JP2003335579A - Piezoelectric ceramic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric ceramic material having a high piezoelectric constant at a high electric field, and low in the deterioration of the piezoelectricity by continuous operation, and suitable for an actuator and an ink-jet element. <P>SOLUTION: This piezoelectric ceramic material is represented by aPbTiO<SB>3</SB>- bPbZrO<SB>3</SB>-cPb((Zn<SB>1-x</SB>Ni<SB>x</SB>)<SB>1/3</SB>Nb<SB>2/3</SB>)O<SB>3</SB>(wherein a+b+c=100) and its composition is 0.15≤x≤0.35 and within the range surrounded by the lines connecting point A, a=40.0, b=25.0, c=35.0; point B, a=27.5, b=37.5, c=35.0;, point C, a=35.0, b=55.0, c=10.0, and point D, a=50.0, b=40.0, c=10.0, in the triangle (figure 1) with the apexes of PbTiO<SB>3</SB>, PbZrO<SB>3</SB>, and Pb(Ni<SB>1-x</SB>Nb<SB>x</SB>)O<SB>3</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic material, and in particular, it is used as a piezoelectric actuator and a piezoelectric inkjet element because it has a large strain in a high electric field and has little characteristic deterioration even when continuously driven in a high electric field. A piezoelectric ceramic material suitable for

Piezoelectric actuators are precision control elements for steppers of semiconductor manufacturing equipment or high-density HD devices.
It is used as a D precision control element, and the piezoelectric inkjet element is used as a piezoelectric element for inkjet printers.

[0003]

2. Description of the Related Art When a piezoelectric ceramic material is used as an actuator, the piezoelectric constant d is important and the strain is expressed by d × E (electric field).

As a piezoelectric material used for a piezoelectric actuator or an ink jet printer element, a piezoelectric material having a large piezoelectric constant d capable of being driven by a small voltage is desired, and a PZT type material having a high piezoelectric constant has been conventionally used.

[0005] Further, as a technique for improving the piezoelectric properties, JP _{2001-302348, PbTiO 3 -PbZrO 3 -Pb (} Ni 1/3
There is a disclosure that in a Nb _2/3 ) O ₃ ternary piezoelectric material, a large piezoelectric strain can be obtained in a high electric field by adjusting the Pb amount and the rare earth element.

Further, as a material having a better piezoelectric constant, in JP-A-60-103079, PbTiO ₃ -PbZrO ₃ -
Pb (Zn _1/3・ Nb _2/3 ) O ₃ -Pb (Ni _1/3・ Nb _2/3 ) O ₃ quaternary piezoelectric material (hereinafter PT-PZ-PZN-PNN) Is disclosed.

When a piezoelectric material is used as an actuator or an ink jet element, there is a problem of characteristic deterioration due to heat generation during continuous driving. The piezoelectric material expands and contracts by applying a voltage and sending in an electric charge. At that time, a part of the fed energy is consumed as internal loss and heat is generated. The loss is due to the nonlinearity of the piezoelectric material,
It is said that the cause is friction between particles, but the higher the electric field, the larger the internal loss.

As a result, the piezoelectric element may be heated to a temperature near the Curie temperature, which may cause a malfunction and may not operate at all. In particular, when the driving frequency is increased, it is not possible to deal with it even if the heat dissipation structure is devised, and such a malfunction is likely to occur. At a frequency of 10kHz or higher, the element becomes a high heat of 300 ° C or higher and may damage surrounding parts.

As a method of solving the characteristic deterioration of the piezoelectric material due to heat generation, it is one to select a piezoelectric material having a small loss or a piezoelectric material having a high Curie temperature, but generally, a piezoelectric material satisfying these requirements is not available. There is a demand for a material that has low piezoelectricity and is compatible with both piezoelectricity and continuous drive resistance.

However, even with the above-mentioned piezoelectric material, compatibility between piezoelectricity and continuous drive resistance was insufficient.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric ceramic material which solves the problems of the prior art and has both piezoelectricity and continuous drive resistance. .

[0012] None of the above-mentioned prior arts disclose such a problem. For example, in Japanese Patent Laid-Open No. 60-103079, PT-PZ-PZN-PNN four-component piezoelectric material Pb is partly replaced with Ca, Sr, Ba, or Li, Na, Sn,
By adding and containing an oxide such as Cr, the piezoelectric constant, the electromechanical constant, the relative permittivity are all large, and the piezoelectric ceramic composition has a high Curie point to the extent that it does not hinder the use in normal applications. It is disclosed that it can be obtained. However, the piezoelectric constant referred to in this publication is EMAS (Electronic Materials Manufacturers Association).
Is theoretically a value at a zero electric field, and is different from the value at a high electric field required when applied to a piezoelectric actuator or an inkjet element. Therefore, it is unclear whether the piezoelectric material described in this publication can be applied to a piezoelectric actuator or an inkjet element.

On the other hand, in Japanese Patent Laid-Open No. 2001-302348, a large piezoelectric strain constant is obtained in a high electric field (500 kV / m = 500 V / mm), the relative dielectric constant changes little with temperature, and the electric resistance in a high temperature range is small. A piezoelectric ceramic composition having a high rate is disclosed, and it is disclosed that it is extremely useful as a material for an actuator. However, in the case of a piezoelectric actuator or an inkjet element, since a high electric field is repeatedly applied, deterioration of characteristics due to heat generation during continuous driving is an important point. Since this publication does not disclose this point, it cannot be determined how practically it is effective as a material for a piezoelectric actuator or an inkjet element.

[0014]

By the way, in a piezoelectric actuator or a piezoelectric ink jet element, a high electric field of several hundred to several kV / mm is applied to the piezoelectric element to drive it. Therefore,
In order to find piezoelectric materials applicable to these applications, it is essential to measure the piezoelectric constant in a high electric field.

Normally, the values shown in catalogs and the like as the characteristics of piezoelectric materials are differential values defined by the EMAS (Electronic Materials Industries Association) and theoretically at 0 electric field, so that they are suitable for piezoelectric actuators as described above. It is not the value to do. Further, there is no fixed regulation on the characteristic deterioration due to continuous driving, and it is necessary to measure under appropriate conditions.

Therefore, the present inventors conducted various investigations on the high electric field piezoelectric constant near 300 V / mm and the deterioration of the piezoelectricity during continuous driving in various composition systems of the PZT type piezoelectric material, and found good results. The possibility of composition system was investigated.

[0017] As a result, in particular _{PbTiO 3 -PbZrO 3 -Pb ((Zn} -N
i) _1/3 Nb _2/3 ) O ₃ quaternary piezoelectric material (hereinafter PT-PZ-PZN-PNN
It was found that there is a composition region having a large piezoelectric constant in a high electric field and a small heat generation even when driven at a high frequency.

In the present invention, the composition formula: aPbTiO ₃ -bPbZrO ₃ -cPb ((Zn _1-x Ni _x ) _1/3 Nb _2/3 ) O ₃ (however,
a + b + c = 100), and 0.15 ≦ x ≦ 0.35 in a triangular diagram with PbTiO ₃ , PbZrO ₃ , and Pb (Ni _1-x Nb _x ) O ₃ as vertices (see FIG. 1 described later), and a = 40.0 , B = 25.0, c = 35.0 (point A in FIG. 1) a = 27.5, b = 37.5, c = 35.0 (point B in FIG. 1) a = 35.0, b = 55.0, c = 10.0 (point C in FIG. 1) ) A piezoelectric ceramic material having a composition surrounded by regions a = 50.0, b = 40.0, c = 10.0 (point D in FIG. 1).

According to a preferred embodiment of the present invention, in the material of the above composition region, 0.5 to 2.5 atomic% of Pb may be replaced with one or more elements of Ba, Ca and Sr.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the reason for defining the composition of the piezoelectric ceramic material in the present invention as described above will be specifically described.

The PZT-based piezoelectric material according to the present invention was measured for the piezoelectric constant d in a high electric field and was subjected to a continuous drive test under a high electric field alternating current. It has been found to be a piezoelectric material suitable for actuators.

That is, in the PT-PZ-PZN-PNN piezoelectric material, for example, a piezoelectric constant of 150 (pm / V) or more in an electric field of 300 V / mm,
There is a region having a large piezoelectric constant in a high electric field and little deterioration due to heat generation, such as a deterioration rate of -40% or less due to continuous driving.

In yet another embodiment, Pb, which is the A site of this system, is replaced with an appropriate amount of alkaline earth elements such as Ba, Ca, and Sr. According to this, a practical material having a larger piezoelectric constant d is obtained. can get.

[0024] Figure _{1, PbTiO 3 -PbZrO 3 -Pb ((} Zn 1-x Ni x)
FIG. _{3 is} a triangular diagram of _1/3 Nb _2/3 ) O ₃ , showing a region of a composition range of a piezoelectric ceramic material according to the present invention. In the following,
The reason why the composition is limited in the present invention will be described with reference to symbols A, B, C and D in the triangular diagram of FIG.

First, when (PZN + PNN) is larger than AB, the piezoelectricity is remarkably lowered by high electric field driving. On the other hand, if it is less than C-D, the piezoelectric constant is small and it is difficult to apply it to an actuator. Outside of B-C and D-A, that is, when the PT / PZ ratio is out of the range, the piezoelectric constant becomes extremely small, which is not suitable for an actuator.

When X is less than 0.15, the sinterability is deteriorated, and X is
If it exceeds 0.35, the piezoelectric characteristics are likely to deteriorate due to continuous driving. Furthermore, in these materials Pb 0.5-2.
Substituting 5 at% with one or more of Ba, Ca and Sr improves the piezoelectricity. However, the substitution of more than 2.5 atomic% significantly deteriorates the piezoelectric property and also tends to cause deterioration due to continuous driving.

Here, it is more preferable that c is 20 or less (in FIG. 1, 0.1 or more and 0.2 or less) and 0.15 <x <0.30 because the piezoelectric deterioration rate is small. The piezoelectric material of the present invention can be produced by a general piezoelectric ceramic manufacturing method.

That is, powders of oxides and carbonates of the respective constituent elements are weighed and mixed so as to obtain a desired composition, and 60
It can be prepared by calcining at 0 to 1000 ° C., pulverizing and then powdering the obtained powder into a predetermined shape and firing. It is also possible to prepare it by a liquid phase method or the like in which the starting material is supplied in a form other than powder.

The obtained sintered body is processed into a desired shape,
Electrodes are formed and polarized before and after processing. The electrode material and forming method are, for example, Ag paste printing baking method and Cr
There are vapor deposition methods such as -Au and sputtering methods, and there is no particular limitation on the material according to the present invention.

Next, the operation and effect of the present invention will be described with reference to examples.
This will be described more specifically. (Example) PbO, TiO so that the element composition ratio shown in Table 1 may be obtained.₂,
ZrO₂, ZnO, NiO, Nb₂O_Five, BaCO ₃, CaCO₃, SrCO₃of
Weigh each powder, mix in a pot mill and mix with water for 24 hours
After mixing, drying and calcination at 800 ° C. This with a pot mill
It was crushed for 24 hours and dried to obtain a calcined powder.

The resulting calcined powder and PVA (polyvinyl alcohol: binder) aqueous solution were mixed, molded into a block of 15 mm × 6 mm × 2 mm, degreased, and fired at 1150 ° C. Cut the sintered body into 10mm × 3mm × 1mm by lapping machine and processing machine,
Silver paste was applied to both sides of 10 mm × 3 mm, baked at 800 ° C., and polarized in an electric field of 2 to 2.5 kV / mm at 100 ° C.

For the device thus obtained, 30
The piezoelectric constant of 0 V / mm was measured as follows. First, one side of 3 mm x 1 mm of the sample is fixed and supported, and the other side is contacted with a glass rod connected to a differential transformer, and then 10 mm x 3 with electrodes applied.
Lead wires were soldered on the two surfaces of mm, and each was connected to a power supply. Furthermore, a voltage of 0V → 300V → 0V is applied in the same direction as the polarization direction.
A maximum electric field of 300 V / mm was applied at a cycle of 2 seconds, the amount of strain in the longitudinal direction, that is, 10 mm was obtained from the output of the differential transformer, and the piezoelectric constant d _{31 (300 V / mm)} was obtained from the following equation.

ΔL / L = d ₃₁ × E (E = 300 V / mm) The change in piezoelectricity due to heat generation was carried out by measuring and comparing the piezoelectricity before and after the drive test.

First, the piezoelectricity is measured by polarized 10 mm × 3 mm
Connect the electrode surface of × 1mm to the impedance analyzer,
The difference ΔF between the resonance frequency and the anti-resonance frequency of the expansion / contraction mode in the long side direction was obtained.

Next, in the driving test, the electrodes of the sample were connected to a power source, and a sine wave of 150 V / mm (effective value 106 V) on one side and 10 kHz was applied.
It was performed by continuously applying for a minute. The sample was tested while it was left in the air, and spontaneous heat dissipation was performed at room temperature.

After the drive test, ΔF was obtained again by the impedance analyzer, and the deterioration rate (%) = {(ΔF after the drive test / ΔF before the drive test
The deterioration rate of the piezoelectricity was calculated by F) -1} × 100.

Table 1 shows the relationship between the composition of the piezoelectric material, d ₃₁ obtained as described above, and the piezoelectric deterioration rate by the driving test.
Are shown together. The composition examples Nos. 1 to 17 in Table 1 are also shown by numbers in FIG.

Samples Nos. 1 to 17 in Table 1 are those in which the Pb → Ba substitution amount and x are fixed and the ratios of a, b and c are changed.
Sample No. 1 has c> 35 and has a high piezoelectric constant, but a deterioration rate
Over 40%.

Sample No. 17 had c <10 and a piezoelectric constant of 15
It was 0 (pm / V), which was small. On the other hand, sample Nos. 2, 6, 7,
Nos. 11, 12, and 16 were obtained by changing the PT / PZ ratio, but all were outside the scope of the present invention, and the piezoelectric constant was reduced to 150 (pm / V) or less.

Sample Nos. 18 to 21 are a, b, c and Pb →
The amount of Ba substitution is fixed and x is changed. Sample No.18
Was x <0.15 and could not be fired.

Sample No. 21 had x> 0.35 and the deterioration rate was 40.
% Exceeded. Sample No. 22 had no Pb → Ba substitution, but had a piezoelectric constant of 153 pm / V.

Samples Nos. 23 to 28 were prepared by substituting Pb with Ba, Ca, and Sr while changing the amount of substitution. In all cases, when the amount of substitution exceeds 2.5 atom%, the piezoelectric property is significantly deteriorated. .
On the other hand, when Ba, Ca, and Sr were all replaced as in Sample No. 29, the piezoelectric constant was improved and the deterioration rate was not so large.

As described above, the piezoelectric material of the present invention has a high piezoelectric constant in a high electric field and a small deterioration in piezoelectricity due to continuous driving, and thus is a material suitable for an actuator or an inkjet element.

[0044]

[Table 1]

[0045]

As described above, according to the present invention,
Since the piezoelectric constant in a high electric field is high and the deterioration of the piezoelectric property due to continuous driving is small, a material suitable for an actuator or an inkjet element can be obtained, and the present invention is significant from a practical viewpoint.

[Brief description of drawings]

Fig. 1 PbTiO ₃ -PbZrO ₃ -Pb ((Zn _1-x Ni _x ) _1/3 Nb _2/3 ) O ₃
FIG.

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[Procedure amendment]

[Submission date] August 6, 2002 (2002.8.6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (2)

[Claims] 1. A composition _{formula: aPbTiO 3 -bPbZrO 3 -cPb ((} Zn 1-x Ni x) 1/3 Nb 2/3) O 3 ( where,
a + b + c = 100), and PbTiO ₃ , PbZrO ₃ , and Pb (Ni _1-x Nb _x ) O ₃ are vertices in the triangular diagram (FIG. 1), 0.15 ≦ x ≦ 0.35, and a = 40.0, b = 25.0, c = 35.0 (point A in FIG. 1) a = 27.5, b = 37.5, c = 35.0 (point B in FIG. 1) a = 35.0, b = 55.0, c = 10.0 (point C in FIG. 1) a = A piezoelectric ceramic material having a composition surrounded by regions of 50.0, b = 40.0, c = 10.0 (point D in FIG. 1). 2. The Pb content of the material in the composition region is 0.5.
A piezoelectric ceramic material characterized by substitution of up to 2.5 atomic% with one or more elements of Ba, Ca and Sr.