JPH0710638A - Oxide piezoelectric material - Google Patents

Abstract

PURPOSE: To improve the piezoelectric characteristics of oxide piezoelectric materials.

CONSTITUTION: Oxide piezoelectric materials making a basic compsn. of an xPb(Y_2/3W_1/3)O₃-yPbZrO₃-zPbTiO₃ system having the compsn. range of 0.01≤x≤0.20, 0.215≤y and z≤0.764 (provided that x+y+z=1) are prepared. The piezoelectric materials having high electromechanical coupling factors, high piezoelectric constants and low mechanical quality factors are obtained thereby. Furthermore, 0.1-1.0 wt.% of at least either one among La₂O₃, MnO₂, Nb₂O₅, Cr₂O₃ and Ta₂O₅ is made to be contained as an additive to further heighten the piezoelectric characteristics.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to Pb (Y _2/3 W _1/3 )
O ₃ -PbZrO ₃ -PbTiO ₃ system as a basic composition,
The present invention relates to an oxide piezoelectric material having a high electromechanical coupling coefficient and a large piezoelectric constant, and a low mechanical quality coefficient.

[0002]

2. Description of the Related Art Generally, an oxide piezoelectric material has a phase boundary (MPB: Morphotropic Phase) between a tetragonal system and a rhombohedral system.
Boundary) has the most excellent piezoelectric properties.
Since the report of e was published, various attempts were made to improve the piezoelectric and dielectric properties including sinterability by changing the ABO _{3 type} perovskite structure, which is the third component, by adding impurities. Research is ongoing.

For example, a PbZrO ₃ -PbTiO ₃ type oxide piezoelectric material has been conventionally used as a vibrating element such as an ultrasonic vibrator and an acoustic filter, and its application is currently medical equipment, robots, factory automation, It has come to be used as an actuator for nondestructive inspection and precise position determination.

[0004]

By the way, conventionally, as a material used for such various devices, PbZrO ₃
PbTiO ₃ with various impurities such as Nb ₂ O ₅ and WO ₃ added (F. Kulcsar: J. Am. Ceram. Soc, 42 (1959) 343,
H.Banno: Jan.J.Appl.Phy.6 (1976) 954) and Pb (Mg
Various ternary compositions such as _1/3 Nb _2/3 ) O ₃ -PbZrO ₃ -PbTiO ₃ have been developed (Tanaka Tanaka et al .:
Piezoelectric ceramic materials, Gakudonsha ((1943) 110-130), these materials not only have low electromechanical coupling coefficient (Kp), mechanical quality coefficient (Qm), or dielectric constant, but also piezoelectric constant. Due to the low (d ₃₃ ) value, the hydrophone
e), phonopickup, sound detector, sound detector, accelerometer, delay line, etc., of course, ultrasonic motor, deformable mirror
This is not the case even if it is applied as an actuator such as ror).

In particular, when it is applied as an actuator, the electromechanical coupling coefficient and the piezoelectric constant must be large. If the electromechanical coupling coefficient is low, internal heat is generated when the element changes the electrical input into mechanical vibration, resulting in energy loss and deterioration of the characteristics of the piezoelectric oxide material. In addition, the piezoelectric constant must be large in order to generate a large mechanical displacement with respect to the applied electric input.

Therefore, according to the present invention, an oxide piezoelectric having a high electromechanical coupling coefficient and a large piezoelectric constant, which can be sufficiently adapted not only as a signal receiving element having a high electromechanical coupling coefficient and a low mechanical quality coefficient but also as an actuator, is provided. Providing the material has its purpose.

[0007]

Therefore, the oxide piezoelectric material of the present invention has a structure of xPb (Y _2/3 W _1/3 ) O ₃ −.
The yPbZrO ₃ -zPbTiO ₃ system is used as a basic composition, and the composition range is 0.01≤x≤0.20 0.215≤y, z≤0.764 (where x + y + z = 1).

Further, as additives, La ₂ O ₃ , MnO
_2, Nb ₂ O _5, any one of Cr ₂ O ₃ and Ta ₂ O ₃ may be contained 0.1-1.0 wt%. Such an oxide piezoelectric material of the present invention can be easily manufactured by the following generally widely used oxide mixing method.
That is, first, PbO, TiO ₂ , ZrO ₂ , Y ₂ O ₃ , W
Oxides such as O ₃ are accurately weighed at an appropriate ratio, mixed _and pulverized using a zirconia ball mill. On the other hand, as a raw material used at this time, a compound which is easily converted into an oxide when heated, that is, a raw material compound including a hydroxide, a carbonate and the like can be used. 800 for mixed samples
After calcination at -900 ° C, it is further pulverized by a ball mill to make a synthetic powder. Thereafter, this powder is mixed with water or PV.
A small amount of a binder such as an aqueous solution A is added, pressure is applied at a pressure of 1 ton / cm ² , molding is performed, and then sintering is performed at a temperature of 1150 to 1225 ° C. During such sintering, a low volatilization temperature (approximately 880
Sintering is performed in a closed container in order to prevent deterioration of piezoelectric characteristics due to volatilization of PbO having a temperature of (° C.).

Electrodes are formed on both sides of the sintered body thus manufactured by a general method. A direct current electric field of 35 KV / cm is applied to the electrodes for 30 minutes in silicon oil at about 90-110 ° C. Polarization is performed at. Such a through conventional manufacturing process PbZrO ₃ -PbTiO ₃ 2-component or _{Pb (Mg 1/3 Nb 2/3) O} 3 -PbZrO 3 -Pb
An oxide piezoelectric material having a composition different from that of the TiO ₃ ternary piezoelectric material and having excellent piezoelectric characteristics can be easily obtained.

Further, as an additive, Cr₂O₃, La₂O
₃, Ta₂O_Five, MnO₂And Nb ₂O_FiveOne of
When one is added, the oxide to be added is
O, TiO₂, ZrO₂, Y₂O₃, WO₃Oxides of
Zirconia ball mill
Mixed with_,Just crush it and make it as described above.
Yes. And by adding such additives,
The piezoelectric characteristics can be improved.

Here, if the above-mentioned x, y and z are more or less than the above range (0.01≤x≤0.20, 0.215≤y, z≤0.764), good piezoelectric characteristics and dielectric characteristics are obtained. Can't get In addition, Cr ₂ O ₃ , La ₂ O ₃ ,
The same applies to the addition range of each additive of Ta ₂ O ₅ , MnO ₂ and Nb ₂ O ₅ , and if the content is more or less than 0.1 to 1.0% by weight, good piezoelectric properties and dielectric properties can be obtained. Can't get

[0012]

EXAMPLES Examples of the present invention will be described below. First, examples with no additives will be described. _{xPb (Y 2/3 W 1/3) O} 3 -yPbZrO 3 -zPb
In the ternary system of TiO ₃ , PbO, TiO ₂ , ZrO ₂ and Y are adjusted so that the composition range is 0.01 ≦ x ≦ 0.20 0.215 ≦ y, z ≦ 0.764 (where x + y + z = 1).
10 ^-4 g of oxides such as ₂ O ₃ and WO ₃ according to their respective molar ratios
Accurately weighed, mixed _and ground in a zirconia ball mill. Next, the mixed sample is 800-900 ° C.
After calcination in, pulverize again with a ball mill, add a trace amount of binder such as water or PVA aqueous solution to the pulverized product, and
After pressurizing at a pressure of ton / cm ² and molding, 1150-12
Sintered at a temperature of 25 ° C. Since the volatilization temperature (about 880 ° C.) of PbO, which is one of the composition components, is low during sintering, there is a possibility that accurate chemical equivalence may not be achieved and the piezoelectric characteristics may be deteriorated. Powder of the same composition as PbO
Sintering was carried out in a closed container with the powder for atmosphere for volatilization suppression of, and the maintaining time at the maximum temperature was 1 hour.

The formed sintered body which has been sintered has a diameter of 15 m.
After processing into a disk with a thickness of 1 mm and a thickness of 1 mm, electrodes are formed on both sides, and a DC electric field of 35 KV / cm is applied to this electrode for about 90-11.
Polarization was carried out by applying in silicon oil at 0 ° C. for 30 minutes. IRE, STD (Proc.IRE, 137
(1949) 1378), electromechanical coupling coefficient (Kp), mechanical quality factor (Qm) and frequency constant (Frequency Consta)
nt) etc., the measurement results of the respective sintered bodies having different composition ratios are as shown in Table 1 below.

[0014]

[Table 1]

In Table 1 above, F. T is the sintering temperature (° C),
Kp is the electromechanical coupling coefficient (%), K ₃₃ ^TIs around 1 KHz
Permittivity of sample measured at 25 ° C in wavenumber, d₃₃Is the piezoelectric constant
 (× 10^-2C / N) and Qm represent mechanical quality factors, respectively.
As is clear from Table 1, Pb (Y_2/3W_1/3) O₃But
High electromechanical coupling coefficient when solid-soluted at 1-3 mol%
The piezoelectric constant was very large and it showed excellent piezoelectric characteristics.

Pb (Y _2/3 W _1/3 ) O ₃ -Pb of the present invention
ZrO ₃ -PbTiO ₃ 3-element piezoelectric material, conventional Pb
ZrO ₃ -PbTiO ₃ has excellent piezoelectric characteristics over a wide range compared to the binary system and is a binary system P
bZrO ₃ —PbTiO ₃ system and the ternary system Pb (Y of the present invention
_2/3 W _1/3 ) O ₃ -PbZrO ₃ -PbTiO _{3 The} following Table 2 shows a comparison of piezoelectric characteristics with the ternary system.

[0017]

[Table 2]

In Table 2 above, the binary system PbZ
In the case of the rO ₃ —PbTiO ₃ system, the range showing excellent piezoelectric properties is limited to the MPB region, whereas in the case of the composition of the present invention, a material having excellent properties can be easily obtained in a considerably wide composition range. It represents. More specifically, Reference Example 1
In addition, as shown in Reference Example 2, the binary composition has relatively excellent characteristics by confining it to one point. However, according to Examples of the present invention, Example 5 to Example 7 and Example 13- Example 1
It can be observed that the piezoelectric constant (d ₃₃ ) characteristics are improved over a wide range, such as up to 5.

Next, the above Pb (Y _2/3 W _1/3 ) O ₃ −
For the purpose of causing PbZrO ₃ -PbTiO ₃ 3 ternary further piezoelectric properties of the piezoelectric material to improve the, Pb (Y _2/3 W
_{1/3) O 3 -PbZrO 3 -PbTiO 3} 3 ternary embodiment with the addition of additives to will be described. Pb of the present invention
(Y _2/3 W _1/3 ) O ₃ -PbZrO ₃ -PbTiO ₃ 3
In the original system, La ₂ O ₃ , MnO ₂ and Ta ₂ were added as additives.
Any one of O ₅ , Nb ₂ O ₅ and Cr ₂ O ₃ oxide
The piezoelectric characteristics can be improved by adding one.

The manufacturing method in this case is PbO, Ti
In addition to oxides such as O ₂ , ZrO ₂ , Y ₂ O ₃ and WO ₃ , any one of La ₂ O ₃ , MnO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ and Cr ₂ O ₃ is respectively added. It may be added as an additive and accurately weighed to 10 ⁻⁴ g according to each molar ratio, and then manufactured in the same manner as in the case without the additive described above.

In this example, when each additive was added to the composition of Example 14 shown in Table 1 (x = 0.02, y = 0.51, z = 0.47), the piezoelectric characteristics accompanying the addition of the additive were obtained. Table 3 shows the changes in the above.

[0022]

[Table 3]

As is clear from Table 3 above, La
₂O₃, MnO₂, Ta₂O_Five, Nb₂O _FiveAnd Cr₂
O₃By adding a small amount of one of the
In addition to improving the piezoelectric characteristics such as the sum coefficient and the piezoelectric constant, M
nO₂When added, the mechanical properties are not significantly reduced.
Of which mechanical quality factor is required due to increased mechanical quality factor
Can be obtained.

FIG. 1 shows Pb (Y _2/3 W _1/3 ) O ₃ -PbZrO showing the composition ratio range of the oxide piezoelectric material of the present invention.
In ternary genealogical _{3 -PbTiO 3, A, B,} C, the hatched portion enclosed within a polygon in D, shows the composition range of the oxide components of the present invention. Here, the point A of the polygon showing the composition range of the present invention displayed in the ternary diagram of FIG. 1 is Example 47, the point B is Example 38, the point C is Example 1, and the point D is Example 4. Are respectively shown.

FIG. 2 shows Examples 13 to 18 shown in Table 1.
About Pb (Y_2/3W_1/3) O ₃Of the amount of solid solution
Aeromechanical coupling coefficient, mechanical quality coefficient, dielectric constant and piezoelectric constant
It shows each change of. Also, from Example 5
The same inclination is applied to Example 11 and Example 20 to Example 26.
Showed the direction. This is Pb (Y_2/3W_1/3) O₃Solid solution of
Improving various piezoelectric characteristics by selecting appropriate amount
Of course, as shown in Table 3, the amount of additives
To obtain a device with characteristics suitable for the application
It is possible to do.

[0026]

As described above, according to the present invention, it is possible to obtain a novel oxide piezoelectric material having a high electromechanical coupling coefficient and a large piezoelectric constant and excellent in piezoelectric characteristics as compared with conventional ones. Therefore, the application range of the oxide piezoelectric material can be expanded. In addition, La ₂ O ₃ , MnO ₂ , N
The piezoelectric characteristics of the piezoelectric material can be further improved by adding any one of the additives b ₂ O ₅ , Cr ₂ O ₃ and Ta ₂ O ₅ . In particular, when MnO ₂ is added, the mechanical quality factor can be increased without deteriorating the piezoelectric characteristics, and it is possible to obtain an element suitable for a signal power receiving element having a wide signal band width. .

[Brief description of drawings]

FIG. 1 shows xPb (Y _2/3 W showing the composition range of the present invention.
_{1/3) O 3 -yPbZrO 3 -zPbTiO 3} 3 yuan genealogy

FIG. 2 Pb (Y _2/3 W _1/3 ) O of a sample of the present invention
_{3 A} graph showing changes in various piezoelectric characteristics with the amount of solid solution

Claims (2)

[Claims] 1. xPb (Y_2/3W_1/3) O₃-YPbZr
O₃-ZPbTiO ₃An oxide piezoelectric material having a system as a basic composition and a composition range of 0.01 ≦ x ≦ 0.20 0.215 ≦ y, z ≦ 0.764 (where x + y + z = 1). 2. La as an additive₂O₃, MnO₂, N
b₂O_Five, Cr₂O ₃And Ta₂O_FiveOne of
The oxide according to claim 1, which contains 0.1 to 1.0% by weight.
Piezoelectric material.