TW486863B - Piezoelectric device - Google Patents

Abstract

A piezoelectric device operable to excite a thickness extensional third harmonic vibration is provided, which can realize a high performance oscillator with an excellent thermal stability. The piezoelectric device includes a piezoelectric substrate. The piezoelectric substrate is formed from a piezoelectric material containing as major components Sr, Bi, Nb, and O. Vibration electrodes are formed on both of the surfaces of the piezoelectric substrate. The range lying between the vibration electrodes and defined by the overlapped vibration electrodes constitutes an energy trapping range. The value L/t is set to be less than 9, in which L represents the maximum distance between the points at which a straight line parallel to the vibration electrodes intersects the outer circumference of the energy-trapping range, and t represents the distance between the vibration electrodes.

Description

A7 V. Description of the invention (1) Background of the invention 1. Field of the invention The present invention relates to a piezoelectric device, and particularly to an energy-trapping piezoelectric device capable of using, for example, a third harmonic vibration extending in thickness. 2. Description of Related Techniques Traditionally, energy-trapping piezoelectric devices have been recommended, each of which has a pair of energy-trapping vibration electrodes that are opened on the two surfaces of the compact substrate, and are used to excite three extensions in thickness. Harmonic vibration. For the same material, the third harmonic vibration extending in thickness has a frequency constant about three times larger than the fundamental wave. □ Therefore, for a piezoelectric device that can operate using fundamental waves, taking into account the strength of the piezoelectric substrate, the upper limit of the center frequency is about 15 MHz. On the other hand, the upper limit in the center frequency of a piezoelectric device capable of using the third harmonic is about 30 to 40 MHz. That is, the piezoelectric device can be applied to a higher frequency range. However, for an energy-trapping piezoelectric device capable of exciting third-order harmonic vibrations extending in thickness, the most suitable electrode structure varies depending on the type of material. That is, the most appropriate electrode size must be determined for each material type. In particular, it is well known that in energy-trapping piezoelectric devices, the resonance frequency of parasitic vibrations called non-harmonics appears near the resonance frequency of the main vibration. When the electrode size, that is, the energy sinking range is small, non-harmonics are not excited. The maximum value in the non-harmonic electrode size range depends on the type of material. Therefore, 'the maximum electrode size must be determined for each material type. The non-oriented bismuth layer structure compound type ceramic material has excellent thermal stability. Therefore, you can ^ -4- this paper size applies to China National Standard (CNS) A4 specifications (21〇X 297 public love · -------------- install --- (Please read the back first Phonetic notation? Matters again — this page) Order · · · Line · Printed by the Intellectual Property Bureau of the Ministry of Economic Affairs and Consumer Cooperatives 486863 A7

The South-Performance Piezo Device has been implemented. However, for an energy-trapping piezoelectric device capable of exciting third-order various-wave vibrations extending in thickness, the largest value in the non-harmonic non-harmonic electrode size range has not been found. SUMMARY OF THE INVENTION Therefore, ‘an object of the present invention is to provide a piezoelectric device, by which a high-performance vibration soup having excellent thermal stability is achieved.

Device. In order to achieve the above object, according to the present invention, there is provided a piezoelectric device including a piezoelectric substrate containing Sr, Bi, Nb, and 0 as main components, and soil pairs formed on both surfaces of the piezoelectric substrate. Vibrating electrodes facing each other, they can be used to excite the third harmonics extending in thickness within the energy sinking range, which is determined by the relative stacking of electrodes formed on the two surfaces of the piezoelectric substrate The value of L / t is less than 9, where L represents the maximum distance between the point where the straight line parallel to the vibrating electrode and the periphery of the energy fall range intersect, and t represents the distance between the vibrating electrodes. Preferably, 'SrBi2Nb209 is used as a main component in a piezoelectric device. Piezoelectric materials containing Sr, Bi, Nb, and 〇 as main components such as SrBi2Nb209 are hot enough. If this material is used to manufacture a piezoelectric device capable of exciting the third harmonic vibration extending in thickness, setting the value L / t to less than 9 can avoid non-harmonic overlap and achieve good energy sinking. This morning ', if the plane shape of the energy sinking range is circular, the reference number L represents the diameter of the circle. If the shape is elliptical, L represents its long axis. If the shape is rectangular or square, L represents the length of the diagonal. In addition, the use of piezoelectric materials containing Ca, Bi, Ti, and 〇 as main components, and containing -5- This paper size is applicable to China National Standard "CNS" A4 (210 X 297 public love) ----- --------- Equipment --- (Please read the precautions on the back before imfing this page) ·-· Line-Printed by the Consumers 'Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 486863 Employees' Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention (3) Piezoelectric materials with S, Bi, Ti, and O as main components. Fig. 1 illustrates an example of a piezoelectric device of the present invention; Fig. 2 illustrates a side surface of the piezoelectric device of Fig. I Figure 3 illustrates a circuit diagram for estimating the piezoelectric device; Figure 4 is a graph showing the diameter of the energy sinking range with a diameter of 36mm; Figure 5 is a graph showing the resistance at different L / t values in the piezoelectric device of Example 1 Fig. 6 illustrates another example of the piezoelectric device of the present invention; Fig. 7 illustrates the peak-to-valley ratio of impedance when the diameter of the energy sink range is 36 mm in Example 2; Fig. 8 is The graph of the peak-to-trough ratio of the impedance of the piezoelectric device of Example 2 at different L / t values; FIG. 9 is an example A graph of the frequency characteristics of the impedance when the diameter of the energy sink range in 3 is 36 mm; FIG. 10 is a graph of the peak-to-valley ratio of the impedance of the piezoelectric device of Example 3 at different L / t values. 1 illustrates an example of a piezoelectric device of the present invention. FIG. 2 illustrates a side surface of the piezoelectric device. The piezoelectric device 10 includes a piezoelectric substrate 12. The piezoelectric substrate is composed of Sr, Bi, and Nb. And 0 are formed as a piezoelectric ceramic material. For example, a material containing SrBLNhO9 as a main component is used as the piezoelectric material. Circular vibration electrodes 14 and 16 are formed at approximately the centers of both surfaces of the piezoelectric substrate 12. , Opposite to each other. The vibration electrodes 14 and 16 are drawn to the piezoelectric substrate p -6- impedance frequency characteristics -------------- install --- (Please read the precautions on the back first (This page) · --- Lines · Paper sizes are translated to Chinese National Standard (CNS) A4 specifications (210 X 297 mm) 5. The opposite ends of the description of the invention (4).

The vibrating poles 14 and 16 are formed so as to have a diameter substantially equal to that of the temple. Liao Leiqi! ^ 〇 ,, L _ W Soil piece 12 / portion Universal polarization from the vibration electrode 16 side to the vibration electrode 14 side. Needless to say, the piezoelectric substrate is still polarized along the vibration electrode 14 side to the vibration electrode 16 side. Such a piezoelectric device 10 is used as a sag-type piezoelectric device. The portion of the piezoelectric electrode ㈣ located between the vibrating electrode " and therebetween constitutes the energy sinking range. Here, a line parallel to the vibrating electrode ^ i6 and a point at which the periphery of the energy sinking range intersects The maximum distance [, that is, the diameter L of the circular portion of each of the vibration electrodes 14 and 16 in the piezoelectric device 10 of FIG. 1, and the distance ^ between the vibration electrodes 14 and 16 is set in such a manner that the value L / t is less than 9. A piezoelectric device 10 formed of a piezoelectric material containing Sr, Bi, Nb, and 0 as main components (such as SrBuNlO9, etc.) can be used as a high-performance oscillator having high thermal stability. In addition, it is possible to prevent a piezoelectric device whose L / t value is less than 9 from exciting non-harmonics. Example 1 First, SrC03, Bi203, Nb205, and MnC03 were prepared as starting materials. These raw materials were weighed and mixed to A composite of SrBi2Nb209 + i wt% MnC03 was produced. The mixed powder was scorched at 800 to 1 ° C. An appropriate amount of an organic binder was added, and wet milling was performed with a ball mill for 4 hours. By passing the powder through 40 mesh Adjust the particle size. The raw material with the adjusted particle size is molded into a rectangular green sheet under a pressure of 1000 kg / cm2. The size is 30 mm X 20 mm X 1.0 mm thick, and in the atmosphere at 1250 to 1300 degrees Celsius. It is fired for 1 to 5 hours to produce paper with the standard of China National Standard (CNS) A4 (210 X 297 mm). V. Description of the invention (5) Porcelain with rectangular green sheet shape. Cutting and polishing to form a rectangular green sheet of $ mm × 5 mm × 0.4 mm thickness. The rectangular green sheet was polarized in the thickness direction. In addition, as shown in FIG. 3, silver was formed by vapor deposition on two major surfaces Electricity "forms a piezoelectric device having a junction as shown in Figs. 2 and 2. The thickness of the formed competitive substrate was 0.4 side. Therefore, the distance between the vibrating electrodes formed on the two main surfaces is 0 4. In the obtained piezoelectric device, the diameter of the energy sinking range, that is, the diameter of the circular portion of each vibrating electrode was set in the range of 10 to 5.2111111. In order to estimate the energy trapping performance of the piezoelectric device for the third harmonic, as shown in FIG. 4, an impedance analyzer 20 is connected, and the frequency characteristic of the impedance is measured. Fig. 4 is a graph showing impedance-frequency characteristics when the electrode diameter is 3.6 mm. In this case, L is 3.6, and {is 04111111, that is, the value of the value is 9. It can be seen that in the piezoelectric device, non-harmonics are superimposed on the resonance frequency of the main vibration. Figure 5 shows the relationship between the value of t / t and the peak-to-valley ratio (ratio of resonance impedance and anti-resonance impedance) of the main vibration and non-harmonics. As shown in Fig. 5, when the value of L / t is 9 or more, non-harmonic overlap. When a piezoelectric device is used as a vibrator, 'non-harmonics cause abnormal oscillations, termination of oscillations, and the like. In addition, when a piezoelectric device is used as a filter, non-harmonics cause a problem, i.e., attenuation is reduced or the like. As described above, regarding materials having at least one pair formed on a piezoelectric substrate containing Sr, Bi, Nb, and 0 as main components such as SrBi2Nb209, which is a bismuth layer structure-type material, ), The energy on the two opposite surfaces traps the vibrating electrode, and excites the third harmonic extending in thickness -8-This paper size applies to China National Standard (CNS) A4 specification (21〇x 297) ---------- Install --- ί Please read the precautions on the back before% page, & order: -_ Line · Intellectual Property Bureau of the Ministry of Economic Affairs, Consumer Cooperatives, Printing Intellectual Property Bureau of the Ministry of Economic Affairs Printed by Employee Consumer Cooperative 486863 5. Description of the invention (6) The device 'can be used in high-performance piezoelectric resonators with excellent thermal resistance by setting the electrode size to have a value of _L㈣ less than 9': = 1 : In the piezoelectric device, the energy sinking electrode has a circular shape. Shape = 疋: round 'or may be square, rectangular, or other cases. T'L represents the length of the longest part. That is, in l represents the longest part of the enlarged length. Circle two table-the length of the long axis. In squares or rectangles, the diagonal angles are shown as follows: In addition, the electrode including the lead-out part may have a shape as shown in Figure 6. In this case, the Overlapping electrodes 14 and 16 define the energy sinking range. In the example, the composition containing the main ingredients of external materials used in Cazhou is added with Mn. This material containing Si and w can be used— In some parts, it is replaced by other elements. This material is capable of sintering. However, in order to improve the firing characteristics of ceramics, additives such as glass 6 < can be added to the composition containing Sr, Bi, ingredients. The main component of the piezoelectric material used in the piezoelectric device at first glance is S: 2Nb209 in this example. However, the ratio of the element amount to the above-mentioned composition is somewhat different from the above, assuming that The main component mainly takes the crystal structure of Cao 2 09, which does not depart from the scope of the present invention. In this case, the advantages can be clearly explained. D. In the present invention, at least one pair of vibration electrodes Formed on both sides of the piezoelectric substrate However, it is not necessary to arrange the electrode on the entire outermost part. For example, the piezoelectric layer can be along the thickness direction = this paper dimension_ ® — (21 ^^ -------------- Installation — (Please read the precautions on the back before this page). Line · 5 Invention Description (7) The outside of the vibrating electrode. Stretch #, p 疋 Preferably, the vibrating electrode 戋 外 邱 + 打: The electrode is formed throughout On the outermost part of the seismic set, the second bu :: pole '"the piezoelectric layer on the outer side. In particular, in the case of the pressure or the name of the filter, a must field device is used to oscillate the accumulation of debris. Adjusting the Jingzhen frequency to the resonance frequency of the electrical device depends on. i type, device thickness, etc. In many =; electrical materials, electrodes, use: coating materials, etc. applied to the vibrating electrode, and dry inertial load method. Therefore, the above-mentioned technique for adjusting the resonance frequency can be easily applied by Gu when the vibration electrode is an external electrode 'v — ㈣. In addition, similar to Η, there are some parasitic vibration mw, and a mass load is applied to the vibrating electrode by applying a coating material or the like. Preferably, the 'vibration electrode is formed as an external electrode. As described above, 'If the outermost vibrating electrode is an external electrode, various actions can be performed on the vibrating electrode. By using the piezoelectric device of the present invention, a high-performance resonator having excellent thermal resistance can be read and written. Example 2 First, SrCO3, Bi203, Ti02, and MnC03 were prepared as starting materials. These raw materials were weighed and mixed to produce SrBi4Ti40i5 + i wt.% MnC03. The mixed powder is calcined at 800 to 1000 degrees Celsius. Thereafter, a suitable organic coagulant 'was added and wet-milled for 4 hours by a ball mill. The particle size was adjusted by passing the powder through a 40 mesh screen. The raw material whose particle size is adjusted is adjusted to a rectangular green sheet with a size of 40 mm X 25 mm X 1.2 mm under a pressure of 1000 kg / cm2, and the paper size is in accordance with Chinese national standards (CNS) ) A4 specification (210 X 297 public) 486863 A7

I ------- Packing --- (Please read the precautions on the back first and then on this page) I will fire i to 5 hours at 1150 to 1300 degrees Celsius in the atmosphere to make rectangular pieces of porcelain. The porcelain is cut and lighted to form a 5 calendar X 5 mm X 0_4 mm thick porcelain. The square green sheet is polarized in the thickness direction. In addition, as shown in Fig. 3, the electrode is formed by vapor deposition on two main surfaces. Thus, a piezoelectric device having a structure as described in FIGS. 1 and 2 is formed. In the manufactured piezoelectric device, the diameter of the energy sinking range, that is, the diameter of the circular portion of each vibrating electrode is set in the range of 1.0 to 5.2 mm. In order to estimate the energy sinking performance of the piezoelectric device to the third chirped wave, as shown in FIG. 3, an impedance analyzer 20 is connected, and the frequency characteristic of the impedance is measured. Fig. 7 is a graph showing an impedance frequency characteristic when the electrode diameter is 3.6. In this case, L is 3.6 mm and t is 0.4 mm, that is, the value L / t is 9. It can be seen that in the piezoelectric device, non-harmonics are superimposed on the resonance frequency of the main vibration. -Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. Figure 8 shows the relationship between the value of L / t and the peak-to-valley ratio of the main vibration and antiresonance (ratio of read impedance to antiresonance impedance). As shown in Fig. 8, when the value of L / t is higher, non-harmonics are overlapped. If a piezoelectric device is used as an oscillator, non-harmonics will cause abnormal oscillation, termination of oscillation, and the like. In addition, if a piezoelectric device is used as a filter, non-harmonics cause a problem, i.e., reduction in attenuation and the like. As described above, there is at least one pair of energy-trapping vibration electrodes formed on the opposite surfaces of a piezoelectric substrate (the piezoelectric substrate containing SrBi4Ti4015 containing a bismuth layer structure mixture type material as a main component), and excites The third-harmonic piezoelectric device extending through the thickness can be used for high-performance piezoelectric -11 with excellent thermal resistance by setting the electrode size to L / t value less than 9.-This paper size applies to Chinese national standards (CNS) A4 size (210 X 297 mm) " TOUOUJ) A7

Called vibrator.

A composition of Mn containing SrBl4Ti4〇i5 as a main component. Si and W can be added to this material 1. In addition, at the “S” M position, other elements have been replaced. This material is available. In order to improve the sintering characteristics of ceramics, additives such as glass components can be added to the original. · ^ A Hundred S Bl4Tl40i5 in the composition as the main component. The main component of the piezoelectric material used in the piezoelectric device of this example contains Sr Bi, Ti, and 0, and is, for example, SrBi4Ti4i5. However, the ratio of the amount of elements may be somewhat different from that of the above-mentioned composition, assuming that the mixture basically takes the crystal structure of SrBqTuOb 'without departing from the scope of the present invention. Also, in this case, the advantages of the present invention can be achieved. Example 3 For example, 'CaCO3, Bi203, Ti02, and MnCO3 were prepared as starting materials. The raw materials were weighed and mixed to produce a composite CaBi4Ti4O15 + 1 wt.% MnC03. The mixed powder was calcined at a temperature of 1 to 1000 degrees Celsius. Thereafter, an appropriate amount of an organic binder was added, and wet grinding was performed with a ball mill for 4 hours. The particle size was adjusted by passing the powder through a 40 mesh screen. The raw material with the particle size adjustment result is molded into a rectangular green sheet under a pressure of 1000 kg / cm2, the size of which is 40 mm X 30 mm X 1.0 mm, and it is fired in the atmosphere at 1100 to i300 degrees Celsius It is made for 1 to 5 hours to produce a porcelain having a rectangular green sheet shape. The porcelain was cut and polished to form a square green sheet 'with dimensions of 5.5 mm X 5.5 mm X 0.4 mm. The square $ green sheet is polarized in the thickness direction. In addition, as shown in Figure 3, in two -12- national paper (CNS) A4 specifications (210 X 297 public) —— (Please read the precautions on the back before this page)...-Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 486863 A7 B7 V. Description of the Invention (1Q) Vapor deposition is performed on the main surface to form a silver electrode. Thereby, a piezoelectric device having a structure as illustrated in FIGS. 1 and 2 is formed. In the resulting piezoelectric device, the diameter of the energy sinking range ', that is, the diameter of the circular portion of each vibrating electrode is set in the range of 1.0 to 5.2 mm. In order to estimate the energy trapping performance of the piezoelectric device for the third harmonic, an impedance analyzer 20 is connected as shown in FIG. 3, and the frequency characteristic of the impedance is measured. Figure 9 is a graph showing the impedance-frequency characteristics at an electrode diameter of 3.6 mm. In this case, L 疋 3.6 mm and t is 0.4 mm, that is, the value of L / t is 9. It can be seen that in the piezoelectric device, non-harmonics are superimposed on the resonance frequency of the main vibration. Figure 10 shows the relationship between the value of L / t and the peak-to-valley ratio (resonance impedance to anti-resonance impedance ratio) of the main vibration and non-harmonics. As shown in Fig. 10, when the value of L / t is 9 or more, the non-harmonic overlap. If a piezoelectric device is used for an oscillator ', non-harmonics may cause abnormal oscillation, termination of oscillation, and the like. In addition, if a piezoelectric device is used for a filter, non-harmonics cause problems such as reduction in attenuation. As described above, 'there are at least a pair of opposing energy-trapping vibrating electrodes formed on both surfaces of a piezoelectric substrate containing CaBuTuO ^ as a main component containing a bismuth-layer structure-type material, and the thickness of the excitation is extended. The third harmonic piezoelectric device is used for a high-performance piezoelectric resonator having excellent thermal resistance by setting the size of the electrode to a value of L / t less than 9. A composition containing 〇 & 8 丨 2 丁 ″ 015 added with Mη may be used. Such materials added with, for example, si and w may be used. In addition, materials in which other elements are replaced at a part of Ca * Ti positions may be used. In addition, Add glass components, such as I ---- — — — — — — — (-Please read the precautions on the back before this page) Order: Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs- 13- V. Description of the invention (11) A composition containing CaBi2Ti4 " as a main component in an adjuvant (to improve the sintering characteristics of ceramic materials) of 1 is available. The piezoelectric device according to the present invention can be obtained. The main components of a piezoelectric material include Bι, Ti, and 〇, and are, for example, CkBQTuo ". However, the ratio of 1 of the element may be different from that of the above-mentioned composition, assuming that the material basically takes the crystal structure of CaBi4Ti4O15, without departing from the scope of the present invention. In the case of money ^ ', the advantages of the present invention can still be obtained. Please read the note on the back before f. Binding on this page

Claims (1)

1. Patent application scope 1. A piezoelectric device includes a piezoelectric substrate containing a piezoelectric material, the piezoelectric material containing Sr, Bi, Nb, and 0 as a main component, and at least one pair oppositely formed on the piezoelectric substrate The vibrating electrodes on the two surfaces can excite the third harmonics that extend over the thickness in the energy sinking range, and the energy m-falling range is formed by f stacked opposite electrodes on the two surfaces of the piezoelectric substrate. It is defined that the value of L / t is less than 9, where L represents the maximum distance between a line parallel to the vibrating electrode and the point at which the periphery of the trapped energy range intersects, and t represents the distance between the vibrating electrodes. 2. If the scope of patent application is the first! The piezoelectric device of the item, wherein the main component of the piezoelectric material is SrBi2Nb209. 3. A piezoelectric device comprising a piezoelectric substrate containing a piezoelectric material, the piezoelectric material containing Sr, Bi, Ti, and 0 as main components, and at least one pair of two oppositely formed on the piezoelectric substrate The vibrating electrodes on each surface can excite the third harmonics extending over the thickness within the energy sinking range, wherein the energy sinking range is defined by the opposite electrodes formed on the two surfaces of the piezoelectric substrate, The value of L / t is less than 9, where l represents the maximum distance between a line parallel to the vibrating electrode and the point where the periphery of the fall range of f can cross, (representing the distance between the vibrating electrodes. Piezoelectric device in which the main of the piezoelectric material This paper size applies to China National Standard (CNS) A4 specifications (210 · X 297 mm) 486863 A8 B8 C8 D8 VI. Patent application scope Composition is SrBi4Ti4015. 5. A piezoelectric device comprising a piezoelectric substrate containing a piezoelectric substrate, the piezoelectric material containing Ca, Bi, Ti, and 〇 as main components, and at least one pair oppositely formed on the piezoelectric substrate. The vibrating electrodes on the two surfaces are able to excite the third harmonic that extends over the thickness in the energy sinking range determined by the opposite electrodes formed on the two surfaces of the piezoelectric substrate, L The value of / t is less than 9 ′, where L represents the maximum distance between a line parallel to the vibrating electrode and the point where the periphery of the energy sink range crosses, and t represents the distance between the vibrating electrodes. '6 · The piezoelectric device according to item 5 of the patent application, wherein the main component of the piezoelectric material is CaBi4Ti4015. ------------- Installation -------- Order · (Please read the precautions on the back first) -Line Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy S National Standard (CNSM4 specification (210 X 297 mm)