JP2011187817A - Liquid ejecting head, liquid ejecting apparatus, and piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator and a liquid ejecting head that include a piezoelectric body made of a bismuth-based compound oxide, a lead content smaller than that of PZT, and a large amount of displacement. <P>SOLUTION: The liquid ejecting head 600 includes a piezoelectric actuator 102 including a platinum electrode 10 preferentially oriented in <111> and a piezoelectric body 30 formed while abutting on the platinum electrode 10. The piezoelectric body 30 includes a solid solution of bismuth lanthanum titanate zincate and lead titanate and the piezoelectric body is preferentially oriented in <100>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element.

  The liquid ejecting head is used in, for example, an ink jet printer as a configuration of the liquid ejecting apparatus. In this case, the liquid ejecting head is used to eject and eject a small droplet of ink, whereby the ink jet printer can perform printing by attaching the ink to a medium such as paper.

  The liquid ejecting head generally includes an actuator that applies pressure to the liquid in order to eject the liquid from the nozzle. Such an actuator includes, for example, a piezoelectric element. As a piezoelectric element provided in the actuator, there is a piezoelectric element having an electromechanical conversion function, for example, a piezoelectric body made of crystallized piezoelectric ceramic or the like sandwiched between two electrodes. Such a piezoelectric element can be deformed when a voltage is applied by two electrodes, and the actuator can be operated in, for example, a flexural vibration mode using the deformation.

  The piezoelectric material used for such applications preferably has high piezoelectric properties such as electromechanical conversion efficiency, and the properties are superior to other materials. Therefore, lead zirconate titanate (PZT) Research and development of materials of the system has been carried out. However, in recent years, demands for further improving the piezoelectric characteristics of piezoelectric materials have increased, and it has become necessary to use materials with a smaller environmental load. With PZT materials, it is difficult to meet these demands. For example, a perovskite oxide piezoelectric material with a low lead content has been developed.

For example, among ceramic materials that do not contain lead and are theoretically considered to have high piezoelectric properties, there are, for example, Bi-based oxides. Currently, only BiFeO ₃ is present in the bulk state at normal pressure. It is known to form a perovskite crystal structure by firing. Many other Bi-based oxides do not form a perovskite-type crystal structure at an atmospheric pressure during firing, but form a perovskite-type crystal structure at a high pressure exceeding several GPa. For example, it is known that Bi (Zn _0.5 , Ti _0.5 ) O ₃ (BZT) cannot form a perovskite crystal structure unless it is fired at a high pressure (about 6 gigapascal).

  Patent Document 1 discloses a composite oxide containing no alkali metal and lead. The document describes that a Curie temperature or the like is evaluated for an oxide having a specific composition, and a piezoelectric material having a high Curie temperature excellent in piezoelectric characteristics can be provided.

JP 2009-256186 A

  On the other hand, when an oxide having a perovskite crystal structure is used as a piezoelectric body of a piezoelectric element, excellent piezoelectric characteristics are exhibited when the direction in which the electric field is applied and the direction of the crystal axis are in a specific relationship. I know that. Therefore, in order to improve the piezoelectric characteristics of the piezoelectric element, it is important to control the crystal orientation of the piezoelectric body. Further, it has been found that the crystal orientation of the piezoelectric body is affected at least by the material of the piezoelectric body and the material of the object that comes into contact when the piezoelectric body crystallizes.

  However, the crystal orientation of the piezoelectric body is greatly affected by slight changes in the composition of the piezoelectric material and the material of the object that comes into contact when the piezoelectric body crystallizes, so it is optimal for each material. Will be converted. Therefore, for example, in a bismuth-based complex oxide, it is difficult to obtain a desired crystal orientation even if a method for controlling the orientation of a PZT crystal is applied as it is.

  An object of some embodiments of the present invention is to provide an actuator and a liquid ejecting head having a lead content smaller than that of PZT and a large amount of displacement. Another object of some embodiments of the present invention is to provide a piezoelectric element including a piezoelectric body having a lead content smaller than PZT and a large displacement.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
A liquid ejecting head comprising a platinum electrode preferentially oriented to <111> and a piezoelectric actuator having a piezoelectric body formed in contact with the platinum electrode,
The piezoelectric body includes a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The piezoelectric body is a liquid ejecting head in which <100> is preferentially oriented.

  The liquid jet head according to this application example includes a piezoelectric body having good crystal orientation. Therefore, the displacement amount of the piezoelectric actuator is large, for example, the ability to eject liquid is high.

[Application Example 2]
In application example 1,
The platinum electrode may be in contact with iridium oxide on the surface opposite to the piezoelectric body.

  According to the liquid ejecting head of this application example, the orientation of the crystal of the piezoelectric body is further improved, the displacement amount of the piezoelectric actuator is large, and, for example, the ability to eject liquid is further enhanced.

[Application Example 3]
In application example 1 or application example 2,
The <100> preferred orientation degree of the piezoelectric body may be 50% or more.

  The liquid jet head of this application example has good orientation of the crystal of the piezoelectric body, the displacement amount of the piezoelectric actuator is large, for example, the ability to eject liquid is high.

[Application Example 4]
In any one of the application examples 1 to 3,
The half width of the rocking curve of the (111) peak of the X-ray diffraction pattern of the platinum electrode may be 10 degrees or less.

  The liquid jet head according to this application example includes a piezoelectric body having good crystal orientation. Therefore, the displacement amount of the piezoelectric actuator is large, for example, the ability to eject liquid is high.

[Application Example 5]
One aspect of the liquid ejecting apparatus according to the invention is as follows.
The liquid ejecting head described in any one of Application Examples 1 to 4 is provided.

  The liquid ejecting apparatus according to this application example includes a liquid ejecting head including a piezoelectric body made of a bismuth-based composite oxide having a small lead content, as compared with PZT. Thereby, the environmental load can be reduced and, for example, the ink ejection performance in ink jet printing is high.

[Application Example 6]
One aspect of the piezoelectric element according to the present invention is:
A platinum electrode preferentially oriented to <111>;
A piezoelectric body disposed in contact with the platinum electrode;
Including
The piezoelectric body includes a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The piezoelectric body is preferentially oriented in <100>.

  The piezoelectric element of this application example includes a piezoelectric body having good crystal orientation. Thereby, the piezoelectric characteristics are good.

[Application Example 7]
One aspect of the liquid jet head according to the present invention is as follows.
A platinum electrode having a preferential orientation of <111>, a lanthanum nickelate layer formed in contact with the platinum electrode, and a piezoelectric actuator in contact with the lanthanum nickelate layer and formed on the opposite side of the platinum electrode A liquid jet head,
The piezoelectric body is a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The solid solution is preferentially oriented to <100>.

  The liquid jet head according to this application example includes a piezoelectric body having good crystal orientation. Therefore, the displacement amount of the piezoelectric actuator is large, for example, the ability to eject liquid is high.

[Application Example 8]
One aspect of the piezoelectric element according to the present invention is:
A platinum electrode preferentially oriented to <111>;
A lanthanum nickelate layer disposed in contact with the platinum electrode;
A piezoelectric body in contact with the lanthanum nickelate layer and disposed on the opposite side of the platinum electrode;
Including
The piezoelectric body is a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The piezoelectric element, wherein the solid solution is preferentially oriented to <100>.

  The piezoelectric element of this application example includes a piezoelectric body having good crystal orientation. Thereby, the piezoelectric characteristics are good.

The schematic diagram of the cross section of the piezoelectric element 100 of embodiment and the piezoelectric actuator 102. FIG. FIG. 3 is a schematic cross-sectional view of a liquid jet head according to an embodiment. FIG. 3 is an exploded perspective view schematically illustrating a liquid ejecting head 600 according to the embodiment. FIG. 6 is a perspective view schematically illustrating a liquid ejecting apparatus according to an embodiment. The XRD pattern of the piezoelectric element of each experimental example, reference example, and comparative example. The rocking curve of the platinum (111) peak in the XRD pattern of Experimental Example 1. The rocking curve of the platinum (111) peak in the XRD pattern of Experimental Example 2. The hysteresis curve of the piezoelectric element of Experimental example 1. The hysteresis curve of the piezoelectric element of Experimental example 2. The hysteresis curve of the piezoelectric element of a reference example. The hysteresis curve of the piezoelectric element of a comparative example.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, the following embodiment demonstrates an example of this invention. Therefore, this invention is not limited to the following embodiment, The various modifications implemented in the range which does not change a summary are also included. Note that not all the configurations described in the following embodiments are essential constituent requirements of the present invention.

1. Piezoelectric Element and Piezoelectric Actuator FIG. 1 is a schematic cross-sectional view of a piezoelectric element 100 according to this embodiment.

  The piezoelectric element 100 according to the present embodiment includes a platinum electrode 10, a conductive layer 20, and a piezoelectric body 30.

1.1. Platinum electrode The platinum electrode 10 is formed above the substrate 1, for example. The substrate 1 can be, for example, a flat plate formed of a conductor, a semiconductor, or an insulator. The substrate 1 may be a single layer or a structure in which a plurality of layers are stacked. Further, the inner structure of the substrate 1 is not limited as long as the upper surface is planar. For example, the substrate 1 may have a structure in which a space or the like is formed. Further, for example, in the case where a pressure chamber or the like is formed below the substrate 1 as in a liquid jet head described later, a plurality of configurations formed below the substrate 1 are combined into one substrate 1. May be considered. Moreover, between the platinum electrode 10 and the board | substrate 1, the layer which provides both adhesiveness, and the layer which provides intensity | strength and electroconductivity may be formed, for example. Examples of such layers include various metals such as titanium, nickel, iridium, and oxide layers thereof.

  The platinum electrode 10 has at least a surface in contact with a piezoelectric body 30 to be described later formed of a material whose main component is platinum. The platinum electrode 10 may have a single layer structure or a structure in which a plurality of other materials are stacked. When the platinum electrode 10 has a single layer structure, the entire platinum electrode 10 is formed of a material whose main component is platinum. The platinum electrode 10 of this embodiment is preferentially oriented to <111>. The orientation of the platinum electrode 10 will be described in detail in the section “1.4. Crystal orientation”.

  The shape of the platinum electrode 10 is not limited as long as it can be opposed to the conductive layer 20. However, in the present embodiment, since the piezoelectric body 30 is formed in a thin film shape, a layered or thin film shape is preferable. The thickness of the platinum electrode 10 can be, for example, 50 nm or more and 300 nm or less. Further, the planar shape of the platinum electrode 10 is not particularly limited as long as the piezoelectric body 30 can be disposed between the conductive layers 20 when the conductive layer 20 is disposed to face the platinum electrode 10. Etc.

  One of the functions of the platinum electrode 10 is to be paired with the conductive layer 20 to be one electrode for applying a voltage to the piezoelectric body 30 (for example, a lower electrode formed below the piezoelectric body 30). Can be mentioned.

  The platinum electrode 10 is formed by sputtering (including DC sputtering, ion sputtering, magnetron sputtering), vapor deposition, or MOCVD (Metal-Organic Chemical Vapor Deposition).

  The substrate 1 may be a diaphragm that has flexibility and can be deformed (bent) by the operation of the piezoelectric body 30. In this case, the piezoelectric element 100 is a piezoelectric actuator 102 including a vibration plate, a platinum electrode 10, a piezoelectric body 30, and a conductive layer 20. Here, that the substrate 1 has flexibility indicates that the substrate 1 can bend. When the substrate 1 is a vibration plate, the deflection of the substrate 1 is sufficient if the volume of the pressure chamber can be changed to the same level as the volume of liquid to be ejected when the piezoelectric actuator 102 is used in a liquid jet head. is there.

When the substrate 1 is a diaphragm, examples of the material of the substrate 1 include inorganic oxides such as zirconium oxide (ZrO ₂ ), silicon nitride, and silicon oxide, and alloys such as stainless steel. Of these, zirconium oxide is particularly suitable as the material of the substrate 1 (vibrating plate) in terms of chemical stability and rigidity. Also in this case, the substrate 1 may have a laminated structure of two or more kinds of the exemplified substances.

  In the present embodiment, the case where the substrate 1 is a diaphragm and is formed of zirconium oxide will be exemplified below. Therefore, the piezoelectric element 100 is substantially the same as the piezoelectric actuator 102 having a vibration plate that has flexibility and can be deformed (bent) by the operation of the piezoelectric body 30. In the following description, the piezoelectric element 100 and the piezoelectric actuator 102 can be read each other.

1.2. Conductive Layer The conductive layer 20 is disposed to face the platinum electrode 10. The entire conductive layer 20 may face the platinum electrode 10, or a part thereof may face the platinum electrode 10. The shape of the conductive layer 20 is not limited as long as it can face the platinum electrode 10, but in the present embodiment, since the piezoelectric body 30 is formed in a thin film shape, a layer shape or a thin film shape is preferable. The thickness of the conductive layer 20 can be, for example, 50 nm or more and 300 nm or less. Further, the planar shape of the conductive layer 20 is not particularly limited as long as the piezoelectric body 30 can be disposed between the two when the conductive layer 20 is opposed to the platinum electrode 10. Etc.

  One of the functions of the conductive layer 20 is to serve as one electrode (for example, an upper electrode formed on the piezoelectric body 30) for applying a voltage to the piezoelectric body 30. Examples of the material of the conductive layer 20 include various metals such as nickel, iridium, and platinum, conductive oxides thereof (for example, iridium oxide), strontium and ruthenium composite oxide (SrRuOx: SRO), lanthanum and nickel. A composite oxide (LaNiOx: LNO) can be exemplified. The first conductive layer 10 may have a single layer structure of the exemplified materials, or may have a structure in which a plurality of materials are stacked.

  Although FIG. 1 shows an example in which the platinum electrode 10 is formed larger than the conductive layer 20 in a plan view, the conductive layer 20 may be formed larger than the platinum electrode 10 in a plan view. In this case, the conductive layer 20 may be formed on the side surface of the piezoelectric body 30, and the conductive layer 20 can also have a function of protecting the piezoelectric body 30 from moisture, hydrogen, and the like.

1.3. Piezoelectric Body In the present embodiment, the piezoelectric body 30 is in contact with at least the platinum electrode 10 and is disposed between the platinum electrode 10 and the conductive layer 20. The piezoelectric body 30 may be in contact with the conductive layer 20. In the example of FIG. 1, the piezoelectric body 30 is provided in contact with the conductive layer 20.

  The piezoelectric body 30 is formed by a thin film method. Here, the thin film method is a sputtering method (including DC sputtering, ion sputtering, magnetron sputtering), vapor deposition method, MOCVD method, MOD (Metal-Organic Decomposition) method, PLD (Pulsed Laser Deposition) (laser ablation) method, It refers to at least one of a mist film forming method and a sol-gel method. That is, the piezoelectric body 30 of the present embodiment is not formed in a bulk state, and is not formed into a thin film by polishing or the like after being formed in a bulk state, for example.

  The thickness of the piezoelectric body 30 is not limited as long as it is formed by a thin film method, and can be, for example, 100 nm or more and 3000 nm or less. In the case where the piezoelectric body 30 having a large thickness is formed by the thin film method, for example, in a method of depositing a material such as a sputtering method, a vapor deposition method, or an MOCVD method, the piezoelectric material 30 can be formed by increasing the deposition time. Further, for example, in a method of performing coating-firing such as the MOD method and the sol-gel method, it can be formed by repeatedly stacking the method. Furthermore, when laminating, each layer may be laminated using a different thin film method.

  The piezoelectric body 30 of the present embodiment is a solid solution of bismuth lanthanum zinc titanate and lead titanate.

More specifically, the piezoelectric body 30 is made of bismuth lanthanum titanate (Bi, La) (Zn, Ti) O ₃ ) (hereinafter sometimes abbreviated as “BLZT”), and lead titanate PbTiO. ₃ (hereinafter, this may be abbreviated as “PT”) (hereinafter, this may be abbreviated as “PT-BLZT”), for example,
_{(1-u) Pb (1} + v) TiO 3 -u (Bi (1-w) La w) (Zn (1-x) Ti x) O 3 ··· ( Formula I)
Can be expressed as:

This PT-BLZT is a complex oxide represented by ABO ₃ as a general formula, and is classified into a so-called perovskite oxide, and can have a perovskite crystal structure by crystallization. PT-BLZT can exhibit piezoelectricity by being crystallized and taking a perovskite crystal structure. Accordingly, the piezoelectric body 30 can be deformed by applying an electric field by the platinum electrode 10 and the conductive layer 20 (electromechanical conversion). By this deformation, for example, the substrate 1 can be bent or vibrated, and the piezoelectric actuator 102 can be configured.

When the solid solution of the piezoelectric body 30 of the present embodiment is represented by the type of the above (formula I), u, v, w, and x can take values of 0 or more and 1 or less. These values may represent the amount of raw material charged when the piezoelectric body 30 is formed, or may represent the composition of the piezoelectric body 30 after formation. For example, “v” in the formula can represent the amount of lead raw material charged in excess of the stoichiometric ratio of PbTiO ₃ . Therefore, the neutrality of the charge of the chemical formula may appear to be unsatisfactory, and in that case, it is understood that the value of the charge or the degree of crystal defects is indicated.

  The piezoelectric body 30 of this embodiment is preferentially oriented to <100>. The orientation of the piezoelectric body 30 will be described in detail in the section “1.4. Crystal orientation”.

  The piezoelectric body 30 of this embodiment is a solid solution of bismuth lanthanum titanate and lead titanate, and the molar ratio (BLZT / PT) of bismuth lanthanum titanate to lead titanate in the solid solution is, for example, It can be 0.38 or more and 38 / 0.61 or less. That is, when the solid solution of the piezoelectric body 30 of the present embodiment is represented by the type of the above (formula I), 0.28 ≦ u ≦ 0.38 can be satisfied.

  If the molar ratio (BLZT / PT) of the solid solution of the piezoelectric body 30 to bismuth lanthanum titanate to lead titanate is within this range, the withstand voltage of the piezoelectric element 100 can be made very good. Thereby, the voltage applied to the piezoelectric element 100 can be increased, and for example, the displacement of the piezoelectric actuator 102 can be increased. And such a piezoelectric body 30 can improve the discharge performance of the ink in inkjet printing, for example. The BLZT / PT ratio is more preferably 0.39 or more and 0.49 or less.

  In the solid solution of the piezoelectric body 30 of the present embodiment, the molar ratio (Bi / La) of bismuth to lanthanum in bismuth lanthanum titanate may be 1.00 or more and 2.33 or less. That is, when the solid solution of the piezoelectric body 30 of the present embodiment is represented by the above-described (formula I) type, 0.3 ≦ w ≦ 0.5 can be satisfied. In this way, the shape of the hysteresis loop of the piezoelectric element 100 can be further improved. That is, when the Bi / La ratio is not less than 1.00 and not more than 2.33, the hysteresis loop can be further opened. The Bi / La ratio is more preferably 1.5 or more and 2.33 or less.

  In the solid solution of the piezoelectric body 30 of this embodiment, the molar ratio of lead to titanium (lead / titanium) in lead titanate can be greater than 1.0 and 1.1 or less. Moreover, in the piezoelectric body 30, the lead titanate lead in solid solution may be 10% or less in excess of the lead amount of lead titanate having a stoichiometric composition. That is, when the solid solution of the piezoelectric body 30 of the present embodiment is represented by the above-described (formula I) type, 0 ≦ v ≦ 0.1 can be satisfied. In this way, the amount of heterogeneous phase in the solid solution crystal can be reduced. For example, when the piezoelectric body 30 is crystallized, a phase of a crystal structure such as cubic, tetragonal or rhombohedral may appear, but the molar ratio of lead to titanium in lead titanate (lead / titanium). In the piezoelectric body 30, for example, the ratio of tetragonal crystals can be increased and the amount of other crystal structure phases (heterophases) can be reduced. In this way, the piezoelectric characteristics of the piezoelectric element 100 can be further improved.

  In the solid solution of the piezoelectric body 30 of this embodiment, the molar ratio (Zn / Ti) of zinc to titanium in the bismuth lanthanum titanate may be 0.92 or more and 1.08 or less. That is, when the solid solution of the piezoelectric body 30 of the present embodiment is represented by the above-described (formula I) type, 0.48 ≦ x ≦ 0.5 can be satisfied. In this way, the withstand voltage of the piezoelectric element 100 can be further improved. Thereby, the voltage applied to the piezoelectric element 100 can be further increased, and for example, the displacement of the piezoelectric actuator 102 can be further increased. Such a piezoelectric body 30 can further enhance the ink ejection performance in, for example, inkjet printing. The Zn / Ti ratio is more preferably 0.96 or more and 1.04 or less, and particularly preferably 0.5 in terms of the balance of valences of bismuth, zinc and titanium.

1.4. Crystal orientation and crystallinity 1.4.1. Platinum electrode Generally, when a metal element is formed on a substrate or the like by sputtering (including DC sputtering, ion sputtering), vapor deposition, MOCVD, etc., a specific axis of the crystal is spontaneously specified. It has the property of being oriented in the direction (in this specification, this property is sometimes referred to as self-orientation). Platinum in particular has a strong self-orientation property. That is, in the process in which platinum is formed as the platinum electrode 10, when the crystal structure is adopted, the <111> direction of the crystal tends to be spontaneously oriented in the normal direction of the film surface to be formed. In this specification, such an alignment state may be referred to as “<111> preferential alignment”. Therefore, the platinum electrode 10 described above can be preferentially oriented to <111> when it is formed on the surface of the substrate 1 or the like by sputtering or the like.

  The degree of preferential orientation of the platinum electrode 10 can be evaluated by, for example, a rocking curve of a peak on the (111) plane of X-ray diffraction. When such a rocking curve is used, the degree of preferential orientation of the platinum electrode 10 can be evaluated by the half width of the peak. In the present embodiment, the platinum electrode 10 has a full width at half maximum of a rocking curve of a peak on the (111) plane of X-ray diffraction of 20 ° or less. Further, the half width of the rocking curve of the peak of the (111) plane of the X-ray diffraction of the platinum electrode 10 is more preferably 10 ° or less.

  The piezoelectric element 100 of the present embodiment can have an iridium oxide or titanium oxide layer on the surface of the platinum electrode 10 opposite to the piezoelectric body 30. By having such a layer, the <111> preferred orientation of the platinum electrode 10 can be made better, and the adhesion between the platinum electrode 10 and the substrate 1 or the like can be enhanced.

1.4.2. Piezoelectric body On the other hand, ceramics exhibiting piezoelectricity are generally crystallized to form a perovskite-type crystal structure when formed by a thin film method. During the conversion, the surface of the object in contact with the ceramic is strongly affected. For example, when PZT (lead zirconate titanate) is used as the piezoelectric body of the piezoelectric element, the properties and materials of the electrodes of the piezoelectric element affect the orientation of the PZT crystal.

  It has also been found that the displacement of the piezoelectric element increases when the orientation of the ceramic perovskite crystal is preferentially oriented in a predetermined direction. Therefore, for example, when the piezoelectric body is PZT, in order to preferentially orient PZT to <100>, the material, orientation, surface modification, etc. of the electrode are performed, and PZT spontaneously becomes <100>. In many cases, the preferred orientation is used. For example, when the ceramic is formed on the platinum thin film so as to be preferentially oriented to <100>, the platinum thin film is preferentially oriented to <111>, so that the crystal orientation of the buffer layer or the like is controlled on the surface of the platinum thin film. The ceramic is preferentially oriented to <100> by forming a thick layer.

  The piezoelectric body 30 of this embodiment uses a solid solution (PT-BLZT) of bismuth lanthanum titanate and lead titanate. Therefore, PT-BLZT of the piezoelectric body 30 can be preferentially oriented to <100> by being directly formed on the platinum electrode 10 by a thin film method. That is, the piezoelectric body 30 of the present embodiment can be obtained without modifying the surface of the platinum electrode 10 or disposing a layer for controlling crystal orientation between the platinum electrode 10 and the piezoelectric body 30. Can be preferentially oriented to <100>. Such spontaneous orientation of the piezoelectric body 30 of the present embodiment is considered to be caused by the interaction of PT-BLZT and the platinum electrode 10 when PT-BLZT is crystallized.

  Accordingly, in the piezoelectric element 100 of the present embodiment, the piezoelectric body 30 has a crystal structure in which PT-BLZT is a perovskite type, has high crystallinity, and the crystal orientation is <100> preferential orientation. Therefore, for example, it exhibits good ferroelectric characteristics such as having good hysteresis characteristics, and can exhibit good piezoelectric characteristics such as increasing the amount of displacement per intensity of the applied electric field.

The <100> preferred orientation degree of the piezoelectric body 30 can be 50% or more. <100> The preferential orientation degree, when measured with X-ray diffraction pattern of the piezoelectric body 30, (100) intensity of the diffraction peak _I (100) of the plane, (110) intensity _{I (110)} of the diffraction peak of the plane And (111) plane diffraction peak intensity I ₍₁₁₁₎ , I ₍₁₀₀₎ / [I ₍₁₀₀₎ + I ₍₁₁₀₎ + I ₍₁₁₁₎ ] The intensity of the diffraction peak may be a peak area. When the <100> preferential orientation degree of PT-BLZT of the piezoelectric body 30 is 50% or more, the piezoelectric characteristics can be further improved. The preferred orientation degree of the piezoelectric body 30 is, for example, changing the composition of PT-BLZT, changing the composition of the platinum electrode 10, changing the temperature and environmental conditions during crystallization of PT-BLZT, It can be changed by at least one of the above.

1.4.3. Crystallinity As described above, the piezoelectric body 30 of the present embodiment has good crystal orientation, but the piezoelectric body 30 of the present embodiment also has good crystallinity. The crystallinity here refers to, for example, the quality and quantity of crystals. Such crystallinity of the piezoelectric body 30 can be evaluated based on, for example, the peak height and peak width of the XRD pattern.

  The piezoelectric element 100 of the present embodiment has one of the features that the platinum electrode 10 and the piezoelectric body 30 are in direct contact with each other. However, the crystal orientation between the platinum electrode 10 and the piezoelectric body 30 is improved. A controlling layer may be interposed. Examples of such a layer include a layer made of titanium and LNO (lanthanum nickelate). The piezoelectric body 30 of the present embodiment can be preferentially oriented to <100> even when formed on the platinum electrode 10 through such a layer that controls the crystal orientation.

1.5. Operational Effects, etc. Since the piezoelectric element 100 (piezoelectric actuator 102) according to the present embodiment includes the piezoelectric body 30 described above, at least the amount of displacement per applied electric field can be increased. As will be further described by an experimental example described later, in the piezoelectric element 100 of the present embodiment, the platinum electrode 10 is preferentially oriented to <111> and the piezoelectric body 30 is preferentially oriented to <100>.

  The piezoelectric element 100 of this embodiment can be used for a wide range of applications. Applications of the piezoelectric actuator 102 include, for example, a liquid ejecting apparatus such as a liquid ejecting head and an ink jet printer. Applications of the piezoelectric element 100 include various sensors such as a gyro sensor and an acceleration sensor, a tuning fork vibrator, and the like. It can be suitably used for ultrasonic devices such as timing devices and ultrasonic motors.

2. Piezoelectric Element Manufacturing Method The piezoelectric element 100 of the present invention can be manufactured, for example, as follows.

  First, the substrate 1 is prepared, and the platinum electrode 10 is formed on the substrate 1. As described above, the platinum electrode 10 can be formed by, for example, a sputtering method, a plating method, a vacuum evaporation method, or the like. The platinum electrode 10 can be patterned as needed.

  Next, the piezoelectric body 30 is formed on the first conductive layer 20. As described above, the piezoelectric body 30 is formed by, for example, at least one method of a sputtering method, a vapor deposition method, an MOCVD method, a MOD method, a PLD (laser ablation) method, a mist film forming method, and a sol-gel method, or a combination of these methods. Can be formed. Crystallization of the piezoelectric body 30 can be performed in an oxygen atmosphere at, for example, 500 ° C. or more and 800 ° C. or less. Thereby, the piezoelectric body 30 can be crystallized. Crystallization may be performed after the piezoelectric body 30 is patterned. Then, if necessary, the above operation can be repeated a plurality of times to obtain the piezoelectric body 30 having a desired thickness.

  Next, the conductive layer 20 is formed on the piezoelectric body 30. The conductive layer 20 can be formed by, for example, a sputtering method, a plating method, a vacuum evaporation method, or the like. Then, the conductive layer 20 and the piezoelectric body 30 are patterned into a desired shape to form a piezoelectric element. The conductive layer 20 and the piezoelectric body 30 can be simultaneously patterned as necessary. The piezoelectric element 100 of this embodiment can be manufactured by the processes exemplified above.

3. Liquid Ejecting Head Next, as an example of the use of the piezoelectric element (piezoelectric actuator) according to the present embodiment, a liquid ejecting head 600 having these will be described with reference to the drawings. FIG. 2 is a cross-sectional view schematically showing the main part of the liquid jet head 600. FIG. 3 is an exploded perspective view of the liquid ejecting head 600, which is shown upside down from a state in which it is normally used.

  The liquid ejecting head 600 can include the above-described piezoelectric element (piezoelectric actuator). In the following, a liquid ejecting head 600 in which the piezoelectric element 100 is formed on the substrate 1 (the structure including the vibration plate 1 a on the upper portion) and the piezoelectric element 100 and the vibration plate 1 a constitute the piezoelectric actuator 102 will be exemplified. I will explain.

  As shown in FIGS. 2 and 3, the liquid ejecting head 600 includes a nozzle plate 610 having nozzle holes 612, a pressure chamber substrate 620 for forming the pressure chamber 622, and the piezoelectric element 100. Furthermore, the liquid ejecting head 600 can include a housing 630 as illustrated in FIG. 3. In FIG. 3, the piezoelectric element 100 is illustrated in a simplified manner.

  As shown in FIGS. 2 and 3, the nozzle plate 610 has nozzle holes 612. Ink can be ejected from the nozzle holes 612. In the nozzle plate 610, for example, a number of nozzle holes 612 are provided in a line. Examples of the material of the nozzle plate 620 include silicon and stainless steel (SUS).

  The pressure chamber substrate 620 is provided on the nozzle plate 610 (lower in the example of FIG. 3). Examples of the material of the pressure chamber substrate 620 include silicon. As the pressure chamber substrate 620 divides the space between the nozzle plate 610 and the diaphragm 1a, as shown in FIG. 3, a reservoir (liquid reservoir) 624, a supply port 626 communicating with the reservoir 624, and a supply A pressure chamber 622 communicating with the port 626 is provided. In this example, the reservoir 624, the supply port 626, and the pressure chamber 622 will be described separately, but these are all liquid flow paths, and any such flow paths may be designed. Absent. Further, for example, the supply port 626 has a shape in which a part of the flow path is narrowed in the illustrated example, but can be arbitrarily formed according to the design, and is not necessarily an essential configuration. The reservoir 624, the supply port 626, and the pressure chamber 622 are partitioned by the nozzle plate 610, the pressure chamber substrate 620, and the vibration plate 1a. The reservoir 624 can temporarily store ink supplied from the outside (for example, an ink cartridge) through a through hole 628 provided in the vibration plate 1a. The ink in the reservoir 624 can be supplied to the pressure chamber 622 via the supply port 626. The volume of the pressure chamber 622 changes due to the deformation of the diaphragm 1a. The pressure chamber 622 communicates with the nozzle hole 612, and ink or the like is ejected from the nozzle hole 612 when the volume of the pressure chamber 622 changes.

  The piezoelectric element 100 is provided on the pressure chamber substrate 620 (lower in the example of FIG. 3). The piezoelectric element 100 is electrically connected to a piezoelectric element driving circuit (not shown), and can operate (vibrate or deform) based on a signal from the piezoelectric element driving circuit. The diaphragm 1 a can be deformed by the operation of the piezoelectric body 30 to change the internal pressure of the pressure chamber 622 as appropriate.

  As shown in FIG. 3, the housing 630 can accommodate the nozzle plate 610, the pressure chamber substrate 620, and the piezoelectric element 100. Examples of the material of the housing 630 include resin and metal.

  The liquid ejecting head 600 includes the piezoelectric element 100 that is at least <100> preferentially oriented as described above. Therefore, the liquid ejecting head 600 has a large displacement and a high discharge ability of liquid or the like.

  Here, the case where the liquid ejecting head 600 is an ink jet recording head has been described. However, the liquid ejecting head of the present embodiment is, for example, an electrode material ejecting head used for electrode formation such as a color material ejecting head, an organic EL display, and an FED (surface emitting display) used for manufacturing a color filter such as a liquid crystal display. It can also be used as a bio-organic matter ejecting head used for biochip manufacturing.

4). Next, the liquid ejecting apparatus according to the present embodiment will be described with reference to the drawings. The liquid ejecting apparatus includes the above-described liquid ejecting head. Hereinafter, a case where the liquid ejecting apparatus is an ink jet printer having the above-described liquid ejecting head will be described. FIG. 4 is a perspective view schematically showing the liquid ejecting apparatus 700 according to the present embodiment.

  As illustrated in FIG. 4, the liquid ejecting apparatus 700 includes a head unit 730, a driving unit 710, and a control unit 760. The liquid ejecting apparatus 700 further includes an apparatus main body 720, a paper feeding unit 750, a tray 721 on which the recording paper P is installed, a discharge port 722 for discharging the recording paper P, and an apparatus main body 720. And an operation panel 770 disposed on the upper surface.

  The head unit 730 includes an ink jet recording head (hereinafter, also simply referred to as “head”) configured from the liquid ejecting head 600 described above. The head unit 730 further includes an ink cartridge 731 that supplies ink to the head, and a transport unit (carriage) 732 on which the head and the ink cartridge 731 are mounted.

  The drive unit 710 can reciprocate the head unit 730. The drive unit 710 includes a carriage motor 741 serving as a drive source for the head unit 730, and a reciprocating mechanism 742 that receives the rotation of the carriage motor 741 and reciprocates the head unit 730.

  The reciprocating mechanism 742 includes a carriage guide shaft 744 supported at both ends by a frame (not shown), and a timing belt 743 extending in parallel with the carriage guide shaft 744. The carriage guide shaft 744 supports the carriage 732 while allowing the carriage 732 to freely reciprocate. Further, the carriage 732 is fixed to a part of the timing belt 743. When the timing belt 743 is caused to travel by the operation of the carriage motor 741, it is guided to the carriage guide shaft 744 and the head unit 730 reciprocates. During this reciprocation, ink is appropriately discharged from the head, and printing on the recording paper P is performed.

  In the present embodiment, an example of a liquid ejecting apparatus that performs printing while both the liquid ejecting head 600 and the recording paper P move is shown, but the liquid ejecting apparatus of the present invention includes the liquid ejecting head 600 and the recording. Any mechanism may be used as long as the paper P is printed on the recording paper P by changing its position relative to each other. Further, in the present embodiment, an example is shown in which printing is performed on the recording paper P. However, the recording medium that can be printed by the liquid ejecting apparatus of the present invention is not limited to paper, and may be cloth, film, A wide range of media such as metal can be used, and the configuration can be changed as appropriate.

  The control unit 760 can control the head unit 730, the drive unit 710, and the paper feed unit 750.

  The paper feeding unit 750 can feed the recording paper P from the tray 721 to the head unit 730 side. The paper feed unit 750 includes a paper feed motor 751 serving as a drive source thereof, and a paper feed roller 752 that rotates by the operation of the paper feed motor 751. The paper feed roller 752 includes a driven roller 752a and a drive roller 752b that face each other up and down across the feeding path of the recording paper P. The drive roller 752b is connected to the paper feed motor 751. When the paper supply unit 750 is driven by the control unit 760, the recording paper P is sent so as to pass below the head unit 730.

  The head unit 730, the drive unit 710, the control unit 760, and the paper feed unit 750 are provided inside the apparatus main body 720.

  The liquid ejecting apparatus 700 includes a liquid ejecting head 600 with a high pressure resistance. Therefore, the liquid ejection capability of the liquid ejecting apparatus 700 is high.

  Note that the liquid ejecting apparatus 700 exemplified above includes one liquid ejecting head 600, and the liquid ejecting head 600 can perform printing on a recording medium. However, the liquid ejecting apparatus 700 includes a plurality of liquid ejecting heads. May be. When the liquid ejecting apparatus includes a plurality of liquid ejecting heads, the plurality of liquid ejecting heads may be independently operated as described above, or the plurality of liquid ejecting heads may be connected to each other to It may be a gathered head. An example of such a set of heads is a line-type head in which nozzle holes of a plurality of heads have a uniform interval as a whole.

  As described above, the liquid ejecting apparatus 700 as an ink jet printer has been described as an example of the liquid ejecting apparatus according to the present invention. However, the liquid ejecting apparatus according to the present invention can be used industrially. As the liquid (liquid material) discharged in this case, various functional materials adjusted to an appropriate viscosity with a solvent or a dispersion medium can be used. In addition to the exemplified image recording apparatus such as a printer, the liquid ejecting apparatus of the present invention includes a color material ejecting apparatus, an organic EL display, an FED (surface emitting display), and an electrophoretic display used for manufacturing a color filter such as a liquid crystal display. The present invention can also be suitably used as a liquid material ejecting apparatus used for forming electrodes such as electrodes and color filters, and a bioorganic material ejecting apparatus used for biochip manufacturing.

5. Experimental Examples, Reference Examples, and Comparative Examples Experimental examples, reference examples, and comparative examples are shown below to describe the present invention more specifically. In addition, this invention is not limited at all by the following experiment examples.

5.1. Production of Piezoelectric Element The piezoelectric elements of Experimental Example 1, Experimental Example 2, Reference Example, and Comparative Example were produced as follows. In these examples, the materials of the electrodes in contact with the piezoelectric body made of PT-BLZT are different.

  First, a common substrate was prepared in each example. The substrate in each example was a single crystal silicon substrate, and a silicon dioxide produced by thermal oxidation as an insulating film on the single crystal silicon substrate was used.

  In Experimental Example 1, an insulator film made of zirconium oxide or the like is formed on the silicon dioxide of the substrate by a reactive sputtering method, thermal oxidation, or the like. Next, titanium was formed by a DC sputtering method or an ion sputtering method, and platinum was formed thereon by a DC sputtering method or the like. Therefore, in Experimental Example 1, PT-BLZT is formed in direct contact with the platinum electrode.

  In Experimental Example 2, a titanium aluminum nitride film (TiAlN) with a thickness of 50 nm, iridium (Ir) with a thickness of 100 nm, an iridium oxide (IrOx) film with a thickness of 30 nm, and platinum ( Pt) films were sequentially laminated by RF magnetron sputtering or the like. Therefore, in Experimental Example 2, PT-BLZT is formed in direct contact with the platinum electrode.

  In the reference example, after the substrate of Experimental Example 1 was fabricated, lanthanum nickelate (LNO) was further formed on the platinum film to a thickness of 40 nm by a DC sputtering method or the like. Therefore, in the reference example, PT-BLZT is formed in contact with the LNO thin film formed on the platinum electrode.

  In the comparative example, after the substrate of Experimental Example 1 was fabricated, iridium was further formed on the platinum film to a thickness of 10 nm by a DC sputtering method or the like. Therefore, in the comparative example, PT-BLZT is formed in contact with the iridium thin film formed on the platinum electrode.

The piezoelectric bodies of each experimental example, reference example and comparative example were all produced by the chemical solution method. A PT-BLZT precursor solution was applied onto the substrate on which the thin film was formed by spin coating. The same precursor solution was used in each example. Specifically, the molar fractions of the elements are Pb = 35.6 mol%, Ti = 40.4 mol%, Bi = 11.2 mol%, La = 4.8 mol%, and Zn = 8.0 mol%, respectively. Thus, what mixed the metal alkoxide or organic acid metal salt of each element with the solvent (n-butanol) was used. This is expressed by the above formula (1), that is, (1-u) Pb _{(1 + v)} TiO ₃ -u (Bi _(1-w) La _w ) (Zn _(1-x) Ti _x ) O _3. , U = 0.33, v = 0.1, x = 0.5, w = 0.3. The rotation speed and time in the spin coating were initially 500 rpm · 5 sec, and then 3000 rpm · 30 sec.

  Next, the applied precursor film was dried in air at 150 ° C. for 2 minutes to remove the solvent. Subsequently, it heat-processed for 4 minutes at 400 degreeC in air | atmosphere, and removed the organic component in a precursor film | membrane (degreasing | defatting). For each experimental example, reference example, and comparative example, the combination of the precursor solution, drying, and degreasing was repeated three times. Subsequently, it introduce | transduced into the baking furnace (Rapid Thermal Annealing (RTA)), and baked at 700 degreeC for 2 minutes, performing oxygen flow of 0.5 L / min.

  Furthermore, for each experimental example, reference example, and comparative example, each of the group consisting of application of the raw material solution, drying, and degreasing was repeated 3 times, and firing was repeated twice, and thereafter, while oxygen flow of 0.5 L / min was performed, 700 Baked at 5 ° C. for 5 minutes. Here, in any sample, the thickness per layer of the PT-BLZT layer was 100 nm, and as a result, a piezoelectric body having a thickness of 600 nm was obtained.

  Furthermore, a PT film having a film thickness of 100 nm was formed thereon as a conductive layer 20 by DC sputtering. After that, it was introduced into the RTA furnace, the inside of the furnace was flowed with oxygen at a flow rate of 0.5 L / min, and the conductive layer 20 was baked at 650 ° C. for 5 minutes, and the piezoelectric of each experimental example, reference example and comparative example Each element was produced.

5.2. Evaluation of piezoelectric element 5.2.1. X-ray diffraction (XRD)
The X-ray diffraction (XRD) pattern was introduced into the model number D8 Discover manufactured by Bruker AXS without patterning the piezoelectric element of each sample in each experimental example, reference example, and comparative example, and Cu-Kα was used as the X-ray source. Measurements were made at room temperature using a wire. The rocking curve was also measured using the same device.

5.2.2. Evaluation of hysteresis Hysteresis was evaluated by measuring a hysteresis loop using Toyo Technica FCE-1A and evaluating its shape. Hysteresis was collected by patterning the piezoelectric elements of each sample into a circular pattern of 500 μmφ and connecting the two electrodes to the apparatus.

5.3. Evaluation Results FIG. 5 shows XRD patterns of each experimental example, reference example, and comparative example. Referring to FIG. 5, in the patterns of each experimental example and reference example, the diffraction peak attributed to the (110) plane is smaller than the diffraction peak attributed to the (100) plane of PT-BLZT. . As a result of calculating the degree of <100> preferential orientation for these samples, all were about 60%. In contrast, in the piezoelectric element of the comparative example, the diffraction peak attributed to the (110) plane was larger than the diffraction peak attributed to the (100) plane of PT-BLZT.

  Further, in the piezoelectric element of the reference example, although <100> preferential orientation was performed, the peak intensity was slightly smaller than that of the experimental example. Therefore, it was found that the crystallinity was slightly lower in the reference example than in the experimental example.

  6 and 7 show the results of measuring rocking curves for the peaks attributed to the platinum (111) plane in the XRD patterns of the piezoelectric elements of Experimental Examples 1 and 2. FIG. In the piezoelectric element of Experimental Example 1, the half-value width of the peak of the platinum (111) surface is 14.285 °, which is relatively broad, whereas in Experimental Example 2, the peak is 5.786 °, which is relatively sharp. It was found that the platinum electrode in the piezoelectric element 2 was superior in the <111> preferred orientation degree.

  8 to 11 show hysteresis loops of the piezoelectric elements of Example 1, Example 2, Reference Example, and Comparative Example, respectively. 8 to 10, it was found that the piezoelectric elements of Example 1, Example 2 and Reference Example all have a so-called open shape of hysteresis loops and exhibit good piezoelectric characteristics. . The hysteresis loop of the piezoelectric element of the comparative example shown in FIG. 11 is rounded, and it is considered that the piezoelectric element of the comparative example is leaking.

  From the above, in the piezoelectric elements of Experimental Example 1 and Experimental Example 2, the PT-BLZT piezoelectric material formed in contact with the platinum electrode preferentially oriented in <111> is preferentially oriented in <100>. Turned out to be. Further, it was found that the piezoelectric elements of Experimental Example 1 and Experimental Example 2 exhibited good hysteresis characteristics. Therefore, the piezoelectric elements of Experimental Example 1 and Experimental Example 2 are considered to have a large displacement when an electric field is applied. In addition, it was found that the piezoelectric element of the reference example had a PT-BLZT piezoelectric body formed in contact with LNO on the platinum electrode preferentially oriented in <111> and preferentially oriented in <100>. . Further, it was found that the piezoelectric element of the reference example exhibits good hysteresis characteristics. Therefore, it is considered that the displacement amount of the piezoelectric element of the reference example is large when an electric field is applied. In contrast, in the piezoelectric element of the comparative example, the PT-BLZT piezoelectric body formed in contact with iridium on the platinum electrode preferentially oriented to <111> is not preferentially oriented to <100>. found. Further, it has been found that the piezoelectric element of the reference example exhibits a leaky hysteresis characteristic. Therefore, it is considered that the piezoelectric element of the reference example cannot obtain sufficient reliability when an electric field is applied.

  The embodiments and modified embodiments described above can be arbitrarily combined with a plurality of forms. Thereby, combined embodiment can have an effect which each embodiment has, or a synergistic effect.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... Diaphragm, 10 ... Platinum electrode, 20 ... Conductive layer, 30 ... Piezoelectric element, 100 ... Piezoelectric element, 102 ... Piezoelectric actuator, 600 ... Liquid ejecting head, 610 ... Nozzle plate, 612 ... Nozzle hole, 620 ... Pressure chamber substrate, 622 ... Pressure chamber, 624 ... Reservoir, 626 ... Supply port, 628 ... Through hole, 630 ... Housing, 700 ... Liquid ejecting device, 710 ... Drive unit, 720 ... Device body, 721 ... Tray, 722 ... Discharge port, 730 ... Head unit, 731 ... Ink cartridge, 732 ... Carriage, 741 ... Carriage motor, 742 ... Reciprocating mechanism, 743 ... Timing belt, 744 ... Carriage guide shaft, 750 ... Paper feed unit, 751 ... Feed Paper motor, 752 ... feed roller, 752a ... driven roller, 752b ... drive roller, 760 ... control unit, 7 0 ... operation panel

Claims (6)

A liquid ejecting head comprising a platinum electrode preferentially oriented to <111> and a piezoelectric actuator having a piezoelectric body formed in contact with the platinum electrode,
The piezoelectric body includes a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The piezoelectric body is a liquid ejecting head in which <100> is preferentially oriented. In claim 1,
The platinum electrode is a liquid ejecting head in contact with iridium oxide on a surface opposite to the piezoelectric body. In claim 1 or claim 2,
The liquid ejecting head, wherein a <100> preferential orientation degree of the piezoelectric body is 50% or more. In any one of Claims 1 to 3,
The liquid jet head, wherein a half width of a rocking curve of a (111) peak of the X-ray diffraction pattern of the platinum electrode is 10 degrees or less.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1. A platinum electrode preferentially oriented to <111>;
A piezoelectric body disposed in contact with the platinum electrode;
Including
The piezoelectric body includes a solid solution of bismuth lanthanum zinc titanate and lead titanate,
The piezoelectric element is a piezoelectric element preferentially oriented to <100>.

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