JP5118294B2 - Piezoelectric / electrostrictive porcelain composition, piezoelectric / electrostrictive body, and piezoelectric / electrostrictive film type element - Google Patents

Description

  The present invention relates to a piezoelectric / electrostrictive porcelain composition, a piezoelectric / electrostrictive body, and a piezoelectric / electrostrictive film type element. More specifically, the present invention exhibits excellent piezoelectric / electrostrictive characteristics and is environmentally friendly. The present invention relates to a piezoelectric / electrostrictive ceramic composition capable of producing a piezoelectric / electrostrictive body and a piezoelectric / electrostrictive film type element, and a piezoelectric / electrostrictive body and a piezoelectric / electrostrictive film type element using the same.

  Conventionally, piezoelectric / electrostrictive elements are known as elements capable of controlling minute displacements on the order of submicrons. In particular, a piezoelectric / electrostrictive film type element in which a piezoelectric / electrostrictive portion made of a piezoelectric / electrostrictive porcelain composition and an electrode portion to which a voltage is applied is laminated on a substrate made of a ceramic is used for controlling a minute displacement. In addition to being suitable, it has excellent characteristics such as high electromechanical conversion efficiency, high-speed response, high durability, and power saving. These piezoelectric / electrostrictive elements include a piezoelectric pressure sensor, a probe moving mechanism of a scanning tunnel microscope, a linear guide mechanism in an ultra-precision machining apparatus, a servo valve for hydraulic control, a head of a VTR device, and a flat panel type image display device. It is used for various purposes such as constituting pixels or inkjet printer heads.

Various studies have also been made on the piezoelectric / electrostrictive porcelain composition constituting the piezoelectric / electrostrictive portion. For _{example, Pb (Mg 1/3 Nb 2/3)} O 3 -PbZrO 3 -PbTiO 3 ternary solid solution system composition (PZT-based composition), or a part of Pb in these compositions Sr, La or the like A piezoelectric / electrostrictive porcelain composition substituted with a piezoelectric / electrostrictive is disclosed (see, for example, Patent Documents 1 and 2), and is the most important part for determining the piezoelectric / electrostrictive characteristics of a piezoelectric / electrostrictive element. It is expected that a piezoelectric / electrostrictive element having excellent piezoelectric / electrostrictive characteristics (for example, piezoelectric d constant) will be obtained for the part itself.

  However, the PZT composition inevitably contains lead (Pb). In particular, in recent years, the influence on the global environment, such as elution of lead (Pb) by acid rain, tends to be regarded as a problem. For this reason, a piezoelectric ceramic (or piezoelectric ceramic composition) capable of providing a piezoelectric body or a piezoelectric element exhibiting excellent piezoelectric / electrostrictive characteristics without containing lead (Pb) as a piezoelectric / electrostrictive material in consideration of the influence on the environment. (See, for example, Patent Documents 3 to 6).

However, the piezoelectric body obtained using the piezoelectric ceramic (or piezoelectric ceramic composition) disclosed in Patent Documents 3 to 6 is a piezoelectric body obtained using a PZT-based composition containing lead (Pb). It is difficult to obtain a large displacement in comparison with the current situation, and it can be said that the PZT-based composition is superior in terms of superiority and inferiority of the piezoelectric / electrostrictive characteristics. Therefore, even when lead (Pb) is not contained, a piezoelectric / electrostrictive ceramic composition capable of obtaining a piezoelectric / electrostrictive body and a piezoelectric / electrostrictive element exhibiting excellent piezoelectric / electrostrictive characteristics is developed. There was a need.
Japanese Examined Patent Publication No. 44-17103 Japanese Patent Publication No. 45-8145 JP 2003-221276 A JP 2003-277145 A JP 2002-68836 A JP 2004-244299 A

  The present invention has been made in view of such problems of the prior art, and the problem is that the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and is particularly large. An object of the present invention is to provide a piezoelectric / electrostrictive porcelain composition capable of producing a piezoelectric / electrostrictive body and a piezoelectric / electrostrictive film type element capable of obtaining a displacement amount. Furthermore, an object of the present invention is to provide a piezoelectric / electrostrictive body that exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb) and can obtain a particularly large displacement. is there. Another object of the present invention is to provide a piezoelectric / electrostrictive film type element which exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb) and can obtain a particularly large displacement. There is.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors achieve the above-mentioned problems by using as a main component a binary solid solution that does not contain lead (Pb) represented by a predetermined composition formula. As a result, the present invention has been completed.

  That is, according to the present invention, the following piezoelectric / electrostrictive porcelain composition, piezoelectric / electrostrictive body, and piezoelectric / electrostrictive film type element are provided.

[1] A piezoelectric / electrostrictive porcelain composition comprising a binary solid solution represented by the following general formula (1) as a main component.
_{(1-n) (Ag 1} -a-b-c Li a Na b K c) (Nb 1-x-y-z Ta x Sb y V z) O 3 + nM 1 M 2 O 3 ... (1)
(However, in the general formula (1), 0 ≦ a ≦ 0.2, 0 <b ≦ 0.95, 0 ≦ c ≦ 0.95, 0 <(1-a−b−c) ≦ 1, 0) <X ≦ 0.5, 0 <y ≦ 0.2, 0 <z ≦ 0.2, 0 <(y + z) ≦ 0.3, 0.05 ≦ n ≦ 0.2, and M ¹ and M ² satisfies C the combination of the following)
Set look combined C: M ¹ is a combination of two or more metal elements to be trivalent average, M ² is a combination of two or more metal elements to be trivalent average, and, M ^1, Ca, Ce, Sr, made from any two or more metal elements Ba, ^{M 2} is either Mg, Nb, Ni, Zn, Ta, Sb, Ti, Zr, W, Cr, of Fe Consists of two or more metal elements.

[2] Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb , Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Pt, Au , Bi , La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er The piezoelectric / electrostrictive porcelain composition according to the above [1], which contains an oxide of at least one metal element selected from the group consisting of Tm, Yb, and Lu.

[3] A piezoelectric / electrostrictive body composed of crystal particles comprising the piezoelectric / electrostrictive ceramic composition according to [1] or [2].

[4] The piezoelectric / electrostrictive body according to [3], wherein the overall shape is a sheet shape.

[5] A thin-walled substrate made of ceramic, a film-like piezoelectric / electrostrictive portion, and a film-like electrode electrically connected to the piezoelectric / electrostrictive portion, A piezoelectric / electrostrictive film type element fixed on the substrate directly or via the electrode, wherein the piezoelectric / electrostrictive portion is the piezoelectric / electrostrictive porcelain composition according to [1] or [2]. Piezoelectric / electrostrictive film type element composed of crystal grains made of a material.

[6] The piezoelectric / electrostrictive device according to [5], wherein a plurality of the piezoelectric / electrostrictive portions and the electrodes are provided, and the plurality of piezoelectric / electrostrictive portions are alternately sandwiched and stacked by the plurality of electrodes. Membrane element.

[7] The piezoelectric / electrostrictive film element according to [5] or [6], wherein the thickness of the one piezoelectric / electrostrictive portion is 0.5 to 50 μm.

  The piezoelectric / electrostrictive porcelain composition of the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and can obtain a particularly large displacement amount. There is an effect that a strained film type element can be manufactured.

  Further, the piezoelectric / electrostrictive body of the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and has an effect that a particularly large displacement can be obtained.

Furthermore, the piezoelectric / electrostrictive film type element of the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and has an effect that a particularly large displacement can be obtained. is there.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

One embodiment of the piezoelectric / electrostrictive porcelain composition of the present invention is a piezoelectric / electrostrictive porcelain composition mainly composed of a binary solid solution represented by the following general formula (1). In this specification, “having a binary solid solution as a main component” means that the ratio of the binary solid solution to the whole piezoelectric / electrostrictive porcelain composition is 99.5% by mass or more. That is, preferably 99.8% by mass or more.
_{(1-n) (Ag 1} -a-b-c Li a Na b K c) (Nb 1-x-y-z Ta x Sb y V z) O 3 + nM 1 M 2 O 3 ... (1)
(However, in the general formula (1), 0 ≦ a ≦ 0.2, 0 < b ≦ 0.95, 0 ≦ c ≦ 0.95, 0 <(1-a−b−c) ≦ 1, 0 <x ≦ 0.5,0 <y ≦ 0.2,0 <z ≦ 0.2,0 <(y + z) is ≦ 0.3,0.05 ≦ n ≦ 0.2)

Here, in the general formula (1), M ¹ and M ² is a metal element that satisfies C combination shown below, or a combination of two or more metal elements.

2. “Combination C”
M ¹ is a combination of two or more metal elements to be trivalent by leveling flat, M ² is Ri Kumiawasedea of two or more metal elements to be trivalent by leveling flat, and, M ¹ is , Ca, Ce, Sr, Ba, any two or more metal elements, M ² is any one of Mg, Nb, Ni, Zn, Ta, Sb, Ti, Zr, W, Cr, Fe ing from more metal elements. Of M ^1, as a combination of two or more metal elements to be trivalent by smoothing _{flat, (Ca 1/2 Ce 1/2),} (Sr 1/2 Ce 1/2), and _{(Ba 1 / 2} Ce _1/2 ) can be mentioned as a suitable example. Further, the ^{M 2,} as a combination of two or more metal elements to be trivalent by leveling _{Ping, (Mg 2/3 Nb 1/3),} (Ni 2/3 Nb 1/3), (Zn 2 _{/ 3} Nb _1/3 ), (Mg _2/3 Ta _1/3 ), (Mg _2/3 Sb _1/3 ), (Mg _1/2 Ti _1/2 ) (Ni _1/2 Zr _1/2 ) , (Mg _3/4 W _1/4 ), (Mg _1/3 Cr _1/3 Ti _1/3 ), (Mg _1/3 Fe _1/3 Zr _1/3 ), and (Mg _7/12 Ti _{3 / 12} Nb _2/12 ) can be mentioned as a suitable example. Therefore, as a combination example , ( Ba _1/2 Ce _1/2 ) (Mg _2/3 Nb _1/3 ) O ₃ can be cited as a preferred example.

In the piezoelectric / electrostrictive ceramic composition of the present embodiment, Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Pt, Au , Bi , La, Ce, Pr, Nd, Sm, Piezoelectric material having superior piezoelectric / electrostrictive characteristics by containing an oxide of at least one metal element selected from the group consisting of Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu / Electrostrictive body and piezoelectric / electrostrictive film type element can be provided, which is preferable.

  As used herein, “containing an oxide of a metal element” means that the oxide of a metal element can be clearly distinguished from the binary solid solution represented by the general formula (1). In addition to the case where it exists, it is a concept that includes a state in which an oxide of a metal element is incorporated in the general formula (1) representing a binary solid solution. Therefore, a piezoelectric / electrostrictive porcelain composition obtained by adding a larger amount of an oxide of a metal element contained in the general formula (1) than expressed in the general formula (1) is also a piezoelectric of the present invention. / Included in electrostrictive porcelain composition.

  Next, an embodiment of the piezoelectric / electrostrictive body of the present invention will be described. The piezoelectric / electrostrictive body of the present embodiment is a piezoelectric / electrostrictive body composed of crystal particles made of any one of the piezoelectric / electrostrictive porcelain compositions according to the embodiments of the present invention described above. That is, the piezoelectric / electrostrictive body of the present embodiment is composed of crystal particles made of a piezoelectric / electrostrictive ceramic composition whose main component is the binary solid solution represented by the general formula (1). . As described above, the piezoelectric / electrostrictive porcelain composition according to the embodiment of the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and can obtain a particularly large displacement. Therefore, the piezoelectric / electrostrictive body of the present embodiment formed by crystal particles formed by firing the piezoelectric / electrostrictive body is environmentally friendly and has excellent piezoelectricity. / Shows electrostrictive characteristics and can obtain a particularly large displacement.

  In the piezoelectric / electrostrictive body of the present embodiment, the average particle diameter of crystal grains constituting the piezoelectric / electrostrictive body is preferably 0.3 to 20 μm, more preferably 0.5 to 15 μm, and It is especially preferable that it is 8-10 micrometers. If the average particle size is less than 0.3 μm, the domain may not be sufficiently developed in the piezoelectric / electrostrictive body, which may cause deterioration of the piezoelectric / electrostrictive characteristics. On the other hand, if the average particle size is more than 20 μm, the domain in the piezoelectric / electrostrictive body is sufficiently developed, but the domain becomes difficult to move and the piezoelectric / electrostrictive characteristics may be reduced. Note that the piezoelectric / electrostrictive body of the present embodiment can have various shapes as a whole. Specifically, a block-like thing (so-called bulk body), a sheet-like thing, etc. can be mentioned as a suitable example.

  Next, embodiments of the piezoelectric / electrostrictive membrane element of the present invention will be specifically described with reference to the drawings. As shown in FIG. 1, the piezoelectric / electrostrictive film type element 51 of the present embodiment includes a substrate 1 made of ceramics, a film-like piezoelectric / electrostrictive portion 2, and the piezoelectric / electrostrictive portion 2 electrically. The film-like electrodes 4 and 5 are connected, and the piezoelectric / electrostrictive portion 2 is fixed on the substrate 1 with the electrode 4 interposed therebetween. The piezoelectric / electrostrictive portion may be directly fixed on the substrate without interposing an electrode. In this specification, “adhesion” means that both the organic piezoelectric material and the inorganic adhesive material are used in a solid phase reaction between the first piezoelectric portion 2 and the substrate 1 or the electrode 4 without using any organic or inorganic adhesive. A state of tight integration.

  The piezoelectric / electrostrictive portion 2 of the piezoelectric / electrostrictive film type element 51 of the present embodiment is composed of crystal particles made of any one of the piezoelectric / electrostrictive ceramic compositions according to the embodiments of the present invention described above. It is. That is, the piezoelectric / electrostrictive portion 2 of the piezoelectric / electrostrictive film type element 51 of the present embodiment is made of a piezoelectric / electrostrictive porcelain composition mainly composed of a binary solid solution represented by the general formula (1). It is comprised by the crystal grain which becomes.

  As described above, the piezoelectric / electrostrictive porcelain composition according to the embodiment of the present invention exhibits excellent piezoelectric / electrostrictive characteristics without containing lead (Pb), and can obtain a particularly large displacement. Therefore, the piezoelectric / electrostrictive film type element of the present embodiment including the piezoelectric / electrostrictive portion 2 formed using the piezoelectric / electrostrictive film type element has consideration for the environment. In addition, it has excellent piezoelectric / electrostrictive characteristics and can obtain a particularly large displacement.

  In addition, in the piezoelectric / electrostrictive portion 2 of the piezoelectric / electrostrictive film type element 51 of the present embodiment, it is preferable that the average particle diameter of crystal grains constituting the piezoelectric / electrostrictive portion 2 is 0.3 to 20 μm, and 0.5 to 15 μm. It is more preferable that the thickness is 0.8 to 10 μm. If the average particle size is less than 0.3 μm, the domain may not be sufficiently developed in the piezoelectric / electrostrictive portion 2, so that the bending displacement decreases and the linearity of the bending displacement with respect to the electric field in the high electric field region May cause degradation. On the other hand, if the average particle size is more than 20 μm, the domain in the piezoelectric / electrostrictive portion 2 is sufficiently developed, but the domain becomes difficult to move and the bending displacement may be reduced.

  Further, as shown in FIG. 3, the piezoelectric / electrostrictive film type element 51 of the present embodiment includes a plurality of piezoelectric / electrostrictive portions 2 and 3 and a plurality of electrodes 4, 5, and 6, and includes a plurality of piezoelectric / electrostrictive elements. It is also preferable that the strained portions 2 and 3 are alternately sandwiched and laminated by a plurality of electrodes 4, 5 and 6. This configuration is a so-called multilayer configuration and is preferable because a large bending displacement can be obtained at a low voltage.

  In the piezoelectric / electrostrictive film type element 51 (see FIG. 1) of the present embodiment, the thickness of the piezoelectric / electrostrictive portion 2 is preferably 0.5 to 50 μm, and more preferably 0.8 to 40 μm. 1.0 to 30 μm is particularly preferable. If the thickness of the piezoelectric / electrostrictive portion 2 is less than 0.5 μm, densification of the piezoelectric / electrostrictive portion may be insufficient. On the other hand, if the thickness of the piezoelectric / electrostrictive portion 2 exceeds 50 μm, the shrinkage stress of the piezoelectric / electrostrictive porcelain composition at the time of firing increases, and the substrate 1 is thickened to prevent the substrate 1 from being destroyed. Therefore, it may be difficult to cope with the downsizing of the element. As shown in FIG. 3, when the configuration of the piezoelectric / electrostrictive film type element 51 is a so-called multilayer type, the thicknesses of the piezoelectric / electrostrictive portions 2 and 3 are the respective piezoelectric / electrostrictive portions 2 and 3. The thickness of

  The substrate constituting the piezoelectric / electrostrictive film type element according to the embodiment of the present invention is made of ceramics, but the type of the ceramics is not particularly limited. However, at least one selected from the group consisting of stabilized zirconium oxide, aluminum oxide, magnesium oxide, mullite, aluminum nitride, silicon nitride, and glass in terms of heat resistance, chemical stability, and insulation. Ceramics containing are preferred. Among these, stabilized zirconium oxide is more preferable because it has high mechanical strength and excellent toughness. The “stabilized zirconium oxide” referred to in the present invention refers to zirconium oxide in which the phase transition of the crystal is suppressed by adding a stabilizer, and includes partially stabilized zirconium oxide in addition to stabilized zirconium oxide. .

  As stabilized zirconium oxide, zirconium oxide contains, for example, 1 to 30 mol% of a calcium oxide, magnesium oxide, yttrium oxide, scandium oxide, ytterbium oxide, cerium oxide, or rare earth metal oxide as a stabilizer. Things can be mentioned. Of these, those containing yttrium oxide as a stabilizer are preferred in that the mechanical strength of the vibration part is particularly high. Under the present circumstances, it is preferable to contain 1.5-6 mol% of yttrium oxide, and it is still more preferable to contain 2-4 mol%. Further, those containing 0.1 to 5 mol% of aluminum oxide are preferable. The stabilized zirconium oxide crystal phase may be a cubic + monoclinic mixed phase, a tetragonal + monoclinic mixed phase, a cubic + tetragonal + monoclinic mixed phase, etc. The main crystal phase is preferably a tetragonal crystal or a mixed phase of tetragonal crystal + cubic crystal from the viewpoints of strength, toughness, and durability.

  The thickness of the substrate is preferably 1 μm to 1 mm, more preferably 1.5 to 500 μm, and particularly preferably 2 to 200 μm. If the thickness of the substrate is less than 1 μm, the mechanical strength of the piezoelectric / electrostrictive film type element may be lowered. On the other hand, when the voltage exceeds 1 mm, when a voltage is applied to the piezoelectric / electrostrictive portion, the rigidity of the substrate with respect to the generated contraction stress increases, and the bending displacement of the piezoelectric / electrostrictive portion may decrease.

  However, as shown in FIG. 2, the shape of the substrate 1 is arranged in a portion other than the portion corresponding to the fixing surface 1a and the thin portion 1c having the above-mentioned thickness, where the fixing surface 1a is formed on one surface thereof. The shape provided with the thick part 1b thicker than the thin part 1c provided may be sufficient. The electrode 4 (or piezoelectric / electrostrictive portion) is disposed in a region substantially corresponding to the fixing surface 1a. When the substrate 1 has such a shape, a piezoelectric / electrostrictive film type element having a sufficiently large bending displacement and a high mechanical strength can be obtained. Further, a common substrate 20 as shown in FIG. 4 in which the shape of the substrate 1 shown in FIG. 2 is continuously formed is used, and the first piezoelectric / electrostrictive portion 12 and the second piezoelectric / electrostrictive portion 13 are used. , And a plurality of piezoelectric / electrostrictive film type element units 10 including the electrodes 4, 5, 6 may be disposed on the common substrate 20.

  There is no particular limitation on the surface shape of the substrate (the shape of the surface to which the electrode 4 is fixed in FIG. 1) in the piezoelectric / electrostrictive film type element according to the embodiment of the present invention, and for example, a rectangle, a square, a triangle, an ellipse , Surface shapes such as a perfect circle, a square with R, a rectangle with R, or a combination of these. Further, the shape of the entire substrate is not particularly limited, and may be a capsule shape having an appropriate internal space.

  Further, as the shape of the thin portion of the substrate, the linear portion of the bending displacement with respect to the electric field is high, and as shown in FIG. 7, the central portion is a surface on which the piezoelectric / electrostrictive portions 2 and 3 are disposed. A shape bent to the opposite side, or a shape in which the cross-sectional shape in the thickness direction is a W shape having three inflection points as shown in FIG. 8 is preferable. The bent shape shown in FIG. 7 can be formed by utilizing the shrinkage in the firing process of each piezoelectric / electrostrictive portion 2 and 3, and the W shape shown in FIG. / It can be formed by adjusting the firing shrinkage start timing and the firing shrinkage amount with the electrostrictive portion 3, and the shape of the thin portion 1c.

  In the piezoelectric / electrostrictive film type element of the present embodiment, the electrode is electrically connected to the piezoelectric / electrostrictive portion, and is disposed between the piezoelectric / electrostrictive portions. Further, the electrode is preferably disposed in a state including a region that substantially contributes to a bending displacement of the piezoelectric / electrostrictive portion. For example, as shown in FIG. It is preferable that the electrodes 4, 5, 6 are disposed in a region of 80 area% or more including the vicinity of the central portion of the formation surface of the second piezoelectric / electrostrictive portion 13.

  Further, as shown in FIGS. 5A and 5B, when the common substrate 20 is shared by a plurality of piezoelectric / electrostrictive film type element units 10a to 10c, each piezoelectric / electrostrictive element film type is used. The lowermost layer electrode 14 and the uppermost layer electrode 16 in the units 10a to 10c are shared between the piezoelectric / electrostrictive film type element units 10a to 10c, and correspond to the piezoelectric / electrostrictive portions 2a to 2c and 3a to 3c. It is good also as the integrated electrode 14 arrange | positioned in an area | region. When such an integrated electrode 14 is used, it is not necessary to have a shape corresponding to each of the piezoelectric / electrostrictive portions 2a to 2c and 3a to 3c, and alignment when forming the electrodes becomes easy.

  In the piezoelectric / electrostrictive film type element of this embodiment, examples of the material of the electrode include at least one metal selected from the group consisting of Pt, Pd, Rh, Au, Ag, and alloys thereof. Among these, platinum or an alloy containing platinum as a main component is preferable in terms of high heat resistance when firing the piezoelectric / electrostrictive portion. In view of the fact that the piezoelectric / electrostrictive portion can be formed at a lower firing temperature, an alloy such as Ag—Pd can also be suitably used. There are no particular restrictions on the dimensions of the electrodes. For example, as shown in FIGS. 6, 12A, and 12B, the electrodes 4, 5, and 6 have the same dimensions, and the electrodes 4, 5, 6 may be provided at a corresponding position in the same range in the thickness direction. Also, as shown in FIG. 9, each electrode 4, 5, 6 is provided in a wider range from the electrode 4 located in the lowermost layer to the range corresponding to the electrodes located in the lower layer sequentially. Is also preferable. With such a configuration, the piezoelectric / electrostrictive portion located in the upper layer can be distorted more than the piezoelectric / electrostrictive portion located in the lower layer, so that bending efficiency is improved and bending displacement is expressed more effectively. be able to.

  However, when a large bending displacement is obtained by increasing the driving voltage of the piezoelectric / electrostrictive film type element, as shown in FIG. 10, the electrode 5 positioned in the middle is the electrode 4 positioned in the lower layer or the upper layer. It is preferable that the electrode is provided in a wider range than 6, or the electrode 5 located in the middle is provided in a narrower range than the electrodes 4 and 6, as shown in FIG. By adopting such a configuration, the piezoelectric / electrostrictive portions 2 and 3 are likely to be thin (short direction). It can be avoided. In addition, in the case where a wide and narrow difference is provided in the area where the electrode is provided, the wide and narrow difference is preferably optimized in consideration of the electric field distribution. For example, the ratio of the area where the electrodes are provided (area of the formation surface) between the adjacent electrodes 4, 5 (or 5, 6) across the piezoelectric / electrostrictive portion 2 (or 3) is 0.5-2. It is preferable that it is 0.67-1.5, and it is especially preferable that it is 0.83-1.2. 9 to 11, the symbol P represents the width of the lower electrode, the symbol Q represents the width of the intermediate electrode, and the symbol R represents the width of the upper electrode.

  If the piezoelectric / electrostrictive film type element of the present invention is used, a hard disk actuator as shown in FIG. 13, for example, can be configured. That is, the hard disk actuator shown in FIG. 13 includes a ceramic body 40 having an arm portion 31 and a piezoelectric / electrostrictive operating portion 32 disposed on the arm portion 31. It is an actuator that functions as a diaphragm and has desired good vibration characteristics.

  FIG. 14 is a sectional view schematically showing still another embodiment of the piezoelectric / electrostrictive film type device of the present invention. As shown in FIG. 14, a piezoelectric / electrostrictive operating portion in which a lower electrode 23 a, a piezoelectric / electrostrictive portion 30, and an upper electrode 23 b are sequentially stacked on the surface (fixed surface 82) of a substrate 22 having a cavity 80. 35 can also be provided. On the other hand, as shown in FIG. 15, the lower electrode 23a, the second piezoelectric / electrostrictive portion 24a, the intermediate electrode 23c, and the first piezoelectric / electrostrictive are formed on the surface (fixed surface 82) of the substrate 22 having the cavity 80. A so-called multilayered piezoelectric / electrostrictive operating portion 35 having a portion 24b and an upper electrode 23b may be provided.

  In addition, as shown in FIG. 16, on the surface (fixed surface 82) of the substrate 22 having the cavity 80 in which the predetermined hole 81 is formed, the lower electrode 23a, the second piezoelectric / electrostrictive portion 24a, the intermediate electrode 23c, a first piezoelectric / electrostrictive portion 24b, and a so-called multilayered piezoelectric / electrostrictive operating portion 35 including the upper electrode 23b may be provided. Further, as shown in FIG. 17, the substrate 22 has a thin portion 83 and a thick portion 84, and the piezoelectric / electrostrictive operation portion 35 is provided on the surface (fixed surface 82) of the thin portion 83. It is also possible to arrange.

  In the piezoelectric / electrostrictive membrane element of the present embodiment, the thickness of the electrode is preferably 15 μm or less, and more preferably 5 μm or less. If it exceeds 15 μm, the electrode may act as a relaxation layer, and the bending displacement may be reduced. In addition, the thickness of the electrode should just be 0.05 micrometer or more from a viewpoint of exhibiting the function as a substantial electrode.

  Next, a method for preparing a piezoelectric / electrostrictive porcelain composition according to an embodiment of the present invention will be described. The piezoelectric / electrostrictive porcelain composition of the present embodiment is composed of a single element constituting each element, an oxide of each of these elements, a carbonate, a compound containing a plurality of these elements, and the like. Mix to achieve desired composition ratio. As a mixing method, a general method may be used, for example, a ball mill. Specifically, a predetermined amount of various raw materials, cobblestones, and water are placed in a ball mill apparatus and rotated for a predetermined time to prepare a mixed slurry. Thereafter, the mixed raw material can be obtained by removing the moisture contained in the obtained mixed slurry by evaporating, drying, filtering and the like.

  By calcining the obtained mixed raw material, a piezoelectric / electrostrictive porcelain composition can be obtained. The calcination may be performed in the air or in an oxygen atmosphere. In the obtained piezoelectric / electrostrictive porcelain composition, the ratio of the intensity of the strongest diffraction line of the phase other than the perovskite phase to the intensity of the strongest diffraction line of the perovskite phase is 5% or less in the diffraction intensity by the X-ray diffractometer. It is preferable that it is 2% or less.

  When the obtained piezoelectric / electrostrictive porcelain composition is pulverized using a general pulverizer such as a ball mill, an attritor, or a bead mill, it can be made into a particulate (or powder) piezoelectric / electrostrictive component. . The average particle size of the particulate piezoelectric / electrostrictive porcelain composition is preferably 0.1 to 1.0 μm, and more preferably 0.2 to 0.7 μm. The particle diameter may be adjusted by heat-treating the powder of the piezoelectric / electrostrictive porcelain composition obtained by pulverization at a predetermined temperature. In this case, finer particles are preferable because they can be integrated with other particles to form a powder having a uniform particle diameter, and a piezoelectric / electrostrictive film having a uniform particle diameter can be formed. The piezoelectric / electrostrictive porcelain composition may be prepared, for example, by an alkoxide method, a coprecipitation method, or the like. Further details of the method for preparing the piezoelectric / electrostrictive porcelain composition are described in the aforementioned Patent Documents 3 to 6.

  Next, a method for manufacturing a piezoelectric / electrostrictive body according to an embodiment of the present invention will be described. First, the powdered piezoelectric / electrostrictive porcelain composition obtained by the above method is compacted to a desired size at an appropriate pressure. By firing the obtained green compact at 800 to 1300 ° C. for 1 minute to 10 hours, a fired body having a predetermined shape can be obtained. Next, after cutting into an appropriate size, etc., an electrode is formed, and a polarization treatment is performed to obtain a piezoelectric / electrostrictive body (bulk body).

  Further, in order to make the entire shape of the piezoelectric / electrostrictive body into a sheet shape, a plasticizer, a dispersing agent, a solvent, etc. are added to the piezoelectric / electrostrictive porcelain composition, and a slurry is obtained using a general mixing device such as a ball mill. Then, it can be formed into a sheet by a general sheet forming machine such as a doctor blade.

  Next, a method for manufacturing a piezoelectric / electrostrictive film type device according to an embodiment of the present invention will be described. First, a layer made of a piezoelectric / electrostrictive porcelain composition is formed on a substrate made of ceramics or on an electrode formed on the surface of the substrate. Examples of the method for forming the electrode include ion beam, sputtering, vacuum deposition, PVD, ion plating, CVD, plating, aerosol deposition, screen printing, spraying, or dipping. Of these, the sputtering method or the screen printing method is preferable from the viewpoint of bonding properties with the substrate and the piezoelectric / electrostrictive portion. The formed electrode is selected at an appropriate temperature depending on its material, but can be integrated with the substrate and / or the piezoelectric / electrostrictive portion by heat treatment at about 800 to 1400 ° C. This heat treatment may be performed every time the electrode is formed, or may be performed at the same time as the baking for the layer made of the piezoelectric / electrostrictive porcelain composition. However, after the layer made of the piezoelectric / electrostrictive porcelain composition is formed, heat treatment at a temperature exceeding the firing temperature of the layer made of the piezoelectric / electrostrictive porcelain composition is not performed.

  Examples of a method for forming a layer made of a piezoelectric / electrostrictive porcelain composition on a substrate include ion beam, sputtering, vacuum deposition, PVD, ion plating, CVD, plating, sol-gel, aerosol deposition, screen printing, and spraying. Or a method such as dipping. Among these, the screen printing method is preferable in that it can be easily and continuously formed with a highly accurate shape and thickness. In the case of producing a piezoelectric / electrostrictive film type element having a plurality of piezoelectric / electrostrictive portions and electrodes and alternately sandwiching and laminating them, the piezoelectric / electrostrictive ceramic composition is formed on a substrate. An electrode is formed on the layer by the same method as described above. In addition, the layer which consists of a piezoelectric / electrostrictive porcelain composition, and an electrode are alternately and repeatedly formed on this electrode until it becomes a desired multilayer.

  Then, the laminated body obtained by laminating | stacking the layer which consists of a piezoelectric / electrostrictive porcelain composition, and an electrode on a board | substrate alternately is integrally baked. By this firing, the piezoelectric / electrostrictive portion constituted by crystal particles made of the piezoelectric / electrostrictive porcelain composition can be fixed to the substrate directly or via an electrode. Note that this firing is not necessarily performed integrally, and may be performed sequentially each time a layer made of a piezoelectric / electrostrictive porcelain composition is formed, but from the viewpoint of production efficiency, the electrode is included. It is preferable to fire integrally. The firing temperature is preferably 950 to 1350 ° C, and more preferably 1000 to 1300 ° C. The maximum temperature holding time during firing is preferably 10 minutes to 10 hours, more preferably 20 minutes to 5 hours. Firing may be performed in the air or in an oxygen atmosphere.

  Thereafter, polarization treatment is performed under appropriate conditions. In that case, it is preferable to carry out the polarization treatment by heating as in a known method. The heating temperature is preferably 40 to 200 ° C., although it depends on the Curie point of the piezoelectric / electrostrictive porcelain composition.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

( Example 3 , Reference Examples 1, 2, 4 and Comparative Example 1)
Platinum (Pt) is formed on a substrate (1.6 × 1.1 mm × thickness 10 μm) made of zirconia (ZrO ₂ ), which is molded and fired by a green sheet lamination method and stabilized by yttria (Y ₂ O ₃ ). The lower electrode film (1.2 × 0.8 mm × thickness 3 μm) is formed by screen printing and integrated with the substrate by heat treatment at 1300 ° C. for 2 hours. On the lower electrode film, a piezoelectric / electrostrictive porcelain composition represented by the composition formula shown in Table 1 was laminated by a screen printing method with dimensions of 1.3 × 0.9 mm × thickness of 15 μm, and 1200 ° C. for 3 hours. Baked. Further, an upper electrode film (1.2 × 0.8 mm × thickness 0.5 μm) made of gold (Au) is laminated thereon by a screen printing method and heat-treated, so that a piezoelectric / electrostrictive film type element ( Example 3 , Reference Examples 1, 2, 4 and Comparative Example 1) were produced.

(Measurement of bending displacement)
The bending displacement (μm) of each of the produced piezoelectric / electrostrictive membrane elements of Example 3 , Reference Examples 1, 2 , 4 and Comparative Example 1 was measured according to the following method. The results are shown in Table 1.

[Bending displacement]: The bending displacement (μm) generated when a voltage was applied between the upper and lower electrode films so that the electric field was 3 kV / mm was measured with a laser displacement measuring instrument. In Table 1, “average” of “flexural displacement (μm)” indicates that 10 piezoelectric / electrostrictive membrane elements of each of the examples , reference examples, and comparative examples were manufactured, and these flexural displacements were calculated. It is an average value in the case of measurement, and “variation” is a difference between the maximum value and the minimum value of the measured bending displacement.

From the results shown in Table 1, the piezoelectric / electrostrictive film type element of Example 3 showed a sufficient bending displacement as compared with the piezoelectric / electrostrictive film type element of Comparative Example 1, and there was a variation in bending displacement. It turned out to be few.

  The piezoelectric / electrostrictive body and the piezoelectric / electrostrictive film type element of the present invention exhibit excellent piezoelectric / electrostrictive characteristics and are suitable for actuators, sensors, and the like.

It is sectional drawing which shows typically one Embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is a top view which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows a more specific example of embodiment shown in FIG. FIG. 4 is a cross-sectional view showing another more specific example of the embodiment shown in FIG. 3. It is sectional drawing which shows another more specific example of embodiment shown in FIG. It is sectional drawing which shows another more specific example of embodiment shown in FIG. It is sectional drawing which shows another more specific example of embodiment shown in FIG. It is sectional drawing which shows another more specific example of embodiment shown in FIG. It is X-X 'sectional drawing of embodiment shown in FIG. FIG. 7 is a top view of the embodiment shown in FIG. 6. It is a front view which shows the example of application to the actuator for hard disks of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention. It is sectional drawing which shows typically other embodiment of the piezoelectric / electrostrictive film type | mold element of this invention.

Explanation of symbols

1, 22: Substrate, 1a, 82: Fixed surface, 1b, 84: Thick part, 1c, 83: Thin part, 2, 2a, 2b, 2c, 3, 3a, 3b, 3c, 30: Piezoelectric / electrostrictive Part, 4, 5, 6, 14, 16: electrode, 10, 10a, 10b, 10c: piezoelectric / electrostrictive membrane element unit, 12, 24b: first piezoelectric / electrostrictive part, 13, 24a: second 15: bottom piezoelectric / electrostrictive portion, 20: common substrate, 23a: lower electrode, 23b: upper electrode, 23c: intermediate electrode, 31: arm portion, 32, 35: piezoelectric / electrostrictive Actuator, 40: Ceramic body, 51: Piezoelectric / electrostrictive film type element, 80: Cavity, 81: Hole, P: Width of lower electrode, Q: Width of intermediate electrode, R: Width of upper electrode

Claims (7)

A piezoelectric / electrostrictive porcelain composition mainly composed of a binary solid solution represented by the following general formula (1).
_{(1-n) (Ag 1} -a-b-c Li a Na b K c) (Nb 1-x-y-z Ta x Sb y V z) O 3 + nM 1 M 2 O 3 ... (1)
(However, in the general formula (1), 0 ≦ a ≦ 0.2, 0 <b ≦ 0.95, 0 ≦ c ≦ 0.95, 0 <(1-a−b−c) ≦ 1, 0) <X ≦ 0.5, 0 <y ≦ 0.2, 0 <z ≦ 0.2, 0 <(y + z) ≦ 0.3, 0.05 ≦ n ≦ 0.2, and M ¹ and M ² satisfies C the combination of the following)
Set look combined C: M ¹ is a combination of two or more metal elements to be trivalent average, M ² is a combination of two or more metal elements to be trivalent average, and, M ^1, Ca, Ce, Sr, made from any two or more metal elements Ba, ^{M 2} is either Mg, Nb, Ni, Zn, Ta, Sb, Ti, Zr, W, Cr, of Fe Consists of two or more metal elements. Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Pt, Au , Bi , La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, The piezoelectric / electrostrictive porcelain composition according to claim 1, comprising an oxide of at least one metal element selected from the group consisting of Yb and Lu.   A piezoelectric / electrostrictive body composed of crystal particles comprising the piezoelectric / electrostrictive porcelain composition according to claim 1.   4. The piezoelectric / electrostrictive body according to claim 3, wherein the overall shape is a sheet shape. A thin substrate made of ceramic, a film-like piezoelectric / electrostrictive portion, and a film-like electrode electrically connected to the piezoelectric / electrostrictive portion, wherein the piezoelectric / electrostrictive portion is on the substrate A piezoelectric / electrostrictive film type element fixed directly or via the electrode,
A piezoelectric / electrostrictive film type element, wherein the piezoelectric / electrostrictive portion is composed of crystal particles made of the piezoelectric / electrostrictive porcelain composition according to claim 1.   6. The piezoelectric / electrostrictive film element according to claim 5, wherein a plurality of the piezoelectric / electrostrictive portions and electrodes are provided, and the plurality of piezoelectric / electrostrictive portions are alternately sandwiched and stacked by the plurality of electrodes.   The piezoelectric / electrostrictive film type element according to claim 5 or 6, wherein the one piezoelectric / electrostrictive portion has a thickness of 0.5 to 50 µm.

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