WO2008142933A1 - 圧電単結晶素子 - Google Patents
圧電単結晶素子 Download PDFInfo
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- WO2008142933A1 WO2008142933A1 PCT/JP2008/057640 JP2008057640W WO2008142933A1 WO 2008142933 A1 WO2008142933 A1 WO 2008142933A1 JP 2008057640 W JP2008057640 W JP 2008057640W WO 2008142933 A1 WO2008142933 A1 WO 2008142933A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/09—Forming piezoelectric or electrostrictive materials
- H10N30/093—Forming inorganic materials
- H10N30/095—Forming inorganic materials by melting
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/04—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
- H10N30/045—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning by polarising
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
Definitions
- the present invention relates to a piezoelectric single crystal device. More specifically, it is an element made of a piezoelectric single crystal material and uses a polarization direction (or teii mode, vioration mode) that is flat in the polarization direction (or PD).
- a piezoelectric element the present invention relates to a piezoelectric single crystal element focused on improving an electromechanical coupling factor in a vibration direction by applying a predetermined process to a device plane.
- a piezoelectric single crystal device has a rectangular parallelepiped (cuboid) with c »a, b as shown in Fig. 1, and its longitudinal direction (direction parallel to c) is the polarization direction 3 (or PD).
- the conversion efficiency of electrical energy and mechanical energy with respect to the magnitude of 3 vibrations in the polarization direction (longitudinal vibration mode) when voltage is applied to the direction is the electromechanical coupling of the longitudinal vibration mode. It is proportional to the square root of the coefficient k 33. Accordingly, the electromechanical coupling coefficient k 33 means that the efficiency is better larger listening.
- the piezoelectric single crystal element may have a plate shape or a disk shape in addition to the above-mentioned rectangular parallelepiped, and the electromechanical coupling coefficient can be similarly determined for each shape.
- piezoelectric single crystal material As the piezoelectric single crystal material are well known, for example, lead zinc niobate Pb (Z / 3 Nb 2/ 3) 0 3 (zinc lead niobate) and lead titanate PbTi0 3 (lead titanate) and the solid solution ( solid solution) (PZN - PT or abbreviated Rozetanyutau) or lead magnesium niobate Pb (Mgi / 3 N 2/ 3) 0 3 ( solid solution of magnesium lead niobate) and lead titanate PbTi0 3 (PMN - PT or Piezoelectric single crystal material consisting of (abbreviated as PMNT).
- PMNT Piezoelectric single crystal material consisting of
- a flat piezoelectric single crystal device having a desired element area and thickness of several tens of millimeters (hereinafter referred to as “flat plane type piezoelectric single crystal device”). ) Force 3 ⁇ 4 are shown open. And then the force, although the element is easy to produce, the electromechanical coupling coefficient k t of the direction parallel to the polarization direction when the polarization in the normal direction (normal direction) of the flat plate surface is at about 60% at most Compared to the conventional Zocon lead titanate Pb (Zr, Ti) 0 3 (zircon lead titanate) (PZT) sintered poly crystal piezoelectric device It is only equivalent or a few percent better, and will not be protected by sufficient piezoelectric properties.
- the present invention relates to a piezoelectric single crystal element using a vibration mode in a direction parallel to the polarization direction, and by applying a predetermined treatment to the element surface, an electric machine parallel to the polarization direction of a conventional flat piezoelectric single crystal element
- An object of the present invention is to provide a piezoelectric single crystal element that can easily obtain an electromechanical coupling coefficient better than the transfer coefficient k t .
- k t is usually used to represent an electromechanical coupling coefficient parallel to the polarization direction of the plate-like piezoelectric single crystal element. Disclosure of the invention
- the gist of the present invention is as follows.
- a piezoelectric single crystal element using a vibration mode in the polarization direction either one of the element surfaces having the polarization direction as a normal direction has a depth extending substantially perpendicular to the element surface, Electro-mechanical coupling in a direction parallel to the division direction by having a comb-shaped structure in which a plurality of slits filled with an insulating material are provided at a predetermined pitch.
- a piezoelectric single crystal element characterized by a coefficient of 65% or more.
- the pitch of the grooves is not more than 1.0 times the thickness in the polarization direction of the piezoelectric single crystal element, and the depth of the grooves is 0.25 to 0.5 times the thickness in the polarization direction of the piezoelectric single crystal element.
- the piezoelectric single crystal element has x Pb (Al, A2, '' ⁇ , ⁇ 1, ⁇ 2, ⁇ ) 0 3 + (1- ⁇ ) PbTi0 3 (where x is the mole fraction) ), And 0 to x to 1))
- A1, A2, ⁇ is one or more elements selected from the group consisting of Zn, Mg, Ni, Cd, In, Y and Sc, and B1, B2, ⁇ 'are One or more elements selected from the group consisting of Nb, Ta, Mo and W, and having a complex perovskite structure (1) or (2), Single crystal element.
- the piezoelectric single crystal element further includes 0.5 mass ⁇ of one or more elements selected from the group consisting of Cr, Mn, Fe, Co, Al, Li, Ca, Sr, and Ba in the solid solution!
- a depth extending in a direction substantially perpendicular to the element surface is provided on one of the element surfaces having the polarization direction as a normal direction.
- the electromechanical coupling coefficient is 65% or more, which is about 60% at the maximum of the conventional flat piezoelectric single crystal element, lead zirconic titanate (P?; T) sintered polycrystalline piezoelectric element.
- the conversion efficiency proportional to the square of the electromechanical coupling coefficient means that the efficiency is 1.2 times or more. This effect shows the effectiveness of the piezoelectric single crystal element according to the present invention.
- Fig. 1 is a diagram showing the orientation and shape of a general piezoelectric element using an electromechanical coupling coefficient k33 in a direction parallel to the polarization direction.
- Fig. 2A is a perspective view showing the orientation and shape of the piezoelectric single crystal element material according to the present invention
- Fig. 2B is a cross-sectional view taken along the line I-I of Fig. 2A, showing the piezoelectric single crystal element Shown with electrodes on both element surfaces of the material.
- Fig. 3 A schematic perspective view of the perovskite structure (RM0 3 ).
- Figure 4 A perspective view showing the orientation and shape of a plate-like piezoelectric single crystal element obtained by a conventional method. is there.
- FIG. 5 PMN-PT (PMNT) phase diagram.
- 1 0 Piezoelectric (single crystal) element material
- 10 A Piezoelectric single crystal element of the present invention
- 10 B Flat plate piezoelectric (single crystal) element
- 1 1 Groove
- 1 2 3 ⁇ 4 pole
- 1 3 Insulating material
- L Groove pitch
- D Groove width
- t Groove depth
- T Thickness of polarization direction of element
- PD Polarization direction Best mode for carrying out the invention
- the plate-shaped piezoelectric single crystal element is easy to manufacture, but the electromechanical coupling coefficient k t in the thickness direction of the element parallel to the polarization direction of the piezoelectric element polarized in the normal direction of the plane of the plate is at most It is about .60%, which is equivalent or only a few percent better than the conventional piezoelectric material, lead zirconate titanate (PZT) sintered polycrystalline piezoelectric element.
- PZT lead zirconate titanate
- the plate-like piezoelectric single crystal element is polarized in the direction perpendicular to the crystal plane unique to the single crystal material selected as the element plane, but is realized in the thickness direction electromechanical coupling coefficient k t Is not unique to the crystal direction of the single crystal piezoelectric material, but is a compound vibration mode in which many vibration modes are mixed. Therefore, the excellent thickness direction inherent to the crystal direction of the single crystal material is This is probably because the electromechanical coupling coefficient is not shown. With regard to this situation, the present inventor has intensively studied, and by providing a plurality of grooves filled with an insulating material at a predetermined arrangement pitch on the element surface, it is inherent to a single crystal piezoelectric material.
- the present invention provides a piezoelectric single crystal element that has an electromechanical coupling coefficient close to that of an excellent electromechanical coupling coefficient and can easily obtain a favorable electromechanical coupling coefficient compared to a conventional flat piezoelectric single crystal element. It was found that this was possible, and the present invention was completed. Hereinafter, the reasons for limitation of the piezoelectric single crystal element of the present invention will be described.
- the present description relates to a piezoelectric single crystal element that utilizes a vibration mode in the polarization direction, and has a depth extending in a direction substantially perpendicular to the element surface, on either one of the element surfaces having the polarization direction as a normal direction.
- the electromechanical coupling coefficient of a device structure separated by a groove filled with an insulating material is Since it becomes close to the excellent electromechanical coupling coefficient in the thickness direction inherent to the crystal direction of the single crystal material, the electromechanical coupling coefficient parallel to the polarization direction of the entire element is the same as that of the conventional flat piezoelectric single crystal element. Good values can be easily obtained compared to those.
- the direction of the groove is substantially perpendicular to the element surface in order to secure the strength of the comb-like structure in the vibration direction when the comb-like structure is vibrated after processing. There must be.
- the insulating material preferably has a specific resistance equal to or higher than that of the piezoelectric material, and a relative dielectric constant of 1/10 or less of the piezoelectric material.
- wax (wax), an epoxy material, etc. mark oxy mater i a l
- the aim of this patent is to obtain characteristics similar to those of strip samples. Material filled in the groove (wax, etc.) Force If the specific resistance is smaller than the pseudo strip portion of the piezoelectric material left uncut, the voltage drop between the “electrode and (filling material and piezoelectric strip portion)” is small.
- the strip part receives electric fields from various directions using the filling material as an electrode, and the polarization direction differs in each part of the strip.
- the target direction cannot be polarized. Therefore, the specific resistance of the material filled in the groove needs to be equal to that of the piezoelectric body or larger than that of the piezoelectric body.
- the material that fills the groove (such as a box) 1 If the dielectric constant is equal to or greater than that of the quasi-striped portion of the piezoelectric material that is left uncut, It may become the same. Therefore, the relative dielectric constant of the substance filled in the groove is preferably 1/10 or less of the piezoelectric material. Wax and poxy materials meet this requirement. In addition, wax and epoxy are not piezoelectric materials but are simply paraelectric materials and do not contribute to vibration.
- the groove pitch L provided on the element surface is preferably 1.0 times or less the thickness T in the polarization direction of the piezoelectric single crystal element.
- the arrangement pitch L provided on the element surface targeted by the present invention is the thickness in the polarization direction of the piezoelectric single crystal element.
- T is 1.0 times or less (LZTlO).
- the depth t of the groove provided on the element surface is preferably 0.25 to 0.50 times the thickness in the polarization direction of the piezoelectric single crystal element.
- the depth t of the groove provided on the element surface targeted by the present invention is 0.25 to 0.50 times the thickness T in the polarization direction of the piezoelectric single crystal element (0.25 t / T ⁇ 0.50). Is preferred.
- the depth of the groove is too shallow, resulting in a mixture of several vibration modes.
- the electric current in the direction parallel to the polarization direction of the entire piezoelectric single crystal element is obtained. This is because the value of the mechanical coupling coefficient is reduced.
- the strength against vibration of the element after grooving deteriorates, and there is a risk of breaking during vibration.
- the groove is processed by a precision cutting machine such as a dicing saw, as will be described later.
- a precision cutting machine such as a dicing saw
- the width of the groove depends on the thickness of the precision cutting machine.
- the width of the groove is not particularly limited as long as the filling material can be filled to every corner of the groove, but since the thickness of a dicing saw that is usually used is 50 to 100 / im, the groove width is also about 5 0 to 1 0 0 ⁇ .
- the crystal structure targeted by the present invention is that the unit cell of a solid solution single crystal is schematically shown in FIG. 3, and Pb ions are located at the corners of the unit cell and oxygen ions are located at the center of the unit cell.
- the perovskite structure (RM0 3 ) is such that the M ion is located at the body center of the unit cell.
- the M ion at the body center position in Fig. 3 is not a single element ion, but two ions.
- a composite perovskite structure consisting of any of the above multiple element ions (Al, A2, ⁇ , Bl, B2, ⁇ ) is desirable.
- the single crystal element of the present invention has the following structure and structure.
- the piezoelectric element of the present invention has x Pb (Al, A2, ⁇ , ⁇ , B2,- ⁇ ) 0 3 + (1-) PbTiOs (where X is a mole fraction, 0 ⁇ ⁇ 1 , Wherein A1, A2,..-Are one or more selected from the group consisting of Zn, Mg, Ni, Cd, In, Y, and Sc From the elements, ⁇ 1 ⁇ 2, ⁇ has a composition consisting of one or more elements selected from the group consisting of Nb, Ta, Mo and W, and has a longitudinal vibration mode when it has a composite belobskite structure.
- the unit cell of the solid solution single crystal is such that Pb ions are located at the corners of the unit cell, oxygen ions are located at the center of the unit cell, and M ions are It has a perovskite structure (RM0 3 ) that is located in the heart, and the M ions at the body center in Fig. 3 are not a single element ion, but Zn, Mg, Ni, Cd, In, Y, and It is preferable that the composite belovskite structure be composed of one or more elements selected from the group consisting of Sc and one or more elements selected from the group consisting of Nb, Ta, Mo and W.
- solid solution of lead zinc niobate Pb (Zn 1/3 Nb 2/3 ) 0 3 and lead titanate PbTiOs - in case of using has The molar fraction X is preferably 0.80 0.98, and more preferably 0.89 0.95.
- a solid solution single crystal lead magnesium niobate And lead titanate PbTiOs (PMN-PT or PMNT) are used, the molar fraction X is preferably 0.60 0.80, more preferably 0.64 0.78. is there.
- the composition of the single crystal should be Cr, Mn, Fe, Co.
- One or more elements selected from the group consisting of Al, Li, Ca, Sr and Ba may be added at 0.5 mass ppm to 5 mass%. If the amount is less than 0.5 mass ppm, the effect of the addition is not remarkable, and if it exceeds 5 mass%, it is difficult to obtain a single crystal and there is a possibility that it becomes polycrystalline.
- the effect of adding these elements can be achieved, for example, by adding Mn Cr, Fe, Co to improve the mechanical quality factor Qm and suppress deterioration over time. Further, the addition of Sr and Ba improves the relative dielectric constant £ r.
- the method for manufacturing a piezoelectric single crystal element of the present invention includes a step of manufacturing a single crystal ingot, and a single crystal element material having a predetermined shape (for example, wafer) from the single crystal ingot. , A step of cutting a flat single crystal element material from the single crystal material, and a plurality of grooves extending substantially perpendicular to the surface on the surface of the flat single crystal element material. A step of filling the grooves with an insulating material, and a main polarization that polarizes the single crystal element material by applying an electric field in a predetermined direction to the polarization direction of the flat single crystal element material. It has the process, It is characterized by the above-mentioned.
- the reasons for limitation of the present invention in each step will be described.
- the manufacturing method of single crystal ingot added with ⁇ 5% by mass is to dissolve the raw material adjusted to the above composition in flux and then to cool it down and solidify it, or above the melting point There is a method of solidifying in one direction after being heated and melted.
- the former method includes the flux method, the kilopross method, or the TSSG method (top seeded solution growth), and the latter includes the melt Bridgman method and the CZ method (Chiyoklarsky method).
- the present invention is not particularly limited.
- the [001] axis orientation of the single crystal ingot is It is generally determined by the Laue method, and crystallographic orientations such as the [010] axis orientation and the [100] axis orientation that are almost perpendicular to the [001] axis orientation are determined as needed. Furthermore, the wafer surface (the widest surface) (001) surface is polished, an accurate orientation is determined using an X-ray direction finder, etc., and the above-mentioned polished surface is displaced. To correct.
- a single crystal is roughly cut using a cutting machine.
- a single crystal ingot is cut parallel to the polished surface (001) surface, such as a wire saw or an inner diamond saw. Cut the board with the appropriate thickness to obtain the board (wafer). It is also possible to include a step of chemical etching using an etchant after cutting, if necessary.
- the wafer obtained by rough cutting is ground or polished with a grinding machine or grinding machine such as a lapping machine or polishing machine to obtain a wafer having a desired thickness.
- a chemical etching process using an etching solution may be included as necessary.
- a flat piezoelectric single crystal element material as shown in Fig. 4 is cut from the wafer.
- the [001] direction is the polarization direction PD
- the (010) plane and the (100) plane are the end faces, for example, almost perpendicular to the (001) plane.
- a precision cutting machine such as a dicing saw or a cutting saw.
- a plurality of grooves having a depth extending in a direction substantially perpendicular to the element surface is formed on one of the element surfaces whose normal direction is the polarization direction of the obtained plate-like piezoelectric single crystal element material.
- the groove is parallel to the element end face, for example, [100] direction, direction (A direction) or [010] direction, With a precision cutting machine such as dicing saw, etc. so that it is perpendicular to the element surface, at a predetermined pitch L and depth t Formed by making incisions.
- the pitch L of the grooves provided on the element surface is preferably 1.0 times or less the thickness in the polarization direction of the piezoelectric single crystal element, and the depth t of the groove provided on the element surface is The thickness is preferably 0.25 to 0.5 times the thickness T in the polarization direction of the piezoelectric single crystal element.
- the width of the groove is not specified, but depends on the thickness of the precision cutting machine as described above. The width of the groove is not particularly defined as long as the filling material can be filled to every corner of the groove, but the thickness of the dicing saw that is usually used is 50 to 100 ⁇ , so the groove width is also about 5 0 to 1 0 0
- An insulating material is filled in the groove formed in the piezoelectric single crystal material.
- the insulating material include wax and epoxy material.
- the insulating material is filled by, for example, placing a piezoelectric single crystal material on a hot plate set to a temperature higher than the melting temperature (coating) and applying molten wax (coating) penetration). '
- the direction of the electric dipole is in various directions for each domain, so it does not show piezoelectricity but is in an unpolarized state.
- a polarization process that aligns the direction of the electric twin for each domain is required.
- the polarization time is preferably adjusted according to the polarization treatment temperature and the applied electric field selected within the above preferred range, and the upper limit is preferably 180 minutes.
- the polarization step is performed in the polarization direction 3 of the cut piezoelectric single crystal element material at a temperature higher than the Curie temperature Tc of the piezoelectric single crystal element material, preferably in a temperature range of 190 to 220 ° C. Cooling to room temperature (electric field cooling) with a DC electric field of 250 to 500 V / mm applied. By making the temperature higher than the Curie temperature Tc, the direction of the electric dipole is returned to disorder and then cooled to below the Curie temperature with a DC electric field applied to align the direction of the electric dipole. is there. In addition, when the lower limit value of the preferable applied electric field range is less than 250 V / nmi, polarization is insufficient.
- the cooling rate is preferably a cooling rate that does not cause cracks in the element during cooling.
- the Curie temperature Tc is a transition temperature at which the electric dipoles do not align in a disordered direction when the temperature is higher than that, and the piezoelectric single crystal element does not exhibit piezoelectricity or dielectricity. And the value determined by the composition (see line Tc in Fig. 5). Note that the above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims. Example Next, a piezoelectric single crystal element according to the present invention was prototyped and its characteristics were evaluated, which will be described below. (Example 1 and Comparative Example 1)
- Example 1 is 73 mol% lead magnesium niobate (PMN) +27 mol% lead titanate (PT) (composition formula: Pb [(Mg, N) o.73Tio.27] 0 3 , PMN— PT Alternatively, a solid solution single crystal of PMNT) was used as the material for the piezoelectric single crystal device.
- the shape of the fabricated piezoelectric single crystal element 10A is shown in Fig. 2A.
- a flat wafer having the (010) plane and (100) plane almost perpendicular to the (001) plane is cut out, and then a lapping device and a polishing device are used. Then, each flat wafer was ground and polished until the thickness of the wafer was 1.000 mm and 0.470 ⁇ . Then, a groove parallel to the (010) plane (in the direction of arrow ⁇ in FIG. 2) is formed on the (001) surface of the flat wafer using a dicing saw equipped with a blade having a thickness of 50 111.
- a single-crystal element was produced by polarization by applying an electric field of 700 V / mm in the [001] direction for 30 minutes with a polarization device installed in a constant-temperature bath at ° C.
- the piezoelectric single crystal element was manufactured in a manner in which the thickness T, the groove depth t, and the groove pitch L were variously changed, and was within the preferred range of the present invention (LZT 1.0 and 0.25).
- LZT 1.0 and 0.25 the preferred range of the present invention
- a total of 10 samples were produced, 2 samples and 2 samples of 0.470 nun thickness. '
- the electromechanical coupling coefficient in the direction parallel to the polarization direction was measured as an index for evaluating the characteristics of the fabricated piezoelectric single crystal element.
- Measured values for Example 1 (groove arrangement pitch, groove width D, comb width L—D, groove depth t, groove pitch and thickness ratio LZT, groove depth and thickness Table 1 shows the ratio tZT, resonance frequency. &, Antiresonant frequency fa, and electromechanical coupling coefficient parallel to the polarization direction.
- the electromechanical coupling coefficient is known from the impedance curve and phase of the vibration mode in the polarization direction obtained using the impedance 'gain' phase 'analyzer (manufactured by HP,-device number: ⁇ 1 9 4 ⁇ ). (See Electronic Materials Industry Association Standard: EMAS-6 0 0 8, 6 1 0 0).
- Example 2 a flat piezoelectric single crystal element was fabricated as shown in FIG. 4, and the characteristics were investigated.
- Example 1 With respect to the plate-like piezoelectric single crystal element material 10B shown in FIG. 4 manufactured by the above method, Example 1 was performed except that the step of forming a groove on the element surface and the step of filling the groove with an insulating material were not performed. It was produced by the same method.
- the plate-like piezoelectric single crystal element was manufactured in a total of 6 sheets, 3 samples of l.OOOOmin thickness and 3 samples of 0.470 mm thickness, and the characteristics were measured by the same method as in Example 1.
- Table 2 shows the measured values (resonance frequency fr, antiresonance frequency fa, electromechanical coupling coefficient k t ) for Comparative Example 2.
- Example 1 The piezoelectric elements of Example 1 (Nos. 1 to 6) shown in Table 1 all have an electromechanical coupling coefficient of 67.:! To 73.0%, which is 65% or more.
- the piezoelectric single crystal element of Comparative Example 1 ( ⁇ ⁇ 7 to 10) in Table 1 and the flat piezoelectric single crystal element of Comparative Example 2 in Table 2 have an electromechanical coupling coefficient parallel to the polarization direction of 55.2%. It is found to be inadequate as the characteristics of the compression element using the vibration mode in the direction, which is ⁇ 58.6% and 60% or less.
- Example 2 and Comparative Example 3 Comparative Example 3
- Example 2 60 mol% lead magnesium niobate (PMN) +40 mol% lead titanate (PT) (composition formula: Pb ⁇ (Mg, Nb) o.6oTi 0 .4o ] 0 3j PMN- PT or PMNT ) was used in the same manner as in Example 1 except that the solid solution single crystal was used as the material for the piezoelectric single crystal element.
- PT lead titanate
- the piezoelectric single crystal element was manufactured in a manner in which the thickness T, the groove depth t, and the groove pitch L were changed in various ways, and within the preferred range of the present invention (LZT 1.0 and 0.25 ⁇ t ZT ⁇ 0.5) 3 samples of 1.000 mm thickness, 3 samples of 0.470 mni thickness, and 2 samples of OOOmm thickness, 0.470 ⁇ thickness sample, which is outside the scope of the present invention as Comparative Example 3. A total of 10 sheets of 2 sheets were produced.
- Example 2 (groove arrangement pitch L, groove width D, comb width L—D, groove length t, groove arrangement pitch / thickness ratio L / T, groove depth and Table 3 shows the thickness ratio tZT, resonance frequency fr, antiresonance frequency fa, and electromechanical coupling coefficient parallel to the polarization direction.
- Comparative Example 4 is 60 mol% lead magnesium niobate (PMN) + 40 mol% lead titanate (PT) (composition formula: Pb [(Mg, Nb) o.eoTi o.4o] 0 3) PMN—PT or (PMNT) solid solution single crystal is used as the material for the piezoelectric single crystal element, and the step of forming a groove on the element surface and the step of filling the groove with an insulating material are not performed on the manufactured flat piezoelectric single crystal element material. Except for this, the same method as in Example 1 was used.
- the plate-like piezoelectric single crystal element was manufactured in a total of 6 sheets, 3 samples of l.OOOOmm thickness and 3 samples of 0.470mm thickness, and the characteristics were measured by the same method as in Example 1.
- Table 4 shows the measured values for Comparative Example 4 (resonance frequency fr, antiresonance frequency fa, electromechanical coupling coefficient k t ).
- each of the piezoelectric elements of Example 3 (No .:! To 6) shown in Table 3 has an electromechanical coupling coefficient of 65.7 to 73.2%, which is 65% or more.
- the piezoelectric single crystal element of Comparative Example 3 (No. 7 to 10) in Table 3 and the flat piezoelectric single crystal element of Comparative Example 4 in Table 4 have an electromechanical coupling coefficient parallel to the polarization direction of 55.1% to 57.8% and less than 60% It can be seen that the characteristics of the piezoelectric element utilizing the direction vibration mode are insufficient.
- Example 3 Ca was added to 76 mol% lead magnesium niobate (PMN) +24 mol% lead titanate (PT) so as to be 0.5 mass% (composition formula: Pb (Ca) [(Mg, Nb ..) 0 76 Ti 0 24 ] O 3, solid solution of) - except that using a single crystal as the material of the piezoelectric single crystal device was prepared in the same way as in example 1.
- the piezoelectric single crystal element was fabricated in variously modified thicknesses T, groove depths t, and groove pitches L, and within the preferred range of the present invention (LZT 1.0 and 0.25 ⁇ t / T ⁇ 0.5) 3 samples of 1.000 mm thickness, 3 samples of 0.470 mm thickness, and 2 samples of 1.000 mm thickness and 0.470 mm thickness of sample 2 which are outside the scope of the present invention as Comparative Example 5. A total of 10 sheets were produced.
- Example 3 (groove arrangement pitch L, groove width D, comb width L 1 D, groove depth t, ratio of groove arrangement pitch and thickness L / T groove depth and thickness Table 5 shows the ratio tZT, resonance frequency fr, antiresonance frequency fa, and electromechanical coupling coefficient parallel to the polarization direction.
- no pyrochlore phase which is a different phase, was observed.
- the plate-like piezoelectric single crystal element was manufactured in a total of six samples, three samples having a thickness of ⁇ . ⁇ and three samples having a thickness of 0.470 mm, and the characteristics were measured in the same manner as in Example 3.
- Table 6 shows the measured values (resonance frequency £ r, antiresonance frequency fa, 'electromechanical coupling coefficient k t ) for Comparative Example 6.
- no pyrochlore phase which is a different phase, was observed.
- Example 3 (No. 1 to 6) piezoelectric elements shown in Table 5 All of the children have an electromechanical coupling coefficient of 65.3% to 68.3-73.8%.
- the piezoelectric single crystal element of Comparative Example 5 (No. 7 to 10) in Table 5 and the flat piezoelectric single crystal element of Comparative Example 6 in Table 6 have an electromechanical coupling coefficient parallel to the polarization direction of 56.1%. It is found to be insufficient as a characteristic of a piezoelectric element using a vibration mode in the direction.
- Example 4 66 mol% lead magnesium niobate (PMN) +66 mol% lead indium niobate (PIN) +34 mol% lead titanate (PT) was added so that Ca might be 0.5 mass% (composition formula : Pb (Ca) [(Mg, Nb, In) o.66Tio.34] 0 3 ,) was used in the same manner as in Example 1 except that a solid solution single crystal was used as the material of the piezoelectric single crystal element. .
- the piezoelectric single crystal element was manufactured in a manner in which the thickness T, the groove depth t, and the groove arrangement pitch L were variously changed, and within the preferred range of the present invention (L / T ⁇ 1.0 0.25 ⁇ t /T ⁇ 0.5)
- Example 7 shows the ratio t / T, resonance frequency fr, antiresonance frequency fa, and electromechanical coupling coefficient parallel to the polarization direction. In the piezoelectric single crystal ingot, no pyrochlore phase, which is a different phase, was observed.
- Table 7 and Table 8 show the following.
- the piezoelectric elements of Example 5 (Nos. 1 to 6) shown in Table 7 all have an electromechanical coupling coefficient of 66.3 to 73.5%, which is 65% or more.
- the piezoelectric single crystal element of Comparative Example 7 (No. 7 to: 10) in Table 7 and the flat piezoelectric single crystal element of Comparative Example 8 in Table 8 have an electromechanical coupling coefficient parallel to the polarization direction of 55.7. From 5 to 58.6%, which is less than 60%, it is clear that the characteristics of piezoelectric elements using the vibration mode in that direction are insufficient.
- either one of the element surfaces having the polarization direction as a normal direction is substantially perpendicular to the element surface.
- An electromechanical coupling coefficient parallel to the polarization direction of a conventional plate-like piezoelectric single crystal element is provided by providing a plurality of grooves having an extending depth and filled with an insulating material with a predetermined arrangement pitch. It has been found that it is possible to provide a piezoelectric single crystal element that can easily obtain a better electromechanical coupling coefficient than k t .
Abstract
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KR20097021038A KR101285936B1 (ko) | 2007-05-18 | 2008-04-14 | 압전 단결정 소자 |
US12/450,164 US8004164B2 (en) | 2007-05-18 | 2008-04-14 | Piezoelectric single crystal device |
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JP2019145581A (ja) * | 2018-02-16 | 2019-08-29 | Tdk株式会社 | 圧電素子 |
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WO2012021608A2 (en) | 2010-08-10 | 2012-02-16 | Trs Technologies, Inc. | Temperature and field stable relaxor-pt piezoelectric single crystals |
WO2013132747A1 (ja) * | 2012-03-08 | 2013-09-12 | コニカミノルタ株式会社 | 圧電デバイス、超音波探触子、液滴吐出装置および圧電デバイスの製造方法 |
KR101952854B1 (ko) * | 2013-07-16 | 2019-02-27 | 삼성전기주식회사 | 압전 소자 및 그 제조 방법, 그리고 상기 압전 소자를 구비하는 구동 어셈블리 |
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US6020675A (en) | 1995-09-13 | 2000-02-01 | Kabushiki Kaisha Toshiba | Ultrasonic probe |
JP3849976B2 (ja) * | 2001-01-25 | 2006-11-22 | 松下電器産業株式会社 | 複合圧電体と超音波診断装置用超音波探触子と超音波診断装置および複合圧電体の製造方法 |
JP3987744B2 (ja) * | 2002-03-25 | 2007-10-10 | 敏夫 小川 | ドメイン制御圧電単結晶素子 |
JP4222467B2 (ja) * | 2002-04-18 | 2009-02-12 | テイカ株式会社 | コンポジット圧電体およびその製造方法 |
JP3856380B2 (ja) * | 2002-04-26 | 2006-12-13 | テイカ株式会社 | コンポジット圧電振動子およびその製造方法 |
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JP5322419B2 (ja) * | 2006-09-26 | 2013-10-23 | 株式会社東芝 | 超音波探触子及び圧電振動子 |
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JPH0984194A (ja) * | 1995-09-13 | 1997-03-28 | Toshiba Corp | 超音波プローブ |
JPH0983038A (ja) * | 1995-09-14 | 1997-03-28 | Toshiba Corp | 酸化物圧電単結晶の製造方法 |
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