KR100691560B1 - Piezoelectric ceramic composition for low temperature sintering - Google Patents

Abstract

The present invention relates to a piezoelectric ceramic composition exhibiting excellent piezoelectric properties even at a low sintering temperature of 900 ° C or less. The piezoelectric ceramic composition of the present invention is represented by the general formula xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ , where 0.08 ≦ x ≦ 0.20 and x + y + z = 1. In another aspect, the present invention provides a composition by improving the mechanical quality factor while maintaining an excellent piezoelectric constant by substituting or adding Mn to the composition.

Piezoelectric Ceramic Compositions, Piezoelectric MEMS Devices, Stacked Monolithic Piezoelectric

Description

Piezoelectric Ceramic Composition for Low Temperature Sintering {PIEZOELECTRIC CERAMIC COMPOSITION FOR LOW TEMPERATURE SINTERING}

1 is the first embodiment, when the sintering temperature is 900 ℃ in _{Pb (Zn 0 .5 W 0 .5} ) O graph showing linear shrinkage and changes in the dielectric constant of the _third drive ratio.

Figure 2 is an embodiment 1 when the sintering temperature is 900 ℃ in _{Pb (Zn 0 .5 W 0 .5} ) O a graph showing the electromechanical coupling factor and piezoelectric constant change in accordance with the ₃ mole ratio.

3 is a graph showing a change in linear shrinkage rate and dielectric constant according to the sintering temperature of ceramics prepared under the conditions of Specimen 5 to 8 of Example 1. FIG.

4 is a graph showing changes in electromechanical coupling coefficients and piezoelectric constants according to the sintering temperature of ceramics prepared under the conditions of Specimen 5 to 8 of Example 1. FIG.

Figure 5 is a graph showing the electromechanical coupling factor and the change of the mechanical quality factor of the _{Pb (Mn 0 .5 W 0 .5} ) O 3 substitution amount in the second embodiment.

FIG. 6 is a graph showing changes in electromechanical coupling coefficients and mechanical quality coefficients according to MnO addition in Example 3. FIG.

Figure 7 is an electron micrograph taken a cross section of the thick film implemented on a silicon substrate.

8 is an electron micrograph of a piezoelectric thick film monolithic cantilever completed by a micromachining method.

9 is a graph showing the electrical and mechanical behavior of the finished cantilever in the liquid phase.

The present invention relates to a lead oxide-based piezoelectric ceramic composition that can be widely applied to piezoelectric resonators, piezoelectric filters, piezoelectric actuators, piezoelectric transformers, and the like.

A lead oxide-based piezoelectric ceramic material is a PbZrO ₃ -PbTiO ₃ 2-component or three-component piezoelectric ceramic composition such as _{Pb (Mg ⅓ Nb ⅔) O3} -PbZrO 3 -PbTiO 3 has been widely used. Such piezoelectric ceramic materials are generally sintered at 1200 to 1300 ° C. However, when the lead oxide piezoelectric ceramics are sintered at 1100 ° C. or higher, lead oxide is volatilized, and the volatilization of lead oxide causes unevenness in composition, making it difficult to obtain excellent material properties and causing environmental pollution by toxic substances. have. Therefore, in order to suppress volatilization of lead oxide, a piezoelectric ceramic composition having a lower sintering temperature is required.

Recently, multilayer monolithic piezoelectric materials using multiple layers of piezoelectric ceramics have been used for piezoelectric actuators, piezoelectric transformers, and the like. The stacked monolithic piezoelectric laminates an electrode layer between a plurality of piezoelectric ceramic layers and piezoelectric ceramic layers and then fires them together. However, since the sintering temperature of the general piezoelectric ceramic material described above is 1200 to 1300 ° C, an expensive precious metal electrode material such as Pt should be used to manufacture a monolithic piezoelectric material using them. Therefore, in order to manufacture a laminated monolithic piezoelectric material using an inexpensive metal electrode such as an Ag / Pd alloy, a piezoelectric ceramic composition having a sintering temperature of about 1000 ° C. is required, and the sintering temperature of the piezoelectric ceramic material is lowered below 1000 ° C. Increasingly, the Ag / Pd alloy can increase the composition of Ag, which is a cheaper metal, further reducing material costs.

On the other hand, by applying micromachining technology to piezoelectric thin films and thick films, it is possible to manufacture piezoelectric microelectromechanical system (MEMS) devices such as micro actuators and sensors, among which a relatively large displacement is required. In this case, a piezoelectric thick film material having a thickness of several micrometers to several tens of micrometers should be used, and a method of manufacturing the piezoelectric thick film material using a screen printing method has been widely attempted. The method of manufacturing the piezoelectric thick film by the screen printing method has an advantage in that the manufacturing process is simple and the manufacturing cost is low. In particular, there is no need for a patterning process, and a thick film having a desired pattern size can be directly formed on a substrate.

However, in order to form a piezoelectric thick film on a silicon substrate and use it as a MEMS (Micro Electro Mechanical System) device, a manufacturing technology capable of heat treatment at low temperature must be developed. When the piezoelectric thick film is manufactured by the screen printing method, the piezoelectric powder is mixed with a binder, an organic solvent, and the like to prepare a paste, which is then printed on a Si substrate and heat-treated. There is a problem that the reaction between the material and the Si substrate occurs to significantly lower the piezoelectric properties. In order to overcome this problem, attempts have been made to form a diffusion barrier such as stabilized zirconia between the silicon substrate and the lower electrode before the thick film is formed. . Therefore, in order to manufacture a MEMS device using a piezoelectric thick film, a piezoelectric ceramic powder having a composition that can be sintered at a low temperature of 900 ° C. or lower must be used as a raw material.

Many studies have been attempted to lower the sintering temperature of lead oxide piezoelectric ceramic materials. According to the research report, there are two kinds of piezoelectric ceramic compositions capable of low temperature sintering at around 1000 ° C.

First, there is a composition for adding an oxide or glass frit that is melted at a low temperature such as PbO, B ₂ O ₃ -Bi ₂ O ₃ -CdO, to a PbZrO ₃ -PbTiO ₃ two-component system. Low temperature melting additives such as PbO, B ₂ O ₃ -Bi ₂ O ₃ -CdO are melted at a low temperature of about 850 ° C. to obtain a compact sintered body at a sintering temperature of about 900 ° C. However, in the case of producing a red-type monolithic piezoelectric material using such a low temperature molten oxide or lead oxide-based piezoelectric ceramic material containing a glass composition, these additives melt at the sintering temperature and react with the metal electrode, thereby deteriorating the electrical properties of the piezoelectric body. There are disadvantages. In addition, when the piezoelectric thick film is manufactured on the Si substrate using the piezoelectric ceramic composition, many liquid phases generated during the sintering of the thick film react with the substrate to form unwanted compounds at the interface, thereby lowering the piezoelectric properties. Second, the third component is added to form a eutectic liquid at low temperature while forming a solid solution with PbZrO ₃ -PbTiO ₃ two-component system. At this time, Pb-based composite perovskite oxide is mainly used to improve piezoelectric properties as a third component, and Pb (Ni _⅓ , Nb _⅔ ) O ₃ -PbZrO ₃ -PbTiO ₃ three-component systems are known as a representative composition. In addition, various piezoelectric properties may be obtained using a small amount of additives such as MnO and Cr ₂ O ₃ in the three-component ceramic composition. Therefore, it is considered that it is preferable to select the first three-component composition as the low-temperature sintering composition for the laminated monolithic piezoelectric or piezoelectric thick film. However, the sintering temperature of most three-component piezoelectric ceramic materials so far known is required to lower the sintering temperature to around 900 ° C in order to be used in MEMS devices using Si substrates or inexpensive laminated monolithic piezoelectric materials.
In addition, low-temperature sintered dielectric ceramics for lead-type multilayer ceramic capacitors are made of [Pb (Zr _0.5 Ti _0.5 ) O ₃ ] x · [Pb (Mn _0.5 W _0.5 ) O ₃ ] y · [Pb (Zn _0.5 W _0.5 ) O ₃ ] z (x + y + z = 1) has been reported (Japanese Patent Laid-Open No. 02-188461). However, in the case of the above composition, the sintering temperature is still high around 1,000 ° C., and the piezoelectric properties are not measured at all, so the applicability to piezoelectric ceramics is unknown.

An object of the present invention is to provide a piezoelectric ceramic composition exhibiting excellent piezoelectric properties even at a low sintering temperature of 900 ° C. or lower.

In order to achieve the above object, the present invention provides a piezoelectric ceramic composition represented by the general formula xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (x + y + z = 1). Here, the range of x is 0.08≤x≤0.20. If the x value is lower, a dense sintered body can be obtained, but the piezoelectric properties are lowered. In another aspect, the present invention provides a piezoelectric ceramic composition by improving the mechanical quality coefficient while maintaining a good piezoelectric constant by solid solution or addition of Mn to the composition.

The piezoelectric ceramic composition according to the present invention can be used for piezoelectric resonators, filters, sensors, and the like. In addition, the piezoelectric ceramic composition according to the present invention can be applied to a multilayer monolithic piezoelectric material and used in piezoelectric actuators and piezoelectric transformers. In addition, the piezoelectric ceramic composition according to the present invention can be used as a thick film material of a piezoelectric MEMS device using a silicon substrate.

Hereinafter, a preferred embodiment of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

Example 1

As starting materials for piezoelectric ceramic materials, powdery PbO, ZrO ₂ , TiO ₂ , ZnO, MnO, and WO ₃ were used. Each raw material was weighed in a plastic container so as to have the following composition, and mixed by zirconia ball and ball mill for 24 hours with distilled water.

_{Composition: xPb (Zn 0 .5 W 0} .5) O 3 -yPbZrO 3 -zPbTiO 3, 0.08≤x≤0.20, y = z = (1-x) / 2

The mixed powder was dried and then calcined at 800 ° C. for 3 hours. The calcined powder was again ball milled with binder (1 wt% PVA) under the same conditions as before calcination. It was dried, granulated using a 100 mesh sieve, and then molded into a disc shape having a diameter of 9 mm by applying a pressure of 1.2 ton / cm 2. The binder in the molded specimen was volatilized and then sintered at 800 to 950 ° C. for 1 hour. In order to measure the electrical properties of the sintered specimen, silver paste was coated on both surfaces, and then heat-treated at 650 ° C. for 10 minutes to form a silver electrode. In order to impart piezoelectric properties, the specimen was immersed in a silicon oil container maintained at 120 ° C. and polarized by applying an electric field of 2.5 kV / mm for 30 minutes. Dielectric and piezoelectric properties were measured using an impedance analyzer (HP 4192A) and d ₃₃ meters.

The experimental results are shown in Table 1. All specimens with PZW (Pb (Zn _0.5 W _0.5 ) O ₃ ) content of 0.08 ~ 0.15 showed more than 10% shrinkage when the sintering temperature was over 850 ℃, and the sintering temperature was 800 ℃ when the PZW content was 0.2 (Sample No. 17) also showed a high linear shrinkage of 12.4%.

[Table _{1] xPb (Zn 0 .5 W} 0 .5) O 3 -yPbZrO 3 -zPbTiO 3 (y = z = (1-x) / 2) piezoelectric properties of the ceramic

No. Composition (x) Sintering Temperature (℃) Shrinkage (%) Dielectric constant Dielectric loss (tanδ) k _p (%) d ₃₃ (pC / N) Q _m One 0.08 800 8.9 835 0.015 23.2 166 173 2 0.08 850 10.3 1044 0.016 27.2 170 100 3 0.08 900 12.0 1138 0.014 25.9 136 100 4 0.08 950 12.7 1165 0.016 28.2 158 98 5 0.10 800 8.6 869 0.014 32.9 259 132 6 0.10 850 12.5 1331 0.018 43.1 304 94 7 0.10 900 13.4 1419 0.018 43.1 306 96 8 0.10 950 13.5 1504 0.016 44.3 302 94 9 0.12 800 9.1 897 0.016 28.2 203 133 10 0.12 850 11.0 1102 0.017 34.3 243 107 11 0.12 900 13.1 1359 0.020 40.0 276 93 12 0.12 950 13.6 1202 0.017 36.7 251 124 13 0.15 800 9.1 882 0.019 18.6 145 139 14 0.15 850 11.5 1094 0.018 27.6 176 98 15 0.15 900 13.2 1295 0.020 31.5 211 102 16 0.15 950 13.6 1321 0.020 31.9 219 124 17 0.20 800 12.4 950 0.021 22.7 138 111 18 0.20 850 14.6 1425 0.023 25.0 144 114 19 0.20 900 14.6 1346 0.020 32.5 206 118 20 0.20 950 14.7 1545 0.019 39.4 271 110

XPb when the 1 is the sintering temperature is _{900 ℃ (Zn 0 .5 W 0} .5) O 3 -yPbZrO 3 -zPbTiO 3 (y = z = (1-x) / 2) in accordance with the linear PZW content of ceramics Change in shrinkage and dielectric constant. The linear shrinkage increased significantly when the PZW content increased from 0.08 to 0.1 and slowly increased when the PZW content increased above 0.1. Dielectric constant increased when PZW content increased from 0.08 to 0.1 and decreased slowly when PZW content increased above 0.1.

XPb when the 2 is the sintering temperature is _{900 ℃ (Zn 0 .5 W 0} .5) O 3 -yPbZrO 3 -zPbTiO 3 (y = z = (1-x) / 2) in accordance with the electrical content of the ceramic PZW It is a change in the mechanical coupling coefficient (k _p ) and the piezoelectric constant (d ₃₃ ). Both the electromechanical coefficient and the piezoelectric constant (d ₃₃ ) increased significantly when the PZW content increased from 0.08 to 0.1 and decreased again when the PZW content increased above 0.1. However, in the composition range having a PZW content of 0.1 or more, the electromechanical coefficient was maintained at 30% and the piezoelectric constant was 200 pC / N or higher.

If the Fig. 1 and 2 from _{xPb (Zn 0 .5 W 0 .5} ) O 3 -yPbZrO 3 -zPbTiO 3 (y = z = (1-x) / 2) the composition range from ceramic 0.08≤x≤0.2, It can be seen that it has excellent piezoelectric properties even at a low sintering temperature of 900 ° C., and the most preferable composition is about x = 0.1.

Figure 3 shows the change in the linear shrinkage and dielectric constant with the sintering temperature of 0.1Pb (Zn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ ceramics x x 0.1 which is considered the most preferred composition in the present invention. Both linear shrinkage and dielectric constant increased significantly as the sintering temperature increased from 800 ℃ to 850 ℃ and gradually increased when the sintering temperature increased above that.

4 is a change in electromechanical coupling coefficient (k _p ) and piezoelectric constant (d ₃₃ ) according to the sintering temperature of 0.1Pb (Zn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ ceramics. Both the electromechanical coupling coefficient and the piezoelectric constant (d ₃₃ ) increased as the sintering temperature increased from 800 ° C to 850 ° C, almost unchanged when the sintering temperature increased above that, and the electromechanical coefficient above 43% and the piezoelectric constant. The constant showed very good piezoelectric properties above 300 pC / N. Therefore, the preferable sintering temperature of 0.1Pb (Zn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ ceramics is considered to be 850 ° C, but the electromechanical coefficient is 32.9% even when the sintering temperature is very low at 800 ° C. The piezoelectric constant is 259 pC / N, which shows comparatively excellent piezoelectric properties, and thus can be sufficiently applied to multilayer monolithic piezoelectric materials.

In addition, when the ratio of y and z in the xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbZrO ₃ (x + y + z = 1.0) ceramics composition is changed, the same sintering temperature as in the above embodiment is obtained. Various piezoelectric properties can be obtained while maintaining.

Example 2

As mentioned above, the xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ ceramics provided by the present invention show excellent piezoelectric properties at low sintering temperature. However, the mechanical quality factor (Q _m ) is low, around 100. Therefore, the compositions can be used in various applications such as piezoelectric actuators, piezoelectric sensors, piezoelectric ignition elements, etc., but are not suitable for applications such as piezoelectric resonators and filters requiring a high mechanical quality factor (Q _m ). This embodiment provides a composition having a high mechanical quality factor with an excellent piezoelectric constant at a low sintering temperature of about 900 ℃.

Using the starting materials used in Example 1, piezoelectric ceramic materials having the following compositions were produced in the same manner as in Example 1, and the properties thereof were measured. All specimens were sintered at the same temperature of 900 ° C.

Composition: xPb (Zn _0.5 W _0.5 ) O ₃ -yPb (Mn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ (x + y = 0.1)

This composition is x = 0.1 which is considered to be the most preferable composition in xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (y = z = (1-x) / 2) three-component ceramics of Example 1 It is a four-component piezoelectric ceramics in which _0.1 Pb (Zn _0.5 W _0.5 ) O ₃ -0.45 PbZrO ₃ -0.45 PbTiO ₃ ceramics is used as a basic composition and a part of PZW is replaced with PMW (Pb (Mn _0.5 W _0.5 ) O ₃ ). At this time, the sum of the content (x) of PZW and the content (y) of PMW was fixed at 0.1.

The properties of this composition are shown in Table 2. As can be seen from Table 2, the linear shrinkage after sintering was maintained at 10% or more until the substitution amount of PMW (y) was 0.04. It can be seen that this was not done.

TABLE 2 Piezoelectric Properties of xPb (Zn _0.5 W _0.5 ) O ₃ -yPb (Mn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ Ceramics (x + y = 0.1)

No. Pb (Mn _0.5 W _0.5 ) O ₃ Substitution amount (y) Sintering Temperature (℃) Shrinkage (%) Dielectric constant Dielectric loss (tanδ) k _p (%) d ₃₃ (pC / N) Q _m 7 0 900 13.4 1419 0.018 43.1 306 96 21 0.02 900 10.9 1260 0.003 41.9 289 618 22 0.04 900 10.0 994 0.002 33.9 220 708 23 0.06 900 7.0 790 0.001 21.9 144 496 24 0.08 900 8.1 765 0.001 12.1 68 581

FIG. 5 shows an electromechanical mechanism with increasing substitution amount (y) of PMW in xPb (Zn _0.5 W _0.5 ) O ₃ -yPb (Mn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ (x + y = 0.1) ceramics It is the change in the coupling coefficient (k _p ) and the mechanical quality factor (Q _m ). xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (y = z = (1-x) / 2) Substitution of PMW in three-component ceramics significantly increased the mechanical quality factor (Q _m ). have. In particular, in the case of specimen No.21 with y = 0.02, the mechanical quality factor (Q _m ) was greatly improved to 618 while the electromechanical coupling coefficient (k _p ) was still high at 41.9%. In the case of specimen No. 22 with y = 0.04, the electromechanical coupling coefficient (k _p ) is 33.9%, which is relatively high, and the mechanical quality factor (Q _m ) is 708, which is very high. In the composition with a PMW substitution of 0.06 or more, the mechanical quality factor is high, but the electromechanical quality factor is 30% or less, which is not preferable. Accordingly, the preferred substitution range of PMW in xPb (Zn _0.5 W _0.5 ) O ₃ -yPb (Mn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ (x + y = 0.1) quaternary ceramics is 0 <y≤ 0.06.
This does not overlap with the composition range of the dielectric ceramics reported in Japanese Patent Application Laid-Open No. 02-188461, and when the composition of [Pb (Mn _0.5 W _0.5 ) O ₃ ] y in the dielectric ceramics is 0.1 mol or more, it is 900 ° C or less. Piezoelectric properties are expected to be very bad at the sintering temperature.

Example 3

The present invention provides another composition capable of improving the low mechanical quality factor (Q _m ) of the xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (x + y + z = 1) ceramics.

Using the starting material of Example 1, piezoelectric ceramic materials having the following compositions were prepared in the same manner as in Example 1, and their properties were measured. All specimens were sintered at the same temperature of 900 ° C.

_{Composition:. 0.1Pb (Zn 0 .5 W} 0 .5) O 3 -0.45PbZrO 3 -0.45PbTiO 3 + z wt% MnO (0 <z ≤ 1.0)

This composition is x = 0.1 which is considered to be the most preferable composition in xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (y = z = (1-x) / 2) three-component ceramics of Example 1 0.1 Pb (Zn _0.5 W _0.5 ) O ₃ -0.45 PbZrO ₃ -0.45 PbTiO ₃ Ceramics are the basic composition, and MnO is added in an amount of 0 to 1.0 wt%.

The properties of this composition are shown in Table 3. As can be seen from Table 3, the linear shrinkage after sintering is maintained at 10% or more until the amount of MnO added is 0.5 wt%. When the amount of MnO added is 1.0wt%, the shrinkage is not more than 10%. It can be seen that.

[Table _{3] 0.1Pb (Zn 0 .5 W} 0 .5) O 3 -0.45PbZrO 3 -0.45PbTiO 3 + z wt.% Ceramic piezoelectric properties of the MnO

No. MnO addition amount (z) Sintering Temperature (℃) Shrinkage (%) Dielectric constant Dielectric loss (tanδ) k _p (%) d ₃₃ (pC / N) Q _m 7 0 900 13.4 1419 0.018 43.1 306 96 25 0.2 900 10.4 1107 0.013 37.3 247 603 26 0.5 900 10.3 1056 0.014 40.2 264 610 27 1.0 900 8.2 914 0.012 32.8 248 379

6 is _{0.1Pb (Zn 0 .5 W 0 .5} ) O 3 -0.45PbZrO 3 -0.45PbTiO 3 + z wt.% MnO (0 <z ≤ 1.0) electromechanical coupling factor with the addition of MnO in the ceramic ( k _p ) and mechanical quality factor (Q _m ). _{xPb (Zn 0 .5 W 0 .5} ) O 3 -yPbZrO 3 -zPbTiO 3 (y = z = (1-x) / 2) The addition of MnO in the three-component system ceramics is greatly increased mechanical quality factor (Q _m) It can be seen that. Up to 0.5 wt% of MnO, the mechanical quality factor (Q _m ) was greatly improved to 600 or more without significantly lowering the electromechanical coupling coefficient (k _p ). When the amount of MnO added increased to 1 wt%, kp decreased to 32.8% and the mechanical quality factor (Q _m ) also decreased significantly to 379. Thus, the preferred substitution range of MnO in _0.1 Pb (Zn _0.5 W _0.5 ) O ₃ -0.45 PbZrO ₃ -0.45 PbTiO ₃ + z wt.% MnO composition is 0 <z≤1.0.

In Examples 2 and 3, the improvement of the mechanical quality factor was judged to be due to Mn replacing B site of the perovskite crystal structure by PMW substitution or MnO addition, and xPb (Zn _0.5 W) provided in the present invention. _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (x + y + z = 1) For three-component ceramics, both PZW was replaced with PMW (Example 2) and MnO was added (Example 3) The mechanical quality factor was improved while maintaining low sintering temperature and good piezoelectric properties.

Example 4

0.1Pb (Zn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ powder exhibiting the above-described piezoelectric properties may be used in the form of a film according to the user's use.

In order to use the film as a film, the powder must be made into a paste having fluidity. To this end, a vehicle composed of an alcohol-based organic polymer material is synthesized, and the powder is uniformly mixed to distribute the powder evenly in the synthesized vehicle. Prepared with a paste with one composition.

The prepared paste was printed on a single crystal silicon substrate by screen printing, and the printed thick film was dried and sintered to finally form a finished thick film having a dense microstructure of about 20 μm. 7 shows a cross section of a thick film implemented on a silicon substrate.

Meanwhile, the thick film prepared by applying the powder was made into a piezoelectric thick film monolithic cantilever by applying a micromachining process. FIG. 8 shows a piezoelectric thick film monolithic cantilever completed by a micromachining method.

By applying the completed cantilever to the actual air and liquid phase, the electrical and mechanical properties of the air and in the liquid were observed according to the voltage applied to the cantilever and the corresponding displacement of the resonance frequency. The viscosity was measured while varying.

9 shows the electrical and mechanical behavior of the completed cantilever in the liquid phase. As can be seen from these results, the piezoelectric thick film cantilever made by applying the above 0.1Pb (Zn _0.5 W _0.5 ) O ₃ -0.45PbZrO ₃ -0.45PbTiO ₃ powder has excellent electrical and mechanical properties in air as well as liquid. It can prove that it can be used as a viscosity sensor and a biosensor.

In the above embodiments, xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ (y = z = (1-x) / 2) three-component system was used as a main component of the piezoelectric ceramic composition of the present invention. MnO was added as a minor component to improve the mechanical quality factor. However, the main and subcomponents of the piezoelectric ceramic composition of the present invention are not limited only to the above compositions. The ratio of y and z of the piezoelectric ceramic composition of the present invention can be changed, and Sr, Ba, Ca, La and the like can be substituted for Pb sites of the piezoelectric ceramics of the present invention. In addition, in order to obtain various piezoelectric properties, small amounts of other subcomponents such as Cr and Fe may be added instead of Mn. Even in this case, excellent piezoelectric properties will be maintained at a sintering temperature of 900 ° C. or less provided by the Pb (Zn _0.5 W _0.5 ) O ₃ -PbZrO ₃ -PbTiO ₃ three-component system of the present invention.

According to the present invention, it is possible to produce piezoelectric ceramics having excellent piezoelectric properties even when sintered at a lower temperature (800 ° C to 900 ° C) than the prior art. Therefore, when the piezoelectric ceramic composition according to the present invention is used, a MEMS device or a low-cost multilayer monolithic piezoelectric body using a Si substrate having excellent piezoelectric properties can be manufactured.

In addition, due to the low sintering temperature, there is very little volatilization of Pb, so that it is possible to obtain piezoelectric ceramics having uniform characteristics.

Claims (6)

As a composition represented by the following general formula xPb (Zn _0.5 W _0.5 ) O ₃ -yPbZrO ₃ -zPbTiO ₃ x + y + z = 1, x is in the range of 0.08≤x≤0.2 Piezoelectric ceramic composition. The piezoelectric ceramic composition according to claim 1, further comprising MnO, wherein the amount of MnO added is more than 0 wt% and 1.0 wt% or less. The piezoelectric ceramic composition according to claim 1, wherein any one material selected from Sr, Ba, Ca, and La is partially substituted instead of Pb. _{xPb (Zn 0.5 W 0.5) O} 3 -yPbZrO 3 -zPbTiO 3 (x + y + z = 1) in the Pb (Zn _0.5 W _0.5) O ₃ to a part in which the composition substituted with _{Pb (Mn 0.5 W 0.5) O} 3 , A piezoelectric ceramic composition, wherein the substitution amount of Pb (Mn _0.5 W _0.5 ) O ₃ is in the range of more than 0 and 0.06 or less in molar ratio with respect to the total composition. The piezoelectric ceramic composition according to claim 4, wherein Cr or Fe is partially substituted in place of Mn of Pb (Mn _0.5 W _0.5 ) O ₃ . A piezoelectric ceramic thick film prepared using the piezoelectric ceramic composition according to any one of claims 1 to 5.

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