JP2003206179A - Piezoelectric ceramic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic which has a wide operating temperature range, exhibits a large displacement and can be easily fired and which is also excellent from the viewpoints of pollution reduction, environment conservation and ecology. <P>SOLUTION: A piezoelectric substrate 1 comprises a composition containing a perovskite-type oxide, (Na<SB>1-x-y</SB>K<SB>x</SB>Li<SB>y</SB>)(Nb<SB>1-z</SB>Sb<SB>z</SB>)O<SB>3</SB>and a tungsten bronze-type oxide M(Nb<SB>1-w</SB>Sb<SB>w</SB>)<SB>2</SB>O<SB>6</SB>(wherein M is an alkaline earth metal element). In the formula, it is preferable that (x), (y), (z) and (y) satisfy following relations: 0.1≤x≤0.9; 0<y≤0.2; 0<z<0.1 and 0≤w<0.1, and the content of the tungsten bronze-type oxide in the composition is ≤5.3 mol%. Thereby, it becomes possible to raise Curie temperature and enlarge the displacement, and further to easily fire the composition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic containing a composition containing a perovskite type oxide and a tungsten bronze type oxide, and is particularly suitable for a vibration element such as an actuator, a sounding body or a sensor. Regarding piezoelectric ceramics.

[0002]

2. Description of the Related Art An actuator using a piezoelectric ceramic is
It utilizes the piezoelectric phenomenon that mechanical strain and stress are generated when an electric field is applied. This actuator is capable of obtaining a small amount of displacement with high accuracy and has a feature that generated stress is large, and is used, for example, for positioning precision machine tools and optical devices. Conventionally, lead zirconate titanate (PZT), which has excellent piezoelectricity, has been most often used as a piezoelectric ceramic used in an actuator. However, since lead zirconate titanate contains a large amount of lead, the recent adverse effects on the global environment, such as the elution of lead due to acid rain, have become a problem. Therefore, it is desired to develop a lead-free piezoelectric ceramic that replaces lead zirconate titanate.

As a piezoelectric ceramic containing no lead, for example, one containing barium titanate (BaTiO ₃ ) as a main component is known (see Japanese Patent Laid-Open No. 2-159079). This piezoelectric ceramic has excellent relative permittivity εr and electromechanical coupling coefficient kr, and is promising as a piezoelectric material for actuators. As another piezoelectric ceramic containing no lead, for example, one containing sodium potassium potassium niobate as a main component is known (Japanese Patent Application Laid-Open No. 49-125900 or Japanese Patent Publication No. 57-6713).
(See the official gazette). This piezoelectric ceramic has a Curie temperature of 350.
It is expected to be used as a piezoelectric material because it has a high temperature of ℃ or higher and an excellent electromechanical coupling coefficient kr. Further, recently, a composite of sodium potassium niobate and a tungsten bronze type oxide has been reported (see Japanese Patent Laid-Open No. 9-165262).

[0004]

However, these lead-free piezoelectric ceramics have lower piezoelectric characteristics than lead-based piezoelectric ceramics, and there is a problem that a sufficiently large amount of generated displacement cannot be obtained. . Further, in a piezoelectric ceramic containing barium titanate as a main component, the Curie temperature of barium titanate is as low as about 120 ° C., so that the operating temperature range is 100.
There was also a problem that it was limited to below ℃. Further, in the piezoelectric ceramic containing sodium potassium lithium niobate as a main component, there is a problem that sodium, potassium and lithium are easily volatilized during firing, which makes firing difficult.

The present invention has been made in view of the above problems, and an object thereof is to have a wide operating temperature range, obtain a large amount of generated displacement, facilitate firing, reduce pollution, and protect the environment. It is to provide excellent piezoelectric ceramics from the standpoint of sex and ecological viewpoint.

[0006]

A piezoelectric ceramic according to the present invention contains a composition containing a perovskite type oxide and a tungsten bronze type oxide, and the perovskite type oxide is sodium (Na), potassium (K). ) And lithium (Li), a second element containing niobium (Nb) and antimony (Sb), and oxygen (O), and the content of antimony in the second element is 10 mol. It is within the range of less than%.

The piezoelectric ceramic according to the present invention contains a perovskite type oxide and a tungsten bronze type oxide, and the perovskite type oxide is sodium, potassium,
Since it contains lithium, niobium and antimony,
The Curie temperature is high, a large electromechanical coupling coefficient kr, a relative dielectric constant εr, and a generated displacement amount are obtained, and firing is easy.

The content of potassium in the first element of the perovskite oxide is 10 mol% or more and 90% or more.
The content is preferably in the range of mol% or less, and the content of lithium in the first element is preferably 20 mol% or less.

Further, the content of the tungsten bronze type oxide in the composition is preferably 5.3 mol% or less. The tungsten bronze type oxide comprises a third element containing at least one of alkaline earth metal elements, a fourth element containing at least niobium in the group consisting of niobium and antimony, and oxygen. Is preferred. The third element preferably contains at least one selected from the group of alkaline earth metal elements consisting of magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba).

Furthermore, an oxide containing at least one of a transition metal element and a rare earth metal element as a sub-component, particularly an oxide containing manganese (Mn) as a main component, is prepared by using this composition as a main component. It is preferably contained in the range of 0.01% by mass or more and 1% by mass or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

A piezoelectric ceramic according to an embodiment of the present invention is
It contains a composition containing a perovskite type oxide and a tungsten bronze type oxide as main components. In this composition, the perovskite type oxide and the tungsten bronze type oxide may or may not be in solid solution.

The perovskite type oxide is composed of a first element, a second element and oxygen. The first element contains sodium, potassium and lithium, and the second element contains niobium and antimony. In such cases,
This is because it is possible to obtain more excellent piezoelectric characteristics by not containing lead or by reducing the content of lead. In addition, the Curie temperature can be increased and the operating temperature range can be widened. The chemical formula of this perovskite oxide is represented by, for example, Chemical formula 1.

[0014]

[Formula 1] (Na _1-xy K _x Li _y ) _m (Nb _1-z Sb _z ) O _{3 In the} formula, x is 0 <x <1, y is 0 <y <1, and z is 0 <z <.
It is a value within the range of 0.1. m is 1 if it is a stoichiometric composition, but it may deviate from the stoichiometric composition. The oxygen composition is stoichiometrically determined and may deviate from the stoichiometric composition.

The content of potassium in the first element is preferably in the range of 10 mol% or more and 90 mol% or less. That is, for example, x in Chemical formula 1
Is preferably in the range of 0.1 ≦ x ≦ 0.9 in terms of molar ratio. If the content of potassium is too low, the relative permittivity εr, the electromechanical coupling coefficient kr and the amount of generated displacement cannot be increased sufficiently, and if the content of potassium is too high, the volatilization of potassium during firing is severe. , Because firing is difficult.

The content of lithium in the first element is 2
It is preferably 0 mol% or less, and more preferably 2 mol% or more and 10 mol% or less. That is, for example, y in the chemical formula 1 is preferably in the range of 0 <y ≦ 0.2 and more preferably in the range of 0.02 ≦ y ≦ 0.1 in terms of molar ratio. If the lithium content is too high, the relative permittivity ε
This is because it is not possible to sufficiently increase r, the electromechanical coupling coefficient kr, and the generated displacement amount.

The content of antimony in the second element is preferably more than 0 mol% and less than 10 mol% as shown in Chemical formula 1, for example. This is because if the content of antimony is too large, the electric resistance decreases and polarization cannot be performed.

The composition ratio of the first element to the second element (first element / second element), for example, m in Chemical formula 1
Is preferably in the range of 0.95 or more and 1.05 or less in terms of molar ratio. When it is less than 0.95, the relative dielectric constant ε
This is because r, the electromechanical coupling coefficient kr, and the amount of generated displacement become small, and when it exceeds 1.05, polarization becomes difficult due to a decrease in sintered density.

The tungsten bronze type oxide comprises a third element, a fourth element and oxygen. The third element preferably contains, for example, at least one kind of alkaline earth metal element, and particularly contains at least one kind of alkaline earth metal element group consisting of magnesium, calcium, strontium and barium. It is preferable. The fourth element preferably contains, for example, at least niobium in the group consisting of niobium and antimony, and more preferably contains antimony. This is because in such a case, more excellent piezoelectric characteristics can be obtained by not containing lead or reducing the content of lead. The chemical formula of this tungsten bronze type oxide is represented by, for example, Chemical formula 2.

[0020]

Embedded image In the formula M (Nb _1-w Sb _w ) ₂ O ₆ , M represents the third element, and w is a value within the range of 0 ≦ w <1. The composition ratio of the third element, the fourth element and oxygen is stoichiometrically determined, and may deviate from the stoichiometric composition.

The fourth element may be the same as or different from the second element. The content of antimony in the fourth element is preferably less than 10 mol%. This is because if the content of antimony becomes too large, the electric resistance decreases and polarization becomes impossible.

The composition ratio of the perovskite type oxide to the tungsten bronze type oxide is preferably within the range shown in Chemical formula 3 in terms of molar ratio. That is, the content of the tungsten bronze type oxide in the composition was 0 mol.
% And 5.3 mol% or less is preferable. By including the tungsten bronze type oxide in addition to the perovskite type oxide, the firing can be facilitated, and the relative permittivity εr and the electromechanical coupling coefficient kr can be obtained.
While the generated displacement amount can be increased, the electromechanical coupling coefficient kr and the generated displacement amount become small when the content of the tungsten bronze type oxide is too large.

[0023]

Embedded image In the formula, (1-n) A + nB, A is a perovskite type oxide, B is a tungsten bronze type oxide, and n is 0 <n ≦ 0.0.
It is a value within the range of 53.

This piezoelectric ceramic also contains, in addition to the above-mentioned composition as the main component, 0.01 mass% of the main component of an oxide containing at least one of a transition metal element and a rare earth metal element as a sub-component. % Or more and 1 mass% or less is preferable. This is because the piezoelectric characteristics can be further improved by improving the sinterability. Of these, oxides containing the transition metal element manganese are preferable.
The oxide of this subcomponent may exist in the grain boundary of the composition of the main component, or may exist in a part of the composition of the main component in a diffused state.

The piezoelectric ceramic may contain lead (Pb), but its content is preferably 1% by mass or less, and more preferably no lead. Volatilization of lead during firing and release of lead into the environment after it is distributed to the market as a piezoelectric component and disposed of can be suppressed to a minimum, reducing pollution, environmental resistance and ecological viewpoints. This is because it is preferable.

This piezoelectric ceramic is preferably used as a material for a vibration element such as an actuator which is a piezoelectric element, a sounding body or a sensor.

FIG. 1 shows a configuration example of a piezoelectric element using the piezoelectric ceramic according to this embodiment. This piezoelectric element includes a piezoelectric substrate 1 made of the piezoelectric ceramic of the present embodiment, and a pair of electrodes 2 and 3 provided on a pair of opposing surfaces 1a and 1b of the piezoelectric substrate 1, respectively. Piezoelectric substrate 1
Is polarized in the thickness direction, that is, the direction in which the electrodes 2 and 3 face each other, and when a voltage is applied via the electrodes 2 and 3, it is possible to cause longitudinal vibration in the thickness direction and radial vibration in the radial direction. It has become.

The electrodes 2 and 3 are made of metal such as gold (Au), for example, and are provided on the entire surfaces of the opposing surfaces 1a and 1b of the piezoelectric substrate 1, respectively. An external power source (not shown) is electrically connected to the electrodes 2 and 3 via a wire (not shown), for example.

The piezoelectric ceramic and the piezoelectric element having such a structure can be manufactured, for example, as follows.

First, as the raw materials of the main components, for example, sodium, potassium, lithium, alkaline earth metal elements,
Oxide powders containing niobium and antimony are prepared as needed. In addition, as a raw material of the subcomponent, if necessary, for example, an oxide powder containing at least one of a transition metal and a rare earth element is prepared. The raw materials for these main components and subcomponents may be not oxides, but carbonates or oxalates that become oxides by firing. Then, these raw materials are sufficiently dried, and then weighed so that the final composition falls within the above range.

Subsequently, for example, the weighed starting materials are thoroughly mixed in an organic solvent or water with a ball mill or the like, dried, and press-molded to 750 ° C. to 1100.
Calcination is performed at ℃ for 1 to 4 hours. After calcination, for example,
The calcined product is sufficiently crushed in an organic solvent or water with a ball mill or the like, dried again, and a binder is added to granulate. After granulating, the granulated powder is press-molded using a uniaxial press molding machine, a hydrostatic molding machine (CIP) or the like.

After the molding, for example, the molded body is heated to remove the binder, and further, at 950 ° C. to 1350 ° C. for 2 hours.
Bake for ~ 4 hours. After firing, the obtained sintered body is processed as required to form the piezoelectric substrate 1, and the electrodes 2 and 3 are formed.
And a polarization treatment is performed by applying an electric field in heated silicone oil. As a result, the piezoelectric ceramic described above and the piezoelectric element shown in FIG. 1 are obtained.

As described above, according to the present embodiment, the perovskite type oxide containing sodium, potassium and lithium as the first element and niobium and antimony as the second element and the tungsten bronze type oxide are used. Since the content of antimony in the second element is set to be less than 10 mol%, the Curie temperature can be increased to, for example, 150 ° C. or higher, the operating temperature range can be widened, and the generated displacement can be increased. The amount can be increased. It can also be easily baked.

Therefore, it is possible to increase the applicability of piezoelectric ceramics and piezoelectric elements that do not contain lead or that contain a small amount of lead. In other words, there is little volatilization of lead during firing, there is a low risk of lead being released into the environment even after it has been distributed to the market and disposed of, and it is an extremely excellent piezoelectric material from the viewpoint of low pollution, environmental friendliness and ecological viewpoint. It is possible to utilize the porcelain and the piezoelectric element.

Particularly, if the content of potassium in the first element is set to 10 mol% or more and 90 mol% or less, more excellent piezoelectric characteristics can be obtained, and
Baking can be made easier.

If the content of lithium in the first element is 20 mol% or less, or the composition ratio of the first element to the second element (first element / second element). Is a molar ratio of 0.95 or more and 1.05 or less, or the content of the tungsten bronze-type oxide in the composition is 5.3 mol% or less, the generated displacement The amount can be larger.

Further, the tungsten bronze type oxide is
In particular, if a third element containing at least one of alkaline earth metal elements, a fourth element containing at least niobium in the group consisting of niobium and antimony, and oxygen are used, 3 elements are magnesium,
By including at least one selected from the group of alkaline earth metal elements consisting of calcium, strontium, and barium, more excellent piezoelectric characteristics can be obtained.

In addition, if the content of antimony in the fourth element is set to be less than 10 mol%, the generated displacement amount can be further increased.

Furthermore, an oxide containing at least one of a transition metal element and a rare earth metal element as a sub-component should be contained within the range of 0.01% by mass or more and 1% by mass or less of the main component. For example, the sinterability can be improved and the piezoelectric characteristics can be further improved.

[0040]

EXAMPLES Further, specific examples of the present invention will be described.

(Examples 1 and 2) A piezoelectric element as shown in FIG. 1 is used by using a piezoelectric ceramic containing as a main component a composition containing the perovskite type oxide and the tungsten bronze type oxide shown in Chemical formula 4. Was produced. This embodiment will be described with reference to FIG. 1 and using the reference numerals shown in FIG.

[0042]

[Chemical 4]

First, sodium carbonate (Na ₂ CO ₃ ) powder and potassium carbonate (K ₂ CO ₃ ) were used as raw materials for the main components.
Powder, lithium carbonate (Li ₂ CO ₃ ) powder, barium carbonate (BaCO ₃ ) powder, niobium oxide (Nb ₂ O ₅ ) powder and antimony pentoxide (Sb ₂ O ₅ ) were prepared, respectively. In addition, manganese carbonate (Mn
CO ₃ ) powder was prepared. Then, the raw materials of the main component and the subcomponents were sufficiently dried and weighed, and then mixed in water for 5 hours by a ball mill and dried to obtain a raw material mixed powder.

At this time, the blending ratio of the raw material mixed powders of Examples 1 and 2 was adjusted, and the content of antimony in the composition of the main component, that is, the values of z and w in Chemical formula 4, were as shown in Table 1. Changed. The amount of the manganese carbonate powder, which is the raw material of the accessory component, is the same as that of the carbonate of the raw material of the main component.
O ₂ was converted to the dissociated oxide, and was adjusted to be 0.5 mass% with respect to the converted total mass of the raw materials of the main components. That is, the content of manganese oxide in the piezoelectric ceramic is 0.31 mass% with respect to the main component.

[0045]

[Table 1]

Subsequently, this raw material mixed powder was press-molded and calcined at 850 ° C. to 1000 ° C. for 2 hours. After calcination, it was ground in water using a ball mill, dried again, and polyvinyl alcohol was added for granulation. After granulating, this granulated powder is about 40MP by a uniaxial press molding machine.
It is shaped into a cylinder with a diameter of 17 mm under the pressure of
Hydrostatic molding was performed at a pressure of 0 MPa.

After molding, the molded body was molded at 650 ° C. for 4 hours.
It is heated for an hour to remove the binder, and further 950 ° C-135
It was calcined at 0 ° C. for 4 hours. After that, the fired body was sliced and lapped to form a disk-shaped piezoelectric substrate 1 having a thickness of 0.6 mm, and a silver paste was printed on both surfaces and baked at 650 ° C. to form electrodes 2 and 3. . After forming the electrodes 2 and 3, an electric field of 3 kV / mm to 10 kV / mm was applied for 1 minute to 30 minutes in silicone oil of 30 ° C. to 250 ° C. to perform polarization treatment. Thereby, the piezoelectric elements of Examples 1 and 2 were obtained.

The piezoelectric elements obtained in Examples 1 and 2 were left for 24 hours and then, as piezoelectric characteristics, relative dielectric constant εr, electromechanical coupling coefficient kr, and displacement generated when an electric field of 3 kV / mm was applied. The quantity was measured. Relative permittivity εr
And an electromechanical coupling coefficient kr is measured by an impedance analyzer (HP41 manufactured by Hewlett Packard).
94A), the frequency when measuring the relative permittivity εr was set to 1 kHz. An eddy current displacement measuring device as shown in FIG. 2 was used to measure the generated displacement amount. In this displacement measuring device, a sample 13 is sandwiched between a pair of electrodes 11 and 12, a displacement sensor 14 detects a displacement of the sample 13 when a direct current is applied, and a displacement detector 15 obtains the generated displacement amount. It is a thing. The results are shown in Table 1. The generated displacement amount shown in Table 1 is a value obtained by dividing the measured value by the thickness of the sample and multiplying by 100 (measured value / thickness of sample × 1
00).

As Comparative Example 1 to this Example, piezoelectric elements were manufactured in the same manner as in Examples 1 and 2 except that antimony was not contained, that is, the values of z and w in Chemical formula 4 were set to 0. It was made. Further, as Comparative Example 2 with respect to this Example, except that the content of antimony in the second element and the fourth element was 10 mol%, that is, the values of z and w in Chemical formula 4 were 0.1, Piezoelectric elements were produced in the same manner as in Examples 1 and 2. The amount of manganese carbonate powder mixed in the raw material mixed powder was set so that the content of manganese oxide in the piezoelectric ceramic was 0.31% by mass with respect to the main component, as in Examples 1 and 2.
Also in Comparative Examples 1 and 2, in the same manner as in Examples 1 and 2,
Relative permittivity εr, electromechanical coupling coefficient kr and 3kV / m
The amount of displacement generated when an electric field of m was applied was measured. The results are also shown in Table 1.

As shown in Table 1, according to Examples 1 and 2, the relative permittivity ε is higher than that of Comparative Example 1 containing no antimony.
Excellent values could be obtained for r and the amount of displacement generated. Further, in Comparative Example 2 in which the content of antimony in the second element and the fourth element was 10 mol% or more, polarization could not be performed and the characteristics could not be measured. That is, it was found that when the second element contained a perovskite oxide containing antimony within the range of less than 10 mol%, the generated displacement amount could be increased.

(Example 3) Other than using the composition shown in Chemical formula 5 as a main component and setting the content of the tungsten bronze type oxide, that is, the value of n to be 0.053 as shown in Table 2. A piezoelectric element was manufactured in the same manner as in Example 1. The amount of manganese carbonate powder mixed in the raw material mixed powder was set so that the content of manganese oxide in the piezoelectric ceramic was 0.31% by mass with respect to the main component, as in Example 1. Further, as Comparative Example 3 with respect to this Example, a piezoelectric element was produced in the same manner as in Example 3 except that antimony was not included, that is, the values of z and w in Chemical formula 5 were set to 0. Further, as Comparative Example 4 with respect to this Example, a piezoelectric element was produced in the same manner as in Example 1 except that the tungsten bronze type oxide and antimony were not included.

[0052]

[Chemical 5]

[0053]

[Table 2]

Also in Example 3 and Comparative Examples 3 and 4,
In the same manner as in Example 1, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the amount of displacement generated when an electric field of 3 kV / mm was applied were measured. The results are shown in Table 2 together with the results of Example 1 and Comparative Example 1.

As shown in Table 2, according to the third embodiment,
Similar to Example 1, larger values were obtained than Comparative Example 3 with respect to relative permittivity εr, electromechanical coupling coefficient kr, and amount of generated displacement. Further, as the value of n in Chemical formula 5 increased, that is, as the content of the tungsten bronze type oxide increased, the relative permittivity εr, the electromechanical coupling coefficient kr, and the generated displacement amount increased, showing maximum values. After that, it tended to become smaller. That is, it has been found that the piezoelectric characteristics can be improved and the amount of generated displacement can be increased by containing 5.3 mol% or less of the tungsten bronze type oxide in the main component.

(Examples 5 and 6) Except that the composition shown in Chemical formula 6 was used as the main component and the content of potassium in the first element, that is, the value of x was changed as shown in Table 3.
A piezoelectric element was produced in the same manner as in Example 1 except for the above. In addition,
The amount of manganese carbonate powder mixed in the raw material mixed powder was set so that the content of manganese oxide in the piezoelectric ceramic was 0.31% by mass based on the main component, as in Example 1.
In addition, as Comparative Examples 5 and 6 with respect to this example, z and w in Chemical formula 6 should be excluded so that antimony is not included.
Piezoelectric elements were produced in the same manner as in Examples 5 and 6 except that the value of was set to 0. Comparative Example 5 corresponds to Example 5, and Comparative Example 6 corresponds to Example 6.

[0057]

[Chemical 6]

[0058]

[Table 3]

In Examples 5 and 6 and Comparative Examples 5 and 6, similarly to Example 1, the relative permittivity εr, the electromechanical coupling coefficient kr, and the amount of displacement generated when an electric field of 3 kV / mm was applied. It was measured. The results are shown in Table 3 together with the results of Example 1 and Comparative Example 1.

As shown in Table 3, according to Examples 5 and 6, similar to Example 1, larger values of relative permittivity εr, electromechanical coupling coefficient kr, and generated displacement than those of Comparative Example were obtained. Was given. Further, as the value of x in Chemical formula 6 increases, that is, as the content of potassium increases, the relative permittivity εr, the electromechanical coupling coefficient kr, and the generated displacement amount increase, exhibiting the maximum value, and then decreasing. A trend was seen. That is, it was found that when the content of potassium in the first element is 10 mol% or more and 90 mol% or less, the piezoelectric characteristics can be improved and the generated displacement amount can be increased.

(Example 7) The composition shown in Chemical formula 7 was used as a main component, and the contents of potassium and lithium in the first element, that is, the values of x and y were changed as shown in Table 4. Except for the above, the piezoelectric element was manufactured in the same manner as in Example 1 except for the above. The amount of the manganese carbonate powder mixed in the raw material mixed powder was 0.31% by mass with respect to the main component as the content of manganese oxide in the piezoelectric ceramic as in Example 1.
So that Further, as Comparative Example 7 with respect to this Example, a piezoelectric element was produced in the same manner as in Example 7 except that antimony was not included, that is, the values of z and w in Chemical formula 7 were set to 0. .

[0062]

[Chemical 7]

[0063]

[Table 4]

Also in Example 7 and Comparative Example 7, similar to Example 1, the relative permittivity εr and the electromechanical coupling coefficient k were obtained.
The amount of displacement generated when an electric field of r and 3 kV / mm was applied was measured. The results are shown in Table 4 together with the results of Example 1 and Comparative Example 1.

As shown in Table 4, according to Example 7,
Similar to Example 1, larger values were obtained for the relative permittivity εr, the electromechanical coupling coefficient kr, and the generated displacement than those of Comparative Example 7. Further, when the value of y in Chemical formula 7 becomes large,
That is, when the content of lithium increases, the relative permittivity εr,
The electromechanical coupling coefficient kr and the generated displacement tended to be small. That is, the content of lithium in the first element is 20 mol% or less, more preferably 2 mol.
It has been found that the piezoelectric characteristics can be improved and the generated displacement amount can be increased when the content is in the range of 10% to 10% by mol.

Example 8 The same as Example 1 except that the composition shown in Chemical formula 8 was the main component and the composition of the third element, that is, M was changed as shown in Table 5. Then, a piezoelectric element was manufactured. Strontium carbonate (SrCO ₃ ) powder and calcium carbonate (CaCO ₃ ) powder were used as starting materials for strontium and calcium. The amount of manganese carbonate powder mixed in the raw material mixed powder was set so that the content of manganese oxide in the piezoelectric ceramic was 0.31% by mass with respect to the main component, as in Example 1. Further, as Comparative Example 8 with respect to this Example, a piezoelectric element was produced in the same manner as in Example 8 except that antimony was not included, that is, the values of z and w in Chemical formula 8 were set to 0. .

[0067]

[Chemical 8]

[0068]

[Table 5]

Also in Example 8 and Comparative Example 8, similar to Example 1, the relative permittivity εr and the electromechanical coupling coefficient k were obtained.
The amount of displacement generated when an electric field of r and 3 kV / mm was applied was measured. The results are shown in Table 5 together with Example 1 and Comparative Example 1.

As shown in Table 5, according to the eighth embodiment,
Similar to Example 1, larger values were obtained for the relative permittivity εr, the electromechanical coupling coefficient kr, and the generated displacement than those of Comparative Example 8. That is, it was found that excellent piezoelectric characteristics can be obtained even if another alkaline earth metal element is included as the third element.

In the above example, the composition of the composition containing the perovskite type oxide and the tungsten bronze type oxide was specifically described with reference to some examples. However, the composition described in the above embodiment is described. Within the range, similar results can be obtained with other compositions. Further, in the above-mentioned examples, the case where the contents of antimony in the second element and the fourth element, that is, the values of z and w in Chemical formulas 4 to 8 are the same, is shown. Similar results can be obtained for different cases.

Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made. For example, in the above embodiments and examples, the case where the composition of the perovskite-type oxide and the tungsten bronze-type oxide is contained is described. It may further contain other components.

Further, in the above-mentioned embodiment and examples,
The composition of the main component contains sodium, potassium and lithium as the first element, niobium and antimony as the second element, and at least one of alkaline earth metal elements as the third element, The case where at least niobium in the group consisting of niobium and antimony is contained as the element 4 has been described, but the first element, the second element, the third element, and the fourth element are other than these elements. It may further contain an element.

Further, in the above-mentioned embodiment and example,
Although the case where the main component composition is contained in addition to the subcomponents has been described, the present invention can be widely applied to the case where the main component composition is contained and the subcomponents are not contained. Further, the same can be applied to the case where other subcomponents are included.

In addition, in the above embodiment, the piezoelectric element having a single-layer structure has been described as an example, but the present invention can be similarly applied to a piezoelectric element having another structure such as a laminated structure. . Further, as the piezoelectric element, a vibration element such as an actuator, a sounding body and a sensor are given as an example.
The present invention can be applied to other piezoelectric elements.

[0076]

As described above, according to the piezoelectric ceramic according to any one of claims 1 to 8, the first element contains sodium, potassium and lithium and the second element contains niobium and Since the perovskite type oxide containing antimony and the tungsten bronze type oxide are contained and the content of antimony in the second element is set to be less than 10 mol%, the Curie temperature is set to be 150 ° C. or higher. Therefore, the operating temperature range can be widened, and the generated displacement amount can be increased. It can also be easily baked. Therefore, it is possible to increase the usability of piezoelectric ceramics and piezoelectric elements that do not contain lead or that contain a small amount of lead. In other words, there is little volatilization of lead during firing, there is a low risk of lead being released into the environment even after it has been distributed to the market and disposed of, and it is an extremely excellent piezoelectric material from the viewpoint of low pollution, environmental friendliness and ecological viewpoint. It is possible to utilize the porcelain and the piezoelectric element.

Particularly, the piezoelectric ceramic according to any one of claims 2 to 8 is more excellent because the content of potassium in the first element is set to 10 mol% or more and 90 mol% or less. Piezoelectric properties can be obtained and firing can be facilitated.

According to the piezoelectric ceramic according to any one of claims 3 to 8, the content of lithium in the first element is set to 20 mol% or less.
Alternatively, since the content of the tungsten bronze type oxide in the composition is set to 5.3 mol% or less,
The amount of generated displacement can be increased.

Further, according to the piezoelectric ceramic of any one of claims 5 to 8, the tungsten bronze-type oxide contains a third element containing at least one of alkaline earth metal elements, Since the fourth element containing at least niobium in the group consisting of niobium and antimony is composed of oxygen, more excellent piezoelectric characteristics can be obtained.

In addition, according to the piezoelectric ceramic of the seventh or eighth aspect, an oxide containing at least one of a transition metal element and a rare earth metal element as a sub-component is added in an amount of 0.01 mass of the main component. % To 1% by mass, the sinterability can be improved.
The piezoelectric characteristics can be further improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a piezoelectric element using a piezoelectric ceramic according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a displacement measuring device used for measuring a generated displacement amount in an example of the present invention.

[Explanation of symbols]

1 ... Piezoelectric substrate, 1a, 1b ... Opposing surface, 2, 3 ... Electrode, 1
1, 12 ... Electrode, 13 ... Sample, 14 ... Displacement sensor, 15
… Displacement detector.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G030 AA02 AA03 AA04 AA07 AA08                       AA09 AA10 AA11 AA20 AA25                       AA42 BA10 CA01 GA03 GA04                       GA08 GA14 GA19 GA22 GA27                 5D004 BB04                 5D019 BB05 HH01

Claims (8)

[Claims] 1. A composition containing a perovskite type oxide and a tungsten bronze type oxide, wherein the perovskite type oxide is sodium (Na),
A first element containing potassium (K) and lithium (Li), a second element containing niobium (Nb) and antimony (Sb), and oxygen (O). Content is 10mo
A piezoelectric ceramic characterized by being in a range of less than 1%. 2. The piezoelectric ceramic according to claim 1, wherein the content of potassium in the first element is in the range of 10 mol% or more and 90 mol% or less. 3. The content of lithium in the first element is 20 mol% or less.
Alternatively, the piezoelectric ceramic according to claim 2. 4. The piezoelectric ceramic according to any one of claims 1 to 3, wherein a content of the tungsten bronze type oxide in the composition is 5.3 mol% or less. 5. The tungsten bronze-type oxide comprises: a third element containing at least one of alkaline earth metal elements; and a fourth element containing at least niobium in the group consisting of niobium and antimony. The piezoelectric ceramic according to any one of claims 1 to 4, characterized in that the piezoelectric ceramic comprises oxygen. 6. The third element is magnesium (M
6. The piezoelectric ceramic according to claim 5, comprising at least one selected from the group of alkaline earth metal elements consisting of g), calcium (Ca), strontium (Sr), and barium (Ba). 7. An oxide containing the composition as a main component and further containing at least one of a transition metal element and a rare earth metal element as a sub-component with respect to the main component.
The piezoelectric ceramic according to any one of claims 1 to 6, wherein the piezoelectric ceramic is contained in a range of 01% by mass or more and 1% by mass or less. 8. The piezoelectric ceramic according to claim 7, further comprising an oxide containing manganese (Mn) as a transition metal.