JPH0551222A - Piezoelectric porcelain material - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric porcelain material having mechanical quality coefft., piezoelectric constant and dielectric loss on certain levels or above and giving large oscillation accompanied by low calorific value as an ultrasonic oscillator by adding MnO2, NiO and Sb2O3 to a specified porcelain compsn. in a prescribed ratio. CONSTITUTION:Starting materials such as PbO, ZrO2, TiO2, SrCO3, CaCO3, BaCO3, MnO2 NiO and Sb2O3 are blended so that 0.1-5mol MnO2, 0.1-5mol NiO and 0.05-2.5mol Sb2O3 are added to 100mol porcelain compsn. obtd. by substituting one or more among Sr, Ca and Ba for <=10 atomic % of Pb in a porcelain compsn. represented by a formula aPbTiO3-bPbZrO3 (where a+b=100 and 43<=a<=53). They are well mixed in a ball mill, calcined at 800-1,100 deg.C and pulverized. The resulting powder is granulated with an org. binder and molded under about 1,000kg/cm<2> pressure. This molded body is calcined at 1,200-1,300 deg.C to obtain a piezoelectric porcelain material having desired piezoelectric characteristics.

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 more particularly to a piezoelectric ceramic material used as a piezoelectric vibrator or a filter, and particularly suitable as a material for ultrasonic vibrators and ultrasonic motors.

[0002]

BACKGROUND OF THE INVENTION Lead zirconate titanate (Pb (Ti, Zr) O ₃ ) is a porcelain composition which has been widely known as a piezoelectric ceramic material. Since this compound contains Pb, there are manufacturing problems such as Pb evaporating during firing, but the piezoelectricity is large, the usable temperature is high, and the third component must be replaced or added. This has the advantage that porcelain with a great variety can be obtained, and for this reason it has been used as a material for piezoelectric buzzers, frequency filters, ignition elements and the like.

Further, with the development of mechatronics, there is an increasing need for a displacement element having good response and capable of precise control, and use of a driving element utilizing piezoelectric strain has been attempted.

In recent years, there has been an increasing demand for reduction of pollution in various fields such as electronics, and the cleaning quality in each manufacturing process has come to influence the productivity and the quality of the product. An ultrasonic cleaning device using an ultrasonic motor, which is an example of the above, plays an important role as one of manufacturing facilities. An ultrasonic vibrator using a piezoelectric ceramic material is usually used in these ultrasonic utilizing devices, but the ultrasonic vibrator is generally required to have a large vibration amplitude and a small heat generation. In order to obtain such characteristics, it is necessary for the piezoelectric ceramic material to have a large piezoelectric constant and mechanical quality factor and a small dielectric loss.

However, among conventional materials, for example, Pb (Mn _1/3 Sb _2/3 ) O ₃ -PbTiO ₃ -PbZr known from Japanese Patent Publication No. 47-43513 and Japanese Patent Publication No. 48-12355.
O ₃ can increase the mechanical quality factor and the piezoelectric constant, but has a large dielectric loss. In addition,
Pb (Sn _a Sb _1-a ) O ₃ -PbTiO ₃ -PbZr disclosed in Japanese Patent No. 8059
O ₃ has a small dielectric loss but cannot increase the piezoelectric constant. Therefore, for example, when the above-mentioned piezoelectric ceramic material is used as a vibrator of an ultrasonic cleaner, large vibration cannot be obtained and heat generation also becomes large, such as mechanical quality factor, piezoelectric constant, and dielectric loss. There is a problem that either one cannot obtain a desired value.

The present invention has been invented in view of the above problems, and when it is used as an ultrasonic vibrator, it is possible to obtain a large vibration and to generate a small amount of heat. It is an object of the present invention to provide a piezoelectric ceramic material whose quality coefficient, piezoelectric constant and dielectric loss are all above a certain level.

[0007]

In order to achieve the above object, the piezoelectric ceramic material according to the present invention has a composition formula of aPbTiO ₃ -b.
PbZrO ₃ (provided that a + b = 100, 43 ≦ a ≦ 53), and 10 atm% or less of Pb is replaced with one or more of Sr, Ca, and Ba to porcelain composition 100 mol, MnO ₂ is 0.1 to 5 mol, NiO is 0.1 to 5 mol
1 and Sb ₂ O ₃ are added at a ratio of 0.05 to 2.5 mol.

[0008]

According to the above construction, the composition formula is aPbTiO ₃ -b
PbZrO ₃ (provided that a + b = 100, 43 ≦ a ≦ 53), and 10 atm% or less of Pb is replaced with one or more of Sr, Ca, and Ba to porcelain composition 100 mol, MnO ₂ is 0.1 to 5 mol, NiO is 0.1 to 5 mol
l and Sb ₂ O ₃ are added in a proportion of 0.05 to 2.5 mol, the piezoelectric constant and mechanical quality coefficient are both large, the dielectric loss is small, and when used as an ultrasonic transducer A large amount of vibration can be obtained with a small amount of heat generation.

The composition range of each component is limited to the above range because the piezoelectric constant can be increased by substituting 10 atm% or less of Pb with Sr, Ca and Ba, but 10 atm.
This is because if it exceeds%, the piezoelectric constant becomes rather small.

Further, MnO ₂ is effective in increasing the mechanical quality constant and reducing the dielectric loss, but it is 0.1-5 mo.
If it exceeds the range of 1%, the desired effect cannot be obtained.

Further, NiO ₂ has an effect of increasing the piezoelectric constant, but if it is 0.1 mol% or less, the effect is small and it is 5 m.
When it exceeds ol%, a high piezoelectric constant can be obtained, but the dielectric loss becomes large.

Sb ₂ O ₃ is effective in reducing the dielectric loss, but if it is less than 0.05 mol%, the effect cannot be obtained, and if it exceeds 2.5 mol%, the dielectric loss becomes rather large.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of piezoelectric ceramic materials according to the present invention will be described below. PbO, ZrO ₂ as raw materials,
TiO ₂ , SrCO ₃ , CaCO ₃ , BaCO ₃ , MnO ₂ , NiO and Sb ₂ O ₃ were used. The raw materials are not limited to these, and other compounds can be used as long as they finally become the above oxides. These raw materials were weighed so as to have the composition shown in Table 1 and sufficiently mixed using a ball mill. The mixed raw materials were calcined in the temperature range of 800 to 1100 ° C. for about 2 hours, and the calcined product was pulverized again by the ball mill. After adding an appropriate amount of an organic binder to this powder and granulating, the granulated powder is molded into a disc shape having a diameter of 20 mm and a thickness of 1.5 mm at a pressure of about 1000 kg / cm ² , and this is formed into 1200 to 1300. A sintered body was obtained by firing in the temperature range of ° C for about 2 hours. Then, silver electrodes were formed on the front and back surfaces of this disk-shaped sintered body by vapor deposition, and 10
Polarization was performed by applying a DC voltage of 2 to 3 kV / mm in 0 ° C. silicon oil. Table 1 shows the piezoelectric characteristics of the porcelain thus obtained.

[0014]

[Table 1]

[0015]

[Table 1-2]

In Table 1, the items marked with * indicate those outside the scope of the present invention, and all other items indicate those within the scope of the present invention.

As is apparent from Table 1, those within the scope of the present invention have sufficiently satisfactory results in all characteristics. On the other hand, in Comparative Examples, Sample Nos. 1 and 5 had a low PbTiO ₃ ratio and a small piezoelectric constant. Further, in the samples Nos. 8 and 12, the Pb substitution amount was large, and satisfactory results were not obtained in all of the piezoelectric constant, mechanical quality constant and dielectric loss. Sample number 1
No. 3 did not contain MnO ₂ at all, the mechanical quality constant was small, and the dielectric loss was large. Further, the sample No. 16 had a large MnO ₂ content, and satisfactory results could not be obtained in all of the piezoelectric constant, mechanical quality constant and dielectric loss. Sample No. 17 is NiO
Is not included at all, and the piezoelectric constant is reduced. The sample No. 20 had a large NiO content, a small mechanical quality constant, and a large dielectric loss. The sample No. 21 did not contain Sb ₂ O ₃ at all, the mechanical quality constant was small, and the dielectric loss was large.
The sample No. 24 had a large Sb ₂ O ₃ content, a small mechanical quality constant, and a large dielectric loss. As described above, in the piezoelectric ceramic materials according to the above-mentioned examples, since both the piezoelectric constant and the mechanical quality factor are large and the dielectric loss is small, when used as an ultrasonic vibrator, a large amount of heat is generated with a small amount of heat generation. Can be obtained.
Therefore, it can be widely used as a material for ultrasonic transducers, ultrasonic motors, and the like.

[0018]

As described in detail above, in the piezoelectric ceramic material according to the present invention, the composition formula is represented by aPbTiO ₃ -bPbZrO ₃ (where a + b = 100, 43 ≦ a ≦ 53), and
0.1 to 5 mol of MnO ₂ , 0.1 to 5 mol of NiO, and Sb ₂ O ₃ with respect to 100 mol of a porcelain composition in which 10 atm% or less of Pb is substituted with one or more of Sr, Ca, and Ba. Is added at a ratio of 0.05 to 2.5 mol,
Both piezoelectric constant and mechanical quality factor are large, dielectric loss is small, and when used as an ultrasonic transducer,
Large vibration can be obtained with a small amount of heat generation. Therefore, it can be widely used as a material for ultrasonic transducers, ultrasonic motors, and the like.

[0019]

Claims (1)

[Claims] 1. The composition formula is aPbTiO ₃ —bPbZrO ₃ (where a
+ B = 100, 43 ≦ a ≦ 53), and 100 mol of the porcelain composition in which 10 atm% or less of Pb is replaced with one or more of Sr, Ca, and Ba, MnO ₂ is 0.
1-5 mol, NiO 0.1-5 mol, Sb ₂ O ₃ 0.
% Piezoelectric ceramic material, which is added in a proportion of 05 to 2.5 mol.