JP4524558B2 - Piezoelectric ceramic and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric ceramic containing a composition containing a perovskite oxide and a tungsten bronze oxide and suitable for a vibration element such as an actuator, a sounding body or a sensor, and a manufacturing method thereof.

  An actuator using a piezoelectric ceramic uses a piezoelectric phenomenon in which mechanical strain and stress are generated when an electric field is applied. This actuator can obtain a small amount of displacement with high accuracy and has characteristics such as a large generated stress, and is used, for example, for positioning of precision machine tools and optical devices. Conventionally, lead zirconate titanate (PZT) having excellent piezoelectricity has been most frequently used as a piezoelectric ceramic used for an actuator. However, since lead zirconate titanate contains a large amount of lead, recently, adverse effects on the global environment such as elution of lead by acid rain have become a problem. Therefore, development of a piezoelectric ceramic that does not contain lead, which replaces lead zirconate titanate, is desired.

As a piezoelectric ceramic not containing lead, for example, one containing barium titanate (BaTiO ₃ ) as a main component is known (see Patent Document 1). This piezoelectric ceramic is excellent in relative dielectric constant εr and electromechanical coupling coefficient kr, and is promising as a piezoelectric material for an actuator. As another piezoelectric ceramic not containing lead, for example, one containing sodium potassium lithium niobate as a main component is known (see Patent Document 2 or Patent Document 3). This piezoelectric ceramic is expected as a piezoelectric material because it has a high Curie temperature of 350 ° C. or higher and an excellent electromechanical coupling coefficient kr. Furthermore, recently, a composite of sodium potassium niobate and tungsten bronze oxide (see Patent Document 4) and a composite of barium titanate and the like (see Patent Document 5) have also been reported. Yes.
Japanese Patent Laid-Open No. 2-159079 JP 49-125900 A Japanese Patent Publication No.57-6713 Japanese Patent Laid-Open No. 9-165262 JP 2002-23411 A

  However, these lead-free piezoelectric ceramics have lower piezoelectric characteristics than lead-based piezoelectric ceramics, and further improvements in characteristics have been desired.

  The present invention has been made in view of such problems, and the object thereof is to obtain a piezoelectric ceramic that can obtain a larger amount of generated displacement and is excellent in terms of pollution reduction, environmental friendliness, and ecology. It is in providing the manufacturing method.

The piezoelectric ceramic according to the present invention contains, as a main component, a composition containing a first perovskite oxide, a second perovskite oxide, and a tungsten bronze oxide, and the first perovskite oxide is A first element containing sodium (Na) and potassium (K), a second element containing at least niobium from the group consisting of niobium (Nb) and tantalum (Ta), and oxygen (O). The second perovskite oxide is composed of a third element containing an alkaline earth metal element, a fourth element containing titanium (Ti), and oxygen, and the second perovskite oxide in the composition. the content of the object is less than 10 mol%, the content of the tungsten bronze-type oxide is less than 1 mol%, furthermore, the manganese (Mn) as a first subcomponent, a second subcomponent Aluminum (Al), gallium (Ga), indium (In), silicon (Si), those containing at least one kind selected from the group consisting of germanium (Ge) and tin (Sn).

In addition, it is preferable that content of manganese which is a 1st subcomponent is 0.1 to 1 mass% of a main component in conversion of an oxide (MnO), and also contains 2nd subcomponent. The amount is 0.01% by mass or more of the main component in terms of the total amount in terms of oxides ( Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , SiO ₂ , GeO ₂ , SnO ₂ ). It is preferable to be within the range of 1% by mass or less.

  Moreover, it is preferable that content of potassium in a 1st element exists in the range of 10 mol% or more and 90 mol% or less. The first element preferably further contains lithium, and the lithium content in the first element is preferably 10 mol% or less.

Furthermore, motor ring stainless bronze-type oxide includes a fifth element including an alkaline earth metal element, a sixth element including at least niobium selected from the group consisting of niobium and tantalum, it is preferably made of oxygen.

  In addition, the tantalum content in the total of the second element and the sixth element is preferably in the range of 0 mol% to 10 mol%.

A method for manufacturing a piezoelectric ceramic according to the present invention includes a first element including sodium and potassium, a second element including at least niobium in the group consisting of niobium and tantalum, and a first perovskite oxide including oxygen. A composition comprising a third element containing at least one of the alkaline earth metal elements, a fourth element containing titanium and a second perovskite oxide comprising oxygen and a tungsten bronze oxide. A piezoelectric ceramic having a second perovskite-type oxide content of less than 10 mol% and a tungsten bronze-type oxide content of 1 mol% or less . Perovskite-type oxide raw material, second perovskite-type oxide raw material, and tungsten bronze-type oxide raw material In addition, the raw material of manganese (Mn), which is the first subcomponent, and aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge) and tin (second subcomponent) A step of calcining a mixture containing at least one raw material of the group consisting of Sn).

According to a piezoelectric ceramic according to the present invention, a first perovskite oxide containing sodium, potassium and niobium, a second perovskite oxide containing an alkaline earth metal element and titanium, and a tungsten bronze oxide containing composition comprising as a main component, further contains a manganese as a first subcomponent, a as the second subcomponent aluminum, gallium, indium, silicon, and at least one kind selected from the group consisting of germanium and tin Thus, the piezoelectric characteristics such as the generated displacement amount can be further improved. Therefore, it is possible to increase the possibility of use of piezoelectric ceramics and piezoelectric elements that do not contain lead or have a low lead content. In other words, there is little volatilization of lead during firing, the risk of lead being released into the environment even after it has been distributed to the market and discarded, and is extremely excellent in terms of low pollution, environmental friendliness, and ecological viewpoint. Utilization of porcelain and piezoelectric elements can be achieved.

In particular, if the content of manganese, which is the first subcomponent, is converted to oxide (MnO) so that it is 0.1% by mass or more and 1% by mass or less of the main component, the second subcomponent is further increased. Is converted to oxides ( Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , SiO ₂ , GeO ₂ , SnO ₂ ), and in total, 0.01 mass of the main component If it is within the range of not less than 1% and not more than 1% by mass, a higher effect can be obtained.

  Moreover, if the content of potassium in the first element is 10 mol% or more and 90 mol% or less, more excellent piezoelectric characteristics can be obtained and firing can be facilitated.

  Furthermore, if the first element contains 10 mol% or less of lithium, the amount of generated displacement can be further increased.

  Furthermore, if the tungsten bronze type oxide comprises a third element containing an alkaline earth metal element, a fourth element containing at least niobium in the group consisting of niobium and tantalum, and oxygen. More excellent piezoelectric characteristics can be obtained.

  In addition, if the tantalum content in the total of the second element and the sixth element is 10 mol% or less, the generated displacement can be further increased.

Furthermore, according to the piezoelectric ceramic manufacturing method of the present invention, in addition to the first perovskite oxide raw material, the second perovskite oxide raw material, and the tungsten bronze oxide raw material, the raw material of manganese component, and the second subcomponent der luer aluminum, gallium, indium, silicon, a mixture containing at least one material selected from the group consisting of germanium and tin as calcined Therefore, the piezoelectric ceramic of the present invention can be easily obtained, and the piezoelectric ceramic of the present invention can be realized.

  Hereinafter, embodiments of the present invention will be described in detail.

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

  The first perovskite oxide is composed of a first element, a second element, and oxygen. The first element preferably contains at least sodium and potassium, and further preferably contains lithium. The second element preferably contains at least niobium and further contains tantalum. This is because, in such a case, superior piezoelectric characteristics can be obtained without containing lead or by reducing the lead content. The chemical formula of the first perovskite oxide is represented by, for example,

式中、ｘは０＜ｘ＜１、ｙは０≦ｙ＜１、ｚは０≦ｚ＜１の範囲内の値である。ｐは化学量論組成であれば１であるが、化学量論組成からずれていてもよい。酸素の組成は化学量論的に求めたものであり、化学量論組成からずれていてもよい。

In the formula, x is a value within the range of 0 <x <1, y is 0 ≦ y <1, and z is 0 ≦ z <1. p is 1 in the case of a stoichiometric composition, but may deviate from the stoichiometric composition. The composition of oxygen is determined stoichiometrically and may deviate from the stoichiometric composition.

  Note that the potassium content in the first element is preferably in the range of 10 mol% to 90 mol%. 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 potassium content is too small, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the generated displacement cannot be sufficiently increased. If the potassium content is too large, the volatilization of potassium during firing is severe. This is because firing is difficult.

  The lithium content in the first element is preferably 0 mol% or more and 10 mol% or less. That is, for example, y in Chemical Formula 1 is preferably in the range of 0 ≦ y ≦ 0.1 in terms of molar ratio. This is because if the lithium content is too large, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the generated displacement cannot be sufficiently increased.

  The composition ratio of the first element to the second element (first element / second element), for example, p in Chemical Formula 1, is preferably in the range of 0.95 to 1.05 in molar ratio. . This is because if it is less than 0.95, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the generated displacement amount become small, and if it exceeds 1.05, it becomes difficult to polarize because the sintered density decreases. .

  The second perovskite oxide includes a third element including at least an alkaline earth metal element, a fourth element including at least titanium, and oxygen. The alkaline earth metal element is preferably at least one member selected from the group consisting of magnesium, calcium, strontium and barium. This is because in such a case, more excellent piezoelectric characteristics can be obtained. The chemical formula of the second perovskite oxide is represented by, for example,

式中、Ｍ１は第３の元素を表す。第３の元素と第４の元素（Ｔｉ）と酸素との組成比は化学量論的に求めたものであり、化学量論組成からずれていてもよい。

In the formula, M1 represents a third element. The composition ratio of the third element, the fourth element (Ti), and oxygen is determined stoichiometrically and may deviate from the stoichiometric composition.

  The tungsten bronze type oxide is composed of a fifth element, a sixth element, and oxygen. For example, the fifth element preferably includes at least an alkaline earth metal element, and preferably includes at least one selected from the group consisting of magnesium, calcium, strontium, and barium. For example, the sixth element preferably contains at least niobium and further contains tantalum. This is because, in such a case, superior piezoelectric characteristics can be obtained without containing lead or by reducing the lead content. The chemical formula of the tungsten bronze type oxide is represented by, for example, Chemical formula 3.

式中、Ｍ２は第５の元素を表し、ｗは０≦ｗ＜１の範囲内の値である。第５の元素と第６の元素（Ｎｂ_1-w Ｔａ_w ）と酸素との組成比は化学量論的に求めたものであり、化学量論組成からずれていてもよい。

In the formula, M2 represents the fifth element, and w is a value in the range of 0 ≦ w <1. The composition ratio of the fifth element, the sixth element (Nb _1-w Ta _w ), and oxygen is determined stoichiometrically, and may deviate from the stoichiometric composition.

  Note that the sixth element may be the same as or different from the second element. The tantalum content in the total of the second element and the sixth element is preferably 10 mol% or less. This is because if the tantalum content is excessively increased, the electromechanical coupling coefficient kr and the generated displacement amount are decreased.

  The composition ratio of the first perovskite oxide, the second perovskite oxide, and the tungsten bronze oxide is preferably in the range shown in Chemical Formula 4 in terms of molar ratio. That is, the content of the second perovskite oxide in the composition is preferably greater than 0 mol% and less than 10 mol%. By including the second perovskite type oxide, it is possible to increase the relative dielectric constant εr and the amount of generated displacement. On the other hand, if the content of the second perovskite type oxide is too large, sintering becomes difficult. It is. The content of the tungsten bronze type oxide is preferably greater than 0 mol% and 1 mol% or less. By including the tungsten bronze type oxide, the firing can be facilitated and the relative dielectric constant εr, the electromechanical coupling coefficient kr and the generated displacement amount can be increased, while the content of the tungsten bronze type oxide is increased. This is because if the amount is too large, the electromechanical coupling coefficient kr and the generated displacement amount become small.

式中、Ａは第１のペロブスカイト型酸化物、Ｂは第２のペロブスカイト型酸化物、Ｃはタングステンブロンズ型酸化物をそれぞれ表し、ｍは０＜ｍ＜０．１、ｎは０＜ｎ≦０．０１の範囲内の値である。

In the formula, A represents the first perovskite type oxide, B represents the second perovskite type oxide, C represents the tungsten bronze type oxide, m represents 0 <m <0.1, and n represents 0 <n ≦ It is a value within the range of 0.01.

  This piezoelectric ceramic also contains manganese as a constituent element as a first subcomponent in addition to the above composition as the main component. This is because the piezoelectric characteristics can be improved by improving the sinterability. The manganese content is preferably in the range of 0.1% by mass or more and 1% by mass or less of the main component in terms of oxide (MnO). This is because the sinterability can be improved within this range.

In addition to the main component and the first subcomponent, the piezoelectric ceramic further includes, as a second subcomponent, cobalt, iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon as constituent elements. , At least one of the group consisting of germanium and tin. This is because these have a function of improving the piezoelectric characteristics in addition to the improvement of the sinterability. The content of the second subcomponent includes oxides (Co ₃ O ₄ , Fe ₂ O ₃ , NiO, ZnO, Sc ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , SiO ₂ , GeO ₂ , SnO ₂ ), the total amount thereof is preferably in the range of 0.01% by mass to 1% by mass of the main component. This is because the generated displacement can be improved within this range.

  The first subcomponent and the second subcomponent may be present in the grain boundary of the main component composition as oxides, for example, but are diffused and present in a part of the main component composition. Sometimes.

  In addition, although this piezoelectric ceramic may contain lead (Pb), it is preferable that the content is 1 mass% or less, and it is more preferable if it does not contain lead at all. It is possible to minimize lead volatilization during firing and lead release into the environment after being marketed and disposed of as piezoelectric components. It is because it is preferable.

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

  FIG. 1 shows a configuration example of a piezoelectric element using a piezoelectric ceramic according to the present embodiment. The piezoelectric element includes a piezoelectric substrate 1 made of the piezoelectric ceramic according to 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. The piezoelectric substrate 1 is, for example, polarized in the thickness direction, that is, in the direction opposite to the electrodes 2 and 3, and is applied with a voltage via the electrodes 2 and 3, so that the piezoelectric substrate 1 spreads in the longitudinal direction and the radial direction in the thickness direction. It comes to vibrate.

Electrodes 2 and 3, for example, gold (Au) are respectively made of metal such as, opposed surface 1a of the piezoelectric substrate 1, and Re provided respectively it in the entire surface of the 1b. An external power source (not shown) is electrically connected to the electrodes 2 and 3 via, for example, a wire (not shown).

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

  FIG. 2 is a flowchart showing a method for manufacturing the piezoelectric ceramic. First, oxide powders containing, for example, sodium, potassium, lithium, niobium, tantalum, alkaline earth metal elements, or titanium are prepared as raw materials for the elements constituting the main component. Further, for example, an oxide powder containing manganese as a raw material for the first subcomponent, and as a raw material for the second subcomponent, for example, cobalt, iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, An oxide powder containing gallium, indium, silicon, germanium or tin is prepared. The raw materials for these main component, first subcomponent, and second subcomponent may be those that become oxides upon firing, such as carbonates or oxalates, instead of oxides. Next, these raw materials are sufficiently dried, and then weighed so that the final composition is in the above-described range (step S101).

  Subsequently, for example, the second perovskite-type oxide raw material is sufficiently mixed in an organic solvent or water by a ball mill or the like, then dried, and calcined at 1000 ° C. to 1200 ° C. for 2 hours to 4 hours. A perovskite oxide is produced (step S102).

  After producing the second perovskite type oxide, the second perovskite type oxide, the first perovskite type oxide raw material, the tungsten bronze type oxide raw material, the first subcomponent raw material, The raw material of the second subcomponent is sufficiently mixed in an organic solvent or water using a ball mill or the like. Thereafter, the mixture is dried, press-molded, and calcined at 750 ° C. to 1100 ° C. for 1 to 4 hours (step S103). The second perovskite oxide is prepared in this manner and then mixed with the other main component raw materials by mixing the second perovskite oxide raw material and the first perovskite oxide raw material. This is because, when fired, it reacts with the first perovskite oxide and the second perovskite oxide is not generated.

  After calcining, for example, the calcined product is sufficiently pulverized in an organic solvent or water with a ball mill or the like, dried again, and granulated with a binder. After granulation, the granulated powder is press-molded using a uniaxial press molding machine or a hydrostatic pressure molding machine (CIP) (step S104).

  After the molding, for example, the molded body is heated to remove the binder, and further fired at 950 ° C. to 1350 ° C. for 2 hours to 4 hours (step S105). After firing, the obtained sintered body is processed as necessary to form the piezoelectric substrate 1, electrodes 2 and 3 are provided, and an electric field is applied in heated silicone oil to perform polarization treatment (step S106). ). Thereby, the piezoelectric ceramic described above and the piezoelectric element shown in FIG. 1 are obtained.

  Thus, according to this embodiment, the first perovskite oxide containing sodium, potassium and niobium, the second perovskite oxide containing alkaline earth metal element and titanium, and the tungsten bronze oxide The main component is manganese, the first subcomponent is manganese, and the second subcomponent is cobalt, iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon, germanium, and tin. The amount of generated displacement can be further increased because at least one member of the group consisting of:

  Therefore, it is possible to increase the possibility of use of piezoelectric ceramics and piezoelectric elements that do not contain lead or have a low lead content. In other words, there is little volatilization of lead during firing, the risk of lead being released into the environment even after it has been distributed to the market and discarded, and is extremely excellent in terms of low pollution, environmental friendliness, and ecological viewpoint. Utilization of porcelain and piezoelectric elements can be achieved.

  In particular, if the content of manganese, which is the first subcomponent, is converted to oxide and is 0.1% by mass or more and 1% by mass or less of the main component, the content of the second subcomponent Can be converted into oxides, and the total of them can be in the range of 0.01% by mass or more and 1% by mass or less of the main component, whereby a higher effect can be obtained.

  Further, if the potassium content in the first element is 10 mol% or more and 90 mol% or less, more excellent piezoelectric characteristics can be obtained and firing can be facilitated.

  Furthermore, if 10 mol% or less of lithium is included as the first element, or the composition ratio of the first element to the second element (first element / second element) is 0. If it is within the range of 95 or more and 1.05 or less, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the generated displacement can be further increased.

  In addition, if the content of the tungsten bronze oxide in the composition is 1 mol% or less, the electromechanical coupling coefficient kr and the generated displacement can be further increased.

  Furthermore, if the tungsten bronze type oxide comprises a fifth element containing an alkaline earth metal element, a sixth element containing at least niobium from the group consisting of niobium and tantalum, and oxygen. In particular, if the fifth element includes at least one member selected from the group consisting of magnesium, calcium, strontium, and barium, more excellent piezoelectric characteristics can be obtained.

  In addition, if the tantalum content in the total of the second element and the sixth element is 10 mol% or less, the electromechanical coupling coefficient kr and the generated displacement can be further increased.

  Furthermore, in addition to the second perovskite oxide, the first perovskite oxide raw material, and the tungsten bronze oxide raw material, the first subcomponent manganese raw material, and the second subcomponent And at least one raw material in the group consisting of cobalt, iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon, germanium, and tin, and calcining and firing. Therefore, the piezoelectric ceramic according to the present embodiment can be easily obtained, and the piezoelectric ceramic according to the present embodiment can be realized.

  Furthermore, specific examples of the present invention will be described.

( Reference Examples 1-1 to 1-3)
1 using a piezoelectric ceramic containing as a main component a composition containing the first perovskite oxide, the second perovskite oxide, and the tungsten bronze oxide shown in Chemical Formula 5. The device was manufactured by the process shown in FIG. This reference example will be described with reference to FIG. 1 and FIG. 2 using the reference numerals shown in FIG.

First, as raw materials for the main components, sodium carbonate (Na ₂ CO ₃ ) powder, potassium carbonate (K ₂ CO ₃ ) powder, lithium carbonate (Li ₂ CO ₃ ) powder, niobium oxide (Nb ₂ O ₅ ) powder, tantalum oxide (Ta ₂ O ₅ ) powder, barium carbonate (BaCO ₃ ) powder and titanium oxide (TiO ₂ ) powder were prepared. Also, manganese carbonate (MnCO ₃ ) powder was prepared as the first subcomponent raw material, and cobalt oxide (Co ₃ O ₄ ) powder was prepared as the second subcomponent raw material. Next, after sufficiently drying the raw materials of the main component, the first subcomponent and the second subcomponent, the main component becomes the composition shown in Chemical formula 5, and the contents of the first subcomponent and the second subcomponent are oxidized. In terms of the product (MnO, Co ₃ O ₄ ), the main components were weighed so as to have the values shown in Table 1 (see FIG. 2; step S101).

  Subsequently, the barium carbonate powder and the titanium oxide powder were mixed in water by a ball mill, dried, and then fired at 1100 ° C. for 2 hours to produce barium titanate as a second perovskite oxide (FIG. 2; (See step S102).

  After producing barium titanate, this barium titanate, the raw material of the other main component, the raw material of the first subcomponent and the second subcomponent are mixed in water with a ball mill, dried, press molded, Calcination was performed at 850 ° C. to 1000 ° C. for 2 hours (see FIG. 2; step S103). After calcination, the mixture was pulverized in water using a ball mill, dried again, and granulated by adding polyvinyl alcohol. After granulation, this granulated powder was formed into a disk-shaped pellet having a diameter of 17 mm with a pressure of about 40 MPa by a uniaxial press molding machine (see FIG. 2; step S104).

After molding, the molded body was heated at 650 ° C. for 4 hours to remove the binder, and further baked at 950 ° C. to 1350 ° C. for 4 hours (see FIG. 2; step S105). After that, this fired body was processed into a disk shape having a thickness of 0.6 mm to produce a piezoelectric substrate 1, and a silver paste was printed on both sides and baked at 650 ° C. to form electrodes 2 and 3. After forming the electrodes 2 and 3, polarization treatment was performed by applying an electric field of 3 kV / mm to 10 kV / mm in silicone oil at 30 to 250 ° C. for 1 to 30 minutes (see FIG. 2; step S106). . Thereby, piezoelectric elements of Reference Examples 1-1 to 1-3 were obtained.

About the obtained piezoelectric elements of Reference Examples 1-1 to 1-3, after being left for 24 hours, as a piezoelectric characteristic, a dielectric constant εr, an electromechanical coupling coefficient kr, and an electric field generated when an electric field of 3 kV / mm is applied The amount of displacement was measured. An impedance analyzer (HP4194A manufactured by Hewlett-Packard Company) was used to measure the relative dielectric constant εr and the electromechanical coupling coefficient kr, and the frequency when measuring the relative dielectric constant εr was 1 kHz. For the measurement of the generated displacement amount, a displacement measuring device using eddy current as shown in FIG. 3 was used. In this displacement measuring device, a sample 13 is sandwiched between a pair of electrodes 11, 12, the displacement of the sample 13 when a direct current is applied is detected by a displacement sensor 14, and the generated displacement amount is obtained by a displacement detector 15. Is. The results are shown in Table 1. The generated displacement 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 / sample thickness × 100).

As Comparative Example 1-1 with respect to this reference example, a piezoelectric element was fabricated in the same manner as Reference Examples 1-1 to 1-3 except that cobalt as the second subcomponent was not added. For Comparative Example 1-1, the amount of displacement generated when an electric field having a relative dielectric constant εr, an electromechanical coupling coefficient kr, and 3 kV / mm was applied was measured in the same manner as in Reference Examples 1-1 to 1-3. The results are also shown in Table 1.

As shown in Table 1, according to Reference Examples 1-1 to 1-3, a larger displacement amount was obtained than in Comparative Example 1-1 not including cobalt as the second subcomponent. In addition, as the cobalt content increased, the amount of generated displacement increased, showed a maximum value, and then tended to decrease.

  That is, it was found that the amount of generated displacement can be further increased by including manganese as the first subcomponent and cobalt as the second subcomponent. Moreover, it turned out that it is more preferable if content of a 2nd subcomponent shall be in the range of 0.01 mass% or more and 1 mass% or less with respect to a main component in conversion to an oxide.

(Reference Example 2-1～2- 7, Example 2-8 ～2-13)
Reference Example 1-2 except that iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon, germanium or tin is added as the second subcomponent instead of cobalt. A piezoelectric element was produced in the same manner as described above. The raw materials for the second subcomponent are iron oxide (Fe ₂ O ₃ ) powder, nickel oxide (NiO) powder, zinc oxide (ZnO) powder, scandium oxide (Sc ₂ O ₃ ) powder, titanium oxide (TiO ₂ ) powder , Zirconium oxide (ZrO ₂ ) powder, hafnium oxide (HfO ₂ ) powder, aluminum oxide (Al ₂ O ₃ ) powder, gallium oxide (Ga ₂ O ₃ ) powder, indium oxide (In ₂ O ₃ ) powder, silicon oxide ( SiO ₂ ) powder, germanium oxide (GeO ₂ ) powder or tin oxide (SnO ₂ ) powder was used. The content of the second subcomponent includes oxides (Fe ₂ O ₃ , NiO, ZnO, Sc ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , In terms of SiO ₂ , GeO ₂ , SnO ₂ ), all were 0.2% by mass with respect to the main component.

Reference Example 2-1～2- 7, also for Example 2 8 ～2-13, in the same manner as in Reference Example 1-2, the relative dielectric constant .epsilon.r, the electromechanical coupling factor kr, an electric field of 3 kV / mm is applied The amount of displacement generated was measured. The results are shown in Table 2 together with the results of Reference Example 1-2 and Comparative Example 1-1.

  As shown in Table 2, even if it contains iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon, germanium or tin as the second subcomponent, The amount of generated displacement was improved.

  That is, the second subcomponent should contain at least one member selected from the group consisting of cobalt, iron, nickel, zinc, scandium, titanium, zirconium, hafnium, aluminum, gallium, indium, silicon, germanium, and tin. It was found that the piezoelectric characteristics can be further improved.

( Reference Examples 3-1 and 3-2)
A piezoelectric element was fabricated in the same manner as Reference Example 1-2, except that the composition shown in Chemical Formula 6 was included as a main component. At that time, as shown in Table 3 in Reference Examples 3-1 and 3-2, the content of barium titanate, which is the second perovskite oxide in the main component, is 0.5 mol% or 1 mol%, that is, The value of m in Chemical formula 6 was changed to 0.005 or 0.01. Subcomponents are the same as in Reference Example 1-2.

As Comparative Example 3-1 with respect to this reference example, except that barium titanate which is the second perovskite type oxide is not included, that is, except that the value of m in Chemical Formula 6 is set to 0, Piezoelectric elements were fabricated in the same manner as Reference Examples 3-1 and 3-2. Further, as Comparative Example 2-2 with respect to the present Reference Example, except that the content of barium titanate in the main component was 10 mol%, that is, the value of m in Chemical Formula 6 was 0.1, Reference Example 3-1 , 3-2, a piezoelectric element was fabricated. The content of subcomponents is the same as in Reference Examples 3-1 and 3-2.

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

As shown in Table 3, according to Reference Examples 3-1 and 3-2, larger values were obtained for the relative dielectric constant εr and the amount of generated displacement than Comparative Example 3-1, which did not contain barium titanate. Further, as m in Chemical Formula 6 increased, that is, as the content of barium titanate increased, the relative permittivity εr and the generated displacement amount tended to increase. Further, Comparative Example 3-2 having a barium titanate content of 10 mol% could not be sintered and the characteristics could not be measured.

  That is, in addition to the first perovskite oxide and the tungsten bronze type oxide, if the second perovskite type oxide is included in the main component within a range of less than 10 mol%, the generated displacement can be further increased. I understood.

( Reference Examples 4-1 to 4-7)
A piezoelectric element was fabricated in the same manner as Reference Example 1-2, except that the composition shown in Chemical Formula 7 was included as the main component. At that time, in Reference Examples 4-1 to 4-7, the composition of the first element (values of x and y in Chemical formula 7) and the content of barium titanate which is the second perovskite oxide (Chemical formula 7). The value of m in FIG. 4 was changed as shown in Table 4. Subcomponents are the same as in Reference Example 1-2.

Comparative examples 4-1 to 4-6 with respect to this reference example are the same as reference examples 4-1 to 4-7 except that barium titanate, which is the second perovskite oxide, is not included. Thus, a piezoelectric element was produced. Of these, Comparative Example 4-1 corresponds to Reference Example 4-1, Comparative Example 4-2 corresponds to Reference Examples 4-2 and 4-3, and Comparative Example 4-3 corresponds to Reference Example 4-4. Comparative Example 4-4 corresponds to Reference Example 4-5, Comparative Example 4-5 corresponds to Reference Example 4-6, and Comparative Example 4-6 corresponds to Reference Example 4-7.

For Reference Examples 4-1 to 4-7 and Comparative Examples 4-1 to 4-6, an electric field having a relative dielectric constant εr, an electromechanical coupling coefficient kr, and 3 kV / mm was applied in the same manner as Reference Example 1-2. The amount of displacement generated was measured. The results are shown in Table 4.

As shown in Table 4, according to Reference Examples 4-1 to 4-7, similar to Reference Example 1-2, larger values were obtained for the relative dielectric constant εr and the generated displacement amount than for the comparative example. Further, as the value of x in Chemical Formula 7 increases, that is, as the potassium content increases, the relative dielectric constant εr, the electromechanical coupling coefficient kr, and the generated displacement amount increase, and after reaching a maximum value, decrease. There was a trend. That is, it was found that if the potassium content in the first element is 10 mol% or more and 90 mol% or less, the piezoelectric characteristics can be improved and the generated displacement can be increased.

  Furthermore, when lithium was contained as the first element, the relative permittivity εr, the electromechanical coupling coefficient kr, and the generated displacement tended to be larger. That is, it was found that if the first element contains 10 mol% or less of lithium, the piezoelectric characteristics can be improved and the generated displacement can be increased.

( Reference Examples 5-1 and 5-2)
A piezoelectric element was fabricated in the same manner as Reference Example 1-2, except that the composition shown in Chemical Formula 8 was included as a main component. At that time, in Reference Examples 5-1 and 5-2, the content of tantalum (values of z and w in Chemical Formula 8) and the content of barium titanate as the second perovskite oxide (m in Chemical Formula 8) The values were changed as shown in Table 5. Subcomponents are the same as in Reference Example 1-2. Reference Example 5-1 is the same as Reference Example 1-2.

As Comparative Example 5-1 with respect to this reference example, the piezoelectric element was the same as Reference Examples 5-1 and 5-2 except that barium titanate, which is the second perovskite oxide, was not included. Was made. Similarly to Reference Example 1-2, Reference Examples 5-1 and 5-2 and Comparative Example 5-1 generate when an electric field having a relative dielectric constant εr, an electromechanical coupling coefficient kr, and 3 kV / mm is applied. The amount of displacement was measured. The results are shown in Table 5 together with the results of Reference Examples 3-1 and 3-2 and Comparative Example 3-1. Reference Examples 3-1 and 3-2 and Comparative Example 3-1 do not contain tantalum in the second element and the sixth element.

As shown in Table 5, according to Reference Examples 5-1 and 5-2, similar to Reference Example 1-2, larger values were obtained for the relative dielectric constant εr and the generated displacement than Comparative Example 5-1. It was. In addition, the reference examples 5-1 and 5-2 containing tantalum in the second element and the sixth element have a larger amount of generated displacement than the reference examples 3-1 and 3-2 containing no tantalum. Obtained.

  That is, it has been found that the amount of generated displacement can be increased if tantalum is included in the second element or the sixth element.

  In this example, the case where the tantalum contents in the second element and the sixth element, that is, the values of z and w in the chemical formula 8 are the same is shown, but the case where the values of z and w are different. The same result can be obtained.

  In the above-described examples, the composition of the composition including the first perovskite oxide, the second perovskite oxide, and the tungsten bronze oxide has been specifically described by way of example. As long as it is within the range of the composition described in, similar results can be obtained even with other compositions.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above embodiments and examples, the case where the composition of the first perovskite type oxide, the second perovskite type oxide, and the tungsten bronze type oxide is described has been described. In addition, other components other than the first perovskite oxide, the second perovskite oxide, and the tungsten bronze oxide may be further included.

  Moreover, in the said embodiment and Example, the composition of a main component contains at least sodium and potassium of the group which consists of sodium, potassium, and lithium as a 1st element, and from niobium and a tantalum as a 2nd element. And at least one of alkaline earth metal elements as the third element, at least titanium as the fourth element, and at least one of the alkaline earth metal elements as the fifth element. Although the case where at least one of them is included and at least niobium of the group consisting of niobium and tantalum is included as the sixth element has been described, these first element, second element, third element, fourth element These elements, the fifth element and the sixth element may further contain other elements.

  Furthermore, in the said embodiment and Example, although the case where the 1st subcomponent and the 2nd subcomponent were included was demonstrated, it can apply similarly when the other subcomponent is included.

  In addition, in the above-described embodiment, the piezoelectric element having a single layer structure has been described as an example. However, the present invention can be similarly applied to piezoelectric elements having other structures such as a laminated structure. In addition, vibration elements such as actuators, sounding bodies, and sensors have been exemplified as piezoelectric elements, but the present invention can also be applied to other piezoelectric elements.

  It can be used for vibration elements such as actuators, piezoelectric elements such as sounding bodies and sensors.

It is a block diagram showing the piezoelectric element using the piezoelectric ceramic which concerns on one embodiment of this invention. It is a flowchart showing the manufacturing method of the piezoelectric ceramic and piezoelectric element which concern on one embodiment of this invention. It is a block diagram showing the displacement measuring apparatus used for the measurement of the generated displacement amount in the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric substrate, 1a, 1b ... Opposite surface, 2, 3 ... Electrode, 11, 12 ... Electrode, 13 ... Sample, 14 ... Displacement sensor, 15 ... Displacement detector.

Claims (8)

Containing as a main component a composition comprising a first perovskite oxide, a second perovskite oxide, and a tungsten bronze oxide;
The first perovskite oxide includes a first element containing sodium (Na) and potassium (K), and a second element containing at least niobium from the group consisting of niobium (Nb) and tantalum (Ta). And oxygen (O)
The second perovskite oxide comprises a third element containing an alkaline earth metal element, a fourth element containing titanium (Ti), and oxygen.
In the composition, the content of the second perovskite-type oxide of less than 10 mol%, the content of the tungsten bronze-type oxide is less than 1 mol%,
Further, manganese (Mn) as the first subcomponent and aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge) and tin (Sn) as the second subcomponent A piezoelectric ceramic comprising at least one of the above. The content of manganese as the first subcomponent is in the range of 0.1 mass% or more and 1 mass% or less of the main component in terms of oxide (MnO). Piezoelectric ceramic. The contents of the second subcomponents aluminum, gallium, indium, silicon, germanium and tin are oxides (Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , SiO ₂ , GeO ₂ , SnO ₂ ). The piezoelectric ceramic according to claim 1 or 2, wherein the piezoelectric ceramic is in a range of 0.01 mass% or more and 1 mass% or less of the main component in terms of the total. The piezoelectric ceramic according to any one of claims 1 to 3, wherein a content of potassium in the first element is in a range of 10 mol% or more and 90 mol% or less. The piezoelectric ceramic according to any one of claims 1 to 4, wherein lithium is further contained as the first element, and a lithium content in the first element is 10 mol% or less. The tungsten bronze type oxide is
A fifth element including an alkaline earth metal element;
A sixth element containing at least niobium in the group consisting of niobium and tantalum;
It consists of oxygen. The piezoelectric ceramic of any one of Claim 1 thru | or 5 characterized by the above-mentioned. The piezoelectric ceramic according to claim 6, wherein the content of tantalum in the sum of the second element and the sixth element is within the range of 10 mol% or more 0 mol%. A first element comprising sodium (Na) and potassium (K); a second element comprising at least niobium from the group consisting of niobium (Nb) and tantalum (Ta); and a second element comprising oxygen (O). 1st perovskite type oxide, 3rd element containing at least 1 sort (s) of alkaline-earth metal element, 4th element containing titanium (Ti), and 2nd perovskite type oxide consisting of oxygen And a composition containing the tungsten bronze type oxide as a main component, and the content of the second perovskite type oxide in the composition is less than 10 mol%, and the content of the tungsten bronze type oxide Is a method of manufacturing a piezoelectric ceramic having 1 mol% or less ,
In addition to the first perovskite-type oxide raw material, the second perovskite-type oxide raw material, and the tungsten bronze-type oxide raw material, the first subcomponent manganese (Mn) raw material, A mixture containing at least one raw material selected from the group consisting of two subcomponents, aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), and tin (Sn) A method for manufacturing a piezoelectric ceramic, comprising a step of calcining the ceramic.

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