JP2013179110A - Liquid injection head, liquid injection apparatus, piezoelectric element, and piezoelectric ceramic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performances of a non-lead piezoelectric ceramic, and a piezoelectric element, a liquid injection head and liquid injection apparatus which include the piezoelectric ceramic.SOLUTION: A piezoelectric layer (piezoelectric ceramic) 30 includes a perovskite oxide containing at least Bi, Ba, Fe and Ti, has a residual dielectric polarization Pof 24 μC/cmor more, and is preferentially oriented in (110). A piezoelectric element 3 has the piezoelectric layer 30 and an electrode. A liquid injection head (1) includes: a pressure generation chamber 12 communicating with a nozzle opening 71; and the piezoelectric element 3. A liquid injection apparatus (200) includes the liquid injection head (1).

Description

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

As a piezoelectric element, there is one configured by sandwiching a piezoelectric thin film exhibiting an electro-mechanical conversion function, such as a crystallized dielectric material, between electrodes. The piezoelectric element is used, for example, in a liquid ejecting head such as an ink jet recording head as an actuator device.
PZT (lead zirconate titanate, Pb (Zr _x , Ti _1-x ) O ₃ ) used as a piezoelectric material exhibits a large piezoelectric strain (see Patent Document 1). One reason for this is that the relative dielectric constant ε ₃₃ ^T is as high as 1000 to 2000.

式（１）によると、圧電定数は比誘電率の平方根に比例する。このため、比誘電率が大きいＰＺＴは高い圧電定数を示す。 In general, the piezoelectric constant d ₃₃ is used as an index representing the magnitude of piezoelectric strain. A subscript number represents an azimuth. If the number is 33, the pressure and voltage azimuth indicate the same direction. It is known that the piezoelectric constant d ₃₃ is expressed by the following relational expression using an electromechanical coupling coefficient k ₃₃ , a relative dielectric constant ε ₃₃ ^T , and a Young's modulus E.

According to equation (1), the piezoelectric constant is proportional to the square root of the dielectric constant. For this reason, PZT with a large relative dielectric constant shows a high piezoelectric constant.

On the other hand, since PZT contains Pb (lead), research and development of lead-free piezoelectric materials are being performed from the viewpoint of environmental load (see Patent Documents 2 and 3 and Non-Patent Document 1). The BF-BT, that is, (Bi, Ba) (Fe, Ti) O ₃ -based piezoelectric materials exhibit high piezoelectricity among the lead-free piezoelectric materials. However, the relative dielectric constant ε ₃₃ ^T of the BF-BT piezoelectric material is about half or less of PZT. Assuming that the electromechanical coupling coefficient and Young's modulus of the BF-BT piezoelectric material are equivalent to those of PZT, the piezoelectric constant d ₃₃ of the BF-BT piezoelectric material is only about 70% of PZT. Therefore, in the case of the so-called piezoelectric effect / inverse piezoelectric effect, that is, intrinsic piezoelectric strain, the amount of piezoelectric strain of the BF-BT piezoelectric material is only about 70% of PZT.

  A piezoelectric element using a ferroelectric-antiferroelectric phase transition (see Patent Document 4) has been reported as a piezoelectric element exhibiting large piezoelectric strain even with a low relative dielectric constant. This phenomenon is called extrinsic piezoelectric strain different from intrinsic piezoelectric strain, and the above formula (1) does not hold.

JP 2001-223404 A JP 2009-242229 A JP 2009-252789 A JP 2011-097002 A

Tsutomu Sasaki et al., Japanese Journal of Applied Physics 50, 09NA08 (2011)

However, in order to use the ferroelectric-antiferroelectric phase transition, it is necessary to use (Bi, La) (Fe, Mn) O ₃ different from the BF-BT piezoelectric material for the piezoelectric material. Therefore, this technique cannot be applied to the BF-BT piezoelectric material.
The technique of Patent Document 2 is to produce a BF-BT piezoelectric material preferentially oriented to (100) by vapor deposition such as pulsed laser deposition (PLD). As a result of testing, it was found that the BF-BT piezoelectric material preferentially oriented to (100) does not exhibit a piezoelectric strain of about 70% of PZT expected from the above formula (1).

  The above-described problem is not limited to the liquid ejecting head, and similarly exists in piezoelectric elements such as piezoelectric actuators and sensors, and piezoelectric ceramics.

  In view of the above, one of the objects of the present invention is to improve the performance of lead-free piezoelectric ceramics and piezoelectric elements, liquid jet heads, and liquid jet devices using the piezoelectric ceramics.

In order to achieve one of the above objects, the present invention comprises a pressure generating chamber communicating with a nozzle opening,
A liquid ejecting head comprising a piezoelectric layer and a piezoelectric element having an electrode,
The piezoelectric layer includes a perovskite oxide containing at least Bi, Ba, Fe and Ti,
The residual polarization is 24 μC / cm ² or more, and (110) is preferentially oriented.
In addition, the invention includes an aspect of a liquid ejecting apparatus including the liquid ejecting head.

Furthermore, the present invention is a piezoelectric element having a piezoelectric layer and an electrode,
The piezoelectric layer includes a perovskite oxide containing at least Bi, Ba, Fe and Ti,
The residual polarization is 24 μC / cm ² or more, and (110) is preferentially oriented.
The piezoelectric ceramic of the present invention includes a perovskite oxide containing at least Bi, Ba, Fe and Ti,
The residual polarization is 24 μC / cm ² or more, and (110) is preferentially oriented.

A piezoelectric material including a perovskite oxide containing at least Bi, Ba, Fe, and Ti has a remanent polarization of 24 μC / cm ² or more, and a novel exogenous piezoelectric strain when it is preferentially oriented to (110). It was found that a large piezoelectric strain presumed to occur. Therefore, this aspect can provide a piezoelectric ceramic having a large piezoelectric strain, a piezoelectric element having a piezoelectric layer exhibiting a large piezoelectric strain, a liquid ejecting head, and a liquid ejecting apparatus.

Here, the perovskite oxide may contain an additive metal other than Bi, Ba, Fe and Ti, such as Mn (manganese), for the purpose of improving characteristics such as suppressing leakage current, and has a perovskite structure. Impurities may be contained as much as possible.
The piezoelectric layer may be obtained by forming a coating film of a precursor solution containing at least Bi, Ba, Fe and Ti, and firing the coating film.
The piezoelectric layer may be obtained by firing a precursor film containing at least Bi, Ba, Fe and Ti at 750 to 800 ° C.

  When Mn is contained in the perovskite oxide, an effect of increasing the insulation of the piezoelectric layer (improving leakage characteristics) can be obtained.

FIG. 2 is a cross-sectional view schematically illustrating a recording head (liquid ejecting head) 1. 3 is a flowchart illustrating a manufacturing process of the piezoelectric element 3. FIG. 2 is an exploded perspective view for convenience illustrating the outline of the configuration of the recording head 1. FIGS. 3A to 3C are cross-sectional views for illustrating a manufacturing process of the recording head 1. FIGS. 3A to 3C are cross-sectional views for illustrating a manufacturing process of the recording head 1. 2 is a diagram illustrating an outline of a configuration of a recording apparatus (liquid ejecting apparatus) 200. FIG. The figure which illustrates typical polarization-voltage hysteresis. (A) is a graph showing the electric field induced strain-voltage relationship of Comparative Example 2, (b) is a graph showing the electric field induced strain-voltage relationship of Comparative Example 4, and (c) is the electric field induced strain of Example 2— The graph which shows the relationship of a voltage. The graph which plotted the local derivative ((delta) D) / ((delta) V) of the electric field induction distortion-voltage plot from ultimate strain to reverse arrival strain with respect to the voltage. Residual polarization P _r of each example, the orientation, and a diagram showing the measurement results of the maximum amount of strain. Maximum strain of each example - a graph showing the relationship between the residual polarization P _r. (A) is a figure which illustrates typically the direction of the polarization axis of the rhombohedral crystal preferentially oriented to (110), (b) is the direction of the polarization axis of the rhombohedral crystal preferentially oriented to (100). FIG.

  Embodiments of the present invention will be described below. Of course, the embodiments described below are merely illustrative of the present invention.

(1) Overview of liquid ejecting head, liquid ejecting apparatus, piezoelectric element and piezoelectric ceramic:
First, an example of a liquid ejecting head, a liquid ejecting apparatus, a piezoelectric element, and piezoelectric ceramic will be described with reference to FIGS. 1 and 3 includes a piezoelectric layer (piezoelectric ceramic) 30 and electrodes (20, 40). The recording head (liquid ejecting head) 1 includes a piezoelectric element 3 and a pressure generation chamber 12 that communicates with the nozzle opening 71 and in which a pressure change is caused by the piezoelectric element 3. The method for manufacturing a liquid ejecting head includes a step of forming a piezoelectric element and a step of forming a pressure generation chamber. The pressure generating chamber 12 is formed on the silicon substrate 15 of the flow path forming substrate 10. The nozzle opening 71 is formed in the nozzle plate 70. A lower electrode (first electrode) 20, a piezoelectric layer 30, and an upper electrode (second electrode) 40 are sequentially laminated on the elastic film (vibrating plate) 16 of the flow path forming substrate 10 to form the pressure generating chamber 12. A nozzle plate 70 is fixed to the silicon substrate 15. A recording apparatus (liquid ejecting apparatus) 200 illustrated in FIG. 6 includes the liquid ejecting head as described above.
In addition, the positional relationship demonstrated in this specification is only the illustration for demonstrating invention, and does not limit invention. Accordingly, the present invention also includes the second electrode disposed at a position other than the top of the first electrode, for example, below, left, right, and the like.

The piezoelectric layer 30 contains a perovskite oxide containing at least Bi, Ba, Fe and Ti, has a remanent polarization of 24 μC / cm ² or more, and is preferentially oriented to (110). The perovskite oxide may contain another metal (for example, Mn) having a small molar ratio with Bi, Ba, Fe and Ti as main components. Here, the main component is one or more target components whose total molar ratio is larger than the molar ratio of the other contained components. The piezoelectric layer 30 may contain a substance (for example, a metal oxide) other than the perovskite oxide. Of course, the piezoelectric layer containing impurities including Pb is also included in the piezoelectric ceramic of the present technology.

Each metal contained in the perovskite oxide of the piezoelectric layer 30 is arranged at a site corresponding to the atomic radius in the perovskite structure. The perovskite oxide of the piezoelectric layer 30 includes at least Bi and Ba at the A site and at least Fe and Ti at the B site. Such a perovskite oxide includes a lead-free perovskite oxide having a composition represented by the following general formula.
(Bi, Ba) (Fe, Ti) O _z (2)
(Bi, Ba, MA) (Fe, Ti) O _z (3)
(Bi, Ba) (Fe, Ti, MB) O _z (4)
(Bi, Ba, MA) (Fe, Ti, MB) O _z (5)
Here, MA in the formulas (3) and (5) is one or more metal elements excluding Bi, Ba and Pb, and MB in the formulas (4) and (5) is one kind except for Fe, Ti and Pb. These are the above metal elements. As for z, 3 is a standard, but may deviate from 3 within a range in which a perovskite structure can be taken. The ratio of the A site element to the B site element is 1: 1 as a standard, but may be deviated from 1: 1 within a range where a perovskite structure can be taken.

The molar ratio of Bi to the total molar number of Bi, Ba, MA can be, for example, about 50 to 99.9%, and is preferably about 70 to 80% from the viewpoint of increasing the relative dielectric constant of the piezoelectric layer. . The molar ratio of Ba to the total molar number of Bi, Ba, MA can be, for example, about 0.1 to 50%, and is preferably about 20 to 30% from the viewpoint of increasing the relative dielectric constant of the piezoelectric layer. . The molar ratio of MA to the total molar number of Bi, Ba, MA can be, for example, about 0.1 to 33%.
The ratio of the number of moles of Fe to the total number of moles of Fe, Ti, MB can be, for example, about 50 to 99.9%. The mole number ratio of Ti with respect to the total mole number of Fe, Ti, and MB can be, for example, about 0.1 to 50%. The ratio of the number of moles of MB to the total number of moles of Fe, Ti, MB can be, for example, about 0.1 to 33%.

The MB element includes Mn and the like. The molar concentration ratio of Mn in the B site constituent metal can be, for example, about 0.1 to 10%, with the total molar concentration ratio of the B site constituent metal being 100%. When Mn is added, an effect of increasing the insulating property of the piezoelectric layer (improving leakage characteristics) is expected, but a piezoelectric element having piezoelectric performance can be formed without Mn.
Note that perovskite oxides containing at least Bi, Ba, Fe, and Ti are collectively referred to as BF-BT.

The perovskite oxide of the piezoelectric layer 30 includes a mixed crystal (BFM-BT) of bismuth iron manganate (BFM) and barium titanate (BT). This mixed crystal includes a perovskite oxide represented by the following general formula.
_{xBi (Fe 1-y, Mn} y) O z - (1-x) BaTiO z ... (6)
Here, x is 0 <x <1. When x is about 0.7 to 0.8, bismuth manganate ferrate and barium titanate form a phase boundary, which is preferable because piezoelectricity is improved. y is 0 <y <1 and is preferably about 0.001 to 0.1.

The piezoelectric layer 30 of the present technology is preferentially oriented to (110). For example, when only a diffraction peak (110) derived from the perovskite structure of the piezoelectric layer is observed on the X-ray diffraction chart by the X-ray diffraction wide angle method (XRD), the piezoelectric layer is preferentially oriented to (110). It can be said. When only the diffraction peak (100) derived from the perovskite structure of the piezoelectric layer is observed, it can be said that the piezoelectric layer is preferentially oriented to (100). Of course, when observing, the diffraction peak due to the material of the electrode formed under the piezoelectric layer is excluded. For example, when Pt (platinum) is used for the electrode, the diffraction peak of (111) may be removed at the time of observation.
In addition, (110) being preferentially oriented means that the reflection intensity ratio P ₍₁₁₀₎ or P ^* _{(110) of the} (110) orientation plane obtained from the X-ray diffraction chart is a predetermined value P _th (for example 0.5 ) Can be defined as above. Furthermore, when the Lotgering factor F ₍₁₁₀₎ or F ^* ₍₁₁₀₎ is equal to or greater than a predetermined value F _th (for example, 0.5), it can be defined as preferentially oriented to (110).

  The crystal structure of the piezoelectric layer is presumed to be pseudo-cubic in the resolution of the X-ray diffractometer. The term “pseudocubic crystal” as used herein means that the diffraction peaks are not separated enough to be regarded as a ≠ c, and does not necessarily mean that a = b = c is established. However, the degree of orientation described below has no problem when analyzed as cubic crystals.

When no heterogeneous phase is observed in the X-ray diffraction chart, the degree of orientation of the cubic structure can be expressed by the reflection intensity ratio P or the Lotgering factor F obtained by the following calculation formula.
P ₍₁₀₀₎ = A ₍₁₀₀₎ / (A ₍₁₀₀₎ + A ₍₁₁₀₎ + A ₍₁₁₁₎ ) (7)
P ₍₁₁₀₎ = A ₍₁₁₀₎ / (A ₍₁₀₀₎ + A ₍₁₁₀₎ + A ₍₁₁₁₎ ) (8)
F ₍₁₀₀₎ = (P ₍₁₀₀₎ -P0 ₍₁₀₀₎ ) / (1-P0 ₍₁₀₀₎ ) (9)
F ₍₁₁₀₎ = (P ₍₁₁₀₎ -P0 ₍₁₁₀₎ ) / (1-P0 ₍₁₁₀₎ ) (10)
Here, A ₍₁₀₀₎ is the reflection intensity from the (100) orientation plane, A ₍₁₁₀₎ is the reflection intensity from the (110) orientation plane, and A ₍₁₁₁₎ is the reflection intensity from the (111) orientation plane. . Therefore, P ₍₁₀₀₎ is the ratio of the reflection intensity from the (100) orientation plane to the total reflection intensity, and P ₍₁₁₀₎ is the ratio of the reflection intensity from the (110) orientation plane to the total reflection intensity. P _{0 (100)} is the ratio of A ₍₁₀₀₎ to the total reflection intensity when the crystal is non-oriented, and P _{0 (110)} is the ratio of A ₍₁₁₀₎ to the total reflection intensity when the crystal is non-oriented. Ratio.

When Pt (platinum) is used for the electrode (20), since the (111) peak of the crystal is close to the Pt peak, the (111) peak cannot be separated with sufficient accuracy. For this reason, the orientation degree is calculated by the following formula instead.
P ^* ₍₁₀₀₎ = A ₍₁₀₀₎ / (A ₍₁₀₀₎ + A ₍₁₁₀₎ ) (11)
P ^* ₍₁₁₀₎ = A ₍₁₁₀₎ / (A ₍₁₀₀₎ + A ₍₁₁₀₎ ) (12)
F ^* ₍₁₀₀₎ = (P ^* ₍₁₀₀₎ -P ^* _{0 (100)} ) / (1-P ^* _{0 (100)} ) (13)
F ^* ₍₁₁₀₎ = (P ^* ₍₁₁₀₎ −P ^* _{0 (110)} ) / (1-P ^* _{0 (110)} ) (14)
Here, when P ^* _{0 (100)} is the ratio of A ₍₁₀₀₎ with respect to when crystals are not aligned _{(A (100) + A (} 110)), P * 0 (110) crystal is a non-oriented the ratio of _{(a (100) + a (} 110)) a (110) with respect to a. For P ^* ₍₁₀₀₎ and P ^* ₍₁₁₀₎ , for example, P ^* _{0 (100)} = 0.24, P ^* _{0 (110)} = 0.76 obtained using the bulk of BFM-BT should be used. Can do.

P ^* ₍₁₁₀₎ ≧ P _th, or, when the piezoelectric layer as F ^* ₍₁₁₀₎ ≧ F _th are preferentially oriented in the (110), when the residual polarization P _r is 24μC / cm ² or more Fig. 10 shows a large piezoelectric strain as exemplified in Figs.

Moreover, the piezoelectric layer 30 of this technique is the residual polarization P _r is 24μC / cm ² or more. When P _r ≧ 24, a large piezoelectric strain as illustrated in FIGS. 10 and 11 is exhibited when the piezoelectric layer is preferentially oriented to (110).

From the relational expression (1) of the piezoelectric constant d ₃₃ described above, the piezoelectric constant d ₃₃ is proportional to the square root of the relative dielectric constant ε ₃₃ ^T. For example, BiFeO _z (BF), which is a piezoelectric material that does not contain lead, has a low dielectric constant of about 100, and therefore has a low piezoelectric constant. Mixed at a XBiFeO _z of BF and _{BaTiO z (BT) - (1} -x) BaTiO z (BF-BT) is, x = 0.7 to 0.8 in the relative dielectric constant becomes maximum, in the composition region High piezoelectricity. However, as a result of earnest development, in the composition range, the relative dielectric constant of BF-BT including BFM-BT is only about 50% of that of PZT. Assuming that the electromechanical coupling coefficient and Young's modulus of BF-BT are equivalent to PZT, from the above formula (1), the piezoelectric constant of BF-BT is only about 70% of PZT.

The piezoelectric constant d ₃₃ indicates the displacement per unit voltage. Therefore, displacement when applying a constant voltage to the piezoelectric element is proportional to the piezoelectric constant d _33. That the piezoelectric constant d ₃₃ is 70% of PZT means that the displacement due to intrinsic piezoelectric strain remains at 70% of PZT. The piezoelectric layer 30 of the present technology exhibits 70% or more of PZT and a large piezoelectric strain estimated to be an extrinsic piezoelectric strain. In particular, as shown in FIGS. 8A to 8C by comparing the electric field induced strain-voltage relationship, the piezoelectric layer (illustrated in FIG. 8C) of the present technology has a voltage of −10 V to +10 V. In the low voltage region where the polarization is switched, the displacement on the negative side is large. This is presumed to be due to the following reason.

As schematically shown in FIG. 12A, the BF-BT preferentially oriented to (110) has rhombohedral crystal polarization axes whose orientations are 45 ° and 90 ° with respect to the voltage application direction. Some are tilted in two directions. It is conceivable that the direction of the polarization axis is switched between 45 ° and 90 ° in a low voltage region of voltage −10 V to +10 V. If residual polarization P _r is as small as less than 24μC / cm ^2, the extrinsic piezoelectric strain due to switching of the direction of the polarization axis is presumed that it does not appear significantly. On the other hand, the residual polarization P _r is the greater the 24μC / cm ² or more is estimated extrinsic piezoelectric strain due to switching of the direction of the polarization axis and remarkably appear in more than 70% of PZT with large piezoelectric distortion occurs.

On the other hand, as schematically shown in FIG. 12B, BF-BT preferentially oriented to (100) has a rhombohedral crystal polarization axis direction of only 45 ° with respect to the voltage application direction. Since the direction of the polarization axis does not change from 45 °, the BF-BT preferentially oriented to (100) is considered to cause no exogenous piezoelectric strain. Therefore, the residual polarization P _r is also large as 24μC / cm ² or more, the piezoelectric strain is estimated to remain below 70% of the PZT.

  Note that the technique described in Japanese Patent Application Laid-Open No. 2009-242229 (Patent Document 2) describing BF-BT preferentially oriented to (100) has an electric field strength of 0 <E1 <as shown in FIG. When E2 <Emax, E1 to E2 are phase transition regions. That is, the phase transition region is in a positive voltage region where the polarization is not switched, and is not in a low voltage region where the polarization is switched. Therefore, the principle of the extrinsic piezoelectric strain of the present technology is different from that of the extrinsic piezoelectric strain described in JP-A-2009-242229. From this, it is estimated that the extrinsic piezoelectric strain of the present technology is a novel exogenous piezoelectric strain.

FIG. 2 illustrates a manufacturing method including steps S1 to S3 suitable for manufacturing the piezoelectric layer (piezoelectric ceramics) 30 of the present technology.
In the coating step S1, a precursor solution containing at least Bi, Ba, Fe, and Ti, that is, a precursor of the piezoelectric layer 30 is applied to the surface of the lower electrode (first electrode) 20 in a film shape to apply a coating film. 31 is formed. The material of the lower electrode 20 is not particularly limited as long as the piezoelectric layer 30 is preferentially oriented to (110). When a BF-BT piezoelectric layer is formed by a liquid phase method such as a spin coating method, a dip coating method, or an ink jet method, the BF-BT naturally aligns to (110), so that it is preferentially oriented to (110) on many substrates. Thus, a piezoelectric layer can be formed. The precursor solution may contain Bi, Ba, Fe, and Ti as main components and another metal (for example, about 0.1 to 10% Mn) with a small molar ratio. As the metal salt contained in the precursor solution, an organic acid salt such as 2-ethylhexanoate or acetate can be used. The precursor solution includes a solution in which the metal salt is dissolved in a solvent, a sol in which the metal salt is dispersed in a dispersion medium, and the like. As the solvent and the dispersion medium, those containing an organic solvent such as octane, xylene, or a combination thereof can be used. The precursor solution can be applied by a liquid phase method such as a spin coating method, a dip coating method, or an ink jet method. Although the thickness of a coating film is not specifically limited, For example, it can be set as about 0.1 micrometer.

  In the degreasing step S2, the coating film 31 on the lower electrode 20 is degreased to form a degreasing film 32. The degreasing film 32 is also a kind of precursor of the piezoelectric layer 30. For example, when the coating film 31 is heated at a degreasing temperature lower than the crystallization temperature of the perovskite oxide, the coating film 31 is degreased to form a degreasing film 32 having an amorphous oxide containing at least Bi, Ba, Fe, and Ti. The Degreasing includes drying. Of course, it is also possible to heat the coating film 31 at the drying temperature after the drying process after the coating film 31 is heated at the drying temperature, with the drying temperature <the degreasing temperature <the crystallization temperature. Further, after the coating film is heated below the crystallization temperature to form an amorphous oxide, a precursor is coated on the oxide, and the coating film to be formed is degreased to delaminate the amorphous oxide 32. May be formed.

In firing step S3, and crystallized by firing the degreased film 32 on the lower electrode 20, at least Bi, Ba, having a perovskite oxide containing Fe and Ti, the residual polarization P _r is 24μC / cm ² or more And the piezoelectric layer 30 preferentially oriented to (110) is formed. Residual polarization P _r of the piezoelectric layer 30 can be adjusted depending on the sintering temperature. For example, when the degreasing film (precursor) is fired at a relatively high temperature of 750 to 800 ° C., a BF-BT piezoelectric layer of P _r ≧ 24 can be formed. In addition, after baking a degreasing film, a precursor is apply | coated to the surface of the layer which has the formed perovskite type oxide, the formed coating film is degreased, and application and degreasing are repeated as necessary. The degreasing film may be fired to form a piezoelectric layer in which layers having a perovskite oxide are stacked.

  The thickness of the formed piezoelectric layer 30 is not particularly limited as long as it exhibits an electromechanical conversion effect, but can be, for example, about 0.2 to 5 μm. Preferably, the thickness of the piezoelectric layer 30 is suppressed to such an extent that cracks do not occur in the manufacturing process, and the piezoelectric layer 30 is made thick enough to exhibit sufficient displacement characteristics.

Various devices can be used for the heating described above. If an infrared lamp annealing device that can use the RTA (Rapid Thermal Annealing) method is used for heating above the crystallization temperature, the piezoelectric layer 30 can be satisfactorily formed. Can be formed.
Note that the BF-BT piezoelectric layer only needs to have a preferential orientation of P _r ≧ 24 and (110). Therefore, as long as such a piezoelectric layer is formed, the piezoelectric layer may be formed by a vapor phase method such as a sputtering method, a pulse laser deposition (PLD) method, or a metal organic chemical vapor deposition (MOCVD) method. .

After the formation of the piezoelectric layer, there is a second electrode forming step of forming the upper electrode (second electrode) 40 on the surface of the piezoelectric layer 30 as illustrated in FIG.
As a constituent metal of the electrodes (20, 40), one or more of Pt (platinum), Au (gold), Ir (iridium), Ti, and the like can be used. The constituent metal may be in the state of a compound such as an oxide, in an uncombined state, in an alloy state, or in a single metal state. Metals may be included. Although the thickness of an electrode (20, 40) is not specifically limited, For example, it can be set as about 10-500 nm.

  The configuration of the liquid jet head 1 having the piezoelectric layer 30 to be formed is not particularly limited. For example, the liquid jet head 1 has a laminated structure of the piezoelectric layer 30 on the silicon substrate 15 and is a metal layer used for the lower electrode 20 and the wiring. Exists. It is preferable to provide an elastic film layer of an insulating oxide film between the lower electrode and the silicon substrate, because the actuator compliance can be adjusted and the actuator can have a desired rigidity.

Residual polarization P _r of the piezoelectric layer 30, as illustrated in FIG. 7 can be obtained from the hysteresis curve of polarization P- voltage V of the piezoelectric element. In FIG. 7, the saturation polarization P _m is the amount of polarization under a sufficiently high voltage V _m of about 200 to 1000 kV / cm. The residual polarization _Pr is the polarization when the applied voltage is reduced to 0V. The voltage V _c is a voltage that becomes a coercive electric field (E _c ).

(2) Example of manufacturing method of voltage liquid jet head including piezoelectric element:
FIG. 3 is an exploded perspective view in which an ink jet recording head 1 which is an example of a liquid ejecting head is disassembled for convenience. 4 and 5 are cross-sectional views for illustrating the method of manufacturing the recording head, and are vertical cross-sectional views along the longitudinal direction D2 of the pressure generating chamber 12. FIG. The layers constituting the recording head 1 may be bonded and laminated, or may be integrally formed by modifying the surface of a material that is not separated.

The flow path forming substrate 10 can be formed from a silicon single crystal substrate or the like. The elastic film 16 can be formed integrally with the silicon substrate 15 by, for example, thermally oxidizing one surface of the relatively thick and rigid silicon substrate 15 having a film thickness of about 500 to 800 μm in a diffusion furnace at about 1100 ° C. It can be made of silicon dioxide (SiO ₂ ) or the like. The thickness of the elastic film 16 is not particularly limited as long as it exhibits elasticity, but can be, for example, about 0.5 to 2 μm.

Next, as shown in FIG. 4A, a lower electrode (first electrode) 20 for preferentially orienting the piezoelectric layer 30 to (110) is formed on the elastic film 16 by sputtering or the like. In the example shown in FIG. 4B, patterning is performed after the lower electrode 20 is formed. Although the thickness of the lower electrode 20 is not specifically limited, For example, it can be set as about 50-500 nm. As the adhesion layer or the diffusion prevention layer, a layer such as a titanium oxide (TiO _x ), a titanium nitride aluminum (TiAlN) film, an Ir film, an iridium oxide (IrO) film, a zirconium oxide (ZrO ₂ ) film or the like is used as the elastic film 16. After forming the upper electrode, the lower electrode 20 may be formed on the layer.

  Next, as shown in FIG. 2, the above precursor solution containing at least Bi, Ba, Fe and Ti is applied to the surface of the lower electrode 20 (application step S1). The molar concentration ratio of the metal in the precursor solution can be determined according to the composition of the perovskite oxide to be formed. Next, the coating film 31 is heated at a degreasing temperature to form a thin degreasing film 32 containing an amorphous oxide (degreasing process S2 in a broad sense). Preferably, for example, it is heated to about 140 to 190 ° C. and dried (drying step), and then degreased by heating to about 300 to 500 ° C. (a degreasing step in a narrow sense). Next, the degreasing film is heated at, for example, about 750 to 800 ° C. above the crystallization temperature to form a thin film piezoelectric layer (piezoelectric ceramic) 30 containing a perovskite oxide (firing step S3). In addition, in order to thicken the piezoelectric layer 30, the combination of the coating process, the drying process, the degreasing process, and the baking process may be performed a plurality of times. In order to reduce the firing process, the firing process may be performed after the combination of the coating process, the drying process, and the degreasing process is performed a plurality of times. Further, a combination of these steps may be performed a plurality of times.

As a heating apparatus for performing the above-described drying process and degreasing process, a hot plate, an infrared lamp annealing apparatus for heating by irradiation with an infrared lamp, or the like can be used. An infrared lamp annealing device or the like can be used as a heating device for performing the firing step. Preferably, the temperature rising rate is made relatively fast by using an RTA method or the like.
Thus, the piezoelectric layer 30 having a perovskite oxide containing at least Bi, Ba, Fe, and Ti, P _r ≧ 24 μC / cm ² and preferentially oriented in (110) is formed. .

After the piezoelectric layer 30 is formed, as shown in FIG. 4B, the upper electrode 40 is formed on the piezoelectric layer 30 by sputtering or the like. In the example shown in FIG. 4C, after the upper electrode 40 is formed, the piezoelectric layer 30 and the upper electrode 40 are patterned in regions facing the pressure generation chambers 12 to form the piezoelectric element 3. .
In general, one of the electrodes of the piezoelectric element 3 is used as a common electrode, and the other electrode and the piezoelectric layer 30 are patterned for each pressure generating chamber 12 to configure the piezoelectric element 3. The piezoelectric element 3 shown in FIGS. 3 and 5 uses the lower electrode 20 as a common electrode and the upper electrode 40 as an individual electrode.

  Thus, the piezoelectric element 3 having the piezoelectric layer 30 and the electrodes (20, 40) is formed, and the piezoelectric actuator 2 including the piezoelectric element 3 and the elastic film 16 is formed.

  Next, as shown in FIG. 4C, lead electrodes 45 are formed. For example, after forming a gold layer over the entire surface of the flow path forming substrate 10, the lead electrode 45 is provided by patterning for each piezoelectric element 3 through a mask pattern made of a resist or the like. Connected to each upper electrode 40 shown in FIG. 3 is a lead electrode 45 extending on the elastic film 16 from the vicinity of the end on the ink supply path 14 side.

  The electrodes (20, 40) and the lead electrode 45 can be formed by a sputtering method such as a DC (direct current) magnetron sputtering method. The thickness of each layer can be adjusted by changing the voltage applied to the sputtering apparatus and the sputtering processing time.

  Next, as illustrated in FIG. 5A, the protective substrate 50 on which the piezoelectric element holding portion 52 and the like are formed in advance is bonded onto the flow path forming substrate 10 with an adhesive, for example. As the protective substrate 50, for example, a silicon single crystal substrate, glass, a ceramic material, or the like can be used. Although the thickness of the protective substrate 50 is not specifically limited, For example, it can be about 300-500 micrometers. The reservoir portion 51 penetrating in the thickness direction of the protective substrate 50 and the communication portion 13 constitute a reservoir 9 serving as a common ink chamber (liquid chamber). The piezoelectric element holding portion 52 provided in the region facing the piezoelectric element 3 has a space that does not hinder the movement of the piezoelectric element 3. In the through hole 53 of the protective substrate 50, the vicinity of the end portion of the lead electrode 45 drawn from each piezoelectric element 3 is exposed.

Next, after the silicon substrate 15 is polished to a certain thickness, the silicon substrate 15 is further etched to a predetermined thickness (for example, about 60 to 80 μm) by wet etching with hydrofluoric acid. Next, as shown in FIG. 5B, a mask film 17 is newly formed on the silicon substrate 15 and patterned into a predetermined shape. Silicon nitride (SiN) or the like can be used for the mask film 17. Next, the silicon substrate 15 is anisotropically etched (wet etching) using an alkaline solution such as KOH. As a result, a plurality of liquid flow paths including the pressure generating chambers 12 defined by the plurality of partition walls 11 and the narrow ink supply paths 14, and a communication portion 13 that is a common liquid flow path connected to each ink supply path 14. And are formed. The liquid flow paths (12, 14) are arranged in the width direction D1, which is the short direction of the pressure generating chamber 12.
The pressure generation chamber 12 may be formed before the piezoelectric element 3 is formed.

  Next, unnecessary portions at the peripheral portions of the flow path forming substrate 10 and the protective substrate 50 are removed by cutting, for example, by dicing. Next, as shown in FIG. 5C, the nozzle plate 70 is bonded to the surface of the silicon substrate 15 opposite to the protective substrate 50. The nozzle plate 70 can be made of glass ceramics, silicon single crystal substrate, stainless steel, or the like, and is fixed to the opening surface side of the flow path forming substrate 10. For this fixation, an adhesive, a heat welding film, or the like can be used. The nozzle plate 70 is formed with nozzle openings 71 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14. Therefore, the pressure generation chamber 12 communicates with the nozzle opening 71 that discharges the liquid.

  Next, the compliance substrate 60 having the sealing film 61 and the fixing plate 62 is bonded onto the protective substrate 50 and divided into a predetermined chip size. The sealing film 61 is made of, for example, a material having low rigidity such as a polyphenylene sulfide (PPS) film having a thickness of about 4 to 8 μm, and the like, and seals one surface of the reservoir unit 51. The fixing plate 62 is made of a hard material such as a metal such as stainless steel (SUS) having a thickness of about 20 to 40 μm, for example, and an area facing the reservoir 9 is an opening 63.

A driving circuit 65 for driving the piezoelectric elements 3 arranged in parallel is fixed on the protective substrate 50. For the drive circuit 65, a circuit board, a semiconductor integrated circuit (IC), or the like can be used. The drive circuit 65 and the lead electrode 45 are electrically connected via the connection wiring 66. As the connection wiring 66, a conductive wire such as a bonding wire can be used.
Thus, the recording head 1 is manufactured.

The recording head 1 takes in ink from an ink introduction port connected to an external ink supply unit (not shown), and fills the interior from the reservoir 9 to the nozzle opening 71 with ink. When a voltage is applied between the lower electrode 20 and the upper electrode 40 for each pressure generation chamber 12 in accordance with a recording signal from the drive circuit 65, the deformation of the piezoelectric layer 30, the lower electrode 20, and the elastic film 16 causes deformation from the nozzle opening 71. Ink droplets are ejected.
The recording head may have a common lower electrode structure in which the lower electrode is a common electrode and the upper electrode is an individual electrode, or a common upper electrode structure in which the upper electrode is a common electrode and the lower electrode is an individual electrode. Alternatively, the lower electrode and the upper electrode may be a common electrode, and an individual electrode may be provided between the two electrodes.

(3) Liquid ejecting apparatus:
FIG. 6 shows an appearance of a recording apparatus (liquid ejecting apparatus) 200 having the recording head 1 described above. When the recording head 1 is incorporated in the recording head units 211 and 212, the recording apparatus 200 can be manufactured. In the recording apparatus 200 shown in FIG. 6, the recording head 1 is provided in each of the recording head units 211 and 212, and ink cartridges 221 and 222 as external ink supply means are detachably provided. A carriage 203 on which the recording head units 211 and 212 are mounted is provided so as to be able to reciprocate along a carriage shaft 205 attached to the apparatus main body 204. When the driving force of the driving motor 206 is transmitted to the carriage 203 via a plurality of gears and a timing belt 207 (not shown), the carriage 203 moves along the carriage shaft 205. A recording sheet 290 fed by a sheet feeding roller (not shown) is conveyed onto the platen 208 and printed by ink supplied from the ink cartridges 221 and 222 and ejected from the recording head 1.

(4) Example:
Hereinafter, although an example is shown, the present invention is not limited by the following examples.

[Preparation of BFM-BT precursor solution]
In either case, the liquid raw materials of bismuth, iron, manganese, barium, and titanium having 2-ethylhexanoic acid as a ligand are dissolved in a molar ratio of metals: Bi: Fe: Mn = 100: 95: 5, Ba: BFM-BT, which is a 2-ethylhexanoic acid complex solution mixed with Ti = 100: 100 and BFM: BT = 75: 25 and containing bismuth, iron, manganese, barium, and titanium as metal species A precursor solution was prepared. Here, BFM-BT is the general formula (Bi, Ba) (Fe, Ti, Mn) is represented by _{O z, Bi: Fe: Mn} : Ba: Ti = 75: 71.25: 3.75: 25: 25 It becomes. BFM represents the number of moles of Bi, that is, the total number of moles of Fe and Mn, and BT represents the number of moles of Ba, that is, the number of moles of Ti.

[Preparation of piezoelectric thin film of Example]
As the substrate, a platinum-coated silicon substrate having a size of 2.5 cm on a side and specifically, a substrate having layers of Pt / TiO _x / SiO _x / Si was used. A BFM-BT film was formed on this substrate by spin coating.

First, the BFM-BT precursor solution was dropped on the substrate, and the substrate was rotated at 3000 rpm for 30 seconds to form a BFM-BT precursor solution film (coating process). This BFM-BT precursor solution film was heated on a hot plate at 180 ° C. for 2 minutes, and then degreased by heating on a hot plate at 350 ° C. for 3 minutes (drying and degreasing step). The combination of the coating process, the drying process, and the degreasing process was repeated three times, and then the degreased substrate was heated at 750 ° C. for 3 minutes by an RTA method in an oxygen atmosphere using an infrared lamp annealing apparatus (baking process). The BFM-BT piezoelectric thin film (piezoelectric material) of Example 1 in which the number of layers in the spin coating process was set to 12 by repeating the combination of “coating process, drying process and degreasing process 3 times” and “firing process” 4 times. Layer) A sample was formed on the lower electrode. The formed BFM-BT film preferentially oriented to (110) with P _r ≧ 24 is defined as the thin film 1.
Similarly, the BFM-BT piezoelectric thin film sample (thin film 2) of Example 2 was produced by changing the heating conditions of the firing process to 800 ° C. for 3 minutes. Moreover, the BFM-BT piezoelectric thin film sample (thin film 3) of Example 3 was produced by heating at 800 ° C. for 5 minutes by the RTA method after the thin film 1 step.

[Upper electrode production]
A platinum pattern having a thickness of 100 nm was formed on the thin film 1 by DC sputtering using a metal mask. Next, the thin film was baked at 650 ° C. for 5 minutes by an RTA method in an oxygen atmosphere with an infrared lamp annealing apparatus to produce a piezoelectric element (element 1) having each layer of Pt / BFM-BT (upper electrode) Forming step).
Similarly, elements 2 and 3 were produced using the thin films 2 and 3, respectively.

[Comparative Example 1]
A PZT precursor solution was prepared by dissolving lead acetate, zirconium acetylacetonate, and titanium isopropoxide in a mixed solvent of diethanolamine, 2-methoxyethanol, and polyethylene glycol. A substrate having a size of 2.5 cm on a side and having each layer of Ti / Ir / Pt / Ti / ZrO _x / SiO _x / Si was used as the substrate. A comparative thin film 1 was produced in the same manner as in Example 1 except that the heating condition in the firing step was 750 ° C. for 3 minutes and the upper electrode was Ir with a thickness of 50 nm, and a comparative element 1 was produced.

[Comparative Examples 2 and 3]
A comparative thin film 2 with P _r <24 was prepared in the same manner as in Example 1 except that the heating condition in the firing step was 650 ° C. for 3 minutes, and Comparative element 2 was prepared. In addition, a comparative thin film 3 of P _r <24 was prepared in the same manner as in Example 1 except that the heating condition of the firing step was 700 ° C. for 3 minutes, and Comparative element 3 was prepared.

[Comparative Examples 4 and 5]
As the substrate, a lanthanum nickelate (LaNiO _z , LNO) / platinum-coated silicon substrate having a side of 2.5 cm, specifically, a substrate having each layer of LNO / Pt / TiO _x / SiO _x / Si was used. . A comparative thin film 4 was produced in the same manner as in Example 1 except that the heating conditions in the firing step were 750 ° C. and 5 minutes, and a comparative element 4 was produced. Moreover, the heating conditions of the baking process were set to 800 ° C. for 5 minutes, which is the same as in Example 3, and the comparative thin film 5 was manufactured in the same manner as in Example 3, thereby manufacturing the comparative element 5.
In addition, the thickness of the piezoelectric material layer of the thin films 1-3 and the comparative thin films 1-5 was substantially the same.

[Test Example 1]
For the thin films 1 to 3 and the comparative thin films 1 to 5, X-ray diffraction charts were obtained at room temperature by X-ray diffraction wide angle method (XRD) using “D8 Discover” manufactured by Bruker and using CuKα as an X-ray source. The results are shown in FIG.
In the thin films 1 to 3 and the comparative thin films 2 and 3, only diffraction peaks derived from the Pt (lower electrode) and (110) -oriented perovskite structures were observed, and no heterogeneous phase was observed. Moreover, as shown in FIG. 10, F ^* ₍₁₁₀₎ of each of the thin films 1 to 3 and the comparative thin films 2 and 3 was 0.5 or more. Therefore, it was confirmed that the thin films 1 to 3 and the comparative thin films 2 and 3 are preferentially oriented to (110).

Similarly, in the comparative thin film 1 on which the PZT piezoelectric layer was formed, only diffraction peaks derived from the lower electrode and the (100) -oriented perovskite structure were observed. Therefore, it was confirmed that the comparative thin film 1 is preferentially oriented to (100).
Similarly, in the comparative thin films 4 and 5 using the LNO / platinum-coated silicon substrate, only diffraction peaks derived from Pt (lower electrode) and (100) -oriented perovskite structures were observed. Moreover, as shown in FIG. 10, F ^* ₍₁₀₀₎ of the comparative thin films 4 and 5 were all 0.5 or more. Therefore, it was confirmed that the comparative thin films 4 and 5 are preferentially oriented to (100).

[Test Example 2]
For elements 1 to 3 and comparative elements 1 to 5, “FCE-1A” manufactured by Toyo Technica Co., Ltd., using an electrode pattern of φ = 400 μm and applying a triangular wave with a frequency of 1 kHz at room temperature, the polarization amount P [μC / cm ² ] and an applied voltage V were obtained as a hysteresis curve. All of the elements 1 to 3 and the comparative elements 1 to 5 showed good PV hysteresis, and showed good piezoelectric characteristics regardless of orientation. The results of the residual polarization P _r at the time of applying a triangular wave of ± 30 V, shown in Figure 10.

As shown in FIG. 10, the residual polarization P _r of Examples 1 to 3 was 24~36μC / cm ^2. As an example of the voltage V _c obtained from the hysteresis curve, V _c in Example 2 was 8V. On the other hand, the residual polarization P _r of Comparative Example 2-5 was 13~15μC / cm ^2. As an example of the voltage V _c obtained from the hysteresis curve, V _c of Comparative Example 2 was 6V. The residual polarization P _r of Comparative Example 1 formed with the piezoelectric layer of PZT was 18μC / cm ^2.

[Test Example 3]
For the elements 1 to 3 and the comparative elements 1 to 5, the displacement measurement device (DBLI) manufactured by Axact Corporation was used, an electrode pattern of φ = 500 μm was used at room temperature, a triangular wave with a frequency of 1 kHz was applied, and an electric field induced strain The relationship (butterfly curve) between (displacement amount D) and voltage (V) was determined. From this butterfly curve, the maximum strain amount D _pp2 of the piezoelectric thin film was obtained. The results are shown in FIG.

As an example of the result, FIG. 8A shows the relationship of electric field induced strain (displacement amount D) −voltage (V) in Comparative Example 2, and FIG. 8B shows the electric field induced strain (displacement amount D) in Comparative Example 4. FIG. 8C shows the relationship between the voltage (V) and FIG. 8C shows the relationship between the electric field induced strain (displacement amount D) and the voltage (V) in Example 2. In Comparative Example 2, the maximum strain amount D _pp2 = 2.3 nm, which was 64% of the maximum strain amount of Comparative Example 1 in which the PZT piezoelectric layer was formed. In Comparative Example 4, the maximum strain amount D _pp2 = _{1.9 nm,} which is 53% of the maximum strain amount of Comparative Example 1. On the other hand, in Example 2, the maximum strain amount D _pp2 = 3.6 nm, indicating a very large piezoelectric strain equivalent to the maximum strain amount of Comparative Example 1 in which the PZT piezoelectric layer was formed.

When the fact that the relative permittivity of BF-BT including BFM-BT is only about 50% of the relative permittivity of PZT is applied to the relational expression (1) of the piezoelectric constant d ₃₃ described above, the electromechanical coupling coefficient of BF-BT Assuming that the Young's modulus is equivalent to PZT, the piezoelectric constant of BF-BT is only about 70% of PZT. This means that the displacement of BF-BT due to intrinsic piezoelectric strain remains at 70% of PZT. Therefore, the maximum strain amount D _pp2 of Examples 1 to 3 exceeding 2.52 nm, which is 70% of the maximum strain amount of 3.6 nm of Comparative Example 1, causes a large piezoelectric strain that cannot be explained by intrinsic piezoelectric strain. It is presumed that it shows.

Here, the difference in the piezoelectric strain described above will be considered. The piezoelectric strain represented by the piezoelectric constant d ₃₃ in the relational expression (1) described above is an intrinsic piezoelectric strain, that is, a piezoelectric strain that linearly responds to a voltage in a sufficiently polarized state. The ferroelectric is well polarized by applying a 2 times the voltage of the voltage V _c to be the coercive field E _c. V _c of Comparative Example 2 is 6V, since V _c of Example 2 is 8V, by applying at least 16V or more voltage, both can be regarded as being sufficiently polarized. On the other hand, as an electric field induced strain other than the intrinsic piezoelectric strain, an exogenous piezoelectric strain caused by non-180 ° polarization rotation or the like can be considered. This extrinsic piezoelectric strain is observed as non-linear electric field induced strain deviating from the linearity of the above-described intrinsic piezoelectric strain.

FIG. 9 is a plot of the local differential (δD) / (δV) [pm / V] obtained by differentiating the displacement D from the ultimate strain (Dmax) to the reverse ultimate strain (Dmin) with respect to the voltage (V). The graph is shown. In FIG. 9, the solid line indicates Example 2 and the broken line indicates Comparative Example 2. The local differential (δD) / (δV) can be regarded as the local piezoelectric constant d ₃₃ . From FIG. 9, in the sufficiently polarized state, that is, in the region of 16 V or more, the local differential (δD) / (δV) is almost the same in Comparative Example 2 and Example 2. On the other hand, in the low voltage region of 16 V or less, there is a large difference between Comparative Example 2 and Example 2. The local differential (δD) / (δV) of Comparative Example 4 was also almost the same value as Example 2 in a sufficiently polarized state, but a large difference from Example 2 was seen in the low voltage region. .

Comparing the electric field induced strain-voltage butterfly curves of FIGS. 8A, 8B, and 8C, the displacement of Example 2 is compared with Comparative Examples 2 and 4 in the low voltage region where the polarization of voltage −10 V to +10 V is switched. It can be seen that there is a large displacement on the negative side compared to the displacement of. Residual exemplary polarization P _r is as large as 24μC / cm ² or more Example 2, as shown in FIG. 12 (a), 2 types of 45 ° and 90 ° orientation of the polarization axis of the rhombohedral is the voltage applied orientation It is presumed that exogenous piezoelectric strain in which both of them switched reversibly appeared remarkably. On the other hand, in Comparative Example 4 preferentially oriented to (100), the polarization axis is only 45 ° with respect to the voltage application orientation as shown in FIG. Is not expected to appear.

Note that FIG. 7 of Japanese Patent Application Laid-Open No. 2009-252789 (Patent Document 3), which is a publication of an application by the present applicant, shows a piezoelectric of 0.8 Bi (Fe _0.95 , Mn _0.05 ) O ₃ -0.2BaTiO ₃ sample. The constant d ₃₃ is shown to be 64.8 pm / V. This sample, as shown in FIG. 10, the residual polarization P _r is 16μC / cm ^2, were preferentially oriented in the (110). Moreover, the following 30V conversion displacement was used for the maximum distortion amount D _pp2 shown in FIGS.
(30 V in terms of _{displacement) = (d 33/1000)} × 30 [nm] ... (15)
Here, the unit of d ₃₃ is pm / V. The 30V equivalent displacement corresponds to the maximum strain when a voltage of 30V is applied to the piezoelectric layer. The 30V equivalent displacement of d ₃₃ = 64.8 is 1.9 nm, which is smaller than 2.52 nm which is 70% of the maximum strain amount of Comparative Example 1. This is presumed to be because exogenous piezoelectric strain due to switching of the direction of the polarization axis did not appear remarkably because P _r <24.

Further, in FIG. 6 of "Tsutomu Sasaki et al., Japanese Journal of Applied Physics 50, 09NA08 (2011) " (Non-Patent Document 1), the residual polarization P _r of "0.85BF0.15BT" is at 30 .mu.C / cm ² It is shown that there is. As shown in the X-ray diffraction chart of the piezoelectric thin film similar to FIG. 1 of the same document, “0.85BF0.15BT” formed by the vapor phase method is preferentially oriented to (100). Also, the summary of this document shows that the piezoelectric constant d ₃₃ of “0.85BF0.15BT” is 58 pm / V. The 30 V equivalent displacement of d ₃₃ = 58 is 1.7 nm as shown in FIGS. 10 and 11, and is smaller than 2.52 nm which is 70% of the maximum strain amount of Comparative Example 1. This is presumably because the piezoelectric thin film is preferentially oriented to (100), so that the direction of the polarization axis does not change and no exogenous piezoelectric strain appears.

On the other hand, P _r ≧ 24 μC / cm ² and the maximum strain amount D _pp2 of Examples 1 to 3 preferentially oriented to (110) is _{2.9 to 3.6 nm} as shown in FIGS. And exceeding 2.52 nm which is 70% of the maximum strain amount of Comparative Example 1 using PZT. This is presumably because in the low voltage region where the polarization of voltage −10 V to +10 V is switched, the extrinsic piezoelectric strain due to the change of the direction of the polarization axis of the rhombohedral crystal appears remarkably, thereby causing a large piezoelectric strain.

11, the maximum amount of strain D _pp2 of each example - shows the relationship between the residual polarization P _r. In addition to the data of Examples 1 to 3 and Comparative Examples 2 to 5, the graph of FIG. 11 also plots data derived from the above-described literature. As shown in FIG. 11, it can be seen that a large piezoelectric strain does not always occur if the remanent polarization _Pr is large. When the BF-BT piezoelectric layer is preferentially oriented to (100), the piezoelectric strain is small even if P _r ≧ 24.

From the above, you are P _r is 24μC / cm ² or more, and, BF-BT are preferentially oriented in the (110), a new exogenous expressed in the low voltage region where the polarization of the voltage -10V to + 10V switched It can be seen that a large piezoelectric strain presumed to be caused by the unidirectional piezoelectric strain occurs. Therefore, the present technology can provide a piezoelectric ceramic exhibiting a large piezoelectric strain, a piezoelectric element having a piezoelectric layer exhibiting a large piezoelectric strain, a liquid ejecting head, and a liquid ejecting apparatus.

(5) Application and others:
Various modifications can be considered for the present invention.
In the above-described embodiment, an individual piezoelectric body is provided for each pressure generation chamber. However, a common piezoelectric body may be provided for a plurality of pressure generation chambers, and an individual electrode may be provided for each pressure generation chamber.
In the above-described embodiment, a part of the reservoir is formed on the flow path forming substrate. However, the reservoir may be formed on a member different from the flow path forming substrate.
In the above-described embodiment, the upper side of the piezoelectric element is covered with the piezoelectric element holding unit, but the upper side of the piezoelectric element can be opened to the atmosphere.
In the embodiment described above, the pressure generating chamber is provided on the opposite side of the piezoelectric element with the diaphragm interposed therebetween, but it is also possible to provide the pressure generating chamber on the piezoelectric element side. For example, if a space surrounded by fixed plates and piezoelectric elements is formed, this space can be used as a pressure generating chamber.

  The liquid ejected from the fluid ejecting head may be any material that can be ejected from the liquid ejecting head, such as a solution in which a dye or the like is dissolved in a solvent, or a sol in which solid particles such as pigments or metal particles are dispersed in a dispersion medium. Is included. Such fluids include ink, liquid crystal, and the like. The liquid ejecting head includes one that discharges powder or gas. The liquid ejecting head can be mounted on an image recording apparatus such as a printer, a color filter manufacturing apparatus such as a liquid crystal display, an electrode manufacturing apparatus such as an organic EL display, a biochip manufacturing apparatus, and the like.

  The laminated ceramics produced by the production method described above can be suitably used to form ferroelectric thin films for ferroelectric devices, pyroelectric devices, piezoelectric devices, and optical filters. Ferroelectric devices include ferroelectric memory (FeRAM), ferroelectric transistors (FeFET), etc., and pyroelectric devices include temperature sensors, infrared detectors, temperature-electric converters, and the like. Examples of piezoelectric devices include fluid ejection devices, ultrasonic motors, acceleration sensors, and pressure-electric converters. Optical filters include blocking filters for harmful rays such as infrared rays, and photonic crystal effects due to quantum dot formation. And an optical filter using optical interference of a thin film.

As described above, according to the present invention, lead-free piezoelectric ceramics and techniques for improving the performance of piezoelectric elements, liquid ejecting heads, and liquid ejecting apparatuses using the piezoelectric ceramics are provided according to various aspects. can do.
In addition, the configurations disclosed in the embodiments and modifications described above are mutually replaced, the combinations are changed, the known technology, and the configurations disclosed in the embodiments and modifications described above are mutually connected. It is possible to implement a configuration in which replacement or combination is changed. The present invention includes these configurations and the like.

DESCRIPTION OF SYMBOLS 1 ... Recording head (liquid ejecting head), 2 ... Piezoelectric actuator, 3 ... Piezoelectric element, 10 ... Channel formation board | substrate, 11 ... Partition, 12 ... Pressure generating chamber, 15 ... Silicon substrate, 16 ... Elastic film (vibration plate) , 20 ... lower electrode (first electrode), 30 ... piezoelectric layer, 31 ... coating film, 32 ... degreasing film, 40 ... upper electrode (second electrode), 45 ... lead electrode, 50 ... protective substrate, 60 ... compliance Substrate, 65 ... drive circuit, 70 ... nozzle plate, 71 ... nozzle opening, 200 ... recording apparatus (liquid ejecting apparatus), S1 ... coating process, S2 ... degreasing process, S3 ... baking process.

Claims (5)

A pressure generating chamber communicating with the nozzle opening;
A liquid ejecting head comprising a piezoelectric layer and a piezoelectric element having an electrode,
The piezoelectric layer includes a perovskite oxide containing at least Bi, Ba, Fe and Ti,
A liquid jet head having a remanent polarization of 24 μC / cm ² or more and preferentially oriented to (110).   The liquid jet head according to claim 1, wherein Mn is contained in the perovskite oxide.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1. A piezoelectric element having a piezoelectric layer and an electrode,
The piezoelectric layer includes a perovskite oxide containing at least Bi, Ba, Fe and Ti,
A piezoelectric element having a remanent polarization of 24 μC / cm ² or more and preferentially oriented to (110). A perovskite oxide containing at least Bi, Ba, Fe and Ti;
Piezoelectric ceramics having a remanent polarization of 24 μC / cm ² or more and preferentially oriented to (110).

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