KR950014290B1 - Oxide piezo electric material - Google Patents

Abstract

The oxide piezoelectric ceramic material is based on yttrium and tungsten substituted lead oxide, lead zirconate and lead titanate, xPb(Y2/3W1/3)O3-yPbZrO3-zPbTiO3, where x=0.01-0.20, y=0.215-0.764, z=0.215-0.764, x+y+z=1, and 0.01-1.0 wt% one of lanthanum oxide, manganese oxide, niobium oxide, chromium oxide and tantalum oxide. The piezoelectric ceramics is prepared by mixing the starting materials, calcining the mixture at 800-900 deg.C and pulverizing, adding PVA aqueous solution as a binder and molding with 1 ton/cm2 pressure, sintering it at 1,150-1,225 deg.C in the closed container to prevent deterioration of piezoelectric property according to volatilization of lead oxide.

Description

Oxide Piezoelectric Materials

1 is a Pbx (Y _2/3 W _1/3 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ ternary diagram showing the composition range of the present invention.

2 is a graph showing dielectric and piezoelectric properties according to the high capacity of Pb (YW) O ₃ of the sample of the present invention.

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

In general, an oxide piezoelectric material since its reported in Jaffe, which represents the most excellent piezoelectric characteristics in a phase boundary (MPB) between tetragonal system and neungmyeon political presentation conversion of impurities was added and the third component of ABO ₃ in the form of ferro probe Sky tree structure In order to improve the piezoelectric and dielectric properties including sintering, various forms of research have been continuously conducted.

PbZrO ₃ -PbTiO ₃ -based oxide piezoelectric materials have been used as vibration devices such as ultrasonic vibrators, acoustic filters, etc., and their applications have now led to actuators used in medical devices, robots, factory automation, non-destructive testing, and precision positioning.

Conventionally, various materials such as Nb ₂ O ₅ or WO ₃ have been added to PbZrO ₃ -PbTiO ₃ as a material used for manufacturing such components (F. Kulcsar: J. Am. Ceram. Soc, 42 (1959) 343 , H. Banno: Jpn. J. Appl. Phy. 6 (1976) 954) and Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbZrO ₃ -PbTiO ₃ have been developed. (田中哲 · 郞, et al .: 壓電 セ ミ シ ワ 材 料, 學 獻 社, (1973) 11-130), In practice, these materials are values of electromechanical coupling coefficient (Kp), mechanical quality coefficient (Qm), or dielectric constant. In addition to the low piezoelectric constant (d), signal receiving devices such as hydrophones, phonopickups, sound detectors, accelerometers, and delay lines Of course, it is not suitable for the application of actuators such as ultrasonic motors, deformable mirrors.

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

Accordingly, an object of the present invention is to provide an oxide piezoelectric material having a high electromechanical coupling coefficient and a large piezoelectric constant suitable for an actuator application as well as a signal transmission device having a high electromechanical coupling coefficient and a low mechanical quality coefficient.

Such an oxide piezoelectric material of the present invention basically consists of a ternary system of Pb (Y _2/3 W _1/3 ) O ₃ -PbZrO ₃ -PbTiO ₃ .

When the component and the composition ratio of the oxide of the present invention are specifically shown,

xPb (Y _2/3 W _1/3 ) O ₃ -yPbZrO ₃ -zPbTiO ₃

x = 0.01-0.20

y = 0 215-0.764

z = 0.215-0.764

(Where x + y + z = 1)

An oxide piezoelectric material represented by < RTI ID = 0.0 &_gt;< / _RTI > and especially contains 0.1-1.0 wt% of any one of La ₂ O ₃ , NnO ₂ , Nb ₂ O ₅ , Cr ₂ O ₃ and Ta ₂ O ₅ as an additive to such a composition. As a piezoelectric material, the oxide piezoelectric material of the present invention can be easily manufactured by an oxide mixing method which is generally used as follows.

That is, oxides such as PbO, TiO ₂ , ZrO ₂ , Y ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , Cr ₂ O ₅ , Cr ₂ O ₃ , La ₂ O ₃ , Ta ₂ O _5, and MnO ₂ Accurately weigh at the proper ratio and mix and grind using a zirconia ball mill. In addition, as a raw material used at this time, the raw material compound containing the compound which converts easily to an oxide when heated, ie, a hydroxide, a carbonate, etc. can also be used. After mixing, the sample is calcined at 800-900 ℃ and regrind by ball mill to make synthetic powder. Then, the powder is pressurized and molded at a pressure of 1ton / cm ^{2 by} adding a small amount of binder such as water or PVA solution. After sintering at a temperature of 1150-1225 ℃. In this sintering, sintering is performed in a sealed container to prevent degradation of the piezoelectric properties due to volatilization of PbO having a low volatilization temperature (about 880 ° C.).

In this way, the sintering agent produced is formed with electrodes on both sides by a general method, and polarization is performed by applying a DC electric field of 35 kV / cm to the electrode for 30 minutes in silicon oil at about 90-110 ° C.

Through such a manufacturing process conventional PbZrO ₃ -PbTiO ₃ 2 alloy or _{Pb (Mg1 / 3Nb 1/3) O} 3 -PbZrO 3 -PbTiO 3 3 binary piezoelectric material and is provided with a high piezoelectric property as a material having a different composition An oxide piezoelectric material is easily obtained.

Hereinafter, embodiments of the present invention are as follows.

In the ternary system of xPb (Y _2/3 W _1/3 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ ,

0.01≤ x ≤ 0.20

0.215 ≤ y, z ≤ 0.764

(Where x + y + z = 1)

10 ^-4 g of oxides such as PbO, TiO ₂ , ZrO ₂ , Y ₂ O ₃ , WO ₃ , Cr ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ^5, and MnO ₂ , depending on the molar ratio Accurately metered to and mixed in a zirconia ball mill. Next, the mixed sample was calcined at 800-900 ° C. and then pulverized in a ball mill, followed by the addition of a small amount of a binder such as pulverized water or PVA aqueous solution and press-molded at a pressure of 1ton / cm ² , followed by 1150-1225 ° C. Sintered at temperature. When sintering, PbO, one of the compositional components, has a low volatilization temperature (about 880 ° C), so that it is impossible to achieve an accurate chemical equivalence, which may lead to a decrease in piezoelectric properties. Sintering was performed in a closed container, and the holding time at the highest temperature was 1 hour.

The sintered molded sintered body is processed into a disk of 15 mm in diameter and 1 mm in thickness, and then electrodes are formed on both sides, and a DC electric field of 35 kV / cm is applied to the electrodes for 30 minutes in silicon at about 90-110 ° C. It was.

Electrochemical coupling coefficient (kp), mechanical quality factor (Qm) and frequency constant (Frequency Constant) were measured according to IRE and STD (Proe IRE, 137 (1949) 1378) for the polarized specimens. The measurement results of the different sintered bodies are shown in Table 1 below.

TABLE 1

Dielectric Properties of Piezoelectric Mills with Different Compositions

In Table 1, FT is the sintering temperature (° C), kp is the electromechanical coefficient (%), k ₃₃ ^T is the specimen at 25 ℃ with a frequency of 1kH ₂ , and Qm represents the mechanical quality factor.

As can be seen from Table 1, when the Pb (YW) O 邰 13 고용 solid solution is employed, the piezoelectric properties were excellent due to the high electromechanical coupling coefficient and very large piezoelectric constant.

Meanwhile, the Pb (Y`V) O ₃ -PbZrO ₃ -PbTiO ₃ ternary piezoelectric material of the present invention has excellent piezoelectric properties over a significantly wider range than the conventional PbZrO ₃ -PbTiO ₃ binary system. sealed PbZrO comparing the piezoelectric properties of the ₃ -PbTiO ₃ ternary system with _{Pb (YW) O 3 -PbZrO 3} -PbTiO ₃ system of the present invention as shown in the following table 2.

TABLE 2

PZT composition and Pb (YW) O ₃ -PZT

* Reference Example: D.A. Berlincort et al., Proc. IRE, 48 (l960) 220

In Table 2, in the case of binary PbZrO ₃ -PbTiO ₃ system, the range of excellent piezoelectric properties is limited to the MPB region, whereas in the case of the present invention, it is easy to obtain a sintered body as a material having excellent characteristics in a fairly wide composition range. It is shown. In other words, as shown in Reference Example 1 and Reference Example 2, the binary composition shows relatively good characteristics only at one point, but according to the embodiment of the present invention, Examples 5-Example 7, and Example 13 It can be observed that the piezoelectric constant (d ₃₃ characteristic) was improved over a wide area such as Example 15.

Piezoelectric properties by adding one of La ₂ O ₃ , MnO ₂ , Ta ₂ O ₅ , Nb ₂ O _5, and Cr ₂ O ₃ oxides as additives to Pb (YW) O ₃ -PbZrO ₃ -PbTiO ₃ ternary system of the present invention The improvement of the piezoelectric properties according to the addition of these additives to the composition (x = 0.02, y = 0.51, z = 0.47) of Example 14 is shown in Table 3 below.

TABLE 3

Characteristics by Additive Type and Amount

As can be seen in Table 3, the addition of trace amounts of La ₂ O ₃ , MnO ₂ , Ta ₂ O ₅ , Nb ₂ O _5, and Cr ₂ O ₃ improves the piezoelectric properties such as electromechanical coupling coefficient and piezoelectric constant. In the case of MnO ₂ addition, the mechanical quality factor is increased without significantly reducing the piezoelectric properties, thereby obtaining a sintered body suitable for use of the device.

1 is a _ternary diagram of Pb (Y _2/3 W _1/3 ) O ₃ -PbZrO ₃ -PbTiO ₃ showing the composition ratio of the oxide piezoelectric material of the present invention, which is hatched in a polygon surrounded by A, B, C and D. The part represents the composition range of the oxide component of the present invention. The point A of the polygon representing the composition range of the present invention shown 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, respectively.

2 shows the change of electromechanical coupling coefficient, mechanical quality coefficient and dielectric constant according to the high capacity of Pb (YW) O ₂ from Examples 13 to 18. In Example 5, the same tendency was observed in 11, 20 S 26 degrees. .

This indicates that the appropriate piezoelectric properties of Pb (YW) O ₃ can be improved by appropriately selecting a high capacity, as well as compositions and properties suitable for the application can be obtained by controlling the amount of additives as shown in Table 3.

Claims (2)

1 x Pb (Y _2/3 W _1/3 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ system as a basic composition, 0.01 ≤ x ≤ 0.20 0 .215 ≤ y, z ≤ 0 .764 (Where x + y + z = 1) Oxide piezoelectric material having a composition range of. The oxide piezoelectric material according to claim 1, wherein any one of La ₂ O ₃ , MnO ₂ , Nb _l O ₅ , Cr ₂ O _3, and Ta ₂ O ₅ is 0 1-1.0% by weight.