JP2016040798A - Piezoelectric material, manufacturing method of the same, ultrasonic transducer, and ultrasonic imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric material, having both high piezo-electric constant and specific band, capable of being stably produced, an ultrasonic transducer including the same, and an ultrasonic imaging apparatus.SOLUTION: A piezoelectric material 130, having no translational symmetry (periodicity), containing a quasi-crystal of a crystal structure having high orneriness in an atomic arrangement is prepared. The piezoelectric material 130 may be an inorganic material or an organic material. A piezo-electric element of an ultrasonic transducer 100 is constituted of the piezoelectric material 130. The ultrasonic transducer 100 is mounted to the ultrasonic imaging apparatus.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a piezoelectric body, a manufacturing method thereof, an ultrasonic transducer, and an ultrasonic imaging apparatus.

  The piezoelectric body is made of a material such as inorganic ceramics or organic polymer, and is suitably used for sensors, transducers, actuators, and the like. In the piezoelectric body for these applications, it is preferable that both the piezoelectric constant and the specific band are high from the viewpoint of sensitivity and spatial resolution in the application. However, the piezoelectric constant and the specific band are generally in a reciprocal relationship, and it is difficult to increase both at the same time.

As a technique for improving both the piezoelectric constant and the specific band, a composite of PbZrO ₃ / PbTiO ₃ solid solution (PZT) and a polymer material is known. The composite is a 1-3 composite in which the length of a PZT prism is oriented in the vibration direction, and its piezoelectric constant d ₃₃ and specific band depend mainly on the structure of the PZT prism, but for example, d ₃₃ is 50 It is -200pC / N, and a specific band is 50-150% (for example, refer nonpatent literatures 1 and 2).

  On the other hand, a barium titanate crystal film including a quasicrystal in a perovskite structure is known as the inorganic ceramic crystal film (see, for example, Non-Patent Document 3).

Hisao Sakan, “Piezoelectric Ceramics: Polymer Composite Materials”, Solid Physics, Japan, Agne Technology Center, Inc., August 15, 1988, Vol. 23, No. 8, p. 133-143 Kazuo Nakamae, Yoshihiro Hirata, Hirofumi Mizobuchi, Akihashi Hashimoto, Hiroshi Takada, "Development of high-resolution, broadband composite piezoelectric materials", SEI Technical Review, Japan, Sumitomo Electric Industries, Ltd., 2003 September, 163, p. 48-52 Nature, Oct. 10, 2013, 502, 7470, p. 215-218

  However, in the barium titanate crystal film of Non-Patent Document 3, the presence of B-site ions, which cause the perovskite structure crystals to exhibit piezoelectricity, and the presence or absence of polarization due to in-lattice displacement are non-existent. It is unclear from Patent Document 3, and the physical properties of the quasicrystal are also unclear. Therefore, it is not clear from Non-Patent Document 3 whether or not the barium titanate constituting the crystal film is a piezoelectric body.

  Non-Patent Document 3 describes that the quasicrystal is prepared by annealing a barium titanate film formed by magnetron sputtering and molecular beam epitaxy growth at 1070 to 1250K. In applications such as ultrasonic transducers, the piezoelectric body is generally fabricated on a substrate or an electrode. However, annealing at a high temperature described above may cause thermal degradation or modification of the substrate or electrode. is there. Such thermal deterioration and modification are not preferable from the viewpoint of manufacturing an ultrasonic transducer having stable characteristics.

A first object of the present invention is to provide a piezoelectric body that has a high piezoelectric constant and a specific band and can be produced stably.
A second object of the present invention is to provide an ultrasonic transducer or an ultrasonic imaging apparatus having the piezoelectric body.

  The present invention provides a piezoelectric body having a quasicrystalline structure.

  The present invention also includes a step of forming a piezoelectric layer including the quasicrystal by forming a piezoelectric layer on the surface of the base layer for controlling the crystal structure of the piezoelectric body at 700 ° C. or lower. A manufacturing method is provided.

  Furthermore, this invention provides the ultrasonic transducer which has the said piezoelectric material, and the ultrasonic imaging device which has the said ultrasonic transducer.

  According to the present invention, it is possible to provide a piezoelectric body suitable for sensors, actuators, ultrasonic transducers, etc., which has both a high piezoelectric constant and a high specific band and can be stably produced, and has excellent sensitivity. An ultrasonic transducer and an ultrasonic imaging device can be provided.

FIG. 1A is a diagram schematically illustrating a configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention, and FIG. 1B is a block diagram illustrating an electrical configuration of the ultrasonic imaging apparatus. It is a figure which shows typically the structure of the ultrasonic probe in the said ultrasonic imaging device. It is a figure for showing typically composition of an ultrasonic transducer concerning a 1 embodiment of the present invention.

Embodiments of the present invention will be described below.
The piezoelectric body according to the present embodiment includes the quasicrystal.

  “Piezoelectric body” is a substance that exhibits a phenomenon (piezoelectricity) that generates positive and negative charges on the surface of the crystal when stress is applied to the surface of the crystal. For example, a substance, mixture, or compound that is known to exhibit piezoelectricity , Composite compounds, solid solutions and compositions. The piezoelectric body may be inorganic or organic.

Examples of inorganic piezoelectric materials include quartz, lithium niobate, barium titanate, lead titanate, lead metaniobate, zinc oxide, PbZrO ₃ / PbTiO ₃ solid solution (PZT), Pb (Mg _1/3 Nb _2/3 ) O ₃ / PbTiO ₃ solid solution (PMN-PT) and Pb (Zn _1/3 Nb _2/3 ) O ₃ / PbTiO ₃ solid solution (PZN-PT) are included.

  Examples of organic piezoelectric materials include polyvinylidene fluoride-trifluoride ethylene copolymer (P (VDF-3FE)), a kneaded product of P (VDF-3FE) and polyurethane, P (VDF-3FE) and silicone. Kneaded product of polyvinylidene fluoride and nylon, PVDF copolymer by copolymerization of vinylidene fluoride and chlorotrifluoroethylene, polybutadiene-N, N-methylenebisacrylamide-styrene copolymer, poly ( γ-benzyl-L-glutamate), polyurea by vapor deposition polyaddition of methane diisocyanate and diaminofluorene, polyurea by vapor deposition polyaddition of xylylene diisocyanate and p-diaminobenzene, and tetrafluoroethylene-hexafluoropropylene Polymer electrets.

  Further examples of inorganic and organic composite piezoelectric materials include PZT-siloxane-poly (meth) acrylate composites and composites of polylactic acid and calcium phosphate or montmorillonite.

  A “quasicrystal” is a crystal structure that does not have translational symmetry (periodicity) but has high ordering in the atomic arrangement. For example, it does not have translational symmetry and maintains in-plane regularity. However, it has a crystal structure with poor c-axis long-range order. One or more quasicrystals may be used.

  The quasicrystal is confirmed by observing a crystal structure, a low energy electron diffraction image, and the like with a scanning tunneling microscope (hereinafter also referred to as “STN”). Examples of the crystal structure of the quasicrystal include a regular pentagonal plane unsaturated filling, a Penrose pattern, a pattern in which 4 to 6 hexagons are closely packed, and a pentagon and a hexagon as lattice point patterns. A pattern that is closely packed.

  The electron diffraction image generally has a rotational symmetry different from that of a crystal having translational symmetry. It is preferable that the electron beam diffraction image has the rotational symmetry from the viewpoint of increasing the piezoelectricity of the piezoelectric body. The electron beam diffraction image preferably has 5, 8, 10 or 12 times rotational symmetry from the viewpoint of enhancing both the piezoelectricity and the specific band of the piezoelectric body.

  The presence of the quasicrystal in the piezoelectric body enhances both the piezoelectricity and the specific band of the piezoelectric body. The content of the quasicrystal in the piezoelectric body is preferably 30% by mass or more from the viewpoint of enhancing both piezoelectricity and specific band. The upper limit of the content of the quasicrystal in the piezoelectric body is not particularly limited. For example, it may be 96% by mass or less from the viewpoint of productivity, economy, and degree of improvement in piezoelectricity and specific band. Preferably, it is 90 mass% or less.

  For example, the content is determined by dividing the number of lattices attributed to the regular pattern (such as the Penrose pattern) exhibited by the quasicrystal in the 25 nm square field observed by STN by the number of all lattices in the field of view. It is represented by the arithmetic average value of three visual fields.

  The piezoelectric body may further include a configuration other than the piezoelectric body. Examples of the other configurations include a layer (also referred to as a “base layer”) for controlling the crystal structure of the piezoelectric body in contact with the piezoelectric body. The base layer is, for example, a layer for making a part or all of the crystal structure of the piezoelectric body a quasicrystal.

  Examples of the base layer include a single crystal layer and an ordered molecular assembly layer. The base layer only needs to have a thickness sufficient to control the crystal structure of the piezoelectric body to a desired structure. For example, in the case of the single crystal layer, the single crystal is at least a fifth lattice. It only has to be a layer

  Examples of the single crystal layer include, in addition to a normal single crystal layer, a layer having a miscut surface of the orientation plane of the single crystal on the surface. For example, examples of the above base layer for a perovskite piezoelectric material typified by barium titanate, lead zirconate, lead titanate or lead magnesium niobate include a layer having a surface that is miscut Pt (111) It is. The miscut angle depends on the chemical composition of the perovskite (for example, “barium titanate”, etc.) and is, for example, 4 to 6 °. The miscut angle is an angle formed by the normal of the orientation plane and the normal of the surface of the base layer.

The ordered molecular assembly is formed on, for example, an optically flat surface, and is constituted by an array of amphiphilic molecules, for example. Examples of the layer of the molecular assembly include a Langmuir Brodgett film (LB film), an electric field alignment film of liquid crystal, and a supramolecular alignment film. For example, in the case of a quasicrystal of an organic polymer piezoelectric material such as PVDF-3FE, polyurea, or polylactic acid, examples of the base layer include p-C _n H _{2n + 1} phenyl sulfone prepared on an optical smooth surface of a glass substrate. LB film of sodium acid (n = 8-18) is included.

  The spatial arrangement order of atoms or molecules (to be in contact with the quasicrystal) on the surface of the base layer has a certain pattern in the in-plane lattice arrangement of the piezoelectric body (inorganic or organic substance) generated in contact with the base layer. give. For this reason, the structure of the base layer and the preparation conditions thereof are specific to the chemical composition of the quasicrystal to be formed. Therefore, the base layer can be determined according to the chemical composition of the quasicrystal, and can be appropriately selected from, for example, a known combination of an intended quasicrystal and a base layer that provides the quasicrystal.

  The piezoelectric body can be manufactured by a method including a step of forming a piezoelectric body on the surface of the base layer at 700 ° C. or less to form a piezoelectric layer including the quasicrystal. Thus, the piezoelectric body is formed by forming a layer of a desired chemical composition on the base layer by a chemical or physical vapor deposition method.

  The method for manufacturing the piezoelectric body may be a method for manufacturing a piezoelectric layer by so-called epitaxial growth that reflects the surface state of the base layer, and a known film forming method can be applied. Examples of the film forming method include vapor deposition, sputtering, molecular beam epitaxy, metal organic chemical deposition, and chemical solution deposition.

  If the film formation temperature of the piezoelectric body is too high, the organic piezoelectric body may be modified, and if it is an inorganic piezoelectric body, the piezoelectricity may be lowered. From the viewpoint of enhancing both piezoelectricity and specific band, the film forming temperature is preferably 250 to 700 ° C, more preferably 250 to 600 ° C, and more preferably 300 to 450 ° C for an inorganic piezoelectric body. More preferably it is. Moreover, if it is an organic piezoelectric material, it is preferable that the said film formation temperature is -50-300 degreeC from said viewpoint, It is more preferable that it is -30-200 degreeC, It is -20-120 degreeC. Is more preferable.

  The base layer may be further supported by a base material. A substrate is an object having a surface on which a base layer is to be formed. Examples of such base materials include glass substrates, silicon substrates, and non-metallic substrates such as magnesium oxide, metallic substrates such as gold, platinum, and stainless steel, perovskites such as lanthanum nickelate and strontium ruthenate, A substrate formed by depositing the above metal on the surface of a metal substrate and a single crystal layer such as doped strontium titanate are included. The base material can be appropriately determined according to various conditions such as manufacturing conditions of the piezoelectric body, adhesiveness to the base layer, and desired structure of the base layer.

  The piezoelectric body obtained by the above method is usually produced as a single composition film (single layer), and the thickness of the single layer is from the viewpoint of maintaining in-plane ordering even during the growth of the layer. , 500 nm or less is preferable. The thickness of the single layer can be arbitrarily controlled by, for example, the film formation temperature and the film formation time.

  The form of the piezoelectric body is not limited to a layer. From the viewpoint of manufacturing a thicker piezoelectric body or a piezoelectric body having a more complicated shape, the above manufacturing method includes the step of providing a second base layer on the surface of the first piezoelectric layer manufactured on the first base layer. Further, a step of arranging, and forming a second piezoelectric body on the surface of the arranged second base layer at 700 ° C. or less, and forming a second piezoelectric layer containing the quasicrystal on the second base layer It is preferable that the method further includes a step of further forming.

  Here, “first” refers to a base layer or a piezoelectric body when the above-described single layer is manufactured, and “second” refers to a base layer that is newly manufactured on the already manufactured piezoelectric body. Or a piezoelectric body. Both the second base layer and the piezoelectric body can be produced in the same manner as the first base layer and the piezoelectric body.

  Thus, by repeatedly producing the base layer and the piezoelectric body, it is possible to form a thicker or more complicated piezoelectric body layer. For example, a single crystal up to at least the fifth lattice layer is prepared as a second base layer again on a part or all of the surface of the first piezoelectric body, or an ordered molecular assembly such as an LB film. Then, the second piezoelectric body is prepared (laminated) by the same film forming process as that for generating the first piezoelectric body, and the piezoelectric body is obtained as a laminated film by repeating such lamination. It is done.

  When an inorganic material or an organic material is used for both the base layer and the piezoelectric body, the piezoelectric body is usually obtained as a multilayer body having a multilayer structure of the base layer and the piezoelectric body as a repeating unit. When an inorganic substance is used for the base layer and an organic substance is used for the piezoelectric body, similarly, the piezoelectric body is obtained as a laminated body having a laminated structure of the base layer and the piezoelectric body as a repeating unit. When an organic compound is used for the base layer and an inorganic substance is used for the piezoelectric body, the base layer is removed by burning, evaporation, etc. during the piezoelectric film forming process or the subsequent baking process (annealing process). A piezoelectric body is obtained.

  The method for manufacturing the piezoelectric body may preferably include an annealing step from the viewpoint of removing defects of the quasicrystal contained in the piezoelectric body and improving homogeneity. The annealing temperature in the annealing step is preferably 700 ° C. or lower. When the annealing temperature exceeds 700 ° C., the piezoelectricity and the specific band of the piezoelectric body may be lowered together with the above homogeneity.

  The annealing step is also used for the purpose of burning and removing the organic base layer. In this case, the annealing step may be performed in an oxidizing atmosphere in order to effectively promote the burning of the base layer.

  The ultrasonic transducer according to this embodiment has the piezoelectric body according to the above-described embodiment as a piezoelectric body, and the other parts can be configured in the same manner as a known ultrasonic transducer.

  For example, the piezoelectric body can be processed into an array of a plurality of piezoelectric elements by using a known Micromachined Ultrasound Transducer (MUT) in order to obtain a desired beam form with respect to radiated ultrasonic waves. For example, when the piezoelectric body has a thickness of 10 μm or more (the piezoelectric body is a thick film), the array can be processed by a known processing machine such as a diamond cutter (less than 10 μm). In the case of), it can be performed by Micro Electro Mechanical Systems (MEMS) processing.

  An electrode is attached to each piezoelectric element by a flexible printed circuit board (FPC), and arbitrary beam forming is enabled by ultrasonic transmission / reception driving programmed by a computer.

  From the viewpoint of appropriately improving acoustic performance, the ultrasonic transducer has the FPC and electrodes, a backing material that absorbs ultrasonic waves, an acoustic matching layer that prevents reflection of ultrasonic waves, and an ultrasonic wave. Other configurations such as an acoustic lens for focusing the beam may also be included. The ultrasonic transducer may be configured as a layered structure by appropriately laminating these other configurations and the piezoelectric body.

  Furthermore, the ultrasonic transducer may be subjected to waterproofing processing such as parylene coating, for example, on the front surface of the ultrasonic transducer before bonding the acoustic lens so that the ultrasonic transducer can be used in an underwater or water-containing environment. . “Parylene” is a registered trademark of Japan Parylene LLC.

  The ultrasonic imaging apparatus according to the present embodiment includes the ultrasonic transducer according to the present embodiment as an ultrasonic transducer, and other parts are configured in the same manner as a known ultrasonic imaging apparatus. obtain. The ultrasonic imaging apparatus is suitable for, for example, a medical ultrasonic diagnostic apparatus and a nondestructive ultrasonic inspection apparatus.

  FIG. 1A is a diagram schematically illustrating the configuration of the ultrasonic imaging apparatus according to the present embodiment, and FIG. 1B is a block diagram illustrating the electrical configuration of the ultrasonic imaging apparatus.

  As shown in FIG. 1A, the ultrasonic imaging apparatus 200 is disposed on an apparatus main body 201, an ultrasonic probe 202 connected to the apparatus main body 201 via a cable 203, and the apparatus main body 201. An input unit 204 and a display unit 209.

  As shown in FIG. 1B, the apparatus main body 201 includes a control unit 205 connected to the input unit 204, a transmission unit 206 and a reception unit 207 connected to the control unit 205 and the cable 203, a reception unit 207, and And an image processing unit 208 connected to each of the control units 205. Note that the control unit 205 and the image processing unit 208 are each connected to the display unit 209.

  The input unit 204 is a device for inputting data such as a command for instructing start of diagnosis and personal information of a subject, for example, and is, for example, an operation panel or a keyboard provided with a plurality of input switches.

  The control unit 205 includes, for example, a microprocessor, a storage element, and peripheral circuits thereof, and includes an ultrasonic probe 202, an input unit 204, a transmission unit 206, a reception unit 207, an image processing unit 208, and a display unit 209. Is a circuit that performs overall control of the ultrasonic diagnostic apparatus 200 by controlling according to each function.

  For example, the transmission unit 206 transmits a signal from the control unit 205 to the ultrasonic probe 202. For example, the receiving unit 207 receives a signal from the ultrasound probe 202 and outputs the signal to the control unit 205 or the image processing unit 208.

  The image processing unit 208 is, for example, a circuit that forms an image (ultrasonic image) representing an internal state in the subject based on a signal received by the receiving unit 207 under the control of the control unit 205. For example, the image processing unit 208 includes a digital signal processor (DSP) that generates an ultrasonic image of a subject, and a digital-analog conversion circuit (DAC circuit) that converts a signal processed by the DSP from a digital signal to an analog signal. ) Etc.

  The display unit 209 is a device for displaying an ultrasonic image of the subject generated by the image processing unit 208 according to the control of the control unit 205, for example. The display unit 209 is, for example, a display device such as a CRT display, a liquid crystal display (LCD), an organic EL display, or a plasma display, or a printing device such as a printer.

  FIG. 2 is a diagram schematically showing the configuration of the ultrasonic probe 202. As shown in FIG. 2, the ultrasonic probe 202 includes an ultrasonic transducer 100 and a holder 210 that houses the ultrasonic transducer 100. The holder 210 holds the ultrasonic transducer 100 so that the acoustic lens 170 is exposed on the surface of the ultrasonic probe 202. The FPC 120 of the ultrasonic transducer 100 is connected to a connector 211 disposed at the tip of the cable 203. In FIG. 2, a part of the configuration of the ultrasonic transducer 100 is omitted.

  FIG. 3 is a diagram for schematically showing the configuration of the ultrasonic transducer 100. The ultrasonic transducer 100 includes a backing layer 110, a flexible printed circuit board (FPC) 120, a piezoelectric body 130, grooves 140 and 141, a filler 150, an acoustic matching layer 160, an acoustic lens 170, and an adhesive layer 180.

  The backing layer 110 is an ultrasonic absorber that supports the piezoelectric body 130 and can absorb unnecessary ultrasonic waves. That is, the backing layer 110 is mounted on the surface (back surface) opposite to the direction in which ultrasonic waves are transmitted to and received from the subject in the piezoelectric body 130, for example, a living body, and absorbs ultrasonic waves generated on the opposite side of the direction of the subject. .

  Examples of the material of the backing layer 110 include a natural rubber, an epoxy resin, a thermoplastic resin, and a resin-based composite material obtained by press-molding a mixture of at least one of these materials and a powder of tungsten oxide, titanium oxide, ferrite, or the like. , Is included. Examples of the thermoplastic resin include vinyl chloride, polyvinyl butyral, ABS resin, polyurethane, polyvinyl alcohol, polyethylene, polypropylene, polyacetal, polyethylene terephthalate, fluororesin, polyethylene glycol, and polyethylene terephthalate-polyethylene glycol copolymer. included. Of these, resin-based composite materials, particularly rubber-based composite materials or epoxy resin-based composite materials are preferable. The shape of the backing layer 110 can be appropriately determined according to the planar shape of the piezoelectric body 130, the shape of the ultrasonic transducer 100, the ultrasonic probe 200 including the same, and the like.

  The FPC 120 includes, for example, a wiring having a pattern corresponding to a piezoelectric element described later, which is connected to a pair of electrodes for the piezoelectric body 130. For example, the FPC 120 includes a signal lead-out wiring that becomes one electrode and a ground lead-out wiring connected to the other electrode (not shown). The FPC 120 may be a commercially available product as long as it has the appropriate pattern described above.

  Examples of the material of the electrode include gold, platinum, silver, palladium, copper, aluminum, nickel, tin, and alloys containing these metal elements. For example, for the electrode, first, a base metal such as titanium or chromium is formed to a thickness of 0.002 to 1.0 μm by sputtering, and then the material is further partially coated with an insulating material as necessary. Further, it is produced by forming the film to a thickness of 0.02 to 10 μm by a sputtering method, a vapor deposition method or other suitable methods. The electrode can also be produced by forming a layer of the conductive paste by screen printing, dipping, or thermal spraying from a conductive paste in which a fine metal powder and low-melting glass are mixed.

  The backing layer 110 and the FPC 120 can be bonded with, for example, an adhesive (for example, an epoxy-based adhesive) that is usually used in the technical field.

  The piezoelectric body 130 is the piezoelectric body according to the present embodiment described above, and includes a quasicrystal. For example, the piezoelectric body 130 has the laminated structure described above, and the thickness of the piezoelectric body 130 is, for example, 0.05 to 0.4 mm. The piezoelectric body 130 is bonded to the FPC 120 with, for example, a conductive adhesive. The said electrically conductive adhesive is an adhesive agent containing electroconductive materials, such as silver powder, copper powder, and carbon fiber, for example.

  The groove 140 has a depth from the surface of the piezoelectric body 130 to the backing layer 110, and the groove 141 has a depth from the surface of the piezoelectric body 130 into the piezoelectric body 130. The groove 140 defines a main element of the piezoelectric element, and the groove 141 defines three subelements arranged in parallel in one main element. Each of the grooves 140 and 141 is formed by, for example, grooving with a dicing saw, and the width thereof is, for example, 15 to 30 μm.

  The pitch in the main element (distance between the centers of the grooves 140) is, for example, 0.15 to 0.30 mm, and the pitch in the sub element (distance between the centers of adjacent grooves (grooves 141 or 140)) is For example, it is 0.05-0.15 mm.

  Filler 150 fills grooves 140 and 141. Further, the filler 150 is also interposed between the piezoelectric body 130 and the acoustic matching layer 160, but the presence thereof is emphasized in FIG. 3, and between the piezoelectric body 130 and the acoustic matching layer 160, Actually, it exists in a thickness that functions as an adhesive for bonding the two.

  Examples of the material of the filler 150 include epoxy resin, silicone resin, polyethylene, polyurethane, natural rubber, and mixtures thereof. The said epoxy resin is comprised as hardened | cured material of the prepolymer composition containing the prepolymer of an epoxy resin, and the hardening | curing agent for forming a crosslinked network between the said prepolymers, for example.

  Examples of the prepolymer include phenol resins such as phenol novolak resin, cresol novolak resin, phenol aralkyl (including phenylene and biphenylene skeleton) resin, naphthol aralkyl resin, triphenolmethane resin, and dicyclopentadiene type phenol resin. .

  Examples of the curing agent include amine-based curing agents, and examples of the amine-based curing agent include ethylenediamine, triethylenediamine, hexamethylenediamine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)] Triazine compounds such as ethyl-s-triazine, 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), triethylenediamine, benzyldimethylamine, and triethanolamine.

  The filler 150 may further contain elastic resin particles. The elastic resin particles preferably have a reactive functional group on the surface thereof from the viewpoint of enhancing the durability of the filler 150. The reactive functional group may be a group having reactivity between reactive functional groups, or may be a group having reactivity to a specific molecular structure in the epoxy resin. Examples of the elastic resin particles include modified silicone rubber particles. Examples of the modified silicone rubber particles include particles having a silicone elastomer particle, a shell (eg, polysiloxane) covering the particle, and a reactive functional group disposed on the surface of the shell. .

  The content of the elastic resin particles in the prepolymer composition is appropriately determined according to the kind of the prepolymer and the curing agent, the expected volume elastic modulus of the epoxy resin, and the like. For example, if it is a modified silicone rubber particle The content of the prepolymer and the curing agent is 8 to 35% by mass.

  The filler 150 can be made from, for example, a commercially available resin composition containing the prepolymer, a curing agent, and elastic resin particles. Examples of the commercially available products include ALBIDUR EP2240A and ALBIDUR EP5340 (both manufactured by Evonik).

The acoustic matching layer 160 is a layer for matching the acoustic characteristics of the piezoelectric body 130 and an acoustic lens 170 described later. The acoustic matching layer 160 has an acoustic impedance Za (× 10 ⁶ kg / (m ² seconds)) approximately between the piezoelectric body 130 and the acoustic lens 170, and is located on the subject side (surface side) of the piezoelectric body 130. For example, it arrange | positions via the above-mentioned other electrode.

  The acoustic matching layer 160 may be a single layer or a stacked layer, but from the viewpoint of adjusting acoustic characteristics, the acoustic matching layer 160 is preferably a stacked body of a plurality of layers having different acoustic impedances, for example, two or more layers, more preferably four or more layers. is there. The thickness of the acoustic matching layer 160 is preferably λ / 4. λ is the wavelength of the ultrasonic wave. The acoustic matching layer 160 can be made of various materials, for example. The Za of the acoustic matching layer 160 is preferably set so as to approach the acoustic lens Za stepwise or continuously toward the acoustic lens. For example, the kind and content of the additive added to the material It is possible to adjust by.

  Examples of the material include aluminum, aluminum alloy (for example, Al—Mg alloy), magnesium alloy, macor glass, glass, fused quartz, copper graphite, and resin. Examples of the resin include polyethylene, polypropylene, polycarbonate, ABS resin, AAS resin, AES resin, nylon such as nylon 6 and nylon 66, polyphenylene oxide, polyphenylene sulfide, polyphenylene ether, polyether ether ketone, polyamideimide, polyethylene terephthalate. , Epoxy resins and urethane resins. Examples of the additive include zinc white, titanium oxide, silica and alumina, bengara, ferrite, tungsten oxide, yttrium oxide, barium sulfate, tungsten, molybdenum, glass fiber, and silicone particles.

  From the viewpoint of adjusting Za of the acoustic matching layer 160, for example, the surface portion of the acoustic matching layer 160 is preferably made of an epoxy resin and contains silicone particles. As will be described later, when silicone, which is a material of the acoustic lens 170, is dispersed in the base material of the acoustic matching layer 160, Za of the acoustic matching layer 160 can be brought close to that of the acoustic lens 170.

  Each layer of the acoustic matching layer 160 is bonded with, for example, an adhesive (for example, an epoxy-based adhesive) that is usually used in the technical field.

  The acoustic lens 170 is made of, for example, a soft polymer material having an intermediate Za between the subject and the acoustic matching layer 160. Examples of the polymer material include silicone rubber, butadiene rubber, polyurethane rubber, epichlorohydrin rubber, and ethylene-propylene copolymer rubber obtained by copolymerizing ethylene and propylene. Among these, the polymer material is preferably made of silicone rubber and butadiene rubber.

  Examples of the silicone rubber include silicone rubber and fluorine silicone rubber. In particular, silicone rubber is preferable from the viewpoint of the characteristics of the acoustic lens. The silicone rubber refers to an organopolysiloxane having a molecular skeleton composed of Si—O bonds, and having a plurality of organic groups mainly bonded to the Si atoms. Usually, the main component is methylpolysiloxane, and the whole Of these organic groups, 90% or more are methyl groups. In the silicone rubber, at least a part of the methyl group of the methylpolysiloxane may be replaced with a hydrogen atom, a phenyl group, a vinyl group, or an allyl group.

  The silicone rubber can be obtained, for example, by kneading a curing agent (vulcanizing agent) such as benzoyl peroxide in an organopolysiloxane having a high degree of polymerization, followed by heat vulcanization and curing. Depending on the purpose of adjusting the speed of sound and adjusting the density of the acoustic lens 170, an organic or inorganic filler such as silica or nylon powder, or a vulcanization aid such as sulfur or zinc oxide may be further added.

  Examples of the butadiene rubber include butadiene rubber, which is a homopolymer of butadiene, and copolymer rubber mainly composed of butadiene and copolymerized with a small amount of styrene or acrylonitrile. In particular, butadiene rubber is preferable from the viewpoint of the characteristics of the acoustic lens. The butadiene rubber refers to a synthetic rubber obtained by polymerization of butadiene having a conjugated double bond. Butadiene rubber can be obtained by polymerizing butadiene having a conjugated double bond alone at the 1,4-position or at the 1,2-position. The butadiene rubber may be further vulcanized with sulfur or the like.

  The acoustic lens 170 made of silicone rubber and butadiene rubber can be produced, for example, by mixing silicone rubber and butadiene rubber and curing them. For example, the acoustic lens 170 can be obtained by mixing silicone rubber and butadiene rubber at an appropriate ratio by a kneading roll, adding a vulcanizing agent such as benzoyl peroxide, and then heat-vulcanizing and crosslinking (curing). Can do.

  In the above case, it is preferable to further add zinc oxide as a vulcanization aid. Zinc oxide can accelerate vulcanization and shorten the vulcanization time without substantially impairing the lens characteristics of the acoustic lens 170. In addition, other additives may be added as long as the characteristics of the colorant and the acoustic lens are not impaired. The mixing ratio of the silicone rubber and the butadiene rubber can be set as appropriate. For example, the Za of the acoustic lens 170 is approximated to that of the subject, the sound speed in the acoustic lens 170 is smaller than that of the subject, and the attenuation of Za of the acoustic lens 170 is set to be smaller. Is preferred. From such a viewpoint, the mixing ratio of the silicone rubber and the butadiene rubber is preferably 1: 1.

  The adhesive layer 180 is a silicone adhesive layer. As described above, the acoustic lens 170 often includes silicone rubber. For this reason, it is preferable to configure the adhesive layer 180 with the silicone-based adhesive from the viewpoint of improving the adhesiveness between the acoustic matching layer 160 and the acoustic lens 170.

  The silicone-based adhesive is a curable compound or composition containing silicone as a base material. The silicone-based adhesive includes an additive for increasing the affinity for both the acoustic matching layer 160 and the acoustic lens 170, an additive for matching the acoustic characteristics of both the acoustic matching layer 160 and the acoustic lens 170, and the like. These various additives may be further contained.

The silicone-based adhesive may be a liquid rubber (RTV rubber) that cures at room temperature, or a liquid rubber that cures by heating. The silicone adhesive may be a one-pack type or a two-pack type. Examples of the silicone-based adhesive include KE-441, KE-445, KE-471W, KE-1600, KE-1604, KE-1884, KE-1885, KE-1886, KE-4895, KE-4896, KE-4897, KE-4898 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TN3005, TN3305, TN3705, TSE3976-B, ECS0600, and ECS0601 (all manufactured by Momentive Performance Materials Japan GK) Is included.

The adhesive force of the acoustic lens 170 to the acoustic matching layer 160 is determined according to the use of the ultrasonic transducer 100. For example, in the case of the ultrasonic transducer 100 for an ultrasonic diagnostic apparatus, the adhesive force is 0.5N. / Cm ² or more is preferable. From the viewpoint of expressing the adhesive force, the thickness of the adhesive layer 180 is preferably 0.5 μm or more, for example, and the ultrasonic transducer 100 is bonded from the viewpoint of expressing desired acoustic characteristics. It is preferable that the agent layer 180 is as thin as possible in the range in which the desired adhesive force is expressed.

The density of the adhesive layer 180 is preferably 1 g / cm ³ or more from the viewpoint of suppressing the reflection of ultrasonic waves at the adhesive layer 180. The density of the adhesive layer 180 can be determined by, for example, the Archimedes method, and is adjusted by, for example, the type of the silicone-based adhesive, the mixing of the filler into the silicone-based adhesive, the content of the filler, and the like. Is possible.

  The adhesive layer 180 preferably has a Za between the Za of the acoustic matching layer 160 and the Za of the acoustic lens 170 from the viewpoint of the acoustic characteristics of the ultrasonic transducer 100. By using a material having the same acoustic impedance as the Za of the acoustic matching layer 160 or the Za of the acoustic lens 170 as a part or all of the material of the adhesive layer 180, the Za of the acoustic matching layer 160 or the Za of the acoustic lens 170 It is possible to reduce the gap between the adhesive layer 180 and Za.

  The Za of the adhesive layer 180 may not be between the Za of the acoustic matching layer 160 and the Za of the acoustic lens 170. For example, the Za of the acoustic matching layer 160 may be 2.0 MRayls or less, the Za of the acoustic lens 170 may be 1.3 to 1.5 MRayls, and the Za of the adhesive layer 180 is 1.28 MRayls or less. It may be. Note that Za of the acoustic matching layer 160 is Za of the surface portion of the acoustic matching layer 160 (the surface forming the interface with the adhesive layer 180 in the acoustic matching layer 160 or a portion including the same).

  The absolute value of the difference between the Za of the acoustic matching layer 160 and the Za of the adhesive layer 180 may be 0.6 MRayls or more, and the difference between the Za of the acoustic lens 170 and the Za of the adhesive layer 180 may be The absolute value may be greater than or equal to 0.1 MRayls.

  Further, the sound velocity in the adhesive layer 180 may be 1000 m / second or less. The speed of sound in the adhesive layer 180 can be calculated from, for example, the time that a sound transmitted through a separately prepared test piece passes through the test piece, and can be calculated from the time. It is possible to adjust according to the kind, the mixing of the filler into the silicone-based adhesive, the content of the filler, and the like.

The Za of each of the acoustic matching layer 160, the acoustic lens 170, and the adhesive layer 180 is the acoustic velocity of the ultrasonic wave in the acoustic matching layer 160, the acoustic lens 170, or the adhesive layer 180 at 25 ° C. From the density of the lens 170 or the adhesive layer 180, it is obtained from the following formula. In the following formula, Za represents acoustic impedance (MRayls), ρ represents the density of the member or layer (× 10 ³ kg / m ³ ), and C represents the speed of sound (× 10 ³ m / sec). . The speed of sound of the ultrasonic waves is measured according to JISZ2353: 2003, for example, using a single-around sound speed measuring device manufactured by Ultrasonic Industry Co., Ltd.
Za = ρC

  Note that the ultrasonic transducer 100 may include a protective layer that seals portions other than the acoustic lens 170 in the ultrasonic transducer 100. The protective layer is, for example, a layer that integrally covers the acoustic matching layer 160 and the structure closer to the piezoelectric body 130 in the ultrasonic transducer 100. This is a layer for protecting the structure. The protective layer is preferably made of a material having physical and chemical stability. For example, the protective layer is made of a physically and chemically relatively stable resin such as an epoxy resin or polyparaxylylene. Can be done. The said protective layer is produced by the parylene coating mentioned above, for example.

  The thickness of the protective layer can be appropriately determined as long as the desired function is exhibited and the desired acoustic characteristics of the ultrasonic transducer 100 can be exhibited. The thickness of the protective layer is 2 to 4 μm, for example. With this thickness, even if the acoustic impedance of the protective layer is higher than that of the acoustic matching layer 160 and the acoustic lens 170, the desired acoustic characteristics of the ultrasonic transducer 100 can be sufficiently exhibited. It is.

  When the ultrasonic transducer 100 has the protective layer, the acoustic lens 170 is bonded to the protective layer via an adhesive layer 180. In this case, it is preferable that the total sum of the thickness of the adhesive layer 180 and the thickness of the protective layer is sufficiently thin as much as possible from the viewpoint of realizing the desired acoustic characteristics of the ultrasonic transducer 100.

  In the ultrasonic imaging apparatus 200, the control unit 205 receives a signal from the input unit 204 and outputs a signal for transmitting an ultrasonic wave (first ultrasonic signal) to a subject such as a living body to the transmission unit 206. The receiving unit 207 receives an electrical signal corresponding to the ultrasonic wave (second ultrasonic signal) coming from within the subject based on the first ultrasonic signal.

  The ultrasonic transducer 100 is used as the ultrasonic transducer of the ultrasonic probe 202. When ultrasonic waves are transmitted from the piezoelectric body 130, the ultrasonic waves are transmitted through the acoustic matching layer 160, the adhesive layer 180, and the acoustic lens 170, and are transmitted to a subject such as a human body. Then, the light is reflected within the subject, travels through the acoustic lens 170, the adhesive layer 180, and the acoustic matching layer 160 and is received by the piezoelectric body 130. For example, the received ultrasonic wave is converted by the piezoelectric body 130 into an electrical signal corresponding to the amplitude and frequency band. Since the piezoelectric body 130 includes a quasicrystal, both the piezoelectric constant and the specific band are high, and an ultrasonic component can be detected as a sharp main peak even in a broadband ultrasonic measurement.

  The electric signal received by the receiving unit 207 is sent to the image processing unit 208 and processed into an image signal corresponding to the electric signal. The image signal is sent to the display unit 209, and an image corresponding to the image signal is displayed on the display unit 209. The display unit 209 is also configured to display images and operations in accordance with the information input from the input unit 204 and sent via the control unit 205 (display of characters, movement and enlargement of displayed images, etc.). Is also displayed.

  As described above, the ultrasonic imaging apparatus 200 detects an electrical signal of an ultrasonic component as a sharp main peak even in a broadband ultrasonic measurement. Therefore, the ultrasonic imaging apparatus 200 can obtain a higher spatial resolution than the conventional ultrasonic imaging apparatus that does not include a quasicrystal in the piezoelectric body, and thus the measurement result is more accurate and more reliable. Can be obtained.

  The ultrasonic imaging apparatus 200 is applied to a medical ultrasonic diagnostic apparatus. In addition to this, the ultrasonic imaging apparatus 200 can be applied to an apparatus that displays an ultrasonic search result as an image or a numerical value, such as a fish finder (sonar) or a flaw detector for nondestructive inspection.

  As is clear from the above description, the piezoelectric body according to the present embodiment contains the quasicrystal. As described above, according to the piezoelectric body having the quasicrystal structure according to the present embodiment, it is possible to provide a piezoelectric body that has both a high piezoelectric constant and a high specific band and can be stably produced.

  It is even more effective from the viewpoint of improving both the piezoelectricity and the specific band of the piezoelectric body that the quasicrystal has one or more of 5, 8, 10 and 12 times of rotational symmetry in electron diffraction.

  In the piezoelectric body, the content of the quasicrystal of 30% by mass or more is more effective from the viewpoint of enabling control under manufacturing conditions and the viewpoint of increasing both piezoelectricity and specific bandwidth. It is.

  In addition, the fact that the piezoelectric body includes an inorganic piezoelectric body is more effective from the viewpoint of enhancing the sensitivity of the ultrasonic probe, that is, obtaining a deeper diagnostic image, and the piezoelectric body is an organic piezoelectric body. It is even more effective from the viewpoint of increasing the specific band of the ultrasonic probe, that is, obtaining an image having higher spatial resolution.

  In addition, it is more effective from the viewpoint of appropriately adjusting the structure and content of the quasicrystal that the piezoelectric body further includes a base layer for controlling the crystal structure of the piezoelectric body in contact with the piezoelectric body. It is.

  Further, in the method for manufacturing the piezoelectric body, the piezoelectric body is formed on the surface of the base layer for controlling the crystal structure of the piezoelectric body at a temperature of 700 ° C. or less to form a piezoelectric layer including the quasicrystal. Process. Therefore, according to the manufacturing method, it is possible to provide a piezoelectric body that has a high piezoelectric constant and a specific band and can be stably produced.

  In addition, the piezoelectric body includes an inorganic piezoelectric body, and in the film forming step, forming the piezoelectric body at 250 to 700 ° C. is an inorganic piezoelectric body in which both the piezoelectric constant and the specific band are increased. From the viewpoint of obtaining

  In addition, the piezoelectric body includes an organic piezoelectric body, and in the film forming step, forming the piezoelectric body at −50 to 300 ° C. is an organic piezoelectric having both a piezoelectric constant and a specific band increased. It is even more effective from the viewpoint of obtaining the body.

  In addition, the fact that the surface of the base layer is composed of a single crystal is more effective from the viewpoint of increasing the sensitivity of the ultrasonic probe, that is, obtaining a deeper diagnostic image. It is more effective from the viewpoint of increasing the specific band of the ultrasonic probe, that is, obtaining an image having higher spatial resolution.

  The manufacturing method further includes the step of disposing the base layer on the surface of the piezoelectric layer, and forming the piezoelectric body on the surface of the disposed base layer at a temperature of 700 ° C. or less, and including the quasicrystal. Further including the step of further forming a body layer on the base layer is more effective from the viewpoint of producing a thicker piezoelectric body or a piezoelectric body having an intended shape.

  In addition, it is more effective that the base layer is made of an organic compound from the viewpoint of manufacturing a thick or desired-shaped inorganic piezoelectric body.

  Moreover, the ultrasonic transducer according to the present embodiment has the above-described piezoelectric body, and the ultrasonic imaging apparatus according to the present embodiment has the above-described ultrasonic transducer. Therefore, high spatial resolution can be obtained in imaging by transmission / reception of ultrasonic waves, and in the case where a captured image such as an ultrasonic diagnostic apparatus is used for measurement, a measurement result with higher accuracy and higher reliability can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these.

[Example 1]
Radio frequency (RF) sputtering of platinum on a silicon single crystal substrate (thickness: 0.635 mm) gave a platinum thin film having a crystal orientation of (111) and a thickness of 260 nm. This platinum thin film was subjected to Ar ion reactive etching in an ultrahigh vacuum, and a clean 4 ° miscut platinum layer (hereinafter referred to as “4 ° miscut Pt (111)”) miscut at 4 ° was formed. A substrate having was obtained.

  On this substrate, an RF sputtering apparatus is used and a mixed pellet of lead titanate and lead magnesium niobate is used as a target. The substrate temperature is 260 ° C., the gas phase pressure is 10 Pa, the RF output is 90 W, the oxygen flow rate is 10 mL / min, and the Ar flow rate is 30 mL. The film was formed for 960 seconds under the conditions of / min. To obtain a 400 nm solid solution (PMN-PT) thin film of lead magnesium niobate and lead titanate.

  When this thin film was analyzed by STN, a Penrose pattern and a lattice point other than that were observed in the visual field, and PMN-PT corresponding to the former accounted for 56% by mass of the whole. When the thin film was analyzed with a low-energy electron beam diffraction image, 12 rotationally symmetric images were observed.

A platinum electrode was formed on this thin film, and the resulting platinum / PMN-PT / 4 ° miscut Pt (111) / silicon laminate was cut into strips and strips of the laminate (width 4 mm × length). 20 mm). Then, when the d ₃₁ piezoelectric constant and the specific band of the strip were measured using a laser displacement measuring device, the d ₃₁ piezoelectric constant was −5600 pm / V and the specific band was 116%.

  The laminate is processed by a known microelectromechanical system (MEMS) to produce an ultrasonic transducer composed of 192 cells of a circular diaphragm having a diameter of 42 μm, and an ultrasonic imaging having the ultrasonic transducer as a probe. Configured the device. When the phantom was observed at a transmission frequency of 25 MHz using the ultrasonic imaging apparatus, a spatial resolution of 60 μm was obtained at a depth of 45 mm.

[Example 2]
On the clean surface of a layer of strontium titanate single crystal having a crystal orientation of (100) doped with Nb (length 4 mm × width 4 mm × thickness 0.3 mm, hereinafter referred to as “STO”), lead oxide, titanium tetraisopropoxy A precursor solution of lead zirconate-lead titanate solid solution (PZT) obtained from a mixture of side, zirconium tetranormal propoxide and 2-methoxyethanol was spin-coated, 30 minutes at 180 ° C., 14 minutes at 410 ° C., Furthermore, it heated at 680 degreeC for 3 minute (s), and produced the PZT layer on the clean surface of the said single crystal.

  When the obtained PZT layer was analyzed by STN, a pattern in which pentagons and hexagons were closely packed and irregular lattice points were observed in the visual field, and the PZT corresponding to the former was It accounted for 34% by mass. When the PZT layer was analyzed with a low energy electron diffraction image, five rotationally symmetric images were observed.

A gold electrode was formed on the PZT surface of the PZT / STO laminate, and the resulting gold / PZT / STO laminate was cut into a strip to produce a strip (4 mm × 20 mm) of the laminate. Then, by measurement of the _{d 31} piezoelectric constant and the fractional bandwidth of the strip by using a laser displacement measuring device, _{respectively, d 31} piezoelectric constant is -1032pm / V, bandwidth ratio was 137%.

  Further, the laminate was processed by a known MEMS to produce an ultrasonic transducer composed of 192 cells of a circular diaphragm having a diameter of 60 μm, and an ultrasonic imaging apparatus having the ultrasonic transducer as a probe was configured. When the phantom was observed at a transmission frequency of 30 MHz using the ultrasonic imaging apparatus, a spatial resolution of 45 μm was obtained at a depth of 60 mm.

[Example 3]
An LB film of sodium octadecyl sulfonate was prepared on a quartz glass surface having an optically smooth surface. On the surface, xylylene diisocyanate and p-diaminobenzene were vapor deposited and added at 120 ° C. to form a 320 nm polyurea film. On this film, the lamination of the LB film and the polyurea film was repeated 30 times to obtain a laminated film having a total thickness of 10.2 μm.

  When this laminated film was analyzed by STN, a Penrose pattern and irregular lattice points were observed in the visual field, and polyurea corresponding to the former accounted for 94% by mass of the whole. When the laminated film was analyzed with a low-energy electron diffraction image, ten rotationally symmetric images were observed.

This laminated film is peeled off from quartz glass, gold electrodes are formed on both sides, and the obtained gold / the laminated film / gold laminated body is cut into a strip shape to obtain a strip (4 mm × 20 mm) of the laminated body. Produced. Then, when the d ₃₃ piezoelectric constant and the specific band of this strip were measured using a laser displacement measuring device, the d ₃₃ piezoelectric constant was 752 pm / V and the specific band was 520%.

  In addition, an ultrasonic imaging apparatus having a known machine process on the above-mentioned laminate, producing an ultrasonic transducer in which 96 μm × 4 mm strips are aligned in 96 directions in one direction, and having the ultrasonic transducer as a probe is provided. Configured. When the phantom was observed at a transmission frequency of 35 MHz using the ultrasonic imaging apparatus, a spatial resolution of 35 μm was obtained at a depth of 50 mm.

[Example 4]
On the quartz glass surface having an optical smooth surface, gold having a thickness of 150 A was formed with a (001) orientation plane (hereinafter referred to as “Au (001)”). On its surface, a polymer supramolecular liquid crystal composed of n-octylthiodicarboxylic acid, 2,6-diaminopyridine polycondensate and 4-n-octyl-4′-carboxybiphenyl was prepared. The polymer supramolecular liquid crystal is cooled to −20 ° C., and differential evacuation is performed so that a mixed gas of vinylidene fluoride (70% by volume) and chlorotrifluoroethylene (30% by volume) is 4 Pa in a vacuum chamber. The polymer supramolecular liquid crystal was irradiated with an electron beam to form a PVDF copolymer film.

  When this copolymer film was analyzed by STN, a pattern in which 4 to 6 hexagons were most closely packed in the visual field and irregular lattice points were observed, and PVDF corresponding to the former was It accounted for 32% by mass. When the copolymer film was analyzed with a low-energy electron diffraction image, eight rotationally symmetric images were observed.

A gold electrode is formed on the surface of the copolymer film opposite to the quartz glass, and the resulting gold / copolymer film / gold laminate is cut into strips. (4 mm × 20 mm) was produced. When the d ₃₁ piezoelectric constant and the specific band of this strip were measured using a laser displacement measuring device, the d ₃₁ piezoelectric constant was −480 pm / V and the specific band was 614%.

  The obtained copolymer film on the quartz glass substrate is processed by a known MEMS to produce an ultrasonic transducer comprising 192 cells of a circular diaphragm having a diameter of 84 μm, and a probe having the ultrasonic transducer The ultrasonic imaging apparatus is provided. When the phantom was observed at a transmission frequency of 25 MHz using the ultrasonic imaging apparatus, a spatial resolution of 60 μm was obtained at a depth of 120 mm.

[Example 5]
Using platinum having a crystal orientation plane of (111) as a substrate, barium titanate was deposited on the surface with a thickness of 120 nm at room temperature by magnetron sputtering under ultrahigh vacuum. The obtained barium titanate film was annealed at 977 ° C. for 10 seconds, 100 seconds, 1000 seconds, and 10,000 seconds, respectively.

  The barium titanate film obtained by annealing at any time gave a 12-fold rotational symmetry image by low energy electron diffraction. Thus, the formation of quasicrystals was observed. The proportion of the quasicrystal was almost constant regardless of the annealing time, and was 3.6% by mass on average.

The d ₃₁ piezoelectric constant and the specific band of the barium titanate film obtained by annealing for 1000 seconds in the preparation of the quasicrystal were measured with a laser displacement measuring device, and the d ₃₁ piezoelectric constant was −61 pm / V. The bandwidth was 56%.

  Further, the barium titanate film is processed by a known MEMS to produce an ultrasonic transducer composed of 192 cells of a circular diaphragm having a diameter of 42 μm, and an ultrasonic imaging apparatus included in a probe having the ultrasonic transducer is configured. did. When the phantom was observed at a transmission frequency of 25 MHz using the ultrasonic imaging apparatus, a spatial resolution of 260 μm was obtained at a depth of 60 mm.

  In the preparation of the quasicrystal, conditions for increasing the magnetron sputtering temperature to 850 ° C., barium titanate as another film forming means, molecular beam epitaxy in an oxygen atmosphere of barium oxide and titanium, and subsequent annealing temperature of 797 ° C. As a result, the quasicrystal generation ratio, the piezoelectric constant, the specific band, the depth as an ultrasonic imaging apparatus, and the spatial resolution performance are the above-described numerical values in this embodiment. It was almost the same.

[Comparative Example 1]
A barium titanate thin film was obtained in the same manner as in Example 5 except that the annealing step was omitted.

  The low-energy electron diffraction of this thin film showed a mixture of cubic and tetragonal crystals peculiar to perovskite and did not show a rotationally symmetric image. Thus, the formation of quasicrystals was not observed.

The d ₃₁ piezoelectric constant and the specific band of the barium titanate film were measured with a laser displacement measuring device. As a result, the d ₃₁ piezoelectric constant was −39 pm / V and the specific band was 49%.

  Using the barium titanate film, an ultrasonic imaging apparatus was configured in the same manner as in Example 5, and when a phantom was observed at a transmission frequency of 25 MHz, a target image of the phantom could not be obtained at a depth of 60 mm. A spatial resolution of 630 μm was obtained at a depth of 40 mm.

  In addition, the barium titanate thin film was manufactured under other conditions such as changing the magnetron sputtering temperature and applying film formation by molecular beam epitaxy as in Example 5 except that the annealing step was omitted. Formation of a quasicrystal was not recognized, and the piezoelectric constant, specific band, depth as an ultrasonic imaging device, and spatial resolution performance of the thin film were almost the same as the above-described numerical values in this comparative example.

[Comparative Example 2]
In Example 1, instead of the miscut platinum layer, a platinum (111) layer having no miscut is used for the platinum orientation surface, and the film formation temperature by RF sputtering is set to 760 ° C. Then, a PMN-PT film was formed. In the analysis of the obtained PMN-PT film by STN and the low energy electron diffraction pattern, a regular pattern and a rotationally symmetric image were not observed.

In the same manner as in Example 1, when the d ₃₁ piezoelectric constant and the specific band of the PMN-PT film were measured with a laser displacement measuring device, the d ₃₁ piezoelectric constant was 80 pm / V and the specific band was 34%. Met. Further, in the same manner as in Example 1, the PMN-PT film was processed by a known MEMS to produce an ultrasonic transducer consisting of 192 cells of a circular diaphragm having a diameter of 42 μm, and the ultrasonic transducer was used as a probe. The ultrasonic imaging apparatus which has is comprised. When the phantom was observed at a transmission frequency of 25 MHz using the ultrasonic imaging apparatus, a spatial resolution of 450 μm was obtained at a depth of 8 mm.

[Comparative Example 3]
An Au (001) film having a thickness of 150 mm was formed on a quartz glass surface having an optically smooth surface. A PVDF copolymer film was formed on the surface of the Au (001) film in the same manner as in Example 4. In the STN analysis and low-energy electron diffraction image of this copolymer film, neither a regular pattern nor a rotationally symmetric image was observed.

When the d ₃₁ piezoelectric constant and the specific band of the copolymer film were measured with a laser displacement measuring device in the same manner as in Example 4, the d ₃₁ piezoelectric constant was 4 pm / V and the specific band was 46%. there were. Further, in the same manner as in Example 4, the copolymer film was processed with a known MEMS to produce an ultrasonic transducer comprising 192 cells of a circular diaphragm having a diameter of 42 μm, and the array and the ultrasonic transducer were An ultrasonic imaging apparatus included in the probe was configured. When the phantom was observed at a transmission frequency of 25 MHz using the ultrasonic imaging apparatus, a spatial resolution of 360 μm was obtained at a depth of 6 mm.

  According to the present invention, a broadband and highly sensitive ultrasonic probe can be provided. Therefore, according to the present invention, further spread of the ultrasonic imaging apparatus is expected.

100 Ultrasonic transducer 110 Backing layer 120 Flexible printed circuit board (FPC)
DESCRIPTION OF SYMBOLS 130 Piezoelectric body 140, 141 Groove 150 Filler 160 Acoustic matching layer 170 Acoustic lens 180 Adhesive layer 200 Ultrasonic imaging apparatus 201 Apparatus main body 202 Ultrasonic probe 203 Cable 204 Input part 205 Control part 206 Transmission part 207 Reception part 208 Image processing unit 209 Display unit 210 Holder 211 Connector

Claims (15)

  Piezoelectric body with quasicrystal structure   The piezoelectric body according to claim 1, wherein the quasicrystal has one or more of 5, 8, 10 and 12 times rotational symmetry in electron beam diffraction.   3. The piezoelectric body according to claim 1, wherein a content of the quasicrystal is 30% by mass or more.   The piezoelectric body according to claim 1, comprising an inorganic piezoelectric body.   The piezoelectric body according to any one of claims 1 to 4, comprising an organic piezoelectric body.   The piezoelectric body according to claim 5, further comprising a base layer for controlling a crystal structure of the piezoelectric body in contact with the piezoelectric body.   A method for manufacturing a piezoelectric body, comprising: forming a piezoelectric body on a surface of a base layer for controlling a crystal structure of the piezoelectric body at a temperature of 700 ° C. or less to form a piezoelectric layer including the quasicrystal. The piezoelectric body includes an inorganic piezoelectric body,
The method for manufacturing a piezoelectric body according to claim 7, wherein the piezoelectric body is formed at 250 to 700 ° C. The piezoelectric body includes an organic piezoelectric body,
The method for manufacturing a piezoelectric body according to claim 7, wherein the piezoelectric body is formed at −50 to 300 ° C.   10. The method for manufacturing a piezoelectric body according to claim 7, wherein a surface of the base layer is made of a single crystal.   The surface of the said base layer is a manufacturing method of the piezoelectric material as described in any one of Claims 7-9 comprised by the arranged amphiphilic molecule | numerator. Further disposing the base layer on the surface of the piezoelectric layer;
Forming the piezoelectric body on the surface of the disposed base layer at 700 ° C. or less, and further forming a piezoelectric layer including the quasicrystal on the base layer;
The method for producing a piezoelectric body according to claim 7, further comprising:   The method for manufacturing a piezoelectric body according to claim 12, wherein the base layer is made of an organic compound.   The ultrasonic transducer which has the piezoelectric material as described in any one of Claims 1-6. An ultrasonic imaging apparatus comprising the ultrasonic transducer according to claim 14.

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