
The powders of nO ₂ , NiO, Fe ₂ O ₃ , and Co ₃ O ₄ are mixed at a predetermined ratio, calcined at 850 to 1050 ° C. for 3 to 5 hours, and pulverized to obtain the desired powder as described above. A basic powder of the material composition is prepared.

[0039] After mixing the powder and Y ₂ O ₃ partially stabilized ZrO ₂ or stabilized ZrO ₂ in a predetermined ratio, an organic binder were mixed, die pressing, isostatic pressing, etc. After forming into a desired shape by the above, in an oxygen-containing atmosphere such as the air, at 1050 ~ 1350 ℃
Porcelain can be obtained by firing for 5 hours.

The oxide of the first transition metal to be added is
The same effect can be obtained not only at the time of blending but also at the time of mixing with calcined powder during the above manufacturing process. In addition, as the raw material powder used, not only carbonates and oxides, but also compounds such as acetates and organic metals,
Any material can be used as long as it becomes an oxide by a heat treatment process such as firing.

In the piezoelectric ceramic of the present invention, inevitable impurities such as Rb and Hf contained in a small amount in the raw material powder and the like may be mixed, however, there is no problem as long as the characteristics are not affected.

In the piezoelectric ceramic configured as described above, the partially stabilized zirconia particles and / or the stabilized zirconia particles are present at the grain boundaries, so that the grain growth of the perovskite-type composite oxide is suppressed and the structure is reduced. Microcracks, which can cause electrical deterioration inside the porcelain containing perovskite-type composite oxide as a main component, because it can be miniaturized and can improve bending strength and do not show abnormal expansion due to martensitic transformation around 1100 ° C. Since a large number are not generated, even if the added amount is increased, the electrical characteristics are not significantly reduced.

Further, by having the above specific composition, the mechanical quality factor (Qm) is 500 or more and the frequency constant is 1700 KHz, especially when the thickness sliding mode is used.
・ It has excellent characteristics of not less than mm and 18% bending strength.
The pressure can be set to 0 MPa or more, and breakage of the piezoelectric ceramic can be prevented.

The piezoelectric resonator according to the present invention is a piezoelectric resonator having a pair of electrodes formed on opposing surfaces of a piezoelectric substrate.
The piezoelectric substrate is made of the piezoelectric ceramic described above. By using the above-described piezoelectric ceramic as the piezoelectric substrate, the piezoelectric ceramic has good electrical characteristics, can improve the bending strength, and can prevent breakage.

[0045]

EXAMPLES As starting materials, K ₂ CO ₃ , Na ₂ CO ₃ , L
i ₂ CO ₃ , BaCO ₃ , SrCO ₃ , CaCO ₃ , MgC
O ₃ , Bi ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ , V ₂ O ₅ , Ta
₂ O ₅ , Sb ₂ O ₅ powder, and further as oxides of the first transition metal, Sc ₂ O ₃ , TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , M
nO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , NiO, CuO, ZnO
Were weighed so that the composition of the piezoelectric ceramic became the value shown in Tables 1 and 2.

This mixture was mixed with ZrO ₂ balls for 12 hours.
Wet mixed for hours. Then, after drying this mixture,
Calcination was performed at 1,000 ° C. for 3 hours in the air. Stabilized ZrO ₂ or partially stabilized ZrO ₂ having an average particle size of 1 μm was weighed and added to the calcined product in the amounts shown in Tables 1 and 2, and wet-mixed again. Thereafter, a binder such as polyvinyl alcohol (PVA) was mixed with the pulverized product and granulated.

The obtained powder was compressed to a width of 2 at a pressure of 150 MPa.
It was press-formed into a square plate having a size of 5 mm × length 35 mm × thickness 1.5 mm. This molded body was fired in the air at 1150 to 1350 ° C for 2 hours. The obtained porcelain was polished to a thickness of 0.5 mm.

Further, this porcelain is 5 mm wide × 30 m long.
After processing into strips of mx 0.50 mm in thickness and forming silver electrodes on these end faces, a DC electric field of 3 to 5 kV / mm is applied in silicon oil at 200 ° C for 30 minutes to perform polarization treatment. Was. Thereafter, the strips were polished to a thickness of 0.25 mm, silver electrodes were deposited on the upper and lower surfaces thereof, and the width was 1.
A 5 mm × 4.5 mm long thickness sliding mode piezoelectric element was produced.

The capacitance, the resonance / anti-resonance frequency, and the resonance resistance of these piezoelectric elements are measured by an impedance analyzer, and the mechanical quality factor (Q _m ) and the frequency constant in the fundamental vibration in the thickness-shear vibration mode are calculated. I asked. Further, the bending strength was evaluated by a four-point bending strength according to JISR1601. The obtained results are shown in Tables 1 and 2.

As a result of examining the crystal structure of the sample of the present invention, a perovskite-type XRD pattern as a main component and an XRD pattern of added ZrO ₂ were confirmed.

[0051]

[Table 1]

[0052]

[Table 2]

In the sample No. of the present invention, 3-7, 9-43
The mechanical quality factor (Q _m ) is 300 or more, especially 500 or more, the frequency constant is 1700 KHz · mm or more, and the bending strength is 180 MPa or more. It can be seen that both the workability and the piezoelectricity are excellent.

That is, the sample No. 1 to No. 8, it can be seen that if the contained stabilized ZrO ₂ or partially stabilized ZrO ₂ is within the range, a bending strength of 180 MPa or more is exhibited. Sample No. out of range. In Nos. 1 and 2, the effect of improving the bending strength due to the inclusion was not observed, and Sample Nos. In No. 8, the sinterability was reduced, the bending strength was 180 MPa or less, and the mechanical quality factor (Q _m ) and the frequency constant were reduced.

The sample No. As shown in 9-13,
When zirconia stabilized with Y ₂ O ₃ , CaO, or MgO is used, all of the bending strength, the mechanical quality factor (Q _m ), and the frequency constant show excellent characteristics. In particular, Sample No. 1 using zirconia stabilized with Y ₂ O ₃ was used. In 4, 5, 10, and 11, the bending strength was 200 MPa or more, the mechanical quality factor (Qm) was 1100 or more, and the frequency constant was 1790 KHz.
・ It shows excellent characteristics of not less than mm. Sample No. containing zirconia partially stabilized with Y ₂ O ₃ was used. 9 also shows excellent characteristics in bending strength, mechanical quality factor (Q _m ), and frequency constant.

Further, the sample No. From 14 to 19, the range value of the Na content of the molar ratio x is 0.95 to 1.02 in the main component, the mechanical quality factor (Q _m) is 500 or more, frequency constant 1700kHz or more, bending strength of more than 210MPa It can be seen that it is. It can be seen that the mechanical quality factor (Q _m ) increases as the value of x decreases, and shows a peak near 0.98.

[0057] subcomponent _{(M1 1-a Bi a)} (Li 1-b M2 b)
O mole fraction of _f (content ratio) y is 0.08 or less, for example, Sample No. 20 to 24 are mechanical quality factors (Q _m )
Is 500 or more, the frequency constant is 1800 kHz or more, and the bending strength is 200 MPa or more.

Sample No. As shown 25-37, when subcomponent _{(M1 1-a Bi a)} (Li 1-b M2 b) of O _f M1, Bi amount a and M2, Li amount b is in the range of the present invention,
It can be seen that the frequency constant is maintained at 1800 kHz · mm or more while exhibiting high bending strength and a mechanical quality factor (Q _m ).

Further, the sample No. From 38-40, the amount of the first transition metal is in the range of 0.01 to 3 wt%, the mechanical quality factor (Q _m) is 500 or more, frequency constant 1700kH
It is understood that the bending strength is 200 MPa or more. In particular, it can be seen that when the content is 1% by weight, pake is exhibited.

[0060]

According to the piezoelectric ceramic of the present invention, a perovskite-type composite oxide containing at least Na and Nb as metal elements is used as a main component, and partially stabilized zirconia particles and / or stabilized zirconia particles are contained in a total amount of 0.3%. ~ 3
% By weight, the partially stabilized zirconia particles and / or the stabilized zirconia particles are
Since there is almost no solid solution reaction with the perovskite-type composite oxide particles and they are present at the grain boundary, the grain growth of the perovskite-type composite oxide can be suppressed, the structure can be refined, and the bending strength can be improved.

Further, partially stabilized zirconia particles and / or
Alternatively, since the stabilized zirconia particles do not show abnormal expansion due to martensitic transformation around 1100 ° C., a large number of microcracks that cause electrical deterioration do not occur in the porcelain containing a perovskite-type composite oxide as a main component. Even if the amount of addition is increased, the electrical characteristics are not significantly reduced.

By having a specific composition as the perovskite-type composite oxide, particularly, a mechanical quality factor (Qm) of 500 or more and a frequency constant of 1700 KHz · mm or more when utilizing the thickness-slip mode are excellent. In addition, the bending strength can be 180 MPa or more, the breakage of the piezoelectric ceramic can be prevented, and the workability can be improved.

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Claims (6)

[Claims] (1) As a metal element, at least Na and N
A piezoelectric ceramic comprising a perovskite-type composite oxide containing b as a main component, and 0.3 to 3% by weight of the total amount of partially stabilized zirconia particles and / or stabilized zirconia particles. 2. The piezoelectric ceramic according to claim 1, wherein the partially stabilized zirconia particles and / or the stabilized zirconia particles contain 4 to 12 mol% of Y ₂ O ₃ . 3. The method according to claim 1, wherein the perovskite-type composite oxide is Na _x Nb.
_3. The piezoelectric ceramic according to claim 1, wherein O ₃ (where 0.95 ≦ x ≦ 1.02) is satisfied. Wherein the composition formula by molar ratio of the perovskite-type composite _{oxide, (1-y) Na x} NbO 3 -y (M1 1-a B
i _a) (when expressed as _{Li 1-b M2 b) O} f, wherein M1 is K, Na, Li, Ba, Sr, at least one of Ca and Mg, wherein M2 is Ti, V, Nb, Ta And at least one of Sb and x, y, a, b
4. The piezoelectric device according to claim 1, wherein f and f satisfy 0.95 ≦ x ≦ 1.02 y ≦ 0.080 0 ≦ a ≦ 10 <b ≦ 1 f. porcelain. 5. The piezoelectric ceramic according to claim 1, wherein at least one of the first transition metals is contained in an amount of 0.01 to 3% by weight in terms of oxide. 6. A piezoelectric resonator having a pair of electrodes formed on opposing surfaces of a piezoelectric substrate, wherein the piezoelectric substrate is made of the piezoelectric ceramic according to any one of claims 1 to 5. Characteristic piezoelectric resonator.