JP4163068B2 - Piezoelectric ceramic composition and piezoelectric element - Google Patents

Description

The present invention is a piezoelectric ceramic composition containing no lead in the composition, and relates to a piezoelectric element having a piezoelectric ceramic device composition.

Conventionally, PZT (PbTiO ₃ —PbZrO ₃ ) component-based porcelain containing lead has been used as a piezoelectric ceramic composition. This is because the PZT exhibits a large piezoelectric property and has a high mechanical quality factor, and can easily produce materials having various characteristics required for various uses such as sensors, actuators, filters, and the like.
Moreover, since the PZT has a high relative dielectric constant, it can also be used as a capacitor.

However, the piezoelectric ceramic composition made of PZT has excellent characteristics, but contains lead as a constituent element, so harmful lead is eluted from industrial waste of products containing PZT, resulting in environmental pollution. There was a risk of causing. The recent increase in awareness of environmental problems 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 is required, and a piezoelectric ceramic composition represented by the general formula (K _1-x Na _x ) NbO ₃ (where 0 <x <1) ( Non-patent document 1) has attracted attention.

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 was a problem that the piezoelectric characteristics such as the mechanical quality factor Qm were low. Therefore, for example, piezoelectric actuators, piezoelectric filters, piezoelectric vibrators, piezoelectric transformers, piezoelectric ultrasonic motors, piezoelectric gyro sensors, knock sensors, yaw rate sensors, airbag sensors, back sonars, corner sonars that require high piezoelectric d ₃₁ constants, It has been difficult to apply to piezoelectric elements such as piezoelectric buzzers, piezoelectric speakers, and piezoelectric igniters.

In addition, the piezoelectric ceramic composition represented by the above general formula has a problem that it is difficult to apply to a dielectric element such as a capacitor because of its low dielectric properties such as relative dielectric constant ε _33T / ε ₀ and dielectric loss tan δ. 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, and does not contain lead, and has high piezoelectric characteristics and dielectric characteristics. In particular, the piezoelectric d ₃₁ constant, the relative permittivity, the dielectric loss, and the Curie temperature Tc. It is an object of the present invention to provide a piezoelectric ceramic composition excellent in any one or more, and a piezoelectric element using the piezoelectric ceramic composition.

A first aspect of the present invention is represented by the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3, and x, y, z, w, a and b are compositions of 0 <x ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05, respectively. A piezoelectric ceramic composition mainly composed of a compound in a range,
The piezoelectric ceramic composition contains any one or more metal elements selected from Pd, Au, Ru , Re , Ir, and Pt as additive elements,
The total content of the additive elements is 0.001 mol to 0.15 mol with respect to 1 mol of the compound represented by the above general formula (claim 1).

Next, the effects 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 flow out from the waste to the natural world.

The piezoelectric ceramic composition contains a compound represented by the above general formula, and x, y, z, and w in the general formula are in the above ranges, respectively.
Therefore, the piezoelectric ceramic composition has piezoelectric characteristics such as piezoelectric d ₃₁ constant, electromechanical coupling coefficient Kp, piezoelectric g ₃₁ constant, dielectric characteristics such as dielectric constant ε _33T / ε ₀ , dielectric loss tan δ, and 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} a (Nb 1-zw Ta z Sb w) b O 3 Hereinafter, it is referred to as “basic composition” as appropriate.

Furthermore, the piezoelectric ceramic composition includes, as an additive element, one or more metal elements selected from Pd, Au, Ru , Re , Ir, and Pt in addition to the compound having the basic composition represented by the above general formula. , The total content is within the above range. Therefore, the piezoelectric ceramic composition of the present invention includes at least one of the piezoelectric d ₃₁ constant, the piezoelectric g ₃₁ constant, the electromechanical coupling coefficient Kp, the relative dielectric constant ε _33T / ε ₀ , the dielectric loss tan δ, and the Curie temperature Tc. These characteristics are further improved, and even better than the piezoelectric ceramic composition represented by the above general formula and not containing the additive element.
In the piezoelectric ceramic composition, the additive element may be contained by substitution addition to the compound represented by the above general formula, or added externally to the compound represented by the above general formula. May be contained.

Thus, since the piezoelectric ceramic composition of the present invention does not contain lead, it is safe for the environment and has excellent piezoelectric characteristics, so that it can be used as a high-performance piezoelectric element.
The piezoelectric ceramic composition is also excellent in dielectric properties such as relative permittivity and dielectric loss in addition to the piezoelectric properties. Therefore, it can be used as a high-performance dielectric element. That is, the piezoelectric ceramic composition according to the first aspect of the invention is a concept including not only a piezoelectric ceramic composition having piezoelectric characteristics but also a dielectric ceramic composition having dielectric characteristics.

The second invention is a piezoelectric element characterized by comprising a piezoelectric ceramic composition of the first invention (Claim 8).

The piezoelectric element of the second invention has the piezoelectric ceramic composition of the first invention (Invention 1). Therefore, the piezoelectric element does not contain lead and is safe for the environment.
In addition, the piezoelectric element can use the property of the piezoelectric ceramic composition, such as the piezoelectric d ₃₁ constant, that is excellent in piezoelectric characteristics. Therefore, the piezoelectric element can be used as a highly sensitive piezoelectric sensor element, a piezoelectric vibrator having high electromechanical energy conversion efficiency, an actuator element, and the like.

In the first invention , the compound represented by the general formula {Li _x (K _{1 -y} Na _y ) _{1 -x} } _a (Nb _{1 -zw} Ta _z Sb _w ) _b O ₃ is x, y, The ranges of z and w are 0 < x ≦ 0.2, 0.05 ≦ 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 characteristics such as the piezoelectric d ₃₁ constant and the dielectric characteristics are reduced, and the desired There is a possibility that a piezoelectric ceramic composition having the above characteristics cannot be obtained.
In the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) compound represented by _b O _3, the range of y is, 0 ≦ y ≦ 0.85 is more preferable, and 0.05 ≦ y ≦ 0.75 is still more preferable. In these cases, the piezoelectric d ₃₁ constant and the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition can be further improved. Still more preferably, 0.05 ≦ y <0.75 is satisfied, 0.35 ≦ y ≦ 0.65 is further preferable, and 0.35 ≦ y <0.65 is more preferable. Most preferably, 0.42 ≦ y ≦ 0.60.

As described above, the piezoelectric ceramic composition is mainly composed of a compound having a perovskite structure (ABO ₃ ). In the present invention, the element configuration of the A site in the perovskite structure (ABO ₃ ) corresponds to K, Na or K, Na, Li, and the element configuration of the B site corresponds to Nb, Ta, Sb. In the composition formula of this 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 a few percent, specifically about 3% in the firing process, etc., and all constituent elements are a few percent in the mixed pulverization or granulation process, specifically, May vary by about 3%. In other words, variation from the stoichiometric composition may occur due to manufacturing variations.

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

In the piezoelectric ceramic composition of the present invention, even if the composition ratio is intentionally changed as described above, electrical characteristics such as piezoelectric characteristics do not change greatly.
Therefore, in the present invention, the compound represented by the above general formula {Li _x (K _{1 -y} Na _y ) _{1 -x} } _a (Nb _{1 -zw} Ta _z Sb _w ) _b O ₃ has a perovskite structure. When the composition formula ABO ₃ is applied, the composition ratio of the A site atom and the B site atom can be shifted to about ± 5 mol% with respect to 1: 1. In order to reduce the number of lattice defects in the formed crystal and obtain high electrical characteristics, the composition is preferably up to about ± 3%.
That is, the compound represented by the above general formula as the main component of the piezoelectric ceramic composition is [Li _x (K _{1 -y} Na _y ) _1-x ] _a (Nb _{1 -zw} Ta _z Sb _w ) _b O ₃ (0 < x ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05) Is included. As described above, in the above formula, the ranges of a and b are preferably 0.97 ≦ a and b ≦ 1.03.

Also that the scope of x in the above general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3 is 0 <x ≦ 0.2 Is preferred.
In this case, since Li is an essential component, the piezoelectric ceramic composition can be fired more easily during its production, further improves the piezoelectric characteristics, and further increases the Curie temperature Tc. Can do. This is because by making Li an essential component within the above range, the firing temperature is lowered, and Li serves as a firing aid and enables firing with fewer voids.

In the first invention, the piezoelectric ceramic composition contains any one or more metal elements selected from Pd, Au, Ru , Re , Ir, and Pt as additive elements. The total content of is 0.001 mol to 0.15 mol with respect to 1 mol of the compound represented by the above general formula.

When the total content is less than 0.001 mol or more than 0.15 mol, the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition is decreased, and a piezoelectric ceramic composition having desired piezoelectric characteristics is obtained. There is a risk that it will not be possible.
Note that the content of the additive element is the number of moles of each metal element of Pd, Au, Ru , Re , Ir, and Pt.

Also, the additional element of the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3 compound represented by Li, K, Na , Nb, Ta, and Sb are replaced with at least one metal element selected from the above Pd, Au, Ru , Re , Ir, and Pt, the metal element or the above It can take the form which exists in the grain | grain or the grain boundary of the said piezoelectric ceramic composition in the state of compounds, such as an oxide thru | or perovskite structure compound.

In particular, a metal element that can be +1 or +2 such as Pd or Au can be arranged by substituting at least part of Li, K, and Na of the compound represented by the above general formula. On the other hand, for metal elements that can be +3 to +6 valence, such as Pd, Ru , Re , Ir, Pt, etc., the compounds represented by the above general formula should be arranged by substituting at least part of Nb, Ta, Sb. You can also. Further, by taking such a substitutional solid solution form, characteristics such as the piezoelectric d ₃₁ constant can be further improved.

Next, the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition is represented by the above general formula and is preferably larger than the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition not containing the additive element .
If the piezoelectric d ₃₁ constant of a piezoelectric ceramic composition (hereinafter referred to as a basic piezoelectric ceramic composition) that is represented by the above general formula and does not contain the additive element is larger, the effect of the additive element is sufficiently obtained. 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.

The above-mentioned “larger than the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition represented by the above general formula and not containing the additive element” means that the piezoelectric d ₃₁ constant of the piezoelectric ceramic composition containing the additive element is This means that it is larger than the basic piezoelectric ceramic composition having the basic composition of this piezoelectric ceramic composition and not containing the above-mentioned additive elements, and the electromechanical coupling coefficient Kp, piezoelectric g ₃₁ constant described later. This also applies to the relative dielectric constant, dielectric loss, and Curie temperature Tc.

Next, the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition is represented by the above general formula and is preferably larger than the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition not containing the additive element .
When the electromechanical coupling coefficient Kp of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) which is represented by the above general formula and does not contain the additive element is larger, the effect of the additive element can be sufficiently obtained. 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 the piezoelectric element becomes easier.

Next, the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition is represented by the above general formula and is preferably larger than the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition not containing the additive element .
When the piezoelectric g ₃₁ constant of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) which is represented by the above general formula and does not contain the additive element is larger, the effect of the additive element can be sufficiently obtained. , 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, the relative dielectric constant of the piezoelectric ceramic composition is represented by the above general formula and is preferably larger than the relative dielectric constant of the piezoelectric ceramic composition not containing the additive element .
When the relative dielectric constant of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) which is represented by the above general formula and does not contain the additive element is larger, the effect of the additive element can be sufficiently obtained. Application to a dielectric element such as a capacitor becomes easier.

Next, the dielectric loss of the piezoelectric ceramic composition is represented by the above general formula, and is preferably smaller than the dielectric loss of the piezoelectric ceramic composition not containing the additive element .
When the dielectric loss of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) represented by the above general formula and not containing the additive element is smaller than that of the additive element, the effect of the additive element can be sufficiently obtained. Application to a dielectric element such as the above becomes easier.

Next, the Curie temperature Tc of the piezoelectric ceramic composition is represented by the above general formula and is preferably larger than the Curie temperature Tc of the piezoelectric ceramic composition not containing the additive element .
When the temperature is higher than the Curie temperature of the piezoelectric ceramic composition (basic piezoelectric ceramic composition) which is represented by the above general formula and does not contain the additive element, the effect of the additive element can be sufficiently obtained. Use in a high temperature environment exceeding 100 ° C. such as the vicinity of an automobile engine becomes easier.

Next, the piezoelectric ceramic composition preferably has a piezoelectric d ₃₁ constant of 30 pm / V or more ( claim 2 ).
In this case, taking advantage of the high piezoelectric d ₃₁ constant of 30 pm / V or more, the piezoelectric ceramic composition can be used as a 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 and the like.
When the piezoelectric d ₃₁ constant is less than 30 pm / V, the piezoelectric element may not be used as a piezoelectric element having sufficient characteristics for practical use.

In order to obtain a piezoelectric sensor characteristic with higher sensitivity or a larger piezoelectric actuator characteristic, the piezoelectric d ₃₁ constant is more preferably 40 pm / V or more. More preferably, it is 80 pm / V or more. Even 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, excellent in conversion efficiency between mechanical energy and electrical energy, 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, the piezoelectric ceramic composition may not be used for a piezoelectric element that requires excellent conversion efficiency between the mechanical energy and the electrical energy. .
Further, in order to obtain a further excellent conversion efficiency between mechanical energy and electrical energy, the electromechanical coupling coefficient Kp is more preferably 0.34 or more. More preferably, 0.4 or more is good. More preferably, 0.5 or more is good.

Next, the piezoelectric ceramic composition preferably has a piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N or more (claim 3 ).
In this case, the piezoelectric ceramic composition is used as a piezoelectric transformer, an ultrasonic motor element, a sensor element or 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.

When the piezoelectric g ₃₁ constant is less than 7 × 10 ⁻³ Vm / N, the piezoelectric ceramic composition may not be used for a piezoelectric element that requires an excellent step-up ratio.
In order to obtain a further excellent boost 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 .
In this case, the piezoelectric ceramic composition can be used as a dielectric element such as a capacitor having a large electrostatic capacity by utilizing a high relative dielectric constant of 400 or more.

When the relative dielectric constant is less than 400, the capacitance decreases, and the piezoelectric ceramic composition may not be used as a dielectric element such as a capacitor.
The relative dielectric constant is preferably 430 or more. More preferably, 600 or more is good.

Next, the piezoelectric ceramic composition preferably has a dielectric loss of 0.09 or less .
In this case, taking advantage of the low dielectric loss of 0.09 or less, the piezoelectric ceramic composition is used as a dielectric element such as a capacitor, 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 and the like.

  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, 0.025 or less is good.

Next, the piezoelectric ceramic composition is preferably the Curie temperature Tc is 200 ° C. or higher (claim 4).
In this case, utilizing the high Curie temperature Tc of 200 ° C. or higher, the piezoelectric ceramic composition can be used in a high temperature environment exceeding 100 ° C., for example, in the vicinity of an automobile engine.
When the Curie temperature Tc is less than 200 ° C., the piezoelectric ceramic composition decreases in characteristics such as the piezoelectric d ₃₁ constant and the electromechanical coupling coefficient Kp when the piezoelectric ceramic composition is used in a high temperature place such as in the vicinity of an automobile engine. There is a risk. Therefore, more preferably, the Curie temperature Tc is preferably 250 ° C. or higher.

Next, the piezoelectric ceramic composition preferably has a piezoelectric d ₃₁ constant of 30 pm / V or higher and a Curie temperature Tc of 200 ° C. or higher.
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, etc. in a high temperature environment exceeding 100 ° C. .
In order to obtain more sensitive piezoelectric sensor characteristics or greater piezoelectric actuator characteristics, the piezoelectric d ₃₁ constant is preferably 40 pm / V or more. More preferably, it is 80 pm / V or more. Even more preferably, the piezoelectric d ₃₁ constant is 100 pm / V or more.
The Curie temperature Tc is more preferably 250 ° C. or higher.

Next, the piezoelectric ceramic composition is preferably piezoelectric g ₃₁ constant at 7 × 10 ^-3 Vm / N or more, and is the Curie temperature Tc is 200 ° C. or higher (claim 6).
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 in a high temperature environment exceeding 100 ° C.
In order to obtain a further excellent boost ratio, the piezoelectric g ₃₁ constant is more preferably 8 × 10 ⁻³ Vm / N or more.
The Curie temperature Tc is more preferably 250 ° C. or higher.

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

Next, the piezoelectric ceramic composition preferably has a dielectric loss of 0.09 or less and a Curie temperature Tc of 200 ° C. or more .
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 or the like in a high temperature environment exceeding 100 ° C.
The dielectric loss is more preferably 0.035 or less. More preferably, 0.02 or less is good.
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. 7 ).
In this case, the piezoelectric ceramic composition can be used in a high temperature environment exceeding 100 ° C., and can be excellent in sensitivity and conversion efficiency between mechanical energy and electric energy.
In order to obtain more sensitive piezoelectric sensor characteristics or greater piezoelectric actuator characteristics, the piezoelectric d ₃₁ constant is more preferably 40 pm / V or more. The electromechanical coupling coefficient Kp is more preferably 0.34 or more.

Moreover, the piezoelectric ceramic composition is represented by, for example, the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3, and x, y , Z, w, a, b are 0 <x ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦, respectively. A compound having a composition range of 1.05 and an additive containing any one or more metal elements selected from Pd, Au, Ru , Re , Ir, and Pt with respect to 1 mol of the compound represented by the above general formula It can manufacture by mixing and baking so that element amount may be 0.001 mol-0.15 mol. At this time, the above metal element may be substituted for the compound represented by the above general formula, or may be added externally. Further, in the piezoelectric ceramic composition obtained after the firing, as a result of the addition of the additive, any one or more of Li, K, Na, Nb, Ta, and Sb of the compound represented by the above general formula At least a part of which is substituted with at least one metal element selected from Pd, Au, Ru , Re , Ir, and Pt, or the metal element or an oxide or perovskite structure compound containing the metal element. It is contained in the grain or grain boundary in the piezoelectric ceramic composition. In the present specification, “containing an additive” has the above-mentioned meaning.
The piezoelectric ceramic composition includes, for example, 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. preparative, expressed in after firing the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3, and x, y, z, w, a , B are composition ranges of 0 <x ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05, respectively. In a stoichiometric ratio so as to become a compound in the following or in a stoichiometric ratio considering substitution with a metal element contained in the following additives, and further, Au, Ru , Re , Ir, Pt An additive containing any one or more metal elements selected from the group consisting of the above metal element amount with respect to 1 mol of the compound represented by the above general formula: It can manufacture by mixing and baking so that it may become 0.001 mol-0.15 mol.
The piezoelectric ceramic composition includes, for example, 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. preparative, expressed in after firing the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3, and x, y, z, w, a , B are composition ranges of 0 <x ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05, respectively. Are mixed so that the amount of Pd is 0.001 mol to 0.15 mol with respect to 1 mol of the compound represented by the above general formula. It can be manufactured by firing. At this time, a compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, a compound containing Sb, and the above additive , When mixed at a stoichiometric ratio considering substitution with the metal element contained in the additive, Li, Na, K, Nb, Ta, and Sb in the compound represented by the above general formula At least a part of any one or more kinds can be positively replaced with the metal element contained in the additive .
On the other hand, in the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3 compound to become such stoichiometric ratio expressed after firing Then, 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 together. By further mixing the additive and firing it, a piezoelectric ceramic composition containing the additive as the metal element or an oxide or perovskite structure compound containing the metal element can be positively produced.
Examples of the additive include one or more metal elements selected from the above Pd, Au, Ru , Re , Ir, and Pt, or compounds containing these metal elements.
As a result of the addition of the additive, the metal element contained in the additive is added as an additive element after the calcination by the general formula {Li _x (K _{1 -y} Na _y ) _{1 -x} } _a (Nb _{1 -zw} Ta _z The compound represented by Sb _w ) _b O ₃ may be substituted for at least a part of Li, K, Na, Nb, Ta, and Sb, and may be contained in the piezoelectric ceramic composition. Further, the metal element or an oxide containing the metal element or a compound such as a perovskite structure compound may be contained in the grain or grain boundary in the piezoelectric ceramic composition.

Examples of the compound containing the lithium, for example, _{Li 2 CO 3, Li 2 O} , LiNO 3, there is LiOH and the like. Examples of the compound containing sodium include Na ₂ CO ₃ , NaHCO ₃ , and NaNO ₃ .

The compounds containing potassium include K ₂ CO ₃ , KNO ₃ , KNbO ₃ , KTaO _{3 and the} like. Examples of the compound containing niobium include Nb ₂ O ₅ , Nb ₂ O ₃ , and NbO ₂ . Examples of the compound containing tantalum include Ta ₂ O ₅ . Examples of the antimony-containing compound include Sb ₂ O ₅ , Sb ₂ O ₃ , and Sb ₂ O ₄ .

Then, Li ₂ CO ₃ as a compound containing the above-mentioned Li, Na ₂ CO ₃ as a compound containing the Na, K ₂ CO ₃ as a compound containing the K, as the compound containing the Nb is nb ₂ O _5, as the compound containing the Ta using Sb ₂ O ₅ or Sb ₂ O ₃ content _of a compound containing Ta ₂ O _5, the Sb, as the additives, PdO _2, Ag ₂ O , Au, Au ₂ O, Ru ₂ O, RhO, Re ₂ O ₅ , OsO ₂ , IrO ₂ , and PtO ₂ are preferably used.
In this case, the piezoelectric ceramic composition can be easily produced.

Next, the Aspect 2 (claim 8), as the piezoelectric element, for example a piezoelectric actuator, a piezoelectric filter, a piezoelectric vibrator, a piezoelectric transformer, piezoelectric ultrasonic motor, a piezoelectric gyro sensors, knock sensors, yaw rate sensor, There are airbag sensors, back sonar, corner sonar, piezoelectric buzzer, piezoelectric speaker, piezoelectric igniter and so on.

(Example 1)
Next, the piezoelectric ceramic composition according to the 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 mainly composed of compounds in the composition ranges of 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, and 0 <w ≦ 0.2. The piezoelectric ceramic composition contains at least one metal element selected from Pd, Ag, Au, Ru, Rh, Re, Os, Ir, and Pt as an additive element. And the sum total of content of the said additional element is 0.001 mol-0.15 mol with respect to 1 mol of compounds represented by the said general formula.

The method for producing a piezoelectric ceramic composition of this example includes a compound containing Li, a compound containing Na, a compound containing K, a compound containing Nb, a compound containing Ta, and 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 Mixing in a stoichiometric ratio such that the compound is in the composition range of 0 ≦ x ≦ 0.2, 0 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, and Pd , Ag, Au, Ru, Rh, Re, Os, Ir, and Pt are mixed with an additive containing any one or more metal elements and fired.

Hereinafter, the manufacturing method of the piezoelectric ceramic composition of this example will be described in detail.
First, as a raw material 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 having 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 were prepared.

Among these raw materials, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Sb ₂ O ₅ are represented by 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. The stoichiometric ratio is 04, that is, the stoichiometric ratio is such that the above general formula is {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 7 types of blends.

The compounding amount of the additive relative to the blended compound is expected to be obtained by _{{Li 0.04 (K 0.5 Na 0.5} ) 0.96} (Nb 0.86 Ta 0.1 Sb 0.04) O 3 1mol at the stoichiometric ratio PdO ₂ , Ag ₂ O, Au, RuO ₂ , Re ₂ O ₇ , IrO _2, or PtO ₂ as the additive is 0.01 mol, 0.005 mol, 0.01 mol, 0.01 mol, 0.005 mol, respectively. , 0.01 mol, 0.01 mol. That is, 0.01 mol of metal element contained in each additive was mixed.
And each said compound was mixed in acetone with the ball mill for 24 hours, respectively, and the mixture was produced.

Next, each mixture was calcined at 750 ° C. for 5 hours, and then each calcined mixture was ground in a ball mill for 24 hours. Subsequently, polyvinyl butyral was added as a binder and granulated.
Each granulated powder is pressure-molded into a disk shape having a diameter of 13 mm and a thickness of 2 mm at a pressure of ² ton / cm ² , and the resulting molded body is fired at a temperature of 1000 to 1300 ° C. for 1 hour. Was made. In addition, the specific calcination temperature at this time selected the temperature in which the sintered body of the maximum density is obtained by calcination for 1 hour within the above temperature range of 1000 ° C. to 1300 ° C. At this time, all the fired bodies were densified to a relative density of 98% or more.

Next, both sides of each fired body were subjected to parallel polishing and circular polishing, 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 100 ° C. silicone oil for 10 minutes to polarize in the thickness direction to obtain a piezoelectric ceramic composition.
In this way, seven types of piezoelectric ceramic compositions (samples E1 to E7) were produced. Table 1 shows the mixing ratio of 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 manufacturing 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 was prepared by firing, and this was pulverized. The piezoelectric ceramic composition similar to the samples E1 to E7 can be produced by mixing with the additive and then performing calcination, granulation, molding and firing in the same manner as in the production method of this example.

In addition, 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 in a partially intact form or basic. A compound such as a perovskite structure compound is formed with one or more of Li, Na, K, Nb, Ta, and Sb, which are constituent elements of the composition, and in the form, in the grain boundary or grain boundary of each piezoelectric ceramic composition And a part thereof is 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 atom in each additive is included in each part in a substituted state. In particular, a metal element that can be +1 or +2 such as Ag, Pd, or Au is easily replaced with at least part of Li, K, and Na of the above compound. Further, metal elements that can be +3 to +6 valence such as Pd, Ru, Rh, Re, Os, Ir, and Pt are easily replaced with at least a part of Nb, Ta, and Sb of the above 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 produced 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 comparative materials.

Among these raw materials, K ₂ CO ₃ , Na ₂ CO ₃ , and Nb ₂ O ₅ are converted into the above general formula {Li _x (K _{1 -y} Na _y ) _1-x } (Nb _{1 -zw} Ta _z Sb _w ) O. ₃ , the stoichiometric ratio such that x = z = w = 0 and y = 0.5, that is, the stoichiometric ratio such that the general formula is (K _0.5 Na _0.5 ) NbO ₃ The mixture was then mixed in acetone for 24 hours by a ball mill to obtain a mixture.
This mixture was calcined, granulated, molded, fired and polarized in the same manner as the above samples E1 to E7, and a piezoelectric ceramic composition (sample C1) as a comparative product was produced.
Sample C1 is a piezoelectric ceramic composition containing (K _0.5 Na _0.5 ) NbO ₃ .

Next, the sample C2 is produced 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 subjected to 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, Stoichiometric ratio, that is, a stoichiometric ratio such that the above 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 acetone with 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 the above 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 the main component, similar to the above samples E1 to E7, but on the other hand contains the above-mentioned additional elements. It is a piezoelectric ceramic composition that is not used.
Table 1 shows the composition ratio of the sample C1 and the sample C2.

Next, for the samples E1 to E7, the samples C1 and C2, the piezoelectric d ₃₁ constant, the electromechanical coupling coefficient Kp, the piezoelectric g ₃₁ constant, the relative dielectric constant ε _33T / ε ₀ , the dielectric loss tan δ, and the Curie temperature Tc are set. Each was measured.

The piezoelectric d ₃₁ constant, the piezoelectric g ₃₁ constant, and the electromechanical coupling coefficient Kp were measured by a resonance-antiresonance method using an impedance analyzer (Precision Impedance Analyzer 4294A manufactured by Agilent).
The dielectric loss tan δ and relative dielectric constant 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 was defined as the temperature at which the relative dielectric constant ε _33T / ε ₀ was the highest.
The results are shown in Table 2.

As can be seen from Table 2, the above-mentioned conventional piezoelectric ceramic compositions are the samples E1 to E7 in terms of their piezoelectric d ₃₁ constant, electromechanical coupling coefficient Kp, relative permittivity ε _33T / ε ₀ , and dielectric loss tan δ. The sample C1 had characteristics superior to those of the sample C1.
Further, the samples E1 to E7 have a piezoelectric d ₃₁ constant, an electromechanical coupling coefficient Kp, a piezoelectric g ₃₁ constant, a relative dielectric constant ε _33T / ε ₀ , a dielectric loss tan δ, and a Curie temperature Tc, even when compared with the sample C2. However, it had excellent characteristics equivalent to or better than the above.
In particular, with respect to the piezoelectric d ₃₁ constant, the total number of electrical solutions Kp, and the relative dielectric constant 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, focusing on the piezoelectric d ₃₁ constant, as known from Table 2, the piezoelectric d ₃₁ constant of the sample E2 has the highest value of 122.4pm / V.

When a charge detection circuit or a current detection circuit is used, the piezoelectric d ₃₁ constant is generally proportional to the output voltage of a piezoelectric sensor such as an acceleration sensor, a weight sensor, an impact sensor, or a knock sensor. From this point of view, a piezoelectric ceramic composition having a higher piezoelectric d ₃₁ constant can produce a sensor element having a larger charge sensor output. It can be said that it is preferable to have a piezoelectric d ₃₁ constant of at least 30 pm / V or more in order to produce a sensor element having characteristics equal to or higher than those of the sample C1 as a comparative product. Further, in order to produce a highly sensitive sensor element by increasing the signal-to-noise ratio (SN ratio) and the output voltage, the piezoelectric d ₃₁ constant is preferably 80 pm / V or more. More preferably, it is 100 pm / V or more.

When used as an actuator, the piezoelectric d ₃₁ constant is generally proportional to the generated strain or displacement of the piezoelectric actuator. From this point of view, a piezoelectric ceramic composition having a higher piezoelectric d ₃₁ constant can produce an actuator element having a larger strain or displacement. It can be said that it is preferable to have a piezoelectric d ₃₁ constant of at least 30 pm / V or more in order to manufacture an actuator element having characteristics equal to or higher than those of a comparative product. More preferably, it is 40 pm / V or more. In order to fabricate an actuator having a larger displacement, the piezoelectric d ₃₁ constant is preferably 80 pm / V or more. More preferably, it is 100 pm / V or more.

  Further, paying attention to the electromechanical coupling coefficient Kp, as known from Table 2, the electromechanical coupling coefficient Kp of the sample E2 showed the highest value of 0.531.

  In general, 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, an ultrasonic transducer, or the like. From this point of view, piezoelectric transformer elements, ultrasonic motor elements, actuator elements, or ultrasonic vibrators with higher electromechanical energy conversion efficiency can be made with piezoelectric ceramic compositions having a higher electromechanical coupling coefficient Kp. In order to manufacture a piezoelectric transformer element, an ultrasonic motor element, an actuator element, or an ultrasonic vibrator having characteristics equivalent to or better than those of the comparative sample C1, an electromechanical coupling coefficient Kp of at least 0.3 is required. It can be said that it is preferable. More preferably 0.34 or more. More preferably, 0.4 or more is good. Furthermore, 0.5 or more is more preferable.

Further, when paying attention to the Curie temperature Tc, the Curie temperatures Tc of the samples E1 to E7 all take a high value of 200 ° C. or higher. Therefore, the piezoelectric ceramic composition (samples E1 to E7) of this example is a sensor component or actuator component for high temperature such as a knock sensor that can be used stably for a long time even in a high temperature part such as the vicinity of an automobile engine. It can be used as an ultrasonic motor component.
Further, the Curie temperature Tc is preferably 200 ° C. or higher in order to be used stably for a long time as the high temperature sensor part, the actuator part, the ultrasonic motor part or the like. More preferably, the temperature is 250 ° C. or higher.

Moreover, focusing on the piezoelectric g ₃₁ constant, as known from Table 2, the piezoelectric g ₃₁ constant of 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 a piezoelectric sensor, a piezoelectric transformer element, an ultrasonic motor element, etc., like the piezoelectric d ₃₁ constant. Therefore, a piezoelectric ceramic composition having a higher piezoelectric g ₃₁ constant can produce a sensor having a larger voltage sensor output. It can be said that it is preferable to have a piezoelectric g ₃₁ constant of at least 7 × 10 ⁻³ Vm / N or more in order to manufacture a sensor having characteristics equal to or higher than those of the comparative product. More preferably, 8 × 10 ⁻³ Vm / N or more is preferable.

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 dielectric constant ε _33T / ε ₀ is generally proportional to the capacitance of a capacitor such as a multilayer capacitor component. From this point of view, 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 relative dielectric constant of at least 400 or more. More preferably, 430 or more is good. More preferably, 600 or more are good.

  When attention is paid to 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 dielectric loss is proportional to the thermal energy lost by the component when an AC voltage is applied to a component such as a capacitor component, a piezoelectric ultrasonic motor, a piezoelectric actuator, or a piezoelectric transformer. From this point of view, a piezoelectric ceramic composition having a smaller dielectric loss can produce a capacitor with less energy loss and a piezoelectric ultrasonic motor, piezoelectric actuator, and piezoelectric transformer with less heat generation. And in order to produce the said component with little energy loss, it is preferable to have a dielectric loss of 0.09 or less. More preferably, 0.035 or less is good. More preferably, it is 0.025 or less.

  As described above, the piezoelectric ceramic composition (sample E1 to sample E7) of this example does not contain lead in the composition and has excellent piezoelectric characteristics and dielectric characteristics as described above. Therefore, it can be used for high-performance piezoelectric elements and dielectric elements that are safe to the environment.

( Reference example )
In this example, in order 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 an additive is contained in the compound represented by changing the amount thereof.

First, as raw materials for the piezoelectric ceramic composition, high purity of 99% or more of 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 , and the above Ag ₂ O as an additive was prepared.
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 calcined and then the above general formula {Li _x (K _1-y Na _y ) _1−x } (Nb _1−zw Ta _z Sb _w ) O ₃ , x, y, z, and w are x = 0.04, y = 0.5, z = 0.1, w = 0, respectively. The stoichiometric ratio was 0.06, and Ag ₂ O as the additive was blended at different addition amounts to obtain 16 types of blends.

As for the compounding amount of Ag ₂ O, the compound {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ 1 mol expected to be obtained after calcining with the above stoichiometric ratio. In contrast, 0.0005 mol to 0.25 mol of Ag ₂ O as the additive was blended. That is, Ag was added in an amount of 0.001 to 0.5 mol.
And each said compound was mixed in acetone with the ball mill for 24 hours, respectively, and the mixture was produced.

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

In the samples X1 to X16 obtained here, Ag ₂ O as the additive is partly as it is or is composed of Li, Na, K, Nb, Ta, and Sb which are constituent elements of the basic composition. A compound such as a perovskite structure compound is formed with at least one of them, and in that form, it is contained in the grain or grain boundary of each piezoelectric ceramic composition, and a part thereof is the above {Li _0.04 (K _0.5 Na _0.5 ) _0.96 } (Nb _0.84 Ta _0.1 Sb _0.06 ) O ₃ is considered to be contained in a state where Ag in Ag ₂ O is substituted in at least part of Li, K, and Na of the compound represented by O ₃ . In particular, when the addition 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 , that is, When the content of the metal element Ag exceeds 0.2 mol, Ag ₂ O as the additive is precipitated in the form of a compound containing Ag or / and Ag ₂ O or Ag at the grain boundary of the piezoelectric ceramic composition. It becomes easy.
In this example, for the purpose of clarifying the effect when Ag is added, 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 are used. On the other hand, each sample was prepared by an addition method in which Ag was substituted and added. That is, for example, in the sample X8, the composition is {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 prepared a purity of 99% or more of 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, of The raw materials were mixed at a stoichiometric ratio such that after firing, 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 was used. Mixing for a time gave a mixture. Subsequently, this mixture was calcined, granulated, molded, fired and polarized in the same manner as Sample E1 to Sample E7 of Example 1 to obtain a piezoelectric ceramic composition (Sample Y1). Table 3 shows the composition ratio of the sample Y1.

Next, for the samples X1 to X16 and the sample Y1, the piezoelectric d ₃₁ constant, the electromechanical coupling coefficient Kp, the piezoelectric g ₃₁ constant, the relative dielectric constant ε _33T / ε ₀ , the dielectric loss tan δ, and the Curie temperature Tc Each was measured in the same manner as in 1. The results are shown in Table 4. In Table 4, the results of the sample C1 prepared in Example 1 are also shown for comparison.

As is known from Table 4, all of the samples X1 to X9 had higher piezoelectric d ₃₁ constant and relative dielectric constant ε _33T / ε ₀ than those of the sample Y1 and the sample C1. Further, the dielectric loss tan δ was also smaller and superior to those of the sample Y1 and the sample C1.
That is, as is known from Tables 3 and 4, the additive amount of Ag ₂ O as an additive is 0.001 mol to 0 in terms of the content of additive element Ag with respect to 1 mol of the compound represented by the above general formula. When it is .15 mol, it can be seen that the piezoelectric ceramic composition is particularly excellent in piezoelectric d ₃₁ constant, relative dielectric constant ε _33T / ε ₀ , and 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, when the amount of addition of Ag ₂ O as the additive is more than 0.15 mol in the samples X10 to X16, that is, the additive element Ag content, the piezoelectric d ₃₁ constant and the electromechanical coupling coefficient are included. The values of Kp, piezoelectric g ₃₁ constant, relative dielectric constant ε _33T / ε ₀ , dielectric loss tan δ, and Curie temperature Tc were lower than those of sample Y1.

  Thus, according to this example, it can be seen that when the content of the additive element is 0.001 mol to 0.15 mol, the characteristics of the piezoelectric ceramic composition are 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 shown, it has been confirmed that the improvement in characteristics by the additive element may be a substitution addition or an external addition. In addition, the main component of the piezoelectric ceramic composition used in this example is only one composition of a selectable composition, and it has been confirmed that the characteristics are improved in the same manner for other compositions.

Claims (8)

It is represented by the general formula _{{Li x (K 1-y} Na y) 1-x} a (Nb 1-zw Ta z Sb w) b O 3, and x, y, z, w, a, b are respectively 0 <X ≦ 0.2, 0.05 ≦ y ≦ 1, 0 <z ≦ 0.4, 0 <w ≦ 0.2, 0.95 ≦ a, b ≦ 1.05 A piezoelectric ceramic composition comprising:
The piezoelectric ceramic composition contains any one or more metal elements selected from Pd, Au, Ru , Re , Ir, and Pt as additive elements,
The total amount of the additive elements is 0.001 mol to 0.15 mol with respect to 1 mol of the compound represented by the above general formula. The piezoelectric ceramic composition according to claim 1, wherein the piezoelectric ceramic composition has a piezoelectric d ₃₁ constant of 30 pm / V or more. 3. The piezoelectric ceramic composition according to claim 1, wherein the piezoelectric ceramic composition has a piezoelectric g ₃₁ constant of 7 × 10 ⁻³ Vm / N or more.   The piezoelectric ceramic composition according to any one of claims 1 to 3, wherein the piezoelectric ceramic composition has a Curie temperature Tc of 200 ° C or higher. 2. The piezoelectric ceramic composition according to claim 1, wherein the piezoelectric ceramic composition has a piezoelectric d ₃₁ constant of 30 pm / V or more and a Curie temperature Tc of 200 ° C. or more. 2. The piezoelectric ceramic composition according to claim 1, 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. 2. The piezoelectric ceramic composition according to claim 1, wherein the piezoelectric d ₃₁ constant is 30 pm / V or more, the electromechanical coupling coefficient Kp is 0.3 or more, and the Curie temperature Tc is 200 ° C. or more. Piezoelectric ceramic composition. A piezoelectric element comprising the piezoelectric ceramic composition according to any one of claims 1 to 7 .