JP2004244299A - Piezoelectric ceramic composition, its production method, piezoelectric element, and dielectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic composition which is lead-free, has high piezoelectric characteristics, and high dielectric characteristics, and is excellent in, especially, at least one of a piezoelectric charge constant d<SB>31</SB>, a relative permittivity, a dielectric loss, and a Curie temperature Tc, to provide its production method, and to provide a piezoelectric element and a dielectric element using the piezoelectric ceramic composition. <P>SOLUTION: The piezoelectric ceramic composition mainly consists of a compound represented by the formula: äLi<SB>x</SB>(K<SB>1-y</SB>Na<SB>y</SB>)<SB>1-x</SB>}(Nb<SB>1-z-w</SB>Ta<SB>z</SB>Sb<SB>w</SB>)O<SB>3</SB>(wherein x, y, z, and w are in the ranges: 0≤x≤0.2, 0≤y≤1, 0<z≤0.4, and 0<w≤0.2, respectively). This composition contains as an additive element at least one metallic element selected from among Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. The total content of the additive is 0.001 to 0.15 mol per mol of the compound represented by the formula. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a piezoelectric ceramic composition containing no lead in the composition, a method for producing the same, and a piezoelectric element and a dielectric element using the piezoelectric ceramic composition as a material.

Conventionally, a PZT (PbTiO ₃ -PbZrO ₃ ) component-based ceramic containing lead has been used as a piezoelectric ceramic composition. This is because PZT exhibits large piezoelectricity and has a high mechanical quality factor, and can easily produce materials having various characteristics required for each application such as a sensor, an actuator, and a filter.
Further, since the PZT has a high relative dielectric constant, it can be used as a capacitor or the like.

However, while the piezoelectric ceramic composition comprising PZT has excellent properties, it contains lead as a constituent element, so that harmful lead is eluted from industrial waste of products containing PZT, resulting in environmental pollution. Could be caused. And, increasing awareness of environmental issues in recent years has made it difficult to manufacture products that can cause environmental pollution, such as PZT. Therefore, development of a piezoelectric ceramic composition containing no lead in the composition has been demanded, and a piezoelectric ceramic composition represented by the general formula (K _1-x Na _x ) NbO ₃ (where 0 <x <1) (See Non-Patent Document 1).

However, the piezoelectric ceramic composition represented by the general formula (K _1-x Na _x ) NbO ₃ (where 0 <x <1) has a piezoelectric d ₃₁ constant, an electromechanical coupling coefficient Kp, a piezoelectric g ₃₁ constant, There is a problem that the piezoelectric characteristics such as the mechanical quality factor Qm are low. Therefore, for example, high piezoelectric d ₃₁ constant piezoelectric actuator that requires, piezoelectric filters, piezoelectric transducers, piezoelectric transformers, piezoelectric ultrasonic motor, a piezoelectric gyro sensors, knock sensors, yaw rate sensors, airbag sensors, back sonar, corner sonar, It has been difficult to apply to piezoelectric elements such as a piezoelectric buzzer, a piezoelectric speaker, and a piezoelectric igniter.

Further, the piezoelectric ceramic composition represented by the above general formula has a low dielectric property such as a relative dielectric constant ε _33T / ε ₀ and a dielectric loss tan δ, so that it is difficult to apply the composition to a dielectric element such as a capacitor. there were.
"Journal of the American Ceramic Society", USA, 1962, Vol. 45, no. 5, p. 209

The present invention has been made in view of such conventional problems, does not contain lead, have high piezoelectric properties and dielectric properties, in particular the piezoelectric d ₃₁ constant, dielectric constant, dielectric loss, and the Curie temperature Tc An object of the present invention is to provide a piezoelectric ceramic composition excellent in any one or more of the above, a method of manufacturing the same, and a piezoelectric element and a dielectric element using the piezoelectric ceramic composition.

The first invention of the general formula represented by _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w, respectively 0 A piezoelectric ceramic composition mainly comprising a compound having a composition range of ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, and 0 <w ≦ 0.2,
The piezoelectric ceramic composition comprises, as an additive element, at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt.
The piezoelectric ceramic composition according to claim 1, wherein the total content of the additional elements is 0.001 mol to 0.15 mol per 1 mol of the compound represented by the general formula (claim 1).

Next, the operation and effect of the present invention will be described.
The piezoelectric ceramic composition of the present invention does not contain lead in the composition.
Therefore, the piezoelectric ceramic composition is safe because harmful lead does not leak from the waste and the like to nature.

Further, the piezoelectric ceramic composition contains a compound represented by the above general formula, and x, y, z, and w in the above general formula are respectively in the above ranges.
Therefore, the piezoelectric ceramic composition, the piezoelectric d ₃₁ constant, electromechanical coupling factor Kp, piezoelectric properties such as piezoelectric g ₃₁ constant, the dielectric constant ε _33T / ε _0, dielectric properties such as dielectric loss tan [delta, also the Curie temperature Tc Is excellent.
Note that does not contain the additive element, a composition represented by the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, less Where appropriate, referred to as the "basic composition".

Further, the piezoelectric ceramic composition may be any one or more selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt in addition to the compound having the basic composition represented by the general formula. Metal elements are contained as additive elements in the total content range described above. Therefore, the piezoelectric ceramic composition of the present invention comprises at least one of a piezoelectric d ₃₁ constant, a piezoelectric g ₃₁ constant, an electromechanical coupling coefficient Kp, a relative permittivity _{33 33T} / ε ₀ , a dielectric loss tan δ, and a Curie temperature Tc. Are further improved, and are more excellent than the piezoelectric ceramic composition represented by the above general formula and not containing the above-mentioned additive element.
In the piezoelectric ceramic composition, the additive element may be added to the compound represented by the general formula by substitution, or may be externally added to the compound represented by the general formula. May be contained.

As described above, the piezoelectric ceramic composition of the present invention is safe for the environment because it does not contain lead, and has excellent piezoelectric characteristics, so that it can be used as a high-performance piezoelectric element.
Further, the piezoelectric ceramic composition is excellent in dielectric properties such as relative permittivity and dielectric loss in addition to the above piezoelectric properties. Therefore, it can also be used as a high-performance dielectric element. That is, the piezoelectric ceramic composition according to the first aspect of the invention is not limited to the piezoelectric ceramic composition having piezoelectric characteristics, but also includes a dielectric ceramic composition having dielectric characteristics.

The second invention of the general formula represented by _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w, respectively 0 A compound having a composition range of ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, and Pd, Ag, Au, Ru, Rh, Re, Os, There is provided a method for producing a piezoelectric ceramic composition, characterized by mixing with an additive containing at least one metal element selected from Ir and Pt, followed by firing (claim 19).

A mixture obtained by mixing the compound represented by the general formula and the additive can be sintered under normal pressure. Therefore, sintering can be performed easily and at low cost. The piezoelectric ceramic composition obtained after the calcination does not contain lead, the piezoelectric d ₃₁ constant and piezoelectric characteristics such as electromechanical coupling factor Kp, also the excellent dielectric properties such as dielectric loss and dielectric constant Become. Therefore, it can be used as a material for a high-performance piezoelectric element or dielectric element.

Further, in the production method of the present invention, the above-mentioned metal element may be added to the compound represented by the above general formula, or may be externally added.
In addition, in the piezoelectric ceramic composition obtained after the firing, as a result of the addition of the additive, at least one of Li, K, Na, Nb, Ta, and Sb of the compound represented by the general formula is added. Is replaced by at least one kind of metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt, or the metal element or an oxide containing the same. Or, it is contained as a perovskite structure compound in the grains or in the grain boundaries in the piezoelectric ceramic composition. In this specification, “containing an additive” has the same meaning as described above.

According to a third aspect of the present invention, a compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and a compound containing Sb are fired. after represented by the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w respectively 0 ≦ x ≦ 0. 2,0 ≦ y ≦ 1,0 <z ≦ 0.4,0 <w ≦ 0.2 at a stoichiometric ratio which results in a compound in the composition range, or a metal contained in the following additives Mix at a stoichiometric ratio in consideration of substitution by elements, and further mix an additive containing at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. And a method of producing a piezoelectric ceramic composition, characterized by firing.

In the third invention, as described above, a compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and a compound containing Sb are contained. And an additive containing at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt at the above stoichiometric ratio. Bake.
Thereby, the piezoelectric ceramic composition of the first invention can be easily obtained.

  Further, in the piezoelectric ceramic composition obtained after the firing, as a result of the addition of the additives, the compounds represented by the general formulas Li, K, Na, Nb, At least a part of any one or more of Ta and Sb is contained by replacing with at least one metal element selected from the above Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. In addition, the metal element or a compound containing the metal element or an oxide or a perovskite structure compound is contained in the piezoelectric ceramic composition in the grains or in the grain boundaries.

  At this time, the compound containing Li, the compound containing Na, the compound containing K, the compound containing Nb, the compound containing Ta, the compound containing Sb, and the above-mentioned additive are combined. When mixed at a stoichiometric ratio in consideration of substitution by a metal element contained in the additive, Li, Na, K, Nb, Ta, and Sb in the compound represented by the above general formula are mixed. At least a part of any one or more of them can be positively substituted by the metal element contained in the additive.

The above “mixing at a stoichiometric ratio in consideration of the substitution by the metal element contained in the additive” refers to, for example, a case where Li of the compound represented by the general formula is substituted for the metal element of the additive. Is to reduce the amount of the compound containing Li, add the above-mentioned additives by the reduced amount and mix, and as a whole, after firing, the general formula {Li _x (K _1-y Na _y ) _1-x } by such the compound represented by _{(Nb 1-zw Ta z Sb} w) O 3 are mixed at a stoichiometric ratio as synthesized, can be realized. In the case of substituting other atoms such as K, Na, Nb, Ta and Sb in the above general formula, the amount of the compound containing these should be reduced and an additive containing the metal element to be substituted should be added accordingly. And so on. For example, when adding replacing Ag is as _{{Li x (K 1-y} Na y) 1-xu Ag u} (Nb 1-zw Ta z Sb w) O 3.

On the other hand, in the above general formula after firing _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) a compound represented by O ₃ such stoichiometric ratio, A compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and a compound containing Sb are mixed, and the above additive is added thereto. Is further mixed and fired, whereby a piezoelectric ceramic composition containing the above-mentioned additive as the above-mentioned metal element or an oxide or a perovskite structure compound containing the same can be positively produced.

  In the third aspect, the firing can be performed under normal pressure. Then, the piezoelectric ceramic composition obtained after the above-mentioned firing does not contain lead and has excellent piezoelectric characteristics and dielectric characteristics. Therefore, it can be used as a material for high-performance piezoelectric elements and dielectric elements.

  A fourth invention resides in a piezoelectric element having a piezoelectric body made of the piezoelectric ceramic composition of the first invention (claim 22).

The piezoelectric element according to the fourth aspect has a piezoelectric body made of the piezoelectric ceramic composition according to the first aspect (claim 1). Therefore, the piezoelectric element does not contain lead and is environmentally safe.
Further, the piezoelectric element includes the above piezoelectric ceramic composition, can be used as it is the nature of the piezoelectric properties such as piezoelectric d _{3 1} constant excellent. Therefore, the piezoelectric element can be used as a piezoelectric sensor element having high sensitivity, a piezoelectric vibrator having high electromechanical energy conversion efficiency, an actuator element, and the like.

  A fifth invention resides in a piezoelectric element having a piezoelectric body made of a piezoelectric ceramic composition manufactured by the manufacturing method of the second or third invention (claim 23).

  The piezoelectric element according to the fifth aspect of the present invention has a piezoelectric body made of the piezoelectric ceramic composition obtained by the above-described manufacturing method. Therefore, the piezoelectric element can be used as a piezoelectric sensor element having high sensitivity, a piezoelectric vibrator having high electromechanical energy conversion efficiency, an actuator element, and the like, utilizing the excellent characteristics of the piezoelectric ceramic composition as it is.

  A sixth invention resides in a dielectric element having a dielectric made of the piezoelectric ceramic composition of the first invention (claim 24).

  The dielectric element of the sixth invention has a dielectric made of the piezoelectric ceramic composition of the first invention. Therefore, the dielectric element does not contain lead and is environmentally safe. Further, the dielectric element can utilize the property of the piezoelectric ceramic composition, which is excellent in relative permittivity and dielectric loss, as it is. Therefore, it can be used as a capacitor having a large capacitance.

  According to a seventh aspect, there is provided a dielectric element having a dielectric comprising a piezoelectric ceramic composition manufactured by the manufacturing method of the second or third aspect (claim 25).

  The dielectric element of the seventh invention has a dielectric made of the piezoelectric ceramic composition obtained by the above-described manufacturing method. Therefore, the dielectric element can be used as a capacitor or the like having a large capacitance by utilizing the excellent characteristics of the piezoelectric ceramic composition as it is.

Above in the first invention to third invention, the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) compound represented by the O ₃ is, x , Y, z, and w are in the range of 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, and 0 <w ≦ 0.2, respectively.
Here, in the case of x> 0.2, z> 0.4, w> 0.2, z = 0, or w = 0, the piezoelectric and dielectric properties such as a piezoelectric d ₃₁ constant is reduced, desired It may not be possible to obtain a piezoelectric ceramic composition having the following characteristics.
In the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) compound represented by O _3, the range of y is, 0 ≦ y ≦ 0. It is more preferably 85, and further preferably 0.05 ≦ y ≦ 0.75. In these cases, the piezoelectric d31 constant and the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition can be further improved. Still more preferably, 0.05 ≦ y <0.75, more preferably 0.35 ≦ y ≦ 0.65, and even more preferably 0.35 ≦ y <0.65. Most preferably, 0.42 ≦ y ≦ 0.60 is good.

As described above, the piezoelectric ceramic composition contains a compound having a perovskite structure (ABO ₃ ) as a main component. In the present invention, the element configuration of the A site in the perovskite structure (ABO ₃ ) corresponds to K, Na or K, Na, and Li, and the element configuration of the B site corresponds to Nb, Ta, and Sb. In the composition formula of the perovskite structure, when the stoichiometric ratio of the atoms constituting the A site and the atoms constituting the B site is 1: 1, a complete perovskite structure is obtained. In particular, K, Na, Li, and Sb are volatilized by several%, specifically, about 3% in a firing step or the like, and all constituent elements are mixed by several% in a mixing pulverization or granulation step, and specifically, It may fluctuate by about 3%. That is, the stoichiometric composition may fluctuate due to variations in the manufacturing method.

  In order to cope with such compositional fluctuations in the manufacturing process, the compositional ratio of the piezoelectric ceramic composition after firing is increased by ± several%, more specifically ± 3 to 5 by intentionally changing the composition ratio. %. This is the same for, for example, the conventional zirconate titanate (PZT), and the mixing ratio is adjusted in consideration of the evaporation of lead during firing and the incorporation of zirconia from zirconia balls as grinding media. be able to.

In the piezoelectric ceramic composition of the present invention, electrical characteristics such as piezoelectric characteristics do not significantly change even if the composition ratio is intentionally changed as described above.
Accordingly, in the present invention, the general formula _{Li x (K 1-y Na} y) 1-x} (Nb 1-zw Ta z Sb w) compound represented by O _3, this a perovskite structure formula When applied to ABO ₃ , the composition ratio of A-site atoms and B-site atoms can be shifted to about ± 5 mol% with respect to 1: 1. In order to reduce lattice defects in the formed crystal and obtain high electrical characteristics, the composition is preferably up to about ± 3%.
That is, the general compound of formula as the main component of the piezoelectric ceramic _{composition, [Li x (K 1-} y Na y) 1-x] a {(Nb 1-zw Ta z Sb w)} _b O ₃ (0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05) Including. Further, as described above, in the above equation, the range of a and b is preferably 0.97 ≦ a, b ≦ 1.03.

Similarly, the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) range of x of O ₃ is preferably 0 <x ≦ 0.2 .
In this case, since Li is an essential component, the piezoelectric ceramic composition can be more easily fired at the time of its production, further improve the piezoelectric characteristics, and further increase the Curie temperature Tc. Can be. This is because by making Li an essential component within the above range, the firing temperature is lowered, and Li plays the role of a firing aid, enabling firing with few voids.

The value of x in the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3 can be the x = 0.
In this case, the general formula is represented by _{(K 1-y Na y)} (Nb 1-zw Ta z Sb w) O 3. In this case, when preparing the piezoelectric ceramic composition, since the raw material does not include a compound containing the lightest Li such as LiCO ₃ , the raw materials are mixed and the piezoelectric ceramic is mixed. Variations in characteristics due to segregation of the raw material powder when producing the composition can be reduced. In this case, a high relative dielectric constant and a relatively large piezoelectric g constant can be realized.

  Further, in the first invention, the piezoelectric ceramic composition contains, as an additive element, at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. The total content of the additional elements is 0.001 mol to 0.15 mol based on 1 mol of the compound represented by the general formula.

If the total of the content is less than 0.001 mol, or if more than the 0.15 mol, the piezoelectric d ₃₁ constant, etc. of the piezoelectric ceramic composition is reduced to obtain a piezoelectric ceramic composition having a desired piezoelectric characteristics May not be possible.
The content of the additional element is the number of moles of each metal element of Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt.

Also, the additional element of the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3 compound represented by Li, K, Na, Nb , Ta, Sb, at least a part of which is replaced by at least one metal element selected from the group consisting of Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt; The piezoelectric ceramic composition may be in the form of an element or an oxide containing the element or a compound such as a perovskite structure compound in a grain or a grain boundary of the piezoelectric ceramic composition.

In particular, metal elements that can be +1 or +2, such as Ag, Pd, and Au, can be arranged by replacing at least a part of Li, K, and Na of the compound represented by the above general formula. On the other hand, with respect to metal elements that can have a valence of +3 to +6, such as Pd, Ru, Rh, Re, Os, Ir, and Pt, at least a part of Nb, Ta, and Sb of the compound represented by the above general formula is substituted. Can also be placed. Then, by taking the form of such substituents solid solution, further it is possible to further improve the characteristics such as a piezoelectric d ₃₁ constant.

Next, the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition is represented by the above general formula, is preferably larger than the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing no additive element (claim 2) .
Represented by the above general formula, is larger than the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing no additive element (hereinafter referred to suitably basic piezoelectric ceramic composition) may sufficiently the effect of the additive element Capable of piezoelectric actuator, piezoelectric filter, piezoelectric vibrator, piezoelectric transformer, piezoelectric ultrasonic motor, piezoelectric gyro sensor, knock sensor, yaw rate sensor, airbag sensor, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric ignition Application to a piezoelectric element such as a vessel becomes easier.

"Represented by the above general formula, is larger than the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing no additive element" described above and, the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing the above additive element , as compared to the basic piezoelectric ceramic composition containing no additive element has a base composition of the piezoelectric ceramic composition, is intended to mean that a large electromechanical coupling factor Kp that will be described later, the piezoelectric g ₃₁ constant The same applies to the relative dielectric constant, dielectric loss, Curie temperature Tc.

Next, the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition is represented by the general formula, and is preferably larger than the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition not containing the additional element. 3).
When the piezoelectric ceramic composition (basic piezoelectric ceramic composition) represented by the general formula and not containing the additive element is larger than the electromechanical coupling coefficient Kp, the effect of the additive element can be sufficiently obtained. Capable, piezoelectric actuator, piezoelectric filter, piezoelectric vibrator, piezoelectric transformer, piezoelectric ultrasonic motor, piezoelectric gyro sensor, knock sensor, yaw rate sensor, airbag sensor, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric igniter, etc. Is more easily applied to the piezoelectric element.

Next, the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition is represented by the above general formula, is preferably larger than the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition containing no additive element (claim 4) .
Represented by the above general formula, is larger than the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition containing no additive element (basic piezoelectric ceramic composition) can be obtained sufficiently the effect of the additive element , Piezoelectric actuator, piezoelectric filter, piezoelectric vibrator, piezoelectric transformer, piezoelectric ultrasonic motor, piezoelectric gyro sensor, knock sensor, yaw rate sensor, airbag sensor, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric igniter, etc. Application to a piezoelectric element becomes easier.

Next, it is preferable that the relative dielectric constant of the piezoelectric ceramic composition is represented by the general formula and is higher than the relative dielectric constant of the piezoelectric ceramic composition not containing the additional element.
When the relative dielectric constant of the piezoelectric ceramic composition represented by the general formula and not containing the additive element (basic piezoelectric ceramic composition) is larger than that of the piezoelectric ceramic composition, the effect of the additive element can be sufficiently obtained. Application to dielectric elements such as capacitors becomes easier.

Next, it is preferable that the dielectric loss of the piezoelectric ceramic composition is represented by the general formula and is smaller than the dielectric loss of the piezoelectric ceramic composition not containing the additional element.
When the dielectric loss of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) which is represented by the general formula and does not contain the additive element is smaller than that of the piezoelectric ceramic composition, the effect of the additive element can be sufficiently obtained, and And the like, application to dielectric elements becomes easier.

Next, it is preferable that the Curie temperature Tc of the piezoelectric ceramic composition is represented by the general formula and is higher than the Curie temperature Tc of the piezoelectric ceramic composition not containing the additional element (claim 7).
When the temperature is higher than the Curie temperature of the piezoelectric ceramic composition represented by the general formula and not containing the additive element (basic piezoelectric ceramic composition), the effect of the additive element can be sufficiently obtained. It is easier to use in an environment with a high temperature exceeding 100 ° C., such as near an engine of a car.

Next, the piezoelectric ceramic composition is preferably a piezoelectric d ₃₁ constant is 30 Pm/V more (claim 8).
In this case, a piezoelectric actuator, a piezoelectric filter, a piezoelectric vibrator, a piezoelectric transformer, a piezoelectric ultrasonic motor, a piezoelectric gyro sensor, and a knock sensor are used to take advantage of the piezoelectric d ₃₁ constant as high as 30 pm / V or more. It can be used as a yaw rate sensor, airbag sensor, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric igniter, and the like.
Above for the piezoelectric d ₃₁ constant is less than 30 Pm/V, it may not be used as a piezoelectric element sufficiently endure characteristics for practical use.

Further, in order to obtain a piezoelectric sensor characteristics or larger piezoelectric actuator characteristics more excellent in sensitivity, it is more preferable that the piezoelectric d ₃₁ constant is 40 Pm/V more. More preferably, it is 80 pm / V or more. Still more preferably, it is 100 pm / V or more.

Next, the piezoelectric ceramic composition preferably has an electromechanical coupling coefficient Kp of 0.30 or more.
In this case, utilizing the high electromechanical coupling coefficient Kp of 0.30 or more, the piezoelectric ceramic composition can be converted into a piezoelectric actuator, a piezoelectric filter, a piezoelectric vibrator, a piezoelectric transformer, It can be used as a piezoelectric ultrasonic motor, piezoelectric gyro sensor, knock sensor, yaw rate sensor, airbag sensor, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric igniter, and the like.

When the electromechanical coupling coefficient Kp is less than 0.30, there is a possibility that the piezoelectric ceramic composition cannot be used for a piezoelectric element requiring excellent conversion efficiency between the mechanical energy and the electric energy. .
In order to obtain a more excellent conversion efficiency between mechanical energy and electric energy, the electromechanical coupling coefficient Kp is more preferably 0.34 or more. More preferably, it is 0.4 or more. Still more preferably, it is 0.5 or more.

Next, it is preferable that the piezoelectric ceramic composition has a piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N or more (claim 10).
In this case, the piezoelectric ceramic composition is used as a piezoelectric transformer, an ultrasonic motor element, a sensor element, and the like having an excellent step-up ratio by utilizing the high piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N or more. be able to.

If the piezoelectric g ₃₁ constant is less than 7 × 10 ⁻³ Vm / N, the piezoelectric ceramic composition may not be able to be used for a piezoelectric element requiring an excellent boost ratio.
Further, in order to obtain a more excellent step-up ratio, the piezoelectric g ₃₁ constant is more preferably 8 × 10 ⁻³ Vm / N or more.

Next, the piezoelectric ceramic composition preferably has a relative dielectric constant of 400 or more (claim 11).
In this case, the piezoelectric ceramic composition can be used as a dielectric element such as a capacitor having a large capacitance by utilizing a high relative dielectric constant of 400 or more.

If the relative dielectric constant is less than 400, the capacitance may decrease, and the piezoelectric ceramic composition may not be used as a dielectric element such as a capacitor.
Further, the relative permittivity is preferably 430 or more. More preferably, it is 600 or more.

Next, the piezoelectric ceramic composition preferably has a dielectric loss of 0.09 or less (claim 12).
In this case, the piezoelectric ceramic composition can be converted to a dielectric element such as a capacitor, a piezoelectric actuator, a piezoelectric filter, a piezoelectric vibrator, a piezoelectric transformer, a piezoelectric ultrasonic motor, and a piezoelectric gyro sensor by utilizing a low dielectric loss of 0.09 or less. , Knock sensors, yaw rate sensors, airbag sensors, back sonars, corner sonars, piezoelectric buzzers, piezoelectric speakers, and piezoelectric igniters.

  When the dielectric loss exceeds 0.09, the piezoelectric ceramic composition may not be used as a dielectric element such as a capacitor, a piezoelectric transformer element, an ultrasonic motor element, or the like. Therefore, more preferably, the dielectric loss is 0.035 or less. More preferably, the value is 0.025 or less.

Next, the piezoelectric ceramic composition preferably has a Curie temperature Tc of 200 ° C. or higher (claim 13).
In this case, by utilizing the high Curie temperature Tc of 200 ° C. or more, the piezoelectric ceramic composition can be used in a high temperature environment exceeding 100 ° C., for example, near an engine of an automobile.
When the Curie temperature Tc is lower than 200 ° C., when the piezoelectric ceramic composition is used in a high temperature place, for example, near the engine of an automobile, its properties such as a piezoelectric d ₃₁ constant and an electromechanical coupling coefficient Kp are deteriorated. There is a possibility that. Therefore, it is more preferable that the Curie temperature Tc is 250 ° C. or higher.

Next, the piezoelectric ceramic composition preferably has a piezoelectric d ₃₁ constant of 30 pm / V or more and a Curie temperature Tc of 200 ° C. or more (claim 14).
In this case, the piezoelectric ceramic composition can be used as a highly sensitive sensor element, ultrasonic motor element, actuator element, piezoelectric transformer element, piezoelectric vibrator, and the like under a high temperature environment exceeding 100 ° C. .
In order to obtain an excellent piezoelectric sensor characteristic or a larger piezoelectric actuator characteristics of more sensitive, it is preferable that the piezoelectric d ₃₁ constant is 40 Pm/V more. More preferably, it is 80 pm / V or more. Still more preferably, the piezoelectric d ₃₁ constant is preferably 100 pm / V or more.
Further, the Curie temperature Tc is more preferably 250 ° C. or higher.

Next, the piezoelectric ceramic composition preferably has a piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N or more and a Curie temperature Tc of 200 ° C. or more (claim 15).
In this case, the piezoelectric ceramic composition can be used as a piezoelectric transformer, an ultrasonic motor element, a sensor element, or the like having an excellent step-up ratio under a high temperature environment exceeding 100 ° C.
Further, in order to obtain a more excellent boost ratio, the piezoelectric g ₃₁ constant is more preferably 8 × 10 ⁻³ Vm / N or more.
Further, the Curie temperature Tc is more preferably 250 ° C. or higher.

Next, it is preferable that the piezoelectric ceramic composition has an electromechanical coupling coefficient Kp of 0.3 or more and a Curie temperature Tc of 200 ° C. or more.
In this case, in a high temperature environment exceeding a temperature of 100 ° C., the piezoelectric ceramic composition can be converted into a piezoelectric actuator element, a piezoelectric vibrator, a sensor element, a piezoelectric transformer element, an ultrasonic wave element having excellent conversion efficiency between mechanical energy and electric energy. It can be used as a motor element or the like.
In order to obtain a more excellent conversion efficiency between mechanical energy and electric energy, the electromechanical coupling coefficient Kp is more preferably 0.34 or more. More preferably, it is 0.4 or more.
Further, the Curie temperature Tc is more preferably 250 ° C. or higher.

Next, it is preferable that the piezoelectric ceramic composition has a dielectric loss of 0.09 or less and a Curie temperature Tc of 200 ° C. or more (claim 17).
In this case, the piezoelectric ceramic composition can be used as a dielectric element such as a capacitor, a piezoelectric transformer element, an ultrasonic motor element, a sensor element, and the like under a high temperature environment exceeding 100 ° C.
More preferably, the dielectric loss is 0.035 or less. More preferably, it is 0.02 or less.
Further, the Curie temperature Tc is more preferably 250 ° C. or higher.

Next, the piezoelectric ceramic composition preferably has a piezoelectric d ₃₁ constant of 30 pm / V or more, an electromechanical coupling coefficient Kp of 0.3 or more, and a Curie temperature Tc of 200 ° C. or more. 18).
In this case, the piezoelectric ceramic composition can be used in a high-temperature environment exceeding 100 ° C., and can have excellent sensitivity and conversion efficiency between mechanical energy and electric energy.
Further, more excellent piezoelectric sensor characteristics of sensitivity, or to obtain a larger piezoelectric actuator characteristics, it is more preferable that the piezoelectric d ₃₁ constant is 40 Pm/V more. Further, the electromechanical coupling coefficient Kp is more preferably 0.34 or more.

In the second (claim 19) or the third invention (claim 20), the additive is selected from the group consisting of Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. There are more than one kind of metal element or a compound containing these metal elements.
As a result of adding the additives, as the metal element additive element contained in the additive formula after the burning _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb _w ) In some cases, Li, K, Na, Nb, Ta, and Sb of the compound represented by O ₃ are substituted for at least a part of the compound and contained in the piezoelectric ceramic composition. In addition, the metal element or a compound containing the metal element, such as an oxide or a perovskite structure compound, may be contained in the piezoelectric ceramic composition in the grains or at the grain boundaries.

In the third invention (claim 20), examples of the lithium-containing compound include Li ₂ CO ₃ , Li ₂ O, LiNO ₃ , and LiOH. The sodium-containing compounds include Na ₂ CO ₃ , NaHCO ₃ and NaNO ₃ .

Examples of the potassium-containing compound include K ₂ CO ₃ , KNO ₃ , KNbO ₃ , and KTaO ₃ . Examples of the compound containing the above-mentioned niobium, for example _{Nb 2 O 5, Nb 2 O} 3, there is NbO ₂ and the like. Examples of the tantalum-containing compound include Ta ₂ O ₅ . Examples of the compound containing the above antimony, for example, a _{Sb 2 O 5, Sb 2 O} 3, Sb 2 O 4 or the like.

Next, the compound containing Li is Li ₂ CO ₃ , the compound containing Na is Na ₂ CO ₃ , the compound containing K is K ₂ CO ₃ , and the compound containing Nb is Nb ₂ O _5. , The compound containing Ta is Ta ₂ O ₅ , the compound containing Sb is Sb ₂ O ₅ or Sb ₂ O ₃ , and the additive is PdO ₂ , Ag ₂ O, Au, Au ₂ O, Ru _{2 O, RhO, Re 2 O 5} , OsO 2, IrO 2, and it is preferable that any one or more selected from PtO ₂ (claim 21).
In this case, the piezoelectric ceramic composition can be easily produced.

  Next, in the fourth (invention 22) or the fifth invention (invention 23), the piezoelectric element includes, for example, a piezoelectric actuator, a piezoelectric filter, a piezoelectric vibrator, a piezoelectric transformer, a piezoelectric ultrasonic motor, a piezoelectric gyro. There are sensors, knock sensors, yaw rate sensors, airbag sensors, back sonars, corner sonars, piezoelectric buzzers, piezoelectric speakers, and piezoelectric igniters.

  Next, in the sixth (invention 24) or the seventh invention (invention 25), examples of the dielectric element include a capacitor and a multilayer capacitor.

(Example 1)
Next, a piezoelectric ceramic composition according to an example of the present invention will be described.
In this example, the piezoelectric ceramic composition is manufactured and its characteristics are measured.
The piezoelectric ceramic composition of this example is represented by the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w Are piezoelectric ceramic compositions containing, as main components, compounds having composition ranges of 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, and 0 <w ≦ 0.2, respectively. The piezoelectric ceramic composition contains, as an additive element, at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. The total content of the additional elements is 0.001 mol to 0.15 mol based on 1 mol of the compound represented by the general formula.

The method for producing the piezoelectric ceramic composition of the present example comprises a compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and a compound containing Sb. with a compound of the general formula after calcination _{{Li x (K 1-y} Na y) 1-x} is represented by _{(Nb 1-zw Ta z Sb} w) O 3, and x, y, z, w, respectively The compounds are mixed at a stoichiometric ratio such that the compounds fall within the composition ranges of 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, and 0 <w ≦ 0.2. , Ag, Au, Ru, Rh, Re, Os, Ir, Pt, and an additive containing at least one metal element is mixed and fired.

Hereinafter, the method for producing the piezoelectric ceramic composition of the present example will be described in detail.
First, as raw materials of the basic composition of the piezoelectric ceramic composition, high-purity Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Sb ₂ O _{5 with} a purity of 99% or more. And PdO ₂ , Ag ₂ O, Au, RuO ₂ , Re ₂ O ₇ , IrO ₂ , and PtO ₂ as the above additives.

Among these raw materials, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Sb ₂ O ₅ are converted to the above general formula ｛Li _x (K _1-y Na _{y ) 1-x} (Nb 1} -zw Ta z Sb w) at _{O 3, x, y, z} , w , respectively x = 0.04, y = 0.5, z = 0.1, w = 0. And a stoichiometric ratio such that the general formula becomes {Li _0.04 (K _0.5 Na _0.5 ) _0.96 ｝ (Nb _0.86 Ta _0.1 Sb _0.04 ) O _3. PdO ₂ , Ag ₂ O, Au, RuO ₂ , Re ₂ O ₇ , IrO ₂ , or PtO ₂ as the above additives were blended to obtain seven types of blends.

The compounding amount of the above-mentioned additive is based on 1 mol of the compound {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.86 Ta _0.1 Sb _0.04 ) O ₃ which is expected to be obtained by mixing at the above stoichiometric ratio. And 0.01 mol, 0.005 mol, 0.01 mol, 0.01 mol, 0.005 mol of PdO ₂ , Ag ₂ O, Au, RuO ₂ , Re ₂ O ₇ , IrO ₂ or PtO ₂ as the above-mentioned additives, respectively. , 0.01 mol, and 0.01 mol. That is, 0.01 mol of the metal element contained in each additive was blended.
Then, each of the above compounds was mixed in acetone by a ball mill for 24 hours to prepare a mixture.

Next, each of the mixtures was calcined at 750 ° C. for 5 hours, and then each of the calcined mixtures was ground with a ball mill for 24 hours. Subsequently, polyvinyl butyral was added as a binder and granulated.
Each of the granulated powders is pressed at a pressure of ² ton / cm ² into a disc having a diameter of 13 mm and a thickness of 2 mm, and the obtained compact is fired at a temperature of 1000 to 1300 ° C. for 1 hour. Was prepared. The specific firing temperature at this time was selected from the above-mentioned temperature range of 1000 ° C. to 1300 ° C. at which a fired body having the maximum density can be obtained by firing for one hour. At this time, all of the fired bodies were densified to a relative density of 98% or more.

Next, both sides of each fired body were polished in parallel and circularly polished, and then gold electrodes were provided on both sides of the disk sample by sputtering. Then, a DC voltage of 1 to 5 kV / mm was applied between the electrodes in a silicone oil at 100 ° C. for 10 minutes to polarize in the thickness direction to obtain a piezoelectric ceramic composition.
Thus, seven types of piezoelectric ceramic compositions (samples E1 to E7) were produced. Table 1 shows the mixing ratio of the raw materials and additives in each sample. Each sample in Table 1 was prepared by a method of externally adding each metal element in the additive.

In addition, as a method different from the production method of this example, a compound represented by the above {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.86 Ta _0.1 Sb _0.04 ) O ₃ is produced by firing, and this is pulverized. The same piezoelectric ceramic composition as that of the above-mentioned samples E1 to E7 can be produced by mixing with the above-mentioned additives and thereafter performing calcination, granulation, molding and firing in the same manner as in the production method of this example.

In the samples E1 to E7 of this example, PdO ₂ , Ag ₂ O, Au, RuO ₂ , Re ₂ O ₇ , IrO _2, or PtO ₂ as the above-mentioned additives are partially used as they are, A compound such as a perovskite structure compound is formed with at least one of the constituent elements Li, Na, K, Nb, Ta, and Sb, and in the form of a compound such as a perovskite structure within the grains or grain boundaries of each piezoelectric ceramic composition. At least one of Li, K, Na, Nb, Ta, and Sb of the compound represented by {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.86 Ta _0.1 Sb _0.04 ) O _3. It is considered that the Pd, Ag, Au, Ru, Re, Ir, or Pt atoms in each additive are contained in the respective parts in a state of being substituted. In particular, a metal element that can be +1 or +2, such as Ag, Pd, or Au, is easily replaced by at least a part of Li, K, and Na in the above compound. Further, a metal element which can have a valence of +3 to +6, such as Pd, Ru, Rh, Re, Os, Ir, and Pt, is easily replaced by at least a part of Nb, Ta, and Sb of the compound.

Next, in this example, in order to clarify the excellent characteristics of the piezoelectric ceramic composition, comparative products (sample C1 and sample C2) were prepared as follows.
First, high-purity Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Sb ₂ O ₅ having a purity of 99% or more were prepared as raw materials of comparative products.

These raw materials among _{K 2 CO 3, Na 2 CO} 3, and Nb and ₂ O _5, the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O ₃ , the stoichiometric ratio is such that x = z = w = 0 and y = 0.5, that is, the stoichiometric ratio is such that the above general formula is (K _0.5 Na _0.5 ) NbO _3. Then, the mixture was mixed in acetone by a ball mill for 24 hours to obtain a mixture.
This mixture was calcined, granulated, molded, fired, and polarized in the same manner as in Samples E1 to E7 to produce a piezoelectric ceramic composition (Sample C1) as a comparative product.
Sample C1 is a piezoelectric ceramic composition containing (K _0.5 Na _0.5 ) NbO ₃ .

Next, the sample C2 is manufactured as follows.
First, the raw materials Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Sb ₂ O ₅ prepared above are calcined, and after firing, the above general formula {Li _x ( in _{K 1-y Na y) 1} -x} (Nb 1-zw Ta z Sb w) O 3, x = 0.04, y = 0.5, and z = 0.1 and w = 0.04, At a stoichiometric ratio such that the general formula becomes a compound represented by {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.86 Ta _0.1 Sb _0.04 ) O ₃ . The mixture was mixed in a ball mill for 24 hours in acetone to obtain a mixture.

This mixture was calcined, granulated, molded, fired, and polarized in the same manner as in Samples E1 to E7 to produce a piezoelectric ceramic composition (Sample C2) as a comparative product.
Sample C2 contains the compound {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.86 Ta _0.1 Sb _0.04 ) O ₃ as a main component, similarly to the above samples E1 to E7, while containing the above-mentioned additional element. This is a piezoelectric ceramic composition which has not been prepared.
Table 1 shows the composition ratio of Sample C1 and Sample C2.

Next, the sample E1 to E7, the sample C1 and sample C2, the piezoelectric d ₃₁ constant, electromechanical coupling factor Kp, piezoelectric g ₃₁ constant, the dielectric constant ε _33T / ε _0, dielectric loss tan [delta, and the Curie temperature Tc Each was measured.

The piezoelectric d ₃₁ constant, the piezoelectric g ₃₁ constant, and the electromechanical coupling coefficient Kp were measured by a resonance-anti-resonance method using an impedance analyzer (Precision Impedance Analyzer 4294A manufactured by Agilent).
The dielectric loss tan δ and the relative permittivity ε _33T / ε ₀ were measured at a measurement frequency of 1 kHz using the same impedance analyzer as described above.
The Curie temperature Tc is defined as the temperature at which the relative dielectric constant ε _33T / ε ₀ is the highest.
Table 2 shows the results.

As can be understood from Table 2, the sample E1~ sample E7, the piezoelectric d ₃₁ constant, electromechanical coupling factor Kp, relative dielectric constant ε _33T / ε _0, and the dielectric loss tan [delta, conventional piezoelectric ceramic composition explained above The sample C1 had characteristics superior to those of the sample C1.
Further, the sample E1~ sample E7, even when compared to the sample C2, the piezoelectric d ₃₁ constant, electromechanical coupling factor Kp, piezoelectric g ₃₁ constant, the dielectric constant ε _33T / ε _0, dielectric loss tan [delta, Curie temperature Tc Had excellent characteristics of the same level or higher.
In particular, for the piezoelectric d ₃₁ constant, the total number of electrical solutions Kp, and the relative permittivity ε _33T / ε ₀ , most of the samples E1 to E7 are superior to the samples C1 and C2, and the dielectric loss tan δ is All of the samples E1 to E7 were superior to the samples C1 and C2.

Here, paying attention to the piezoelectric d ₃₁ constant, as can be seen from Table 2, the piezoelectric d ₃₁ constant of the sample E2 showed the highest value of 122.4 pm / V.

In the case of using the charge detection type circuit or a current detection type circuit is generally the piezoelectric d ₃₁ constant, the acceleration sensor, weighting sensor, is proportional to the output voltage of the piezoelectric type sensor, such as an impact sensor and the knock sensor. Viewed from that point, it is possible to piezoelectric d ₃₁ constant make a big sensor element of the charge sensor output higher piezoelectric ceramic composition. Then, in making a sensor element having a sample C1 least equivalent properties as a comparative product, it would be preferable to have a piezoelectric d ₃₁ constant over at least 30 pm/V. To generate a highly sensitive sensor element is further enhanced signal-to-noise ratio (SN ratio) and the output voltage, the piezoelectric d ₃₁ constant good not less than 80 pm/V. More preferably, it is 100 pm / V or more.

When used as actuators, generally the piezoelectric d ₃₁ constant is proportional to the generated distortion or displacement of the piezoelectric actuator. Viewed from that point, it is possible to piezoelectric d ₃₁ constant make a big actuator element of higher piezoelectric ceramic composition generates distortion or displacement. And making the actuator element having a comparative product equal or characteristics, it would be preferable to have a piezoelectric d ₃₁ constant over at least 30 pm/V. More preferably, it is 40 pm / V or more. To further prepare the large actuator displacement amount, the piezoelectric d ₃₁ constant good not less than 80 pm/V. More preferably, it is 100 pm / V or more.

  Focusing on the electromechanical coupling coefficient Kp, as can be seen from Table 2, the electromechanical coupling coefficient Kp of the sample E2 showed the highest value of 0.531.

  Generally, the electromechanical coupling coefficient Kp is proportional to the electromechanical energy conversion efficiency of a piezoelectric transformer element, an ultrasonic motor element, an actuator element, or an ultrasonic vibrator. From that point, a piezoelectric ceramic composition having a higher electromechanical coupling coefficient Kp can produce a piezoelectric transformer element, an ultrasonic motor element, an actuator element, or an ultrasonic transducer having higher electromechanical energy conversion efficiency. In order to manufacture a piezoelectric transformer element, an ultrasonic motor element, an actuator element, or an ultrasonic vibrator having characteristics equal to or higher than that of the sample C1, which is a comparative product, an electromechanical coupling coefficient Kp of at least 0.3 or more is required. It can be said that it is preferable to have. More preferably, it is 0.34 or more. More preferably, it is 0.4 or more. Further, it is even more preferably 0.5 or more.

Further, focusing on the Curie temperature Tc, the Curie temperatures Tc of the samples E1 to E7 all have high values of 200 ° C. or higher. For this reason, the piezoelectric ceramic composition (samples E1 to E7) of the present example can be used for a high temperature sensor component such as a knock sensor and an actuator component which can be used stably for a long time even in a high temperature portion such as the vicinity of an automobile engine. , And can be used as ultrasonic motor parts.
In order to use the sensor component, actuator component, ultrasonic motor component, etc. for high temperature more stably for a long time, the Curie temperature Tc is preferably 200 ° C. or more. More preferably, the temperature is 250 ° C. or higher.

Focusing on the piezoelectric g ₃₁ constant, as can be seen from Table 2, the piezoelectric g ₃₁ constant of the sample E7 showed the highest value of 8.94 × 10 ⁻³ Vm / N.

The piezoelectric g ₃₁ constant is proportional to the output voltage of the piezoelectric sensor, the piezoelectric transformer element, the ultrasonic motor element and the like, like the piezoelectric d ₃₁ constant. Therefore, it is possible to make a large sensor voltage sensor output as the piezoelectric g ₃₁ constant high piezoelectric ceramic composition. Then, to produce a sensor having a comparative product equal or characteristics, it would be preferable to have at least 7 × 10 ^-3 Vm / N or more piezoelectric g ₃₁ constant. More preferably, it is 8 × 10 ⁻³ Vm / N or more.

Moreover, focusing on the dielectric constant ε _33T / ε _0, the relative dielectric constant ε _33T / ε ₀ of the sample E1~E7 takes the very high value of 1300 or more.

The relative permittivity ε _33T / ε ₀ is generally proportional to the capacitance of a capacitor such as a multilayer capacitor component. From this viewpoint, a piezoelectric ceramic composition having a higher relative dielectric constant can produce a capacitor having a larger capacitance. In order to manufacture a capacitor, it can be said that it is preferable to have a dielectric constant of at least 400 or more. Further, more preferably, 430 or more are preferable. More preferably, those having 600 or more are good.

  Focusing on the dielectric loss tan δ, the dielectric loss tan δ of the samples E1 to E7 has a very low value of 0.023 or less.

  The above-mentioned dielectric loss is proportional to the heat energy lost by applying an AC voltage to components such as a capacitor such as a capacitor component, a piezoelectric ultrasonic motor, a piezoelectric actuator, and a piezoelectric transformer. From this point of view, a piezoelectric ceramic composition having a smaller dielectric loss can produce a capacitor having a smaller energy loss and a piezoelectric ultrasonic motor, a piezoelectric actuator, and a piezoelectric transformer having a smaller heat generation. In order to produce the above-described component having a small energy loss, the component preferably has a dielectric loss of 0.09 or less. More preferably, it is 0.035 or less. More preferably, it is 0.025 or less.

  As described above, the piezoelectric ceramic composition of this example (samples E1 to E7) does not contain lead in the composition and has excellent piezoelectric properties and dielectric properties as described above. Therefore, it can be used for a piezoelectric element and a dielectric element which are safe for the environment and have high performance.

(Example 2)
This example is to determine the critical range of the content of the additive, the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3 This is an example in which Ag ₂ O as the above-mentioned additive is contained in the compound represented by changing the amount.

First, high-purity Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Ta ₂ O ₅ , Sb ₂ O ₅ having a purity of 99% or more were used as raw materials of the piezoelectric ceramic composition. Ag ₂ O was prepared as an additive.
Of these raw materials, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Sb ₂ O ₅ are calcined and then the above general formula {Li _x (K _1-y Na in _{y) 1-x} (Nb} 1-zw Ta z Sb w) O 3, x, y, z, w , respectively x = 0.04, y = 0.5, z = 0.1, w = 0 0.06, and further, Ag ₂ O as the above-mentioned additive was blended while changing the amount of the additive to obtain 16 kinds of blends.

Regarding the compounding amount of Ag ₂ O, 1 mol of a compound {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O _3, which is expected to be obtained after calcining at the above stoichiometric ratio, In addition, 0.0005 mol to 0.25 mol of Ag ₂ O as the above additive was blended. That is, 0.001 to 0.5 mol of Ag was blended.
Then, each of the above compounds was mixed in acetone by a ball mill for 24 hours to prepare a mixture.

  Next, each mixture was calcined, granulated, molded, fired, and polarized in the same manner as in Samples E1 to E7 of Example 1 to produce 16 types of piezoelectric ceramic compositions. X1 to sample X16. Table 3 shows the mixing ratio of the raw materials and additives in each sample.

In the samples X1 to X16 obtained here, Ag ₂ O as the above-mentioned additive is partially in the form as it is or in the form of the elemental elements of the basic composition of Li, Na, K, Nb, Ta, and Sb. A compound such as a perovskite structure compound is formed with any one or more of them, and is contained in the form within or within the grains of each piezoelectric ceramic composition, and a part thereof is formed by the above-mentioned ΔLi _0.04 (K _0.5 Na _0.5 ) _0.96 It is considered that at least a part of Li, K, and Na of the compound represented by｝ (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ is contained in a state where Ag in Ag ₂ O is substituted. In particular, when the added amount of Ag ₂ O exceeds 0.1 mol with respect to 1 mol of the compound represented by {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ , When the content of the metal element Ag exceeds 0.2 mol, Ag ₂ O as the above additive precipitates at the grain boundaries of the piezoelectric ceramic composition in the form of Ag and / or Ag ₂ O or a compound containing Ag. It will be easier.
In this example, in order to clarify the effect of adding Ag, K and Na in the compound represented by {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ were determined. On the other hand, each sample was prepared by an addition method in which Ag was replaced and added. That is, for example, in the sample X8, the composition was set to {Li _0.04 (K _0.5 Na _0.5 ) _0.86 Ag _1.0 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ .

Further, in this embodiment, to clarify the effects of Ag ₂ O formulation, were prepared samples containing no Ag ₂ O as the additive.
Specifically, first, high purity Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Sb ₂ O ₅ having a purity of 99% or more are prepared. The raw materials are mixed at a stoichiometric ratio such that a compound represented by Li _0.04 (K _0.5 Na _0.5 ) _0.96 ｝ (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ is obtained after calcination, and is mixed in acetone by a ball mill in acetone. Mix for hours to obtain a mixture. Subsequently, the mixture was calcined, granulated, molded, fired, and polarized in the same manner as in Samples E1 to E7 of Example 1 to obtain a piezoelectric ceramic composition (Sample Y1). Table 3 shows the composition ratio of Sample Y1.

Next, the piezoelectric d ₃₁ constant, the electromechanical coupling coefficient Kp, the piezoelectric g ₃₁ constant, the relative permittivity _{33 33T} / ε ₀ , the dielectric loss tan δ, and the Curie temperature Tc of the samples X1 to X16 and the sample Y1 were measured. Each was measured in the same manner as in Example 1. Table 4 shows the results. Table 4 also shows the results of the sample C1 manufactured in Example 1 for comparison.

As can be understood from Table 4, sample X1~X9 are all had high piezoelectric d ₃₁ constant than the sample Y1 and sample C1, a relative dielectric constant ε _33T / ε _0. Also, the dielectric loss tan δ was smaller than Sample Y1 and Sample C1, and was excellent.
That is, as can be seen from Tables 3 and 4, the additive amount of Ag ₂ O as an additive is 0.001 mol to 0 mol per 1 mol of the compound represented by the above general formula. When it is 0.15 mol, the piezoelectric ceramic composition was found to be particularly excellent in the piezoelectric d ₃₁ constant, the relative dielectric constant ε _33T / ε ₀ , and the dielectric loss tan δ.
Moreover, as known by Table 4, the sample X1~X9, the electromechanical coupling factor Kp, piezoelectric g ₃₁ constant, and also in the Curie temperature Tc, showed excellent characteristics comparable with sample Y1.

On the other hand, in the case of the samples X10 to X16, that is, when the addition amount of Ag ₂ O as the additive exceeds 0.15 mol in the content of the added element Ag, the electromechanical coupling coefficient including the piezoelectric d ₃₁ constant is obtained. Kp, piezoelectric g ₃₁ constant, the dielectric constant ε _33T / ε _0, dielectric loss tan [delta, and in all the characteristics of the Curie temperature Tc, was lower than sample Y1.

  Thus, according to this example, it can be seen that when the content of the additional element is 0.001 mol to 0.15 mol, the characteristics of the piezoelectric ceramic composition are most remarkably improved. Although not shown in the table, the same results as in this example were obtained for other metal elements.

  Further, in this example, although not specifically stated, it has been confirmed that the improvement of the characteristics by the above-mentioned additional elements may be either substitutional addition or external addition. In addition, the main component of the piezoelectric ceramic composition used in this example is only one composition of the selectable composition, and it has been confirmed that the characteristics are similarly improved with other compositions.

Claims (25)

It is represented by the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w respectively 0 ≦ x ≦ 0.2 , 0 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, a piezoelectric ceramic composition mainly comprising a compound in the composition range,
The piezoelectric ceramic composition comprises, as an additive element, at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt.
A piezoelectric ceramic composition, wherein the total content of the additional elements is 0.001 mol to 0.15 mol per 1 mol of the compound represented by the general formula. 2. The piezoelectric device according to claim 1, wherein a piezoelectric d ₃₁ constant of the piezoelectric ceramic composition is represented by the general formula, and is larger than a piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing no additional element. Porcelain composition.   The electromechanical coupling coefficient Kp of the piezoelectric ceramic composition according to claim 1 or 2, which is represented by the general formula and is larger than the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition containing no additional element. Characteristic piezoelectric ceramic composition. In any one of claims 1 to 3, the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition is represented by the above general formula, than the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition containing no additive element A piezoelectric ceramic composition characterized by being large.   The relative dielectric constant of the piezoelectric ceramic composition according to any one of claims 1 to 4, wherein the relative dielectric constant of the piezoelectric ceramic composition is represented by the general formula and is larger than the relative dielectric constant of the piezoelectric ceramic composition not containing the additive element. A piezoelectric ceramic composition comprising:   The dielectric loss of the piezoelectric ceramic composition according to any one of claims 1 to 5, wherein the dielectric loss is represented by the general formula and is smaller than the dielectric loss of the piezoelectric ceramic composition not containing the additional element. Piezoelectric ceramic composition.   The Curie temperature Tc of the piezoelectric ceramic composition according to any one of claims 1 to 6, which is represented by the general formula and is higher than the Curie temperature Tc of the piezoelectric ceramic composition containing no additional element. A piezoelectric ceramic composition comprising: In any one of claims 1 to 7, the piezoelectric ceramic composition, the piezoelectric porcelain composition, wherein the piezoelectric d ₃₁ constant is 30 Pm/V more.   The piezoelectric ceramic composition according to any one of claims 1 to 8, wherein the piezoelectric ceramic composition has an electromechanical coupling coefficient Kp of 0.30 or more. According to any one of claims 1 to 9, the piezoelectric ceramic composition, the piezoelectric porcelain composition, wherein the piezoelectric g ₃₁ constant is 7 × 10 ^-3 Vm / N or more.   The piezoelectric ceramic composition according to any one of claims 1 to 10, wherein the piezoelectric ceramic composition has a relative dielectric constant of 400 or more.   The piezoelectric ceramic composition according to any one of claims 1 to 11, wherein the piezoelectric ceramic composition has a dielectric loss of 0.09 or less.   The piezoelectric ceramic composition according to any one of claims 1 to 12, wherein the piezoelectric ceramic composition has a Curie temperature Tc of 200 ° C or higher. In any one of claims 1 to 7, the piezoelectric ceramic composition, the piezoelectric porcelain composition, wherein the piezoelectric d ₃₁ constant is at 30 Pm/V or more and the Curie temperature Tc is 200 ° C. or higher. The piezoelectric ceramic composition according to any one of claims 1 to 7, wherein the piezoelectric ceramic composition has a piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N and a Curie temperature Tc of 200 ° C. or more. Porcelain composition.   The piezoelectric ceramic composition according to any one of claims 1 to 7, wherein the piezoelectric ceramic composition has an electromechanical coupling coefficient Kp of 0.3 or more and a Curie temperature Tc of 200 ° C or more. .   The piezoelectric ceramic composition according to any one of claims 1 to 7, wherein the piezoelectric ceramic composition has a dielectric loss of 0.09 or less and a Curie temperature Tc of 200 ° C or more. In any one of claims 1 to 7, the piezoelectric ceramic composition in the piezoelectric d ₃₁ constant 30 Pm/V above, and in electromechanical coupling coefficient Kp is 0.3 or more, and the Curie temperature Tc is 200 ° C. A piezoelectric ceramic composition characterized by the above. It is represented by the general formula _{{Li x (K 1-y} Na y) 1-x} (Nb 1 -zw Ta z Sb w) O 3, and x, y, z, w respectively 0 ≦ x ≦ 0.2 , 0 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, and compounds selected from the group consisting of Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. A method for producing a piezoelectric ceramic composition, comprising mixing an additive containing at least one metal element and firing the mixture. A compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and a compound containing Sb are fired to obtain a compound of the general formula {Li _x It is represented by _{(K 1-y Na y)} 1-x} (Nb 1-zw Ta z Sb w) O 3, and x, y, z, w respectively 0 ≦ x ≦ 0.2,0 ≦ y ≦ Considering substitution at a stoichiometric ratio so as to be a compound in the composition range of 1,0 <z ≦ 0.4 and 0 <w ≦ 0.2, or with a metal element contained in the following additives: Mixing at a stoichiometric ratio, and further mixing and firing an additive containing at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt. A method for producing a piezoelectric ceramic composition, which is characterized in that: 21. The compound according to claim 20, wherein the compound containing Li is Li ₂ CO ₃ , the compound containing Na is Na ₂ CO ₃ , the compound containing K is K ₂ CO ₃ , and the compound containing Nb is Nb _2. O ₅ , the compound containing Ta is Ta ₂ O ₅ , the compound containing Sb is Sb ₂ O ₅ or Sb ₂ O ₃ , and the additive is PdO ₂ , Ag ₂ O, Au, Au ₂ O, _{ru 2 O, RhO, Re 2} O 5, OsO 2, IrO 2, and a manufacturing method of the piezoelectric ceramic composition which is characterized in that any one or more selected from PtO _2.   A piezoelectric element comprising a piezoelectric body made of the piezoelectric ceramic composition according to claim 1.   A piezoelectric element comprising a piezoelectric body made of the piezoelectric ceramic composition manufactured by the manufacturing method according to any one of claims 19 to 21.   A dielectric element comprising a dielectric comprising the piezoelectric ceramic composition according to claim 1.   A dielectric element comprising a dielectric made of the piezoelectric ceramic composition manufactured by the manufacturing method according to any one of claims 19 to 21.