WO2010102563A1

WO2010102563A1 - Piezoelectric crystal elements

Info

Publication number: WO2010102563A1
Application number: PCT/CN2010/070952
Authority: WO
Inventors: 郑燕青; 孔海宽; 涂小牛; 陈辉; 施尔畏
Original assignee: 上海硅酸盐研究所中试基地; 中国科学院上海硅酸盐研究所
Priority date: 2009-03-10
Filing date: 2010-03-10
Publication date: 2010-09-16
Also published as: CN101834268B; CN101834268A

Abstract

A piezoelectric crystal element comprises a piezoelectric crystal material (1), an electrode layer (2) and lead wires (3). The chemical formula of the piezoelectric crystal material is A_3+xB_1+yAl_3+zSi_2+mO_14+n, wherein -0.2≤x≤0.2, -0.2≤y≤0.2, -0.2≤z≤0.2, -0.2≤m≤0.2, -1.4≤n≤1.4, A is one or both of calcium and strontium, B is at least one selected from tantalum, niobium and stibium. The highest operation temperature of the piezoelectric crystal element is up to 1000ºC and it exhibits some characteristics such as high electrical resistivity at high temperature, high piezoelectric coefficient, high electromechanical coupling factor, no phase transformation from room temperature to its melting point and low price.

Description

Piezoelectric crystal element

The invention relates to a piezoelectric crystal element, belonging to the field of crystal elements. Background art

When some dielectric crystals are deformed by external force, some of them will have opposite positive and negative polarization charges. This kind of no electric field is only due to strain or stress, which is polarized in the crystal. The phenomenon is called positive piezoelectric effect, also known as piezoelectric effect. When an alternating electric field is applied to a piezoelectric material, the piezoelectric material not only generates polarization but also generates strain and stress. This phenomenon of strain or stress generated by an electric field is called an inverse piezoelectric effect.

Book

Piezoelectric devices are mostly made using the positive piezoelectric effect of piezoelectric materials. According to this characteristic, it is possible to measure forces and non-electrical quantities that can be converted into forces, such as displacement, pressure, vibration, acceleration, and the like. Using the above effects, various types of piezoelectric devices have been successfully produced, including acoustic sensors (such as noise, vibration, sound, and ultrasonic sensors), force sensors, pressure sensors, acceleration sensors, and inertial sensors, etc., which are widely used in various national economies. field. Piezoelectric actuators are made using the inverse piezoelectric effect of piezoelectric materials and have a wide range of applications in electroacoustic and ultrasonic engineering.

Since the piezoelectric sensor is made based on the piezoelectric effect, this determines that it cannot be applied to the measurement of static quantities. This is because the charge generated in the piezoelectric material after the external force is applied can be preserved only when the loop has an infinitely large input resistance.

However, the actual situation is not the case. For example, a piezoelectric material having a small resistivity, the charge generated by an external force is quickly neutralized and cannot be detected. In addition, the charge retention time has a proportional relationship with the time constant RC of the piezoelectric material from which the device is fabricated, particularly when the piezoelectric material is coated with electrodes to form a sandwich structure. When the time constant of the measuring loop is not large, the amount of stored charge is very limited, causing the sensor to not work well. In addition, the lowest frequency of use of the sensor is inversely proportional to the time constant, so in order to increase the low-frequency response range of the sensor, it is necessary to increase the time constant of the loop as much as possible. When the time constant of a material is large enough, the frequency of its operation can be very low, and the dynamic response band of the sensor can be used. Broaden to a longer band. Therefore, a large time constant is required for most applications. But this does not depend on increasing the capacitance of the measurement loop to increase the time constant because the sensitivity of the sensor is inversely proportional to the capacitance. A practical approach is to increase the sensitivity of the sensor by increasing the resistivity of the measurement loop, which means that it is necessary to make such devices with materials with large resistivity.

At the same time, most piezoelectric devices such as static sensors and acoustic sensors used to monitor sound waves, vibration, and noise signals are used at room temperature. At present, most of these devices use lithium niobate crystals as piezoelectric elements.

However, in industrial applications, piezoelectric devices capable of operating at high temperatures are often required. Since the lithium niobate crystal has a low resistivity and its maximum use temperature does not exceed 650 °C, it greatly limits the application of the fabricated piezoelectric device.

Another relatively common crystal is tourmaline, but it is expensive, difficult to synthesize, and has a relatively low piezoelectric coefficient and cannot be widely used. Piezoelectric ceramic materials with relatively low price, because of their low Curie temperature, lose piezoelectric properties when they are higher than Curie temperature, and cannot be used as piezoelectric elements of piezoelectric devices, and their application temperature is currently not higher than 650 °C.

In summary, it is highly desirable in industrial applications to be able to fabricate piezoelectric components for use at temperatures above 650 °C. Summary of the invention

In order to solve the above problems, the object is to find a piezoelectric crystal material which is inexpensive, has excellent performance, and can be made into a crystal element for use in a high temperature environment, and the present invention is based on the full investigation of the existing piezoelectric material. The first-principles calculation method is a theoretical guide to design materials.

In the investigation of existing piezoelectric materials, most of the gallium silicate-based piezoelectric crystal materials have excellent performance, but they all contain expensive Ga elements, and the high-temperature performance is not ideal, which greatly limits their Wide range of applications in the field. In response to the above reality, we propose to replace expensive Ga elements with other inexpensive elements to reduce the cost of materials without degrading material properties.

However, the discovery of new materials is not a simple element replacement. The process is very complicated and difficult and requires a lot of theoretical guidance and experimentation. First, the new material after the element replacement may not be stable. Definitely exist. Secondly, the stable existence of new materials after element replacement does not mean that the structure and properties of the materials before being replaced can be maintained. Again, even if the structure and properties of the material before replacement are maintained, there is no guarantee that the new material after the replacement of the element can be prepared into a crystalline material.

According to the above element replacement idea, the present invention predicts the stability and performance of the new material after the Ga element is replaced by the first principle method. Finally, the theoretical calculation results are analyzed, and the new material with excellent selectivity is solid-phase synthesized. After the solid phase synthesis is successful, the crystal growth is studied until the designed crystal material is obtained.

Through a large number of theoretical calculations, it is found that when the expensive A1 element is used instead of the very expensive Ga element, the cost of the crystal material is greatly reduced, and the performance of the crystal is further improved, especially the high temperature performance, and the new element after the replacement of the A1 element. The material can be stable.

According to the theoretical calculation results, through a large number of repeated experimental explorations, a new crystal material designed according to theory was successfully grown. The performance of the new crystal material grown is tested. The performance test results are very close to the theoretical calculation results. The correctness of the theoretical calculation is well demonstrated.

From the above mechanism reasons and a large number of experimental results, lead to:

One of the objects of the present invention is to provide a high temperature piezoelectric crystal element having a structure as shown in Fig. 1, the high temperature piezoelectric crystal element comprising:

1 is a piezoelectric crystal material, 2 is an electrode layer, and 3 is a lead.

The piezoelectric crystal material has a chemical formula of A _3+x B _1+y Al _3+z Si _2+m 0 _14+n , wherein:

-0.2 <x< 0.2, -0.2 <y < 0.2, -0.2 <z < 0.2, -0.2 <m< 0.2, -1.4 <n< 1.4;

A is Ca or Sr or a combination of the two, of which Ca element is preferred;

B is one of three elements of Ta, Nb or Sb, and may also be a combination of several of the three elements, of which a Ta or Nb element is preferred.

The piezoelectric crystal material is preferably a Ca ₃ TaAl ₃ Si ₂ 0 ₁₄ crystal or a Ca ₃ NbAl ₃ Si ₂ 0 ₁₄ crystal. The electrode layer (2) can be used at a temperature of 20 ° C to 1000 ° C, and any metal working normally at a temperature of 20 ° C to 1000 ° C, including a Pt, Ir or Pd electrode layer, can be used. Among them, Pt is preferable as the electrode layer.

The electrode layer (1) is bonded to both surfaces of the piezoelectric crystal material (1) or to any of the surfaces in parallel.

The lead wire (3) can be used at a temperature of 2{rc~iooo°c. Metals that operate normally at temperatures between 20 ° C and 1000 ° C, including Pt, Ir or Pd leads, with Pt being preferred as the lead.

The lead (3) is bonded to the electrode layer (2) to form a via with the electrode layer.

The piezoelectric crystal material may be selected from X-cut, Y-cut, Z-cut, or other rotary cut, wherein X-cut and Y-cut are preferred.

The above X-cut means that the thickness direction of the crystal material is along the X-axis of the physical coordinates. By analogy, γ-cut and z-cut are the thickness directions of the crystal material along the Y-axis of the physical coordinates, respectively.

Z-axis.

The other rotary cuts mentioned above indicate that the thickness direction of the crystal material is not in all other directions along the three coordinate axes of X, Υ, and 物理 in the physical coordinates, at least in three coordinate axes of X, Υ, and Ζ. A coordinate axis is at a certain angle.

The cut type, especially the X cut and the cut cut, is because the crystal material is an anisotropic material, and the properties of the crystals in different directions are very different, for A _3+x B _1+y Al _3+z S i _{2 The +m} 0 _14+n crystal material has a large piezoelectric coefficient and a high electromechanical coupling coefficient for the X-cut and Y-cut wafers, which is advantageous for improving the performance of the prepared piezoelectric crystal device.

A second object of the present invention is to provide a method for preparing a piezoelectric crystal element, which comprises processing a piezoelectric crystal material, preparing an electrode layer, and preparing a lead.

1. The piezoelectric crystal material processing step comprises: aligning, cutting, grinding, and polishing the A _3+x B _1+y Al _3+z S i _2+m 0 _14+n crystal to obtain the piezoelectricity used for the above Piezoelectric wafer of crystal elements.

among them:

-0. 2 < x < 0. 2 , -0. 2 < y < 0. 2, -0. 2 < z < 0. 2 , -0. 2 < m < 0. 2 , -1. 4 < n < 1. 4.

A is Ca, Sr or a combination of both, of which a Ca element is preferred.

The cutting process may use X-cut, Y-cut, Z-cut, or other rotary cuts, of which X-cut and Y-cut are preferred.

Among them, the tangential direction, size and shape of the wafer have different requirements for different applications, and need to be determined according to actual requirements.

The above piezoelectric crystal material is prepared by a usual crystal growth method, and the crystal preparation is performed. Methods have been reported in previous literature.

The crystal preparation process includes:

First, according to the chemical formula A _3+x B _1+y Al _3+z Si _2+m 0 _{14+n, the} raw materials are weighed, mixed, pressed, and sintered at a temperature not lower than 1200 ° C, through solid The phase reaction gives a polycrystalline material.

among them:

-0.2 <x< 0.2, -0.2 <y < 0.2, -0.2 <z < 0.2, -0.2 <m< 0.2, -1.4 <n< 1.4.

A is Ca, Sr or a combination of both, of which a Ca element is preferred.

Among the raw materials selected above:

Ca element is selected from the carbonate, nitrate or oxide of Ca. Among them, CaC0 ₃ is preferred, and the Sr element is selected from the carbonate, nitrate or oxide of Sr. Among them, SrC0 ₃ is preferred, and Ta ₂ 0 _{5 is} selected for Ta element. Nb element is selected as Nb ₂ 0 ₅ , Sb element is selected as Sb ₂ 0 ₅ , A1 element is selected as A1 ₂ 0 ₃ , Si element is selected as Si0 ₂ .

Next, the crystal is grown by a crystal preparation method such as a melt pulling method to obtain a crystal. The melt pulling method is used to grow crystals, using ruthenium or platinum ruthenium, and then the above polycrystalline material is filled into the crucible, and the crucible is placed in the furnace cavity of the crystal growth pulling furnace, and heated for 2 to 3 hours. The polycrystalline material is melted, and the melt is stabilized at a temperature higher than the melting temperature of 80 ° C to 140 ° C for 4 to 10 hours; the Z- or Y-direction seed crystal is used, and the melting temperature is 20 ° C to 80 ° C above the melting temperature. The left and right species start to pull up; the speed is 5 ~ 30rpm, and the pulling speed is 0.5 ~ 3mm / h. After the growth of the crystal is lifted off the melt, it is dropped at a rate of 70 to 120 ° C per hour, and after cooling, A _3+x B _1+y Al _3+z Si _2+m 0 _14+n crystal is obtained.

The growth process is protected by an inert atmosphere such as N ₂ or Ar gas when using ruthenium iridium, to avoid oxidation of ruthenium, and no protective atmosphere is required when using platinum ruthenium.

The raw material heating method uses a commonly used heating method, and among them, it is preferable to use an intermediate frequency induction power source or a resistance heat.

2. The step of preparing an electrode layer of the piezoelectric crystal element comprises: coating an electrode layer slurry on the surface of the piezoelectric wafer, wherein the slurry comprises a Pt, Ir or Pd paste, wherein a Pt paste is preferred, and The slurry is sufficiently dried, and finally sintered at a high temperature of 800 to 1200 ° C to complete the preparation of the electrode layer.

The above electrode layer can be applied to both surfaces of the piezoelectric crystal material (1), as shown in FIG. 1A. Or arrange them in parallel on either side, as shown in Figure 1B. The shape of the electrode layer can be designed according to specific needs.

3. The step of preparing the lead of the piezoelectric crystal element is to solder the upper lead on the electrode layer of the wafer on which the electrode layer has been prepared by high-temperature soldering (the lead includes a Pt, Ir or Pd lead, of which a Pt lead is preferred ), that is, the preparation of the lead is completed.

The above leads are soldered to the electrode layer (2) in Fig. 1 by high temperature, and the electrode layers constitute a path. Depending on the electrode layer, the leads have different soldering methods. However, the main feature is to form a path with the electrode layer.

A third object of the present invention is to provide the above piezoelectric crystal element as a piezoelectric element, which is used at a temperature of 20 ° C to 1000 ° C. In particular, it is applied as a high temperature piezoelectric element, and preferably has a high temperature use temperature of 400 ° C. ~ 1000 °C, further preferably the high temperature use temperature is 650 ° C ~ 1000 ° C.

As a piezoelectric crystal element, it should have excellent high-temperature performance, and the measurement of high-temperature performance must place the high-temperature piezoelectric crystal element in a high-temperature environment. Taking the preferred Ca ₃ TaAl ₃ S i ₂ _{14 14} (CTAS) crystal as an example, the test procedure is as follows:

According to the preparation step of the piezoelectric crystal element, the CTAS crystal is used as the piezoelectric crystal material, and the piezoelectric crystal element shown in FIG. 1A is prepared by using Pt as the electrode layer and the lead material, which is referred to as a CTAS high temperature piezoelectric element. The CTAS high temperature piezoelectric crystal element is then placed in a high temperature furnace, the leads are connected to the sample holder, and the resistance from room temperature to 900 °C is measured with a ke i thl ey 2410 measuring instrument, using a multi-frequency LCR meter (HP 4284A) Measure the dielectric properties from room temperature to 900 °C, and measure the resonant and anti-resonant frequencies from room temperature to 900 °C using the resonant and anti-resonance methods (HP 4294A Precision Impedance Analyzer). According to the measurement results, the high temperature resistivity, piezoelectric coefficient (d _u ), electromechanical coupling coefficient (k ₁₂ ), resonant frequency and antiresonant frequency, and phase angle of the CTAS high temperature piezoelectric crystal element can be obtained.

After measurement, it was found that the above piezoelectric crystal element has excellent high temperature performance (Table 1), and is very suitable for fabricating a piezoelectric device, particularly a piezoelectric device used in a high temperature environment. Since the piezoelectric crystal material for producing a crystal element does not undergo a phase change from room temperature to a melting point, has a large piezoelectric coefficient, and has a high temperature resistivity, the specific high temperature performance will be described in the advantages of the present invention described below.

Compared with the existing piezoelectric crystal material and piezoelectric ceramic material, the piezoelectric material of the piezoelectric crystal element provided by the present invention has the following advantages: (1) No expensive Ga element is used. Existing materials include: GaP0 ₄ , La ₃ Ga ₅ Si0 ₁₄ (LGS), Ca ₃ TaGa ₃ Si ₂ 0 ₁₄ (CTGS) all contain a high proportion of expensive Ga elements, and the cost of the material is very high, which is extremely limited. The wide application of these materials. However, the material of the present invention completely replaces the Ga element with a very inexpensive A1 element, and the cost of the material is greatly reduced. For example, the price of high-purity Ga ₂ 0 ₃ is about 20 times that of high-purity A1 ₂ 0 ₃ , while the content of Ga in CTGS accounts for 30.5%. Therefore, when A1 element completely replaces Ga element, the cost of material drops sharply. Conducive to the large-scale industrial application of materials. Table 1 compares the high temperature performance of CTAS, CTGS and LGS crystals, the raw material price and the cost performance after normalization of the electromechanical coupling coefficient, showing the great advantages of CTAS crystals in high temperature applications. Table 1

(2) Excellent high temperature performance. The resistivity of the CTAS crystal at 600 ° C reaches the order of 10 ⁸ Ω·, and the resistivity at 800 ° C reaches the order of 10 ⁶ Q.cm. The electrical resistance of CTAS and LGS is increased by two at 600 °C. The piezoelectric coefficient (d _u ) of the CTAS crystal increases with increasing temperature, 50 . (Time ^ is 4.34 pC / N, d _u is 5.92 pC / N at 800 ° C, the piezoelectric coefficient at 880 ° C is 50.34% higher than 50 ° C; the electromechanical coupling coefficient (K ₁₂ ) of the crystal with temperature The increase also increases, 600 ° (16.0% for 1 ₁₂ , and 16.6 % for Κ ₁₂ at 800 °C. At 680 °C, CTAS crystals still have excellent piezoelectric properties and can work stably at this temperature. In short, large high temperature resistivity, large piezoelectric coefficient and large electromechanical coupling coefficient make it ideal for piezoelectric devices used in high temperature environments.

(3) There is no phase change from room temperature to melting point. The material of the present invention does not undergo a phase change from room temperature to melting as compared to existing piezoelectric ceramics and ferroelectric single crystals. The temperature range and stability of the material are greatly improved. In summary, the present invention uses A _3+x B _1+y Al _3+z S i _2+m 0 _14+n crystal as a piezoelectric material for a high temperature piezoelectric crystal element, which has no room temperature to melting point. It has the advantages of phase change, large piezoelectric coefficient, high temperature resistivity, high coupling coefficient and low price.

The above high temperature piezoelectric crystal elements can be used up to 1000 ° C and can be widely used in high temperature fields. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a high temperature piezoelectric crystal element relating to the present invention, Fig. 1A is a double-sided coated electrode, and Figure 1B is a single-side coated side-by-side electrode. Among them, 1 is a piezoelectric crystal material, 2 is an electrode layer, and 3 is a lead.

Figure 2 is a plot of the logarithm of resistivity versus temperature for a CTAS crystal. As can be seen from the figure, the logarithm of the resistivity of the CTAS crystal decreases with increasing temperature, but the resistivity at 600 °C reaches the order of 10 ⁸ Ω-cm, and the resistivity at 800 °C reaches 10 ⁶ Ω- Cm order.

Figure 3 is a plot of the piezoelectric coefficient and electromechanical coupling coefficient of a CTAS crystal as a function of temperature. As can be seen from the figure, the piezoelectric coefficient and electromechanical coupling coefficient of the CTAS crystal increase with increasing temperature. The piezoelectric coefficient at 880 °C is 5.92 pC/N, and the electromechanical coupling coefficient at 880 °C is 16.6%.

Figure 4 is a plot of the phase angle and the logarithm of the impedance versus frequency for a CTAS crystal at 680 °C. As can be seen from the figure, the CTAS crystal still has excellent piezoelectric properties at 680 °C. detailed description

The invention is further illustrated below in conjunction with specific embodiments. It is to be understood that the examples are not intended to limit the scope of the invention. The experimental methods in the following examples which do not specify the specific conditions are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Example 1

Use high purity CaC0 ₃ , Ta ₂ 0 ₅ , A1 ₂ 0 ₃ , S i 0 ₂ raw materials, according to Ca: Ta: Al : S i=3: 1 : 3: 2 ingredients, after mixing, briquetting, high temperature It is sintered into a polycrystalline material, and then crystal growth is carried out by a melt pulling method to obtain a Ca ₃ TaAl ₃ S i ₂ ₁₄ (CTAS ) crystal. The crystal is oriented, cut, ground, polished, and processed into a X-cut wafer having a diameter of 9 mm and a thickness of 0.35 mm, then a Pt electrode is coated on both X faces, sintered in a high temperature environment, and finally on a Pt electrode. Solder the Pt lead, The preparation of the CTAS high temperature piezoelectric crystal element is completed.

The CTAS high temperature piezoelectric crystal components are then placed in a special high temperature furnace, the leads are connected to a special sample holder, and the resistance is measured from a room temperature to a high temperature range of 900 °C using a ke i thley 2410 measuring instrument, using a multi-frequency LCR meter. (HP 4284A) measures dielectric properties from room temperature to 900 °C, and uses resonant and anti-resonance methods (HP 4294A Precision Impedance Analyzer) to measure resonant and anti-resonant frequencies from room temperature to 900 °C. According to the measurement results, the high temperature resistivity of CTAS high temperature piezoelectric crystal components can be obtained, as shown in Fig. 2; piezoelectric performance (d _u ) and electromechanical coupling coefficient (k ₁₂ ), see Fig. 3; resonant frequency and antiresonant frequency at high temperature And the phase angle, see Figure 4. Example 1

Use high purity CaC0 ₃ , Nb ₂ 0 ₅ , A1 ₂ 0 ₃ , S i0 ₂ raw materials, according to Ca: Nb: Al: S i=3: 1: 3: 2 ingredients, after mixing, briquetting, high temperature sintering The polycrystalline material is then subjected to crystal growth by melt drawing to obtain Ca ₃ NbAl ₃ S i ₂ 0 ₁₄ crystal. The crystal is oriented, cut, ground, polished, and processed into a Y-cut wafer having a diameter of 9 mm and a thickness of 0.35 mm, and then a Pt electrode is coated on both Y faces, sintered in a high temperature environment, and finally on the Pt electrode. The Pt lead is soldered to complete the preparation of the high temperature piezoelectric crystal element. Example 3

高Use high purity CaC0 ₃ , SrC0 ₃ , Ta ₂ 0 ₅ , A1 ₂ 0 ₃ , S i0 ₂ raw materials, press Ca: Sr: Ta: Al: S i=2. 9: 0. 1: 1: 3: 2 ingredients, after mixing, briquetting, high temperature sintering into polycrystalline material, and then filled into the crucible, put the crucible into the furnace cavity of the medium frequency induction heating crystal growth pulling furnace, protect the atmosphere with N ₂ +0 . 5% 0 ₂ . The specific growth process includes: heating for 3 hours until the polycrystalline material is melted, and the melt is stabilized for 4 hours to stabilize the melt; and the X-direction seed crystal is used to start the pulling growth at a temperature higher than the melting temperature of about 50 ° C; the rotation speed is 15 rpm. , the pulling speed is lmm / h. After the growth of the crystal is lifted off the melt, the temperature is lowered at a rate of 100 ° C per hour, and after cooling, a Ca^Sr^TaALS iA crystal is obtained. The crystal is oriented, cut, ground, polished, and processed to a length of 8 mm, a width of 2 mm, a thickness of 0.3 mm of a Y-cut rectangular wafer, and then a Pt electrode is coated on both Y faces, sintered in a high temperature environment, and finally The Pt lead is soldered on the Pt electrode to complete the preparation of the high temperature piezoelectric crystal element.

Example 4 高Use high purity CaC0 ₃ , Ta ₂ 0 ₅ , Nb ₂ 0 ₅ , Sb ₂ 0 ₅ , A1 ₂ 0 ₃ , S i0 ₂ raw materials, according to Ca: Ta: Nb: Sb: Al: S i=2. : 0. 1: 0. 8: 0. 1 : 3. 1: 2 ingredients, after mixing, briquetting, high temperature sintering into polycrystalline material, then filled into the crucible, placed in the medium frequency induction heating crystal 5% 0 _{2。 In} the furnace chamber of the growth furnace, the protective atmosphere is used N ₂ +0. 5% 0 ₂ . The specific growth process includes: heating up to 3 hours after the polycrystalline material is melted, and keeping the melt stable for 4 hours; using Z-direction seed crystal, starting to grow at a temperature higher than the melting temperature of about 50 ° C; , the pulling speed is lmm / h. After the growth of the crystals, the crystals were lifted off the melt at a rate of 100 ° C per hour, and after cooling, CauSr Ta Nb AluS iA crystals were obtained. The crystal is oriented, cut, ground, polished, and processed into a Z-cut wafer having a diameter of 12 mm and a thickness of 0.35 mm, then a Pd electrode is coated on both Z-planes, sintered in a high temperature environment, and finally on the Pd electrode. The Pt lead is soldered to complete the preparation of the high temperature piezoelectric crystal element. Example 5

高Use high purity CaC0 ₃ , Sb ₂ 0 ₅ , Nb ₂ 0 ₅ , A1 ₂ 0 ₃ , S i0 ₂ raw materials, according to Ca: Sb: Nb: Al: S i=2. 9: 0. 8: 0. 1: 3. 2: 2 ingredients, after mixing, briquetting, high temperature sintering into polycrystalline materials, and then filled into the crucible, placed in the furnace cavity of the medium frequency induction heating crystal growth pulling furnace, to protect the atmosphere N ₂ +0. 5% 0 ₂ . The specific growth process includes: heating for 3 hours until the polycrystalline material is melted, and keeping the melt for 4 hours to stabilize the melt; 釆 using the Y-direction seed crystal, starting the pulling growth at a temperature higher than the melting temperature of about 50 ° C; the rotation speed is 20 rpm , the pulling speed is lmm / h. After the growth of the crystal is lifted off the melt, the temperature is lowered at a rate of 100 ° C per hour, and after cooling, a CauSb Nb AU iA crystal is obtained. The crystal is oriented, cut, ground, polished, processed into a Y-cut wafer having a diameter of 9 mm and a thickness of 0.35 mm, and then a Pd electrode is coated on any of the two Y faces, and sintered in a high temperature environment. Finally, a Pd lead is soldered on the Pt electrode, as shown in Fig. 1B, and the preparation of the high temperature piezoelectric crystal element is completed.

Claims

I. A piezoelectric crystal element, characterized in that it comprises:

Piezoelectric crystal material (1), electrode layer (2), lead (3);

-0.2 <x< 0.2, -0.2 <y < 0.2, -0.2 <z < 0.2, -0.2 <m< 0.

2, -1.4

<n< 1.4;

A is Ca or Sr or a combination of both;

B is one of three elements of Ta, Nb or Sb or a combination of several elements;

The piezoelectric crystal material is selected from X-cut, Y-cut, Z-cut, or other rotary cut types. A piezoelectric crystal element according to claim 1, wherein A is a Ca element.

A piezoelectric crystal element according to claim 1, wherein B is a Ta or Nb element.

The piezoelectric crystal element according to claim 1 or 2 or 3, wherein the piezoelectric crystal material is a Ca ₃ TaAl ₃ Si ₂ 0 ₁₄ crystal or a Ca ₃ NbAl ₃ Si ₂ 0 ₁₄ crystal. .

A piezoelectric crystal element according to claim 1 or 2 or 3, wherein said piezoelectric crystal material is selected from the group consisting of X-cut and Y-cut.

A piezoelectric crystal element according to claim 1 or 2 or 3, wherein said electrode layer is bonded to both surfaces of the piezoelectric crystal material or arranged in parallel on either surface.

The piezoelectric crystal element according to claim 1 or 2 or 3, wherein the lead wire is bonded to the electrode layer to form a path with the electrode layer.

The piezoelectric crystal element according to claim 1 or 2 or 3, wherein the electrode layer comprises a Pt, Ir or Pd electrode layer.

The piezoelectric crystal element according to claim 8, wherein the electrode layer is a Pt electrode layer.

A piezoelectric crystal element according to claim 1 or 2 or 3, wherein said lead wire comprises a Pt, Ir or Pd lead.

A piezoelectric crystal element according to claim 10, wherein said lead is a Pt lead.

12. A method of preparing a piezoelectric crystal element, comprising processing a piezoelectric crystal material, preparing an electrode layer, and preparing a lead, characterized by: (1) The piezoelectric crystal material processing includes:

The body is oriented, cut, ground, and polished to obtain a piezoelectric wafer;

among them:

-0.2 <x< 0.2, -0.2 <y < 0.2, -0.2 <z < 0.2, -0.2 <m< 0.2 -1.4 <n< 1.4;

A is Ca or Sr or a combination of both;

B is one of three elements of Ta, Nb or Sb or a combination of several elements.

The cutting process uses X-cut, Y-cut, Z-cut, or other rotary cuts;

(2) The electrode layer of the piezoelectric crystal element is prepared by coating an electrode layer slurry on the surface of the piezoelectric wafer, drying the slurry, and sintering at 800 to 1200 ° C;

(3) The preparation of the lead of the piezoelectric crystal element described above includes soldering the lead on the electrode layer of the wafer on which the electrode layer has been prepared by high-temperature soldering.

A method of producing a piezoelectric crystal element according to claim 12, wherein A is a Ca element.

A piezoelectric crystal element according to claim 12, wherein B is a Ta or Nb element.

14. A method of fabricating a piezoelectric crystal element according to claim 12, wherein said cut type is selected from X-cut and Y-cut.

A method of producing a piezoelectric crystal element according to claim 12, wherein said slurry comprises a Pt, Ir or Pd paste.

16. The method of preparing a piezoelectric crystal element according to claim 15, wherein: said slurry is a Pt paste.

A method of manufacturing a piezoelectric crystal element according to claim 12, wherein said electrode layer is coated on both surfaces of the piezoelectric crystal material or arranged in parallel on either side.

A method of manufacturing a piezoelectric crystal element according to claim 12, wherein said lead wire comprises a Pt, Ir or Pd lead.

A method of producing a piezoelectric crystal element according to claim 18, wherein said Pt wire is used.

A method of producing a piezoelectric crystal element according to claim 1, wherein: among the materials selected: The Ca element is selected from the carbonate, nitrate or oxide of Ca; the Sr element is selected from the carbonate, nitrate or oxide of Sr; the Ta element is selected from Ta ₂ 0 ₅ ; the Nb element is selected from Nb ₂ 0 ₅ ; the Sb element is selected from Sb ₂ 0 ₅ ; A1 element selects A1 ₂ 0 ₃ ; S i element selects S i0 ₂ .

A piezoelectric crystal element according to claim 20, wherein Ca element is selected

CaC0 ₃ .

The piezoelectric crystal element according to claim 21, wherein the Sr element is selected from SrC0 ₃ .

A piezoelectric crystal element according to any one of claims 1 to 11, which is used for a piezoelectric element used at 20 ° C to 1000 ° C.

A piezoelectric crystal element according to claim 23, which is used for a piezoelectric element used at 400 ° C to 1 000 ° C.

A piezoelectric crystal element according to claim 24, which is used for a piezoelectric element used at 650 ° C to 1 000 ° C.