JP5178065B2 - Piezoelectric ceramics, piezoelectric actuator and liquid discharge head - Google Patents

Description

  The present invention relates to piezoelectric ceramics, piezoelectric actuators, and liquid discharge heads, and more particularly to piezoelectric actuators and liquid discharge heads that are frequently driven, and piezoelectric ceramics used in them.

  In recent years, with the spread of personal computers and the development of multimedia, the use of ink jet recording apparatuses as recording apparatuses that output information to recording media is rapidly expanding. The improvement in performance is remarkable, and the printing quality equivalent to silver halide photography is realized.

  However, the demand for improving the print quality continues, and in order to eject ink with high resolution and high definition, the printer head is required to have a higher density of ink ejection nozzles. Therefore, a piezoelectric actuator element that discharges ink from a nozzle is also required to be formed in a small size and a high density.

  Such an ink jet recording apparatus is equipped with an ink jet head for discharging a liquid, and this type of ink jet head includes a heater as a pressurizing means in an ink flow path filled with ink. A thermal head system that heats and boils ink, pressurizes the ink with bubbles generated in the ink flow path, and discharges it as ink droplets from the ink discharge hole, and a part of the wall of the ink flow path filled with ink. A piezoelectric method is generally known in which a displacement element is bent and displaced, and ink in an ink flow path is mechanically pressurized and ejected as ink droplets from ink ejection holes.

  An ink jet head used in an ink jet recording apparatus using a piezoelectric method has a structure in which a piezoelectric actuator 51 is provided on a flow path member 53 as shown in FIG. 1). The flow path member 53 has a plurality of liquid pressurizing chambers 53 a partitioned by a plurality of partition walls 53 b, and the opening of the liquid pressurizing chamber 53 a is formed to be covered by the piezoelectric actuator 51.

  The piezoelectric actuator 51 includes a common electrode 54, a piezoelectric ceramic layer 55, and an individual electrode 56 stacked in this order on a vibration plate 52, and includes an individual electrode 56, a common electrode 54, and a piezoelectric ceramic layer 55 sandwiched therebetween. A plurality of displacement elements 57 are formed. The piezoelectric ceramic layer 55 sandwiched between the individual electrode 56 and the common electrode 54 is polarized perpendicular to the thickness direction of the piezoelectric ceramic layer 55.

  As shown in FIG. 2B, the individual electrodes 56 are arranged in a matrix on the upper surface of the piezoelectric ceramic layer 55, and the individual electrodes 56 are arranged immediately above the liquid pressurizing chamber 53a. The individual electrode 56 is connected to an individual electrode connection portion 56a for connecting to an external wiring circuit (not shown). The common electrode 54 is also electrically connected to a connection terminal (not shown) for connecting to an external wiring circuit.

  In the ink jet head as described above, a voltage is applied between the common electrode 54 and the predetermined individual electrode 56 to displace the piezoelectric ceramic layer 55 immediately below the individual electrode 56, whereby the displacement element 57 corresponds to the corresponding liquid application. By changing the volume of the pressure chamber 53 a and pressurizing the ink in the liquid pressurizing chamber 53 a, ink droplets can be ejected from the liquid ejection port 58 opened on the bottom surface of the flow path member 53.

  The individual electrodes 56 have an area smaller than that of the liquid pressurizing chamber 53a when viewed from the stacking direction. That is, the piezoelectric ceramic layer 55 has a polarized drive portion 55a directly below the individual electrode 56 and an inactive portion 55b that is not polarized so as to surround the drive portion 55a. Therefore, the displacement element 57 can obtain a large displacement due to the restraining portion 55c that is not displaced.

In such an ink jet head, PZT has been used as a piezoelectric material, and PZT in which zirconia is dispersed in piezoelectric ceramics has been proposed (for example, see Patent Document 2). As a manufacturing method, a manufacturing method in which baking is performed in oxygen has been proposed (see, for example, Patent Document 3).
JP 11-34321 A Japanese Patent Laid-Open No. 10-330164 JP-A-5-139828

  However, in the inkjet head (liquid ejection head) described in Patent Document 1, when a voltage is applied between the common electrode 54 and the individual electrode 56 to repeatedly drive the displacement element 57, the driving unit 55a and the non-driving 55b. Tensile stress and compressive stress are generated between them. The piezoelectric domain wall contained in the piezoelectric body also moves by applying stress from the outside (domain switching), and the expansion and contraction of the porcelain occurs. As a result, when the driving cycle becomes very large, the domain wall moves in the piezoelectric ceramic layer 55 due to the stress between the driving unit 55a and the non-driving unit 55b generated by the expansion and contraction of the porcelain due to the inverse piezoelectric effect of the piezoelectric body itself. The problem of driving deterioration that progresses and the displacement of the driving unit decreases occurs.

  If drive deterioration occurs in the displacement element 57, the amount and speed of the liquid ejected from the liquid ejection head change, which causes a problem that an appropriate image cannot be recorded.

  This problem is greatly affected by the movement of the domain wall in the non-driving unit 55b that is not polarized in the initial state, but driving deterioration occurs due to the change in the polarization method in the driving unit 55a.

  An object of the present invention is to provide a piezoelectric ceramic in which domain switching hardly occurs due to an external stress, and a piezoelectric actuator and a liquid discharge head in which drive deterioration is suppressed.

The piezoelectric ceramic of the present invention, the main crystal grains Ri Do of PZT phase containing therein zirconia, the zirconia is included in the PZT phase is characterized der Rukoto least 1% of the zirconia component.

  Moreover, it is preferable to contain the said zirconia 0.01 volume% or more.

  Moreover, it is preferable that ratio D1 / D2 of the average particle diameter D1 of the said zirconia and the average particle diameter D2 of the said main crystal grain is 0.016-0.07.

  The electric actuator according to the present invention is characterized in that a pair of electrodes are arranged opposite to each other on either the surface or inside of the piezoelectric ceramic.

  The liquid discharge head of the present invention covers the plurality of liquid pressurization chambers on a flow path member having a plurality of liquid pressurization chambers and a plurality of liquid discharge holes communicating with the plurality of liquid pressurization chambers. A diaphragm is laminated, and a common electrode, the piezoelectric ceramic layer according to claim 1 and a plurality of individual electrodes are laminated in this order on the diaphragm.

  According to the piezoelectric ceramic of the present invention, since the main crystal particles are composed of the PZT phase containing zirconia, the main crystal is subjected to stress received from the outside by precipitating zirconia that causes volume change due to external stress in the main crystal particles. It can be relaxed within the particles, and the movement of the domain wall can be suppressed.

  Moreover, when the said zirconia is contained 0.01 volume% or more, since the ratio of the said zirconia which relieves stress becomes high, stress can be relieve | moderated more.

  Further, when the ratio D1 / D2 between the average particle diameter D1 of the zirconia and the average particle diameter D2 of the main crystal particles is 0.016 or more, the volume change of the main crystal particles can be reduced in the main crystal particles. Since there is much quantity of the said zirconia particle | grain, the effect of stress relaxation can be made higher. When D1 / D2 is 0.07 or less, since the PZT phase is sintered at a high density, drive deterioration hardly occurs.

  In the piezoelectric actuator of the present invention, a pair of electrodes are arranged opposite to each other on the surface and inside of the piezoelectric ceramic, so that even when the number of times of driving increases, the piezoelectric ceramic is prevented from being deteriorated and has stable characteristics. Can be maintained.

  The liquid discharge head of the present invention covers the plurality of liquid pressurization chambers on a flow path member having a plurality of liquid pressurization chambers and a plurality of liquid discharge holes communicating with the plurality of liquid pressurization chambers. The diaphragm is laminated, and the common electrode, the piezoelectric ceramic layer according to any one of claims 1 to 3 and a plurality of individual electrodes are laminated in this order on the diaphragm, so that the drive can be performed even if the number of times of driving increases. Since the deterioration is suppressed, variations in the speed of the liquid discharged from the plurality of liquid discharge ports hardly occur, and stable recording can be performed by the discharged liquid.

  FIG. 1A is a schematic sectional view of the piezoelectric ceramic of the present invention. 1 is a piezoelectric ceramic, and 2 is a PZT phase which is a main crystal particle. The PZT phase is a crystalline phase in which lead zirconate titanate or a part thereof is substituted with another element. 3 is zirconia, 3a is included in the PZT phase 2 and 3b is in the grain boundary of the PZT phase 2.

  The piezoelectric ceramic 1 of the present invention includes a PZT phase 2 as a main crystal phase, and it is important that the zirconia 3a is included in the PZT phase 2. Since the zirconia 3a is encapsulated in the main crystal, the volume of the zirconia 3a can be changed by changing the phase even when pressure is applied from the outside. Therefore, the stress of the PZT phase 2 is relieved, and the ferroelectric domain wall is formed. It becomes difficult to move (domain switching). Therefore, even if the application of stress is repeated very frequently, the deterioration of the displacement characteristics of the piezoelectric ceramic 1 can be reduced. When the zirconia 3a is contained in an amount of 0.01% by volume or more, the ratio of the zirconia 3a that relieves stress increases, so that the stress can be further relaxed.

  The zirconia 3 may be precipitated at the grain boundary of the PZT phase 2, but the zirconia 3b precipitated at the grain boundary can directly absorb the volume variation of the crystal grains by the zirconia 3a included in the PZT phase 2. Compared with, the effect of stress relaxation is low.

  The content of zirconia 3a is measured by observing the piezoelectric ceramics 1 processed to have a thickness of 0.1 μm or less, identifying the zirconia 3a included in the PZT phase 2, and zirconia included in the PZT phase 2 by image processing software. The area% of 3a was determined. And since it is the sample which processed the thin layer, the value was made into the volume% of the zirconia 3a in the piezoelectric ceramics 1. FIG.

  Further, when the ratio D1 / D2 between the average particle diameter D1 of zirconia 3a and the average particle diameter D2 of PZT phase 2 is 0.016 or more, the amount of zirconia 3a that can alleviate the volume change of PZT phase 2 is large. The effect of stress relaxation can be further increased.

  Further, the precipitation of the zirconia 3a may inhibit the sintering of the PZT phase 2, but by comparing the degree of grain growth between the zirconia 3a and the PZT phase 2, that is, by examining D1 / D2, the zirconia It can be confirmed that 3a does not inhibit the PZT phase 2 grain growth. When D1 / D2 is 0.07 or less, the zirconia 3a does not inhibit the grain growth of the PZT phase 2, and the PZT phase 2 is sintered at a high density, so that drive deterioration hardly occurs. On the other hand, when D1 / D2 exceeds 0.07, there is a possibility that the sintering of the PZT phase 2 may be inhibited by the zirconia 3a. In this case, the drive deterioration is slightly caused by the insufficient sintering of the PZT phase 2. It is thought to happen.

  Zirconia 3a is preferably monoclinic. The structural phase change of zirconia 3a tends to occur from monoclinic to tetragonal and from tetragonal to cubic, and the reverse change is difficult to place. Therefore, the zirconia 3a is preferably a monoclinic crystal or a tetragonal crystal that easily undergoes stress relaxation due to a structural change, and is a monoclinic crystal that easily undergoes a large volume change from monoclinic to tetragonal to cubic. Is particularly preferred.

Next, the piezoelectric ceramic 1 on which zirconia 3a is deposited will be described. Conventionally, ZrO ₂ has been used as the main raw material of PZT. When the B site element of the perovskite structure occupied by Zr is in excess of the A site element, the B site element, that is, a substance containing Zr may be precipitated at the grain boundary. This is presumably because the B-site element is excessive and the excess element is pushed out of the lattice and deposited. Further, since a highly volatile element such as Pb exists at the A site, Pb is scattered during firing at a high temperature, the A site is likely to be insufficient, and the B site element is likely to precipitate. It is.

  However, in these cases, Zr is precipitated mostly at the grain boundary, and there is no precipitation inside the crystal grains. In this state, the piezoelectric ceramic has little effect of relaxing the stress on the piezoelectric particles with respect to the external stress, and it has hardly been able to suppress the decrease in displacement due to driving. In order to precipitate zirconia 3a inside the PZT phase 2 that generates the stress relaxation effect on the crystal grains, for example, it is obtained by baking in an oxygen atmosphere after forming an excessive B-site element composition.

  Specifically, the A site / B site element ratio of the perovskite composition is set in the range of 0.985 to 0.998, the oxygen concentration during firing is kept at 50% or more, and Pb volatilization at the A site is suppressed. Therefore, it is fired in a sealed state in a firing jig. By setting the A-site / B-site element ratio to 0.985 to 0.998, there is an effect of facilitating precipitation of zirconia 3 at the B site, and at the same time, there is an effect of not deteriorating the displacement characteristics when a piezoelectric actuator is obtained. Further, the pores can be reduced by firing in an atmosphere of 50% oxygen or more, cation vacancies can be formed at the A site, and zirconia 3a can be precipitated inside the PZT phase 2.

The composition of the piezoelectric ceramic 1 of the present invention preferably includes at least one of Sr, Ba, Ni, Sb, Nb, Yb and Te. Thereby, a more stable piezoelectric ceramic can be obtained. Examples of such piezoelectric ceramics include those formed by dissolving Pb (Zn _1/3 Sb _2/3 ) O ₃ and Pb (Ni _1/2 Te _1/2 ) O ₃ as subcomponents.

  Furthermore, it is desirable that the composition of the piezoelectric ceramic 1 further contains an alkaline earth element as the A site constituent element. As the alkaline earth element, Ba and Sr are preferable in that high displacement can be obtained, and 0.02 to 0.07 mol of Ba and 0.02 to 0.12 mol of Sr are included, and the PZT phase 2 is square. In the case of a composition which is a crystal, it is advantageous in obtaining a large displacement.

Such piezoelectric ceramics 1, for _{example, Pb 1-x-y Sr} x Ba y (Zn 1/3 Sb 2/3) a (Ni 1/2 Te 1/2) b Zr 1-a-b- _c Ti _c O ₃ + α mass% Pb _1/2 NbO ₃ , where 0 ≦ x ≦ 0.14, 0 ≦ y ≦ 0.14, 0.05 ≦ a ≦ 0.1, 0.002 ≦ b ≦ 0 .01, 0.44 ≦ c ≦ 0.50, α = 0.1 to 1.0.

  Next, a method for manufacturing the piezoelectric ceramic 1 will be described.

First, a piezoelectric ceramic powder having a purity of 99% and an average particle diameter of 1 μm or less is prepared as a raw material (synthetic raw material). This piezoelectric ceramic powder is produced as follows. PbO, ZrO ₂ , TiO ₃ and, if necessary, other additives (oxides of necessary elements, carbonates, etc.) are mixed and pulverized to an average particle size of 0.5 to 0.8 μm with a ball mill. The obtained powder is calcined at 900 to 1000 ° C., and the calcined powder is pulverized with a ball mill to an average particle size of 0.5 to 0.8 μm.

  An appropriate organic binder is added to this piezoelectric ceramic powder, and it is formed into a tape shape and cut into a desired shape. This is debindered at about 400 ° C. and then fired.

  Since the A site / B site element ratio fluctuates when the amount of Pb volatilized during firing is large, firing is preferably carried out in a closed firing jig, and further in the sealed firing jig. In addition to the ceramic to be fired, it is desirable to place a Pb generation source to reduce the volatilization of Pb from the fired ceramic.

Furthermore, the oxygen concentration during firing is 50% or more. When firing at a concentration lower than 50%, the oxygen concentration during firing is related to the formation of cation vacancies at the A site of the perovskite. Therefore, at an oxygen concentration of 50% or less during firing, monoclinic ZrO ₂ piezoelectrics are produced. There is a possibility that the precipitation at the body grain boundary increases and the drive reliability of the piezoelectric actuator decreases. In addition, the porosity in the fired porcelain increases. In a thin-layer ceramic having a thickness of 100 μm or less as used in a liquid discharge head, the probability that the pores in the porcelain become a source of destruction and breakage during driving increases, and reliability for long-term driving may not be ensured. In order to further suppress drive deterioration, the oxygen concentration during firing is preferably 75% or more, particularly 85% or more.

  In addition, in order to form a piezoelectric actuator using the piezoelectric ceramic 1 of the present invention, a desired surface electrode is formed on the surface after firing and polarized to obtain a piezoelectric actuator. When forming an electrode inside, a part of the green sheet may be coated with an Ag—Pd paste as an internal electrode, another green sheet may be laminated, and pressed at a pressure of 10 to 50 MPa to be integrated. The pair of electrodes provided in the piezoelectric actuator may be any of surface electrodes (that is, front surface and back surface), internal electrodes, or a combination of the surface electrode and the internal electrode.

  The piezoelectric actuator of this embodiment is preferably driven under the condition that the ratio E / Ec between the electric field strength E during driving and the electric field strength Ec of the piezoelectric ceramic layer is smaller than 1. Thereby, the piezoelectric actuator can be stably driven for a long period of time. On the other hand, when it is larger than 1, the contribution of the domain rotation is increased, and the displacement is easily deteriorated.

  Next, the liquid discharge head of the present invention will be described in detail with reference to the drawings.

  FIG. 2A is a schematic cross-sectional view showing a liquid discharge head including the piezoelectric actuator of the present invention, and FIG. 2B is a plan view thereof.

  As shown in FIGS. 2 (a) and 2 (b), the liquid ejection head includes a plurality of liquid pressurizing chambers 53a arranged in parallel, and a flow path member in which a partition wall 53b is formed as a wall partitioning each liquid pressurizing chamber 53a. The piezoelectric actuator 51 described above is joined on 53. The bonding is performed using an adhesive or the like so that the vibration plate 52 contacts the space of the liquid pressurizing chamber 53a. More specifically, the individual electrodes 56 of the displacement element 57, the liquid pressurizing chambers 53a, Are joined to correspond.

  That is, the liquid discharge head includes a piezoelectric actuator 51 in which a common electrode 54, a piezoelectric ceramic layer 55, and individual electrodes 56 are stacked in this order on the diaphragm 52, and a plurality of individual electrodes 56 are arranged on the surface of the piezoelectric ceramic layer 55. Is bonded to the flow path member 53 so that the individual electrode 56 is disposed immediately above the liquid pressurizing chamber 53a. The piezoelectric ceramic layer 55 is made of the piezoelectric ceramic of the present invention.

  A voltage is applied from the drive circuit between the individual electrode 56 and the common electrode 54, the ink in the liquid pressurizing chamber 53 a corresponding to the displacement element 57 to which the voltage is applied and displaced is pressurized, and the piezoelectric actuator 51 is vibrated. By doing so, ink droplets are ejected from the ink ejection holes 58 in which the ink in the liquid pressurizing chamber 53 a is opened on the bottom surface of the flow path member 53.

  By using the piezoelectric ceramic of the present invention as the piezoelectric ceramic of the piezoelectric actuator of such a liquid discharge head, a liquid discharge head can be realized using an inexpensive IC. Since the liquid discharge head is prevented from being deteriorated in displacement characteristics, even if the drive is repeated very frequently, the displacement characteristics of the plurality of displacement elements 57 are unlikely to vary, and stable and highly accurate discharge can be performed.

  The diaphragm 52 is preferably made of a piezoelectric ceramic having the same composition as that of the piezoelectric ceramic layer 55. However, the composition of the diaphragm 52 does not need to completely match the composition of the piezoelectric ceramic layer 55. As long as the effect can be obtained, the composition thereof may be different.

  Further, in the above-described embodiment, the case where the diaphragm 52 and the piezoelectric ceramic layer 55 are each constituted by one layer has been described, but the present invention is not limited to this, and the diaphragm 52 and the piezoelectric ceramic layer 55 are not limited thereto. The ceramic layer 55 may be composed of a plurality of layers. In this case, the thickness of the piezoelectric actuator 51 can be easily adjusted.

  As another embodiment of the piezoelectric actuator of the present invention, an ultrasonic motor using a bending motion of the piezoelectric actuator as a power source can be mentioned. In the ultrasonic motor using the piezoelectric ceramic of the present invention, the bending portion and the piezoelectric ceramic around the bending portion are suppressed from being polarized by the reverse piezoelectric effect, so even if the number of driving cycles increases, It is possible to perform a stable operation with little fluctuation in the operation.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

  The piezoelectric ceramic of the present invention was produced, and a liquid discharge head was produced therefrom, and a drive deterioration test was evaluated. First, PZT piezoelectric ceramic powder having a purity of 99% or more was prepared as a raw material.

The composition of the piezoelectric ceramic _{powder, Pb 1-x-y Sr} x Ba y (Zn 1/3 Sb 2/3) a (Ni 1/2 Te 1/2) b Zr 1-a-b-c Ti c O ₃ + α mass% Pb _1/2 NbO ₃ or the like, provided that 0 ≦ x ≦ 0.14, 0 ≦ y ≦ 0.14, 0.05 ≦ a ≦ 0.1, 0.002 ≦ b Among those satisfying ≦ 0.01, 0.44 ≦ c ≦ 0.50, and α = 0.1 to 1.0, those having the ratio of the A site element to the B site element shown in Table 1 were prepared.

  To this piezoelectric ceramic powder composed mainly of lead zirconate titanate, add butyl methacrylate as an aqueous binder, polycarboxylic acid ammonium salt as a dispersant, isopropyl alcohol as a solvent, and pure water. And this slurry was apply | coated to the 30-micrometer-thick sheet | seat shape on a carrier film by the doctor blade method, and the green sheet was produced. This green sheet was used for both the piezoelectric ceramic layer and the diaphragm.

  Moreover, the common electrode paste containing Ag—Pd alloy powder was printed on the surface of the green sheet for the diaphragm with a thickness of 4 μm to form a common electrode. Furthermore, the green sheet for piezoelectric ceramic layers was laminated | stacked on the diaphragm green sheet with the surface in which the common electrode was printed facing up, and it pressed and obtained the laminated body.

  After degreasing the laminate, the laminate was sintered by holding at the firing temperature and oxygen concentration shown in Table 1 for 4 hours to produce a laminate comprising the piezoelectric ceramic layer 55, the diaphragm 52, and the common electrode 54. Firing was performed by sealing the sample in a firing jig so as to minimize composition fluctuations due to volatilization of Pb.

  Next, individual electrodes 56 and individual electrode connection portions 56 a were formed on the surface of the piezoelectric ceramic layer 55. The individual electrode 56 and the individual electrode connection portion 56a were coated with Au paste by screen printing. This was formed by baking at 600 to 800 ° C. in the atmosphere. Finally, a lead wire was connected to the individual electrode connecting portion 56a with solder, and a piezoelectric actuator 51 having a shape as shown in FIGS. 2A and 2B was obtained.

  Furthermore, the flow path member 53 shown in FIG. 2A was joined to the piezoelectric actuator obtained as described above with an adhesive to produce a liquid discharge head.

  Table 1 shows details of the obtained piezoelectric ceramics and the liquid discharge head. In Table 1, each evaluation value was determined as follows.

  The evaluation of the crystal was performed by processing a sample with a thin layer of 0.1 μm with FIB (focused ion beam) and observing it at 10,000 times using a TEM (transmission electron microscope). About PZT phase 2 and zirconia 3, the crystal was identified and confirmed by the diffraction image of TEM, respectively. In all samples, zirconia 3 was monoclinic. The average crystal particle diameter D2 of the PZT phase 2 was determined by the intercept method. The average crystal particle diameter D1 of zirconia 3a was calculated by measuring the area of each crystal particle, obtaining the diameter of a circle having the same area, and averaging it. Since it is a thin layer processed sample, the area% value of zirconia 3a on the surface observed by TEM was defined as the volume% of zirconia 3a of piezoelectric ceramic 1. In addition, the zirconia 3a included in the PZT phase 2 is an observed cross section in which the entire zirconia 3 is contained in one crystal grain of the PZT phase 2, and the zirconia 3b at the grain boundary of the PZT phase 2 Is zirconia 3 other than the above, and is in contact with the grain boundary of the PZT phase.

An ink using water as a solvent is supplied to the flow path member 53, and a driving voltage waveform having a peak voltage of 25 V, a frequency of 2 kHz, and a duty ratio of 80% is applied to the piezoelectric actuator 51, and continuously for 1 × 10 ¹⁰ cycles. A drive test was conducted by driving.

From Table 1, Sample No. which is within the scope of the present invention. In 2, 3 and 5-20, since the zirconia 3a was included in the PZT phase 2, the drive deterioration was suppressed, and the displacement reduction rate was 3% or less even after driving 10 ¹⁰ times. In contrast, sample no. In No. 1, since the B site element was not excessive, precipitation of zirconia 3 was not observed, and driving deterioration of 10% or more occurred. Sample No. 4 is in a state as shown in FIG. 1B, zirconia 13b precipitates at the grain boundaries of the PZT phase 12, and zirconia included in the PZT phase 12 is not observed (less than 1%), 10% The above drive deterioration occurred.

Sample Nos. In which the average particle diameter D1 of zirconia 3a and the average particle diameter D2 of PZT phase 2 are in the range of D1 / D2 from 0.016 to 0.07 are used. In 2, 3, 7-15, and 18-20, the displacement reduction rate was 1% or less even after driving 10 ¹⁰ times.

(A) is a schematic diagram which shows the state of the crystal | crystallization of the piezoelectric ceramic of this invention, (b) is a schematic diagram which shows the state of the crystal | crystallization of the conventional piezoelectric ceramic. (A) is a schematic partial longitudinal cross-sectional view which shows the liquid discharge head using the piezoelectric actuator of this invention, (b) is the partial top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric ceramics 2 ... PZT phase 3 ... Zirconia 3a ... Zirconia included in PZT phase 3b ... Zirconia in the grain boundary of PZT phase 51 ... Piezoelectric actuator 52 ... Diaphragm 53 ... Channel member 53a ... Liquid pressurization chamber 53b ... Partition 54 ... Common electrode 54a ... Common electrode connection part 55 ... Piezoelectric ceramic layer 55a ... Drive part ( Piezoelectric ceramic layer)
55b ... Non-driving part (piezoelectric ceramic layer)
55c ... Restraint part (piezoelectric ceramic layer)
56 ... Individual electrode 56a ... Individual electrode connection part 57 ... Displacement element 58 ... Liquid discharge port

Claims (6)

Piezoelectric ceramic main crystal grains Ri Do of PZT phase containing therein zirconia, the zirconia is included in the PZT phase is characterized der Rukoto more than 1% of the zirconia component.   2. The piezoelectric ceramic according to claim 1, comprising 0.01% by volume or more of the zirconia.   The piezoelectric ceramic according to claim 1 or 2, wherein a ratio D1 / D2 between the average particle diameter D1 of the zirconia and the average particle diameter D2 of the main crystal particles is 0.016 to 0.07. The piezoelectric ceramic according to any one of claims 1 to 3, which is a sintered body. The piezoelectric actuator, characterized in that arranged one another so opposed to the pair of electrodes to one of the piezoelectric ceramic surface and inside of any one of claims 1 to 4. A vibration plate is laminated on a flow path member having a plurality of liquid pressurizing chambers and a plurality of liquid discharge holes communicating with the plurality of liquid pressurizing chambers so as to cover the plurality of liquid pressurizing chambers. common electrode on a plate, a liquid discharge head, wherein the layer of the piezoelectric ceramic according to any one of claims 1 to 4, and a plurality of individual electrodes are laminated in this order.

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