Piezoelectric material having a perovskite structure for high operating temperatures and its manufacturing process

Abstract

The present invention relates to a compound having a perovskite structure, which has a basic composition, the basic composition Ag x Bi y M z Fe v N w O3, where x + y + z = 0.9 to 1.1 and v + w = 0.9 to 1.1, M is selected from Pb and / or Ba, N is selected from Ti and / or Zr, and it can be used as a basic raw material for the production of perovskite materials having piezoelectric properties at high temperatures and functional ceramics. Furthermore, a process for producing a material having piezoelectric functionality is described, which guarantees consistent high product quality, provides advantages regarding safety, and enables production without using organic solvents. Furthermore, a piezoelectric device comprising the aforementioned perovskite material or a compound having a perovskite structure is described.

Description

【Technical Field】 【0001】 Description Technical Field The present invention relates to a composition having a perovskite structure that can be used as a starting material for manufacturing a perovskite functional ceramic having piezoelectric properties at high temperatures. 【0002】 In addition, a method for manufacturing a material containing a specific composition and a piezoelectric device containing the material are described. 【Background Art】 【0003】 Background Art Piezoelectric materials are characterized in that their electric polarization changes as a result of a mechanical action (piezoelectric effect), or the application of a voltage causes a change in the dimensions of the material or its mechanical operation (converse piezoelectric effect). Based on these functions, piezoelectric elements are widely used in many technical fields as both sensors and actuators in, for example, medical technology, sonar applications, ultrasonic technology, household appliances, mechanical engineering, the automotive industry, and aerospace. 【0004】 The state of the art describes a number of materials suitable as base materials for piezoelectrically active components. For example, German Patent No. 102019135245 B9 discloses a piezoelectric composition containing silver and an oxide, the oxide having a perovskite structure and being at least partially represented by the chemical formula x[Bi m FeO3]-y[Ba n TiO3]. 【0005】 The most common piezoelectric materials today are the ferroelectric crystal lead zirconate titanate Pb(Zr x Ti (1-x))It is manufactured based on O3(PZT), which usually has a perovskite structure like similar barium titanate. Perovskite refers to the general structural type of the closest-packed ionic structure ABX3, where A and B are cations and X is an anion. The distortion of the perovskite structure can cause polarization within the crystal lattice and thus dipole formation, which is the cause of the piezoelectric properties of many perovskites. For example, in lead zirconate titanate (PZT) below the Curie temperature (T c ), titanium ions in the ionic lattice move from their central positions, resulting in a dipole lattice with piezoelectric properties. 【0006】 However, the temperature range for using PZT is very limited. Permanently, and with a sufficient piezoelectric coefficient exceeding 50 pC / N (accompanied by a change in length along the electric field and the poling axis (longitudinal effect)) d 33 While maintaining, the maximum temperature at which PZT can be used is usually about 250 °C. 【0007】 To solve this problem, materials with improved piezoelectric functionality at high temperatures are described in International Publication No. WO 2019 / 243778 A1, U.S. Patent Application Publication No. 2013 / 0207020 A1, and U.S. Patent Application Publication No. 2018 / 0315916 A1, and perovskite materials (Bi a K 1-a )TiO 3-y BiFeO3 - PbTiO3 (or an alternative chemical formula notation where x + y + z = 1.0 and v + w = 1.0, K x Bi y Pb z Fe v Ti w O3) serve as the material base raw material. 【0008】 In International Publication No. WO 2019 / 243778 A1, U.S. Patent Application Publication No. 2013 / 0207020 A1, and U.S. Patent Application Publication No. 2018 / 0315916 A1, (Bi a K 1-a )TiO 3-yAs part of the production of BiFeO3-PbTiO3, in addition to Bi2O3, Fe2O3, and TiO2, PbO is weighed and mixed in as a lead component, and K2CO3 is mixed in as a potassium component. 【0009】 Potassium carbonate (K2CO3) is highly hygroscopic and has a water solubility of L=1120 g / l at 25°C, but alternative potassium compounds are also typically hygroscopic and water solubility (for example, at 25°C, KOH: L=1130 g / l, KNO3: L=316 g / l, K2C2O4: L=360 g / l, K2CO3: L=1120 g / l, and KCl: L=347 g / l). These properties pose significant challenges to the manufacturing processes of piezoelectric ceramic materials in the following aspects. 【0010】 The significant hygroscopicity of potassium compounds leads to constant absorption of humidity, making it difficult to accurately measure a consistent amount of reactant. This can have a particularly negative impact on product quality and the reproducibility of the manufacturing process unless controlled ambient conditions are guaranteed at considerable cost and effort. 【0011】 The high water solubility of potassium compounds also necessitates mixing with an anhydrous medium of organic liquid. The solvents used in U.S. Patent Application Publication 2013 / 0207020A1 and U.S. Patent Application Publication 2018 / 0315916A1, such as isopropyl alcohol, are flammable. Therefore, complex safety precautions are required, particularly with regard to upscaling the manufacturing process. Nevertheless, for environmental reasons in particular, it is desirable to minimize the use of organic solvents in the manufacturing process. 【0012】 European Patent Application Publication No. 3331840A1 describes a process in which the starting material is homogenized in an aqueous suspension and then subjected to spray-freeze granulation in order to prevent water-soluble components such as alkalis from dissolving during subsequent processing and separating during drying. However, in addition to the need for additional process steps, this process cannot minimize the inaccuracies in weighing the starting material. 【0013】 International Publication No. 2019 / 243778A1 describes dry mixing without a liquid medium. However, this process is associated with considerable drawbacks, as the hygroscopic properties of potassium compounds during supply and during actual dry mixing can lead to aggregation, resulting in an undesirable, non-uniform mixing distribution that can degrade the quality of the resulting material. [Overview of the project] [Problems that the invention aims to solve] 【0014】 Taking the above into consideration, the object of the present invention is therefore to provide compounds and materials that feature excellent piezoelectric functionality at high temperatures, while also being able to be supplied in high quality and in large quantities using a simple, cost-effective, and environmentally friendly process. [Means for solving the problem] 【0015】 Summary of the Invention Therefore, as a solution to the above problem, the present invention relates to the basic composition Ag x Bi y M z Fe v N w The present invention provides a compound having a perovskite structure, characterized by having O3, x+y+z=0.9~1.1 and v+w=0.9~1.1, M being selected from Pb and / or Ba, and N being selected from Ti and / or Zr. 【0016】 Furthermore, a piezoelectric material is provided, characterized by containing a perovskite material containing the aforementioned compound. 【0017】 Furthermore, the present invention provides a method for manufacturing the aforementioned materials having piezoelectric properties. Furthermore, a piezoelectric device is described comprising a piezoelectric ceramic body having preferably at least two electrodes, wherein the piezoelectric device includes the aforementioned compound having a perovskite structure or the aforementioned material having piezoelectric functionality. 【0018】 Advantageous embodiments of the present invention can be understood from the dependent claims and the following description. The present invention will be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawing] 【0019】 [Figure 1] An exemplary process for manufacturing a piezoelectric ceramic material according to the present invention is shown. [Figure 2A] This image shows a ceramic image of an exemplary sintered composition. [Figure 2B] This image shows a ceramic image of an exemplary sintered composition. [Modes for carrying out the invention] 【0020】 Detailed description of the invention The present invention and its advantages are described in more detail below with reference to preferred embodiments. 【0021】 In one embodiment, the present invention relates to a compound with a basic composition of Ag x Bi y M z Fe v N w The present invention relates to a compound having a perovskite structure, characterized by having O3, x+y+z=0.9~1.1 and v+w=0.9~1.1, M being Pb and / or Ba, preferably selected from Pb or Ba, and N being Ti and / or Zr, preferably selected from Ti or Zr. 【0022】 In preferred embodiments, M contains both Pb and Ba, so the compound has a basic composition Ag x Bi y (Pb, Ba) z Fe v N w It contains O3, and z is the total mass fraction of both metals in the basic composition. 【0023】 In a more preferred embodiment, M represents Pb, so the compound has the basic composition Agx Bi y Pb z Fe v N w has O3. 【0024】 Preferably, the sum of x, y, and z is 0.95 to 1.05, and the sum of v and w = 0.95 to 1.05. Particularly preferably, x + y + z = 1 and v + w = 1. Generally, x, y, z, v, and w are independent of each other and satisfy 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < v < 1, and 0 < w < 1. 【0025】 Silver compounds characterized by relatively low water solubility and non-hygroscopic properties have been found to be easy to handle and enable the production of materials with excellent piezoelectric properties at high temperatures. 【0026】 In a preferred embodiment, x, y, z, v, and w are 0.005 ≦ x ≦ 0.30 0.40 ≦ y ≦ 0.90 0.01 ≦ z ≦ 0.70 0.40 ≦ v ≦ 0.80 0.20 ≦ w ≦ 0.60 satisfy. 【0027】 In a more preferred embodiment, x, y, z, v, and w are 0.01 ≦ x ≦ 0.20 0.50 ≦ y ≦ 0.80 0.05 ≦ z ≦ 0.50 0.50 ≦ v ≦ 0.70 0.30 ≦ w ≦ 0.50 satisfy. 【0028】 <tmp> In a particularly preferred embodiment regarding the piezoelectric properties in the high temperature range (e.g., determined by T c and d 33 ) x, y, z, v, and w are 0.02 ≦ x ≦ 0.14 \(0.56 \leq y \leq 0.76\) 0.10 ≦ z ≦ 0.42 0.54 ≤ v ≤ 0.62 0.38 ≤ w ≤ 0.46 It satisfies the condition. 【0029】 Perovskites are characterized by having a general structural form of the close-packed ionic structure ABX3, where A and B represent cations and X represents anion. In this respect, the compounds according to the present invention are Ag and Bi (or Ag + and Bi 3+ It is preferable that ) occupies position A in the underlying perovskite basic structure ABO3. Furthermore, or alternatively, in the compounds according to the present invention, Fe and Ti or Zr (or Fe 3+ and Ti 4+ Or Zr 4+ It is preferable that ) occupies position B in the underlying perovskite basic structure ABO3. 【0030】 Typically, the compounds according to the present invention exhibit an orthorhombic / rhombohedral crystal structure. The Goldschmidt tolerance factor t defines the lower limit of the tolerance depending on the ionic radius for forming a perovskite structure (see VMGoldschmidt: Die Gesetze der Krystallochemie. In: Die Naturwissenschaften, Vol. 14, No. 21, 1926, pp. 477-485). This also makes it possible to estimate the degree of strain and to describe the ratio of bond lengths. Compounds according to the present invention preferably have a Goldschmidt perovskite structure tolerance factor t in the range of 0.820-0.880, more preferably in the range of 0.840-0.860. To calculate the Goldschmidt tolerance factor t according to the present invention, the effective ionic radius from RDShannon, "Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides," Acta Crystallography, A32, 1976, pp. 751-767 is used. 【0031】 In further embodiments, the present invention provides a piezoelectric material characterized by comprising a perovskite material containing the above-described compound having a perovskite structure. 【0032】 Preferably, the total amount of non-perovskite phase present in the material is less than 10% by weight, more preferably less than 8% by weight, more preferably less than 5% by weight, even more preferably less than 2% by weight, even more preferably less than 1% by weight, and most preferably less than 0.1% by weight. The amount of non-perovskite phase present in the ceramic may be trace amounts. 【0033】 The material is particularly preferably an X-ray-pure perovskite material that does not have an X-ray-detectable non-perovskite heterogeneity. 【0034】 Perovskite materials also have a basic composition of Ag, where x+y+z=0.9~1.1 and v+w=0.9~1.1. x Bi y M z Fe v N w In addition to O3, it may contain one or more perovskite phases. Further perovskite phases may have a rhombohedral or tetragonal crystal structure. Perovskite materials have a chemical formula (Bi) where 0.4 ≤ a ≤ 0.6 a K 1-a It is preferable that the perovskite phase containing TiO3 is not included. In a more preferred embodiment, the perovskite material does not contain potassium ions. 【0035】 In perovskite materials contained in the material, one or more of Ag, Bi, M, Fe, and N can be substituted by dopants to modify, for example, the Curie temperature and / or piezoelectric activity. 【0036】 The dopant may be added in appropriate amounts, for example, up to 2% by weight, preferably up to 1% by weight, and in embodiments up to 50 atomic%, or up to 20 atomic%, respectively. It is even more preferable that the dopant be added in an amount of at least 0.001% by weight, more preferably at least 0.005% by weight. The percentage by weight refers to the total weight of the perovskite material. 【0037】 The preferred dopant is a metal dopant. For example, a metal dopant functions as a substituent at position A in the underlying perovskite base structure ABO3, and can substitute for Ag and / or Bi, for example. Preferably, the metal dopant for position A is selected from the group consisting of Li, Na, Ca, Sr, Ba, and rare earth metals. Doping at position A with Li, Na, Ca, Sr, or Ba can reduce dielectric loss, modify (e.g., increase) the Curie point, and / or have a positive effect on the phase composition, while substitution with a rare earth metal (such as La or Nd) may improve piezoelectric activity. 【0038】 A metal dopant can be a metal dopant for the B position in the underlying perovskite base structure ABO3, and can substitute for, for example, Fe and / or Ti. 【0039】 A preferred dopant for position B can be selected from the group consisting of, for example, Ti, Zr, W, Nb, V, Ta, Mo, and Mn. The preferred metallic dopant for position B may have a higher valence than the substituted metal, thereby increasing the resistivity of the material and decreasing its conductivity. In a more preferred embodiment with respect to improvements in reducing insulation resistance and dielectric loss, the metallic dopant for position B is Mn. 【0040】 As described above, the material according to the present invention is characterized by advantageous piezoelectric functionality in a high-temperature range (i.e., at operating temperatures above 250°C, typically at least 500°C). 【0041】 Preferably, the material according to the present invention has a piezoelectric constant d greater than 50 pC / N, more preferably greater than 60 pC / N, and particularly preferably greater than 70 pC / N (with changes in length along the electric field and poling axis (longitudinal effect)) as determined in accordance with EN50324. 33 It has the piezoelectric constant d. 33 This ranges from 50 pC / N to 110 pC / N, for example, 60 to 100 pC / N. 【0042】 Furthermore, the material is suitable for permanent use at a maximum operating temperature of preferably at least 450°C, more preferably at least 500°C, and particularly preferably at least 550°C. 【0043】 Curie temperature T of functional ceramics which can be determined according to EN50324 c The temperature is preferably at least 500°C, and more preferably 550°C to 640°C. 【0044】 The absolute permittivity of a material and the permittivity of a vacuum (ε0 = 8.85·10) -12 The dielectric constant number ε, defined as the ratio of F / m, is preferably 100 to 500, for example, 180 to 340. 【0045】 The dielectric loss tanδ of the material, which can be determined by small-signal measurement, is preferably 0.05 or less, more preferably 0.04 or less, for example, 0.01 to 0.03. 【0046】 The present invention also relates to a process for manufacturing the above-mentioned materials having piezoelectric properties, (1) Mixing a combination of raw materials containing Ag, Bi, Pb and / or Ba, Fe, Ti, and O, and grinding the raw material combination as necessary. (2) A combination of mixed and optionally ground raw materials is heat-treated so that x+y+z=0.9~1.1 and v+w=0.9~1.1, and M is selected from Pb and / or Ba, with a basic composition of Ag x Bi y M z Fe vTi w To provide a perovskite material having O3 Includes. 【0047】 In a preferred embodiment, the combination of raw materials includes Ag, Bi, Pb, Ba, Fe, Ti, and O, such that M in the basic composition contains both Pb and Ba. In a more preferred embodiment, M is Pb only. 【0048】 The manufacturing process according to the present invention may include further process steps, as shown in Figure 1, for example. 【0049】 Generally, the process begins with the provision and weighing of raw materials (which may contain dopants). The starting materials are not particularly limited and may include oxides, carbonates, hydroxides, halides, or other salts of the metal used. Preferably, the combination of raw materials includes Bi2O3, Fe2O3, TiO2, and PbTiO3, as well as / or BaTiO3, and one or more compounds selected from Ag2O, AgF, AgCl, AgBr, AgI, AgNO3, AgCNO, AgN3, Ag2S, and AgOH. In relation to the advantageously low water solubility of the individual raw materials, the combination of raw materials includes Bi2O3, Fe2O3, TiO2, and PbTiO3, as well as / or BaTiO3, and one or more compounds selected from Ag2O, AgCl, AgBr, AgI, AgCNO, AgN3, Ag2S, and AgOH. In a particularly preferred embodiment, Ag2O is used as the silver-containing raw material (solubility in water at 25°C L = 0.025 g / l). The composition Ag is such that x + y + z = 0.9 ~ 1.1 and v + w = ​​0.9 ~ 1.1. x Bi y M z Fe v N w Other raw materials (such as metal oxides, e.g., WO3 or MoO3) can be added as needed, as long as they do not inhibit the formation of the perovskite structure containing O3. 【0050】 In contrast to known processes that rely on the use of raw materials with significant hygroscopic properties (such as potassium compounds), the process according to the present invention enables simple and consistently accurate weighing of raw materials and does not require any additional means (e.g., pre-drying and / or weighing in a protective gas atmosphere). 【0051】 The raw material combination is then mixed in a dry or liquid medium and ground as needed, thereby allowing the aqueous medium (e.g., water) to be advantageously used as the liquid mixing and / or grinding medium. By minimizing or eliminating the use of organic solvents, the environmental considerations of the process can be improved, particularly in upscaling the manufacturing process, and the requirements for occupational safety and laboratory safety can be reduced without compromising product quality and consistency. 【0052】 The calcination of mixed and optionally ground raw material combinations is such that x+y+z=0.9~1.1 and v+w=0.9~1.1, M is selected from Pb and / or Ba, and N is selected from Ti and / or Zr, with composition Ag x Bi y M z Fe v N w This enables the provision of perovskite materials containing O3. It should be noted that calcination can be performed either before or after grinding, and coarse grinding and ultrafine grinding processes may be intervened. The calcination conditions are not particularly limited and can be adjusted as appropriate by those skilled in the art. Calcination is usually performed at a temperature of over 600°C to about 900°C. 【0053】 Further processing of the resulting calcined product may be carried out according to known methods. For example, the calcined material can be slurried in a liquid (preferably aqueous) medium and formed into a foil, which may then be supplied to a multilayer process (including, for example, printing, lamination, bonding, and / or separation) before the material is sintered. Alternatively, the calcined material can be subjected to a "co-calcination" process in which, for example, as described in German Patent Application Publication No. 10234787 C1, a green electrode is provided on the foil, which is then laminated to form a piezoelectric element, and then sintered together with the internal electrode in a single process step. Another processing option is that the calcined material is slurried or plasticized in a liquid, preferably aqueous, medium, homogenized with a suitable binder, and then treated by spray granulation and subsequent compression molding before the molding material is sintered. Alternatively, the calcined material may be finely ground (as shown in Figure 1), then granulated, and then compression molded. 【0054】 The sintering conditions are not particularly limited and may be appropriately selected by those skilled in the art. Sintering is usually carried out at a temperature of at least 850°C, preferably 950°C or higher. 【0055】 Sintered materials may be subjected to mechanical treatment (including, for example, grinding and / or cutting), contact, polarization (for example, by applying a DC electric field of about 2 to 10 kV / mm at a temperature of 20 to 150°C), and electrical measurements in order to provide piezoelectric ceramic materials according to known methods. 【0056】 Further embodiments of the present invention relate to piezoelectric devices comprising a compound having the perovskite structure described above or a material having the piezoelectric functionality described above. 【0057】 A piezoelectric device may be a piezoelectric actuator, a piezoelectric sensor, or a piezoelectric transformer. Typically, a piezoelectric device includes a compound according to the present invention having a perovskite structure, or a material according to the present invention having piezoelectric functionality within a piezoelectric ceramic body, and at least two electrodes. 【0058】 Piezoelectric ceramic bodies may be designed as molded bodies (usually mechanically and hydraulically pressed) in the form of discs, plates, rods, hemispheres, or rings, for example. 【0059】 Piezoelectric materials and / or electrodes may be formed as a multilayer structure. A multilayer piezoelectric device may have multiple internal electrode layers and multiple piezoelectric layers, each electrode layer being alternately stacked or layered with its respective piezoelectric layer, and at least one of the multiple piezoelectric layers contains a compound having a perovskite structure according to the present invention or a material having piezoelectric functionality according to the present invention. Furthermore, such a multilayer structure may optionally include one or more additional layers such as buffer layers, substrate layers, conductive portions, and / or insulating layers. The thickness and area of ​​the piezoelectric layers, as well as the number of layers, may be selected depending on the intended use of the multilayer piezoelectric device. 【0060】 In further embodiments, the piezoelectric device may include, for example, a driver circuit, a current monitoring circuit, and switching means, as disclosed in German Patent Application Publication No. 102015101817A1. 【0061】 The application fields of piezoelectric devices according to the present invention are by no means limited and include ultrasonic cleaning, ultrasonic processing, sonar technology, sensor technology, actuator technology, material testing, medical diagnostics and treatment, the automotive industry, aerospace, mechanical engineering, building services, ignition systems, consumer electronics, and audio applications. [Examples] 【0062】 Examples According to the process steps schematically depicted in Figure 1, the perovskite composition Ag has x+y+z=0.9~1.1 and v+w=0.9~1.1. x Bi y Pb z Fe v Ti wVarious exemplary piezoelectric ceramics based on O3 were manufactured as test discs with dimensions of 6.5 mm × 1.0 mm (see Table 2). The individual compositions are shown in Table 1 below. 【0063】 [Table 1] 【0064】 For this purpose, the raw materials Ag2O, Bi2O3, PbTiO3, Fe2O3, and TiO2 were weighed, mixed, and ground in a 1L drum for 4 hours (in desalinated water, 4:1 mixture, ZrO2 ground beads). The particle size after grinding was d 10 =0.7μm, d 50 =1.5μm, and d 90 The particle size was determined using a laser particle size analyzer at 3.5 μm. The sample was dried at 120°C for 24 hours and granulated using a mesh sieve (500 μm). For calcination, the sample was packed into an Al2O3 crucible and calcined in air in a resistance furnace (200°C for 60 minutes, 750°C for 600 minutes, and 950°C for 180 minutes). The cooled sample was subjected to phase analysis via XRD, which allowed for the exclusion of the presence of non-perovskite heterogeneous phases. The calcined material was then placed in a 1 L drum (d 10 =0.7μm, d 50 =1.5μm, and d 90 The material is finely ground for 4 hours in a 3.5 μm particle, dried at 120°C for 24 hours, sieved using a mesh sieve (500 μm), and then subjected to 0.8 wt% PAF (bulk density d Bulk = 2.5 g / cm³ 3 Granulation occurred after the addition of ). A uniaxial dry press (pressure 34kN) produced granules with a diameter of 12mm, a height of 30mm, and a density of 5.2g / cm³. 3A round cylinder with a bulk density was obtained. The compressed body was then sintered according to the conditions listed in Table 1, crushed into a round shape (d=6.5 mm), and cut into discs (d=6.5 mm, h=1.0 mm) with a saw. For ceramic analysis, the sintered discs were crushed, polished, and heat-treated in a resistance furnace at 950°C for 2 hours. The particle size within the ceramic microstructure was imaged by optical microscopy and quantified by cross-sectional line measurement and Saltykov analysis (see Table 2). 【0065】 [Table 2] 【0066】 Figures 2a and 2b show examples of ceramic images of sintered samples B and C. Next, the samples were coated with Ag paste, fired at 850°C, cooled to room temperature, and then subjected to a polarization process (6.5kV / mm in oil at 25°C for 15 minutes). 【0067】 Polarizing materials (cylindrical cylinders with dimensions d=6.5mm and h=7.0mm) were investigated for their piezoelectric and dielectric properties using an impedance analyzer. The results are summarized in Table 3. 【0068】 [Table 3] 【0069】 The data shows that the material according to the present invention has the advantage of a high Curie temperature T c In addition to (550℃~650℃), a high piezoelectric constant d 33 This indicates that it has a value (higher than 70 pC / N). 【0070】 To estimate the maximum operating temperature, the thermal aging stability of exemplary ceramics was tested in a further series of tests. For this purpose, samples were aged at different temperature levels for 20 hours, starting at 300°C in each case, and at which aging temperature T AUntil then, the piezoelectric constant d of the sample (a cylinder with dimensions d=6.5mm and h=7.0mm) 33 It was determined whether the value was at least 60% of the initial value (determined at room temperature). The results of these aging tests are listed in Table 4. 【0071】 [Table 4] 【0072】 The obtained data demonstrates that the perovskite compound according to the present invention enables the provision of functional ceramics having excellent piezoelectric and dielectric properties at high temperatures.

Claims

[Claim 1] Basic composition Ag x Bi y M z Fe v N w O ３ The equation has x + y + z = 0.9 to 1.1 and v + w = ​​0.9 to 1.1, M is Pb, and N is selected from Ti and / or Zr. x, y, z, v, and w are ０．０１≦x≦０．２０ ０．５０≦y≦０．８０ ０．０５≦z≦０．５０ ０．５０≦v≦０．７０ ０．３０≦w≦０．５０ A compound having a perovskite structure, characterized by satisfying the following conditions. [Claim 2] x, y, z, v, and w are ０．０２≦x≦０．１４ ０．５６≦y≦０．７６ ０．１０≦z≦０．４２ ０．５４≦v≦０．６２ ０．３８≦w≦０．４６ A compound having the perovskite structure described in claim 1, satisfying the requirements. [Claim 3] Ag ＋ and Bi ３＋ occupy position A within the underlying perovskite basic structure ABO ３ A compound having the perovskite structure according to claim 1, wherein [Claim 4] Fe ３＋ and Ti ４＋ However, the basic perovskite structure ABO ３ A compound having the perovskite structure according to claim 1, occupying position B within the compound. [Claim 5] A piezoelectric material characterized in that the material comprises a perovskite material containing the compound described in claim 1. [Claim 6] The material according to claim 5, wherein the material comprises an X-ray-pure perovskite material that does not have an X-ray-detectable non-perovskite heterogene. [Claim 7] The perovskite material has a chemical formula (Bi) such that 0.4 ≤ a ≤ 0.6 a K １－a )TiO ３ The material according to claim 5, which does not contain a perovskite phase having the above. [Claim 8] The material according to claim 5, wherein the perovskite material is doped with manganese (Mn). [Claim 9] The material has a piezoelectric constant d greater than 50 pC / N (with respect to the electric field and the change in length along the Poling axis (longitudinal effect)) at an operating temperature of up to 500°C. ３３ The material according to claim 5, having the following characteristics. [Claim 10] A method for producing a piezoelectric material according to any one of claims 5 to 9, (1) Mixing a combination of raw materials containing Ag, Bi, Pb, Fe, Ti and / or Zr, and O, and optionally grinding the combination of raw materials, (2) The combination of mixed and optionally ground raw materials is heat-treated to obtain the composition Ag x Bi y M z Fe v N w O ３ The perovskite material having x + y + z = 0.9 to 1.1 and v + w = ​​0.9 to 1.1, where M is Pb and N is selected from Ti and / or Zr. x, y, z, v, and w are ０．０１≦x≦０．２０ ０．５０≦y≦０．８０ ０．０５≦z≦０．５０ ０．５０≦v≦０．７０ ０．３０≦w≦０．５０ To provide a perovskite material that satisfies the following conditions: Methods that include... [Claim 11] The method according to claim 10, wherein in step (1), an aqueous medium is used as a mixing and / or grinding medium. [Claim 12] The above combination of raw materials is Bi ２ O ３ Fe ２ O ３ , TiO ２ and / or ZrO ２ , as well as PbTiO3, and Ag ２ O, AgF, AgCl, AgBr, AgI, AgNO ３ AgCNO, AgN ３ Ag ２ The method according to claim 10, comprising one or more compounds selected from S and AgOH. [Claim 13] A piezoelectric device comprising a compound having a perovskite structure according to any one of claims 1 to 4, or a material having piezoelectric functionality according to any one of claims 5 to 9.

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