Dielectric substance, dielectric material, and capacitor

Abstract

To provide a dielectric substance having a high relative dielectric constant, and a suppressed variation in relative dielectric constant due to change in electric field.SOLUTION: A dielectric substance has a perovskite-type structure represented by ABX3. A represents an A-site located at a vertex position, B represents a B-site located at a body-centered position, and X represents an X-site located at a face-centered position. Atoms occupying the A-site include Bi, Li, and K. Atoms occupying the B-site include Ti. Atoms occupying the X-site include O.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a dielectric substance, a dielectric material, and a capacitor, and more particularly to a dielectric substance, a dielectric material containing the dielectric substance, and a capacitor including a dielectric layer containing the dielectric material. [Background technology]

[0002] Patent Document 1 describes a dielectric material such as (Bi,Na)TiO-BaTiO3 that exhibits a polarization twist, characterized in that the concentration of anion X-site vacancies introduced by A-site vacancies resulting from the absence of metals located at the A-sites of each vertex of a cubic or pseudocubic crystal having a perovskite structure ABX3 is 1% or less, and the anion octahedra present in the perovskite structure are arranged at an angle ω rotated relative to the crystal axis of the cubic or pseudocubic crystal, and both the angle ω and the polarization value change when an electric field is applied. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 004670 Summary of the Invention [Problem to be solved by the invention]

[0004] BaTiO3 is used as a dielectric material in capacitors and the like, and efforts are being made to improve the relative permittivity of the dielectric material as in Patent Document 1 in order to make capacitors smaller and with higher capacitance.

[0005] However, with the dielectric material described in Patent Document 1, it is difficult to increase the relative dielectric constant while suppressing the change in the relative dielectric constant due to a change in the electric field, and therefore it is difficult to apply it to capacitors.

[0006] An object of the present disclosure is to provide a dielectric substance having a high relative dielectric constant and in which changes in the relative dielectric constant due to changes in an electric field are suppressed, a dielectric material containing this dielectric substance, and a capacitor including a dielectric layer containing this dielectric material. [Means for solving the problem]

[0007] A dielectric material according to one embodiment of the present disclosure has a perovskite structure represented by ABX3. The A represents an A site at a vertex position, the B represents a B site at a body-centered position, and the X represents an X site at a face-centered position. Atoms occupying the A site include Bi, Li, and K. Atoms occupying the B site include Ti. Atoms occupying the X site include O.

[0008] A dielectric material according to one embodiment of the present disclosure contains the dielectric substance.

[0009] A capacitor according to one embodiment of the present disclosure includes a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode, the dielectric layer containing the dielectric material. [Effects of the Invention]

[0010] According to the present disclosure, there are provided a dielectric substance having a high relative dielectric constant and in which changes in the relative dielectric constant due to changes in an electric field are suppressed, a dielectric material containing this dielectric substance, and a capacitor having a dielectric layer containing this dielectric material. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing a unit cell of a perovskite structure. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a capacitor. [Figure 3] FIG. 3 is a field-polarization curve for sample A1 of Example 1. [Figure 4] FIG. 4 is a field-polarization curve for sample A2 of Example 1. [Figure 5] FIG. 5 is a field-polarization curve for sample A3 of Example 1. [Figure 6] FIG. 6 is a field-polarization curve for sample A4 of Example 1. [Figure 7] FIG. 7 is a field-polarization curve for sample A5 of Example 1. [Figure 8] FIG. 8 is a field-polarization curve for sample A6 of Example 1. [Figure 9] FIG. 9 is a field-polarization curve for sample A7 of Example 1. [Figure 10] FIG. 10 is a field-polarization curve for sample A8 of Example 1. [Figure 11] FIG. 11 is a field-polarization curve for sample A9 of Example 1. [Figure 12] FIG. 12 is a field-polarization curve for sample A10 of Example 1. [Figure 13] FIG. 13 is a field-polarization curve for sample A11 of Example 1. [Figure 14] FIG. 14 is a field-polarization curve for sample A12 of Example 1. [Figure 15] FIG. 15 is a field-polarization curve for sample A13 of Example 1. [Figure 16] FIG. 16 is a field-polarization curve for sample A14 of Example 1. [Figure 17] FIG. 17 is a field-polarization curve for sample A15 of Example 1. [Figure 18] FIG. 18 is a field-polarization curve for sample A16 of Example 1. [Figure 19] FIG. 19 is a field-polarization curve for sample A17 of Example 1. [Figure 20] FIG. 20 is a field-polarization curve for sample A18 of Example 1. [Figure 21] FIG. 21 is a field-polarization curve for sample A19 of Example 1. [Figure 22]FIG. 22 is a field-polarization curve for sample A20 of Example 1. [Figure 23] FIG. 23 is a field-polarization curve for sample A21 of Example 1. [Figure 24] FIG. 24 is a field-polarization curve for sample A22 of Example 1. [Figure 25] FIG. 25 is a field-polarization curve for sample A23 of Example 1. [Figure 26] FIG. 26 is a field-polarization curve for sample A24 of Example 1. [Figure 27] FIG. 27 is a field-polarization curve for sample A25 of Example 1. [Figure 28] FIG. 28 is a field-polarization curve for sample A26 of Example 1. [Figure 29] FIG. 29 is a field-polarization curve for sample A27 of Example 1. [Figure 30] FIG. 30 is the electric field-polarization curve for sample A28 of Example 1. [Figure 31] FIG. 31 is a field-polarization curve for sample A29 of Example 1. [Figure 32] FIG. 32 is a field-polarization curve for sample A30 of Example 1. [Figure 33] FIG. 33 is a field-polarization curve for sample A31 of Example 1. [Figure 34] FIG. 34 is a field-polarization curve for sample A32 of Example 1. [Figure 35] FIG. 35 is a field-polarization curve for sample A33 of Example 1. [Figure 36] FIG. 36 is a field-polarization curve for sample A34 of Example 1. [Figure 37] FIG. 37 is a field-polarization curve for sample A35 of Example 1. [Figure 38] FIG. 38 is a field-polarization curve for sample A36 of Example 1. [Figure 39]FIG. 39 is a field-polarization curve for sample A37 of Example 1. [Figure 40] FIG. 40 is the electric field-polarization curve for sample A38 of Example 1. [Figure 41] FIG. 41 is a graph showing the changes in effective relative permittivity and maximum polarization with respect to the changes in maximum electric field, based on Samples A4 to A10 of Example 1. [Figure 42] FIG. 42 is a graph showing the changes in effective relative permittivity and maximum polarization with respect to the changes in maximum electric field, based on Samples A11 to A17 of Example 1. [Figure 43] FIG. 43 is a graph showing the changes in effective relative permittivity and maximum polarization with respect to the changes in maximum electric field, based on Samples A18 to A24 of Example 1. [Figure 44] FIG. 44 is a graph showing the changes in effective relative permittivity and maximum polarization with respect to the changes in maximum electric field, based on samples A31 to A37 of Example 1. [Figure 45] FIG. 45 shows electric field-polarization curves for a sample in Example 1 where x in the composition formula of Bi1 / 2K(1-x) / 2Lix / 2TiO3 is 0.08. [Figure 46] FIG. 46 shows the electric field-polarization curve (hysteresis curve) for sample B1 of Example 1. [Figure 47] FIG. 47 is a graph of electric field versus current density for Sample B1 of Example 1. [Figure 48] FIG. 48 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B1 of Example 1. [Figure 49] FIG. 49 shows the second electric field-polarization curve (second unipolar characteristics) when an electric field from zero to the maximum is applied to sample B1 of Example 1. [Figure 50] FIG. 50 shows the electric field-polarization curve (hysteresis curve) for sample B2 of Example 1. [Figure 51] FIG. 51 is a graph of electric field versus current density for Sample B2 of Example 1. [Figure 52] FIG. 52 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B2 of Example 1. [Figure 53] FIG. 53 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B2 in Example 1. [Figure 54] FIG. 54 shows the electric field-polarization curve (hysteresis curve) for sample B3 of Example 1. [Figure 55] FIG. 55 is a graph of electric field versus current density for Sample B3 of Example 1. [Figure 56] FIG. 56 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B3 of Example 1. [Figure 57] FIG. 57 shows the second electric field-polarization curve (second unipolar characteristics) when an electric field from zero to the maximum is applied to sample B3 in Example 1. [Figure 58] FIG. 58 shows the electric field-polarization curve (hysteresis curve) for sample B4 of Example 1. [Figure 59] FIG. 59 is a graph of electric field versus current density for Sample B4 of Example 1. [Figure 60] FIG. 60 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B4 of Example 1. [Figure 61] FIG. 61 shows the second electric field-polarization curve (second unipolar characteristics) when an electric field from zero to the maximum is applied to sample B4 in Example 1. [Figure 62] FIG. 62 shows the electric field-polarization curve (hysteresis curve) for sample B5 of Example 1. [Figure 63] FIG. 63 is a graph of electric field versus current density for sample B5 of Example 1. [Figure 64]FIG. 64 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B5 of Example 1. [Figure 65] FIG. 65 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B5 in Example 1. [Figure 66] FIG. 66 shows the electric field-polarization curve (hysteresis curve) for sample B6 of Example 1. [Figure 67] FIG. 67 is a graph of electric field versus current density for sample B6 of Example 1. [Figure 68] FIG. 68 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B6 of Example 1. [Figure 69] FIG. 69 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B6 in Example 1. [Figure 70] FIG. 70 shows the electric field-polarization curve (hysteresis curve) for sample B7 of Example 1. [Figure 71] FIG. 71 is a graph of electric field versus current density for sample B7 of Example 1. [Figure 72] FIG. 72 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B7 of Example 1. [Figure 73] FIG. 73 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B7 in Example 1. [Figure 74] FIG. 74 shows the electric field-polarization curve (hysteresis curve) for sample B8 of Example 1. [Figure 75] FIG. 75 is a graph of electric field versus current density for sample B8 of Example 1. [Figure 76] FIG. 76 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B8 of Example 1. [Figure 77] FIG. 77 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B8 in Example 1. [Figure 78] FIG. 78 shows the electric field-polarization curve (hysteresis curve) for sample B9 of Example 1. [Figure 79] FIG. 79 is a graph of electric field versus current density for sample B9 of Example 1. [Figure 80] FIG. 80 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B9 of Example 1. [Figure 81] FIG. 81 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B9 of Example 1. [Figure 82] FIG. 82 shows the electric field-polarization curve (hysteresis curve) for sample B10 of Example 1. [Figure 83] FIG. 83 is a graph of electric field-current density for sample B10 of Example 1. [Figure 84] FIG. 84 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B10 of Example 1. [Figure 85] FIG. 85 shows the second electric field-polarization curve (second unipolar characteristics) when an electric field from zero to the maximum is applied to sample B10 in Example 1. [Figure 86] FIG. 86 shows the electric field-polarization curve (hysteresis curve) for sample B11 of Example 1. [Figure 87] FIG. 87 is a graph of electric field-current density for Sample B11 of Example 1. [Figure 88] FIG. 88 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B11 of Example 1. [Figure 89]FIG. 89 shows the second electric field-polarization curve (second unipolar characteristics) when an electric field from zero to the maximum is applied to sample B11 of Example 1. [Figure 90] FIG. 90 shows the electric field-polarization curve (hysteresis curve) for sample B12 of Example 1. [Figure 91] FIG. 91 is a graph of electric field versus current density for sample B12 of Example 1. [Figure 92] FIG. 92 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample B12 in Example 1. [Figure 93] FIG. 93 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample B12 in Example 1. [Figure 94] FIG. 94 is a graph showing leakage current versus electric field for sample BKLT-Ca20, sample BKLT-Sr20, and sample BNT-BT in Example 1. [Figure 95] FIG. 95 is a semi-logarithmic graph showing leakage current versus electric field for sample BKLT-Ca20 in Example 1. [Figure 96] FIG. 96 is a semi-logarithmic graph showing leakage current versus electric field for sample BKLT-Sr20 in Example 1. [Figure 97] FIG. 97 is a field-polarization curve for sample C1 of Example 2. [Figure 98] FIG. 98 is the electric field-polarization curve for sample C17 of Example 2. [Figure 99] FIG. 99 is the electric field-polarization curve for sample C23 of Example 2. [Figure 100] FIG. 100 is a graph showing the change in effective relative dielectric constant with respect to the change in maximum electric field, based on samples C2 to C9 of Example 2. [Figure 101] FIG. 101 is a graph showing the change in effective relative dielectric constant with respect to the change in maximum electric field, based on samples C10 to C18 of Example 2. [Figure 102] FIG. 102 is a graph showing the change in effective relative dielectric constant with respect to the change in maximum electric field, based on samples C19 to C27 of Example 2. [Figure 103] FIG. 103 shows the electric field-polarization curve (hysteresis curve) for sample D1 of Example 2. [Figure 104] FIG. 104 is a graph of electric field versus current density for sample D1 of Example 2. [Figure 105] FIG. 105 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample D1 of Example 2. [Figure 106] FIG. 106 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample D1 of Example 2. [Figure 107] FIG. 107 shows the electric field-polarization curve (hysteresis curve) for sample D2 of Example 2. [Figure 108] FIG. 108 is a graph of electric field versus current density for sample D2 of Example 2. [Figure 109] FIG. 109 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample D2 of Example 2. [Figure 110] FIG. 110 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample D2 of Example 2. [Figure 111] FIG. 111 shows the electric field-polarization curve (hysteresis curve) for sample D3 of Example 2. [Figure 112] FIG. 112 is a graph of electric field versus current density for sample D3 of Example 2. [Figure 113] FIG. 113 shows the first electric field-polarization curve (first unipolar characteristic) when an electric field from zero to the maximum is applied to sample D3 of Example 2. [Figure 114]FIG. 114 shows the second electric field-polarization curve (second unipolar characteristic) when an electric field from zero to the maximum is applied to sample D3 of Example 2. [Figure 115] FIG. 115 is the electric field-polarization curve for sample E1 of Example 3. [Figure 116] FIG. 116 is a graph of the electric field-polarization curve (hysteresis curve) and electric field-current density for sample E1 of Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Overview Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. The following embodiments are merely some of the various embodiments of the present disclosure, and various modifications are possible depending on the design as long as the object of the present disclosure can be achieved. All figures referenced below are schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. Although the mechanism of action related to the embodiments may be described below, the description of the mechanism of action may be based on speculation, and the present disclosure is not bound by the description of the mechanism of action below.

[0013] In the following description, a dielectric substance refers to a single substance that is a dielectric. A single substance may include a solid solution, i.e., two or more substances that are dissolved together to form a uniform solid phase. A dielectric material is a material that contains a dielectric substance. A dielectric material may contain only the dielectric substance according to the present disclosure, or may contain the dielectric substance according to the present disclosure and other substances. In the following description, atoms may include charged atoms, i.e., ions.

[0014] The dielectric material of the embodiment has a perovskite structure represented by ABX3. The A represents an A site at a vertex position, the B represents a B site at a body-centered position, and the X represents an X site at a face-centered position. Atoms occupying the A site include Bi, Li, and K. Atoms occupying the B site include Ti. Atoms occupying the X site include O.

[0015] The dielectric material of embodiments may have a high dielectric constant.

[0016] Furthermore, dielectrics such as (Bi,Na)TiO—BaTiO described in Patent Document 1 have ferrielectricity and can have a high relative dielectric constant, but the relative dielectric constant changes significantly depending on the change in electric field, and the dielectric constant can be high only within a narrow electric field range.

[0017] In contrast, the dielectric material of the embodiment exhibits only a small change in relative permittivity even when the electric field is changed, and therefore the dielectric material of the embodiment can be effectively applied to the dielectric layer 4 of the capacitor 1.

[0018] The dielectric constant of a dielectric material can be evaluated by its effective dielectric constant. The effective dielectric constant is calculated by measuring the polarization (dielectric polarization moment) of a dielectric material under an electric field sweep, deriving stored energy from the electric field (electric field)-polarization (dielectric polarization moment) curve (hereinafter also referred to as a PE curve) obtained thereby, and then using this stored energy. The higher the effective dielectric constant, the higher the dielectric constant of the dielectric material is evaluated to be. Furthermore, the degree of change in the dielectric constant in response to a change in the electric field can be evaluated by the degree of change in the effective dielectric constant when the sweep range of the electric field is changed. The smaller the degree of change in the effective dielectric constant, the smaller the degree of change in the dielectric constant in response to a change in the electric field is evaluated to be.

[0019] The perovskite structure is shown in Figure 1. The dielectric material of the embodiment may be a tetragonal crystal or a pseudo-tetragonal crystal that is slightly distorted from a tetragonal crystal. The dielectric material of the embodiment may be capable of undergoing phase transition.

[0020] In the dielectric substance of the embodiment, atoms occupying the X sites at the face-center positions include O as described above. The atoms occupying the X sites are, for example, only O. "Only O" means that no atoms other than O are observed occupying the X sites.

[0021] In the dielectric material of the embodiment, atoms occupying the A sites at the vertices include Bi, Li, and K as described above.

[0022] The occupancy rate of Bi in the A site is preferably 35% or more and 50% or less. In this case, there is an advantage that a large polarization value can be obtained when an electric field is applied to the dielectric material. This is presumably because Bi has lone pairs of electrons. It is more preferable for this occupancy rate to be 40% or less.

[0023] The occupancy of Li in the A site is preferably greater than 0% and not more than 6%. This has the advantage that a high relative permittivity can be maintained even when an electric field is repeatedly applied to the dielectric material. This is presumably because the dielectric material can stably maintain a structure of the space group P4bm before and after the application of the electric field. This occupancy is more preferably 5% or less, and even more preferably 4% or less.

[0024] The occupancy of K in the A site is preferably 29% or more and 50% or less. In this case, there is an advantage that a high relative permittivity can be maintained even when an electric field is repeatedly applied to the dielectric material. This is presumably because the dielectric material can stably maintain a structure of the space group P4bm before and after the application of the electric field. This occupancy is more preferably 46% or less, and even more preferably 34% or less.

[0025] The occupancy rate of Bi in the A site may be 50% or less, the occupancy rate of K in the A site may be 50% or less, and the occupancy rate of Li in the A site may be more than 0% and 6% or less, and further the atoms contained in the A site may be only Bi, Li, and K.

[0026] The A site may further contain a vacancy (vacancy site). In this case, the dielectric material may have a higher relative permittivity. This is presumably because the dielectric material is likely to have a structure of the space group P4bm, and in this case, the dielectric material may exhibit ferrielectricity. When a vacancy is contained in the A site, the occupancy of the vacancy in the A site is preferably more than 0.0% and not more than 2.5%. This occupancy is more preferably 0.5% or more, and even more preferably 1.0% or more.

[0027] The atoms occupying the A site may further include a divalent metal ion. In this case, the dielectric constant of the dielectric material may be further increased. This is presumably because the rotational tolerance of the oxygen octahedron in the crystal structure of the dielectric material increases, making it more likely to have a P4bm structure. The divalent metal ion may include, for example, at least one selected from the group consisting of Ba, Ca, and Sr.

[0028] When divalent metal ions are present in the A site, the occupancy of the divalent metal ions in the A site is preferably greater than 0.0% and not greater than 30%. This occupancy is more preferably 10% or greater, and even more preferably 15% or greater. This occupancy is more preferably 25% or less, and even more preferably 20% or less.

[0029] The atoms occupying the A site may further contain Ag. In this case, the dielectric material can still have a high relative permittivity. The advantage of Ag is that it can be used in material design by simply substituting monovalent atoms without reducing the amount of Bi with lone pairs. Since Bi is not reduced, greater polarization can be expected. Furthermore, by substituting with K, the average ionic radius of A can be reduced. Furthermore, sintering is relatively easy. When Ag is included among the atoms occupying the A site, it is preferable that the occupancy of Ag in the A site is greater than 0.0% and not more than 15%.

[0030] In the dielectric material of the embodiment, the atoms occupying the body-centered B site include Ti as described above.

[0031] The occupancy rate of Ti in the B site is preferably 98% or more and 100% or less. In this case, there is an advantage that it is easy to obtain a perovskite structure contained in the dielectric material. This occupancy rate is more preferably 99.9% or more.

[0032] The atoms occupying the B site may further include at least one element selected from the group consisting of Cu and Mn. In this case, when the dielectric material of the embodiment is applied to the capacitor 1, leakage current can be suppressed. This is presumably due to charge compensation to the B site. The total occupancy of Cu and the like in the B site is preferably 0.001% or more and 1% or less. This occupancy is more preferably 0.1% or more.

[0033] The atoms occupying the B site may further contain Nb. In this case, the dielectric material can also have a high relative permittivity. It is believed that the inclusion of Nb can increase the ionic radius of the B site, thereby increasing the rotation tolerance of the crystal. When Nb is included in the atoms occupying the B site, it is preferable that the occupancy rate of Nb in the B site is more than 0% and 2% or less.

[0034] The dielectric material of the embodiment contains the dielectric substance of the embodiment. The dielectric material may contain only the dielectric substance of the embodiment. The dielectric material may contain the dielectric substance of the embodiment and a substance other than the dielectric substance of the embodiment. The substance other than the dielectric substance of the embodiment is, for example, at least one selected from the group consisting of a dielectric substance other than the dielectric substance of the embodiment, a by-product produced simultaneously when producing the dielectric substance of the embodiment, and an appropriate additive.

[0035] As shown in FIG. 2, the capacitor 1 of the embodiment includes a first electrode 2, a second electrode 3, and a dielectric layer 4 interposed between the first electrode 2 and the second electrode 3. The dielectric layer 4 contains the dielectric material of the embodiment. The dielectric layer 4 is, for example, a sintered body of the dielectric material. There are no particular limitations on the materials of the first electrode 2 and the second electrode 3, as long as they are conductive.

[0036] 2. Dielectric Material Embodiments More specific embodiments of the dielectric material will be described below.

[0037] 2.1. First embodiment The dielectric material of the first embodiment is Bi 1 / 2 K (1-x) / 2 Li x / 2 The composition formula is TiO3. This dielectric material is (1-x)Bi 1 / 2 K 1 / 2 TiO3-xBi 1 / 2 Li 1 / 2 This dielectric material is also expressed as TiO3. 1 / 2 K 1 / 2 TiO3 and Bi 1 / 2 Li 1 / 2 It can be considered as a solid solution containing TiO3 in the ratio (1-x):x.

[0038] In the composition formula, x is preferably greater than 0 and less than or equal to 0.2. In this case, the dielectric material can have a higher relative dielectric constant, and the change in relative dielectric constant due to changes in the electric field can be more suppressed. One of the reasons for this is presumably that the dielectric material is likely to have a structure of the space group P4bm, which makes it more likely to exhibit ferrielectricity, and that even if a phase transition occurs when an electric field is applied to the dielectric material, the phase transition is reversible, i.e., the material easily returns to the state before the phase transition when the electric field is removed. x is more preferably 0.08 or more, and even more preferably 0.10 or more. x is more preferably 0.11 or less.

[0039] 2.2. Second embodiment The dielectric material of the second embodiment is Bi (1+δ) / 2 K (1-x)(1-3δ) / 2 Li x(1-3δ) / 2 □ δ It is expressed by the composition formula TiO3.

[0040] □ represents a vacancy at the A site (vacancy site).

[0041] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0042] In the composition formula, δ is preferably greater than 0.0 and less than or equal to 0.025. In this case, the dielectric material can have a higher relative dielectric constant. This is presumably because the dielectric material is likely to have a structure of the space group P4bm, in which case the dielectric material can exhibit ferrielectricity. δ is more preferably 0.005 or more, and even more preferably 0.01 or more. δ is more preferably 0.02 or less.

[0043] The first embodiment can be said to be the case where δ is 0 in the second embodiment.

[0044] 2.3. Third embodiment The dielectric material of the third embodiment is Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 M y It is expressed by the composition formula TiO3.

[0045] In this formula, M is a divalent metal ion.

[0046] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0047] In the composition formula, y is preferably greater than 0.0 and less than or equal to 0.3. In this case, the dielectric material can have a higher relative permittivity. This is presumably because the reduction in the average ionic radius in the crystal structure increases the rotational tolerance of oxygen octahedra, stabilizing the ferrielectric phase, which is a crystal structure with rotation of oxygen octahedra. y is more preferably 0.1 or greater, and even more preferably 0.15 or greater. y is more preferably 0.25 or less, and even more preferably 0.2 or less.

[0048] The divalent metal ion preferably includes at least one selected from the group consisting of Ba, Ca, and Sr. That is, M in the composition formula preferably includes at least one selected from the group consisting of Ba, Ca, and Sr.

[0049] The dielectric material of the third embodiment is, for example, Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Ba y The composition formula of TiO3 is Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Ca y The composition formula of TiO3, or Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Sr y The composition formula of TiO3 is In each composition formula, the preferred range of x and the reasons therefor are the same as those in the first embodiment. The preferred range of y and the reasons therefor are the same as those in the third embodiment.

[0050] The first embodiment can be said to be the case where y is 0 in the third embodiment.

[0051] 2.4. Fourth embodiment The dielectric material of the fourth embodiment is Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ M y It is expressed by the composition formula TiO3.

[0052] In this composition formula, □ represents a vacancy (vacancy site), and M represents a divalent metal ion.

[0053] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0054] The preferred range of y in the composition formula and the reasons for it are the same as those in the third embodiment.

[0055] The preferred range of δ in the composition formula and the reasons for it are the same as those in the second embodiment.

[0056] The divalent metal ion preferably includes at least one selected from the group consisting of Ba, Ca, and Sr. That is, M in the composition formula preferably includes at least one selected from the group consisting of Ba, Ca, and Sr.

[0057] The dielectric material of the fourth embodiment is, for example, Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Ba y The composition formula of TiO3 is Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Ca y The composition formula of TiO3, or Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Sr y The composition formula of TiO3 is In each composition formula, the preferred ranges of x, y, and δ and the reasons for these are as described above.

[0058] The first embodiment can be said to be the third embodiment in which y is 0 and δ is 0. The second embodiment can be said to be the fourth embodiment in which y is 0. The third embodiment can be said to be the fourth embodiment in which δ is 0.

[0059] 2.5. Fifth Embodiment The dielectric material of the fifth embodiment is Bi (1+δ) / 2 K (1-p-x)(1-3δ) / 2 Li x(1-3δ) / 2 Ag p(1-3δ) / 2 □ δ It is expressed by the composition formula TiO3.

[0060] In this composition formula, □ represents a vacancy (vacancy site).

[0061] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0062] The preferred range of δ in the composition formula and the reasons for it are the same as those in the second embodiment.

[0063] In the composition formula, p is preferably greater than 0.0 and equal to or less than 0.3, in which case the dielectric substance can have a high relative dielectric constant.

[0064] 2.6. Sixth Embodiment The dielectric material of the sixth embodiment is Bi (1-q)(1+δ) / 2 K (1-q)(1-x)(1-3δ) / 2 Li (x(1-q)(1-3δ) / 2)+q □ δ Ti (1-q) Nb q It is represented by the formula O3.

[0065] In this composition formula, □ represents a vacancy (vacancy site).

[0066] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0067] The preferred range of δ in the composition formula and the reasons for it are the same as those in the second embodiment.

[0068] In the composition formula, q is preferably greater than 0.0 and equal to or less than 0.02, in which case the dielectric substance can have a high relative dielectric constant.

[0069] 2.7. Seventh Embodiment In the seventh embodiment, in each of the first to sixth embodiments, a portion of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn. That is, in each of the composition formulas in the first to sixth embodiments, a portion of Ti is substituted with at least one selected from the group consisting of Cu and Mn. In this case, when the dielectric substance is applied to the dielectric layer 4 of the capacitor 1, leakage current in the dielectric layer 4 can be suppressed.

[0070] In the first embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi1 / 2 K (1-x) / 2 Li x / 2 Ti 1-z R z It is represented by the formula O3.

[0071] In the second embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi (1+δ) / 2 K (1-x)(1-3δ) / 2 Li x(1-3δ) / 2 □ δ Ti 1-z R z It is represented by the formula O3.

[0072] In the third embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 M y Ti 1-z R z It is represented by the formula O3.

[0073] In the fourth embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ M y Ti 1-z R z It is represented by the formula O3.

[0074] In the fifth embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi (1+δ) / 2 K (1-p-x)(1-3δ) / 2 Li x(1-3δ) / 2 Ag p(1-3δ) / 2 □ δ Ti 1-z R z It is represented by the formula O3.

[0075] In the sixth embodiment, when a part of the atoms (Ti) occupying the B site is substituted with at least one selected from the group consisting of Cu and Mn, the dielectric substance is, for example, Bi (1-q)(1+δ) / 2 K (1-q)(1-x)(1-3δ) / 2 Li (x(1-q)(1-3δ) / 2)+q □ δ Ti (1-q-z) Nb q R z It is represented by the formula O3.

[0076] In each composition formula, R is at least one selected from the group consisting of Cu and Mn. In each composition formula, z is preferably 0.0001 or more and 0.01 or less. It is more preferable that z is 0.001 or more.

[0077] 2.8. Variations In the first to seventh embodiments, a portion of the atoms occupying the A site may be substituted with atoms other than Bi, Li, divalent metal ions, and Ag, or with vacancies, within the scope of the present disclosure. Similarly, a portion of the atoms occupying the B site may be substituted with atoms other than Ti and Nb, or with vacancies. Similarly, a portion of the atoms (O) occupying the X site may be substituted with atoms other than O, or with vacancies, within the scope of the present disclosure.

[0078] 3. Dielectric substance and method for manufacturing dielectric material A method for making a dielectric material and a dielectric material containing the dielectric material is described.

[0079] As raw materials, a compound containing atoms occupying the A site (hereinafter also referred to as a first type raw material) and a compound containing atoms occupying the B site (hereinafter also referred to as a second type raw material) are prepared.

[0080] The first source material includes, for example, a compound selected from the group consisting of oxides and carbonates of atoms occupying the A site. The first source material includes a Bi-containing source material, a K-containing source material, and a Li-containing source material. The Bi-containing source material is, for example, Bi2O. The K-containing source material is, for example, K2CO3. The Li-containing source material is, for example, Li2CO3. The first source material may further include at least one selected from the group consisting of a divalent metal ion-containing source material and an Ag-containing source material. Examples of the divalent metal ion-containing source material include BaCO3, CaCO3, and SrCO3. An example of the Ag-containing source material is Ag2O.

[0081] The second type raw material includes, for example, a compound selected from the group consisting of oxides and carbonates of atoms occupying the B site. The second type raw material includes a raw material containing Ti. The raw material containing Ti is, for example, TiO2. The second type raw material may further include at least one selected from the group consisting of a raw material containing Cu, a raw material containing Mn, and a raw material containing Nb. An example of a raw material containing Cu includes CuO. Examples of raw materials containing Mn include MnO2, Mn2O3, and Mn3O4. An example of a raw material containing Nb includes Nb2O5.

[0082] The mixture containing the first raw material and the second raw material is pre-baked by heating it in an air atmosphere.

[0083] During pre-sintering, for example, the first and second raw materials are first weighed and then mixed. K2CO3 is weighed in a nitrogen atmosphere, then heated in air at 240°C for 4 hours with a heating / cooling rate of 300°C / h, before being mixed with the other raw materials. Li2CO3 is weighed in a nitrogen atmosphere, then heated in air at 450°C for 1 hour with a heating / cooling rate of 300°C / h, before being mixed with the other raw materials.

[0084] Next, ethanol is added to the mixture of the first and second raw materials, and then the mixture is mixed in a planetary ball mill using zirconia balls.

[0085] Next, the zirconia balls are separated from the mixture, and the mixture is then dried in an evaporator and subsequently heated in a vacuum dryer at 200°C for 1 hour or more.

[0086] Next, the mixture is pre-baked by heating in an air atmosphere at a heating temperature of 900°C for a heating time of 4 hours at a heating / cooling rate of 300°C / h.

[0087] The pre-fired mixture is mixed with a binder and then molded to produce a compact, which is then heated in air for main firing, thereby obtaining a dielectric material containing the dielectric substance.

[0088] During the main firing, for example, ethanol is first added to the mixture after the preliminary firing, and then the mixture is mixed in a planetary ball mill using zirconia balls.

[0089] Next, the zirconia balls are separated from the mixture, and the mixture is then dried in an evaporator and subsequently heated in a vacuum dryer at 200°C for 1 hour or more.

[0090] Next, 1 part by mass of polymethyl methacrylate powder is added to the mixture as a binder with respect to 24 parts by mass of the mixture, and then the mixture is passed through a polyethylene mesh with an opening of 177 μm to separate coarse particles.

[0091] Next, the mixture is uniaxially pressed at a pressure of 120 MPa for 3 minutes to produce a pellet-shaped compact with a diameter of 10 mm, and then the compact is cold isostatically pressed at a pressure of 150 MPa for 1 hour.

[0092] Next, the compact is subjected to main firing by heating in air at a heating temperature of 1050 to 1060°C for a heating time of 4 hours at a heating / cooling rate of 300°C / h.

[0093] As a result, a pellet-shaped dielectric material containing the dielectric substance is obtained.

[0094] This pellet-shaped dielectric material is cut to an appropriate thickness, for example, 0.15 to 0.2 mm, to produce the dielectric layer 4 for the capacitor 1 made of the dielectric material.

[0095] The method for manufacturing the dielectric substance and the dielectric layer 4 is not limited to the above, and the specific method and conditions described above can be changed as appropriate.

[0096] As described above, the dielectric material may contain only a dielectric substance, or may contain a dielectric substance and a substance other than the dielectric substance. For example, when a dielectric material is produced by the above method, the dielectric material may contain a small amount of a substance having a layered shape (layered compound). The results of X-ray diffraction measurement of the dielectric material produced by the above method show that the layered compound is Bi 4.5 K 0.5+x Ti4O 15 and Bi4Ti3O 12 This suggests that it contains the following: [Example]

[0097] Specific examples of the present disclosure will be presented below, but the present disclosure is not limited to the following examples.

[0098] [Example 1] 1. Sample Preparation Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ M y Ti (1-z) R z A dielectric material represented by the composition formula O3 was produced. The method for producing the dielectric material is as described in "3. Method for producing dielectric material and dielectric material" in the detailed description of the invention.

[0099] In the dielectric material samples described below, the x value, which relates to the Li occupancy rate, the y value, which relates to the M occupancy rate, and the z value, which relates to the R occupancy rate, were determined from the analytical results using ICP optical emission spectroscopy and X-ray fluorescence spectroscopy. The δ value, which relates to the vacancy occupancy rate, was determined by Rietveld analysis. Furthermore, the X-ray diffraction measurement results of each sample confirmed that each sample had a perovskite structure.

[0100] 2. Exam (1) Measurement of effective relative permittivity For samples A1 to A38 of the dielectric material shown in Table 1, PE curves were measured in the electric field range from 0 kV / cm to the maximum electric field shown in Table 1 using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in hysteresis measurement mode at a frequency of 1 Hz. The PE curves for each of samples A1 to A38 are shown in Figures 3 to 40. The area of ​​the hatched region in each PE curve corresponds to the stored energy. From these PE curves, it can be seen that compared to sample A1, where x is 0.00, samples A2 to A38 have increased stored energy due to the inclusion of Li.

[0101] From this PE curve, Δp (the difference between the maximum polarization and the remanent polarization), the maximum value of polarization (maximum polarization), and the effective relative dielectric constant were determined. The results are shown in Table 1 below.

[0102] It was confirmed that the effective relative dielectric constant of samples A2 to A38 was increased compared to sample 1, and in any case, it can be determined that an effective relative dielectric constant of 1000 or more can be achieved if the maximum electric field is 100 kV / cm.

[0103] The above results also suggest that the maximum polarization tends to be improved when the dielectric material does not have voids, while the effective dielectric constant tends to be improved when the dielectric material has voids.

[0104] Furthermore, based on the above results, the changes in effective relative permittivity and maximum polarization with respect to changes in the maximum electric field (maximum electric field strength) are shown in Figures 41 to 44. Of these, Figure 41 shows the results for samples A4 to A10. Figure 42 shows the results for samples A11 to A17. Figure 43 shows the results for samples A18 to A24. Figure 44 shows the results for samples A31 to A37.

[0105] As shown in this result, the effective relative permittivity changes in response to the change in the maximum electric field, but no sudden change is observed. In addition, the rate of change in the effective relative permittivity is within approximately 20% in the range of maximum electric field values ​​from 40 kV / cm to 80 kV / cm. (1-x+δ) / 2 Na (1-x-3) / 2 Ba x □ δ Similarly, the change in effective relative permittivity with respect to the change in maximum electric field (maximum electric field strength) for a material with a composition of TiO3 (where x = 0.07, δ = 0.015) is shown. In this case, the rate of change in effective relative permittivity is approximately 55%. Therefore, for the above sample, it can be evaluated that the change in relative permittivity with respect to the degree of change in electric field is small. Note that the rate of change in effective relative permittivity is the percentage ratio of the minimum effective relative permittivity to the maximum effective relative permittivity.

[0106] [Table 1]

[0107] (2) Relationship between the application of an electric field and the crystal structure Bi 1 / 2 K (1-x) / 2 Li x / 2Dielectric material samples were prepared in which x in the TiO3 composition formula was varied between 0.00 and 0.11. For each sample, the PE curve (hysteresis loop) was measured in the electric field range of -150 to 150 kV / cm using a ferroelectric characterization system (FCE) manufactured by Toyo Corporation in hysteresis measurement mode at a frequency of 1 Hz. The crystal structure of each dielectric material before and after the test was identified by structural analysis using measurement results obtained by X-ray diffraction. The results are shown in Table 2 below. The PE curve (hysteresis loop) obtained when x was 0.08 is shown in Figure 45.

[0108] [Table 2]

[0109] The results showed that the presence of Li in a dielectric material tends to result in the space group of the crystal structure of the dielectric material being P4bm, and that the space group of the crystal structure tends to remain P4bm even after the dielectric material is exposed to an electric field.

[0110] Furthermore, Figure 45 shows that the waveform of the PE curve changes significantly depending on the polarization value. The areas where the waveform changes significantly are indicated by dashed lines. This result suggests that when a dielectric material contains Li, the material undergoes a phase transition between a phase whose crystalline space group is P4bm (the region between the two dashed lines) and a phase whose crystalline space group is P4mm (the region outside the dashed lines) in response to changes in the electric field, and that this phase transition tends to occur reversibly. This tendency is particularly evident when x is in the range of 0.08 to 0.11.

[0111] (3) Measurement of hysteresis curve, electric field-current density, and unipolar characteristics Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ M y Ti (1-z) R zSamples B1 to B11 were prepared, each having M, R, x, y, z, and δ in the composition formula of O3 as shown in Table 3 below.

[0112] [Table 3]

[0113] For each of Samples B1 to B11, the PE curve (hysteresis curve) was measured in the electric field range of -116 to 116 kV / cm using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in the hysteresis measurement mode at a frequency of 1 Hz.

[0114] In addition, for each of samples B1 to B11, the current density of the current flowing through the dielectric material in the electric field range of -116 to 116 kV / cm was measured in hysteresis measurement mode using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation at a frequency of 1 Hz.

[0115] In addition, for each of samples B1 to B11, the first PE curve (first unipolar characteristics) and the second PE curve (second unipolar characteristics) were measured in hysteresis measurement mode using a ferroelectric characteristic evaluation system FCE manufactured by Toyo Corporation, when an electric field was applied from 0 to the maximum electric field at a frequency of 1 Hz.

[0116] For sample B1, the hysteresis curve is shown in FIG. 46, the electric field-current density measurement results are shown in FIG. 47, the first unipolar characteristics are shown in FIG. 48, and the second unipolar characteristics are shown in FIG.

[0117] For sample B2, the hysteresis curve is shown in FIG. 50, the electric field-current density measurement results are shown in FIG. 51, the first unipolar characteristics are shown in FIG. 52, and the second unipolar characteristics are shown in FIG.

[0118] For sample B3, the hysteresis curve is shown in FIG. 54, the electric field-current density measurement results are shown in FIG. 55, the first unipolar characteristics are shown in FIG. 56, and the second unipolar characteristics are shown in FIG.

[0119] For sample B4, the hysteresis curve is shown in FIG. 58, the electric field-current density measurement results are shown in FIG. 59, the first unipolar characteristics are shown in FIG. 60, and the second unipolar characteristics are shown in FIG. 61.

[0120] For sample B5, the hysteresis curve is shown in FIG. 62, the electric field-current density measurement results are shown in FIG. 63, the first unipolar characteristics are shown in FIG. 64, and the second unipolar characteristics are shown in FIG.

[0121] For sample B6, the hysteresis curve is shown in FIG. 66, the electric field-current density measurement results are shown in FIG. 67, the first unipolar characteristics are shown in FIG. 68, and the second unipolar characteristics are shown in FIG. 69.

[0122] For sample B7, the hysteresis curve is shown in FIG. 70, the electric field-current density measurement results are shown in FIG. 71, the first unipolar characteristics are shown in FIG. 72, and the second unipolar characteristics are shown in FIG.

[0123] For sample B8, the hysteresis curve is shown in FIG. 74, the electric field-current density measurement results are shown in FIG. 75, the first unipolar characteristics are shown in FIG. 76, and the second unipolar characteristics are shown in FIG.

[0124] For sample B9, the hysteresis curve is shown in FIG. 78, the electric field-current density measurement results are shown in FIG. 79, the first unipolar characteristics are shown in FIG. 80, and the second unipolar characteristics are shown in FIG.

[0125] For sample B10, the hysteresis curve is shown in FIG. 82, the electric field-current density measurement results are shown in FIG. 83, the first unipolar characteristics are shown in FIG. 84, and the second unipolar characteristics are shown in FIG.

[0126] For sample B11, the hysteresis curve is shown in FIG. 86, the electric field-current density measurement results are shown in FIG. 87, the first unipolar characteristics are shown in FIG. 88, and the second unipolar characteristics are shown in FIG.

[0127] For sample B12, the hysteresis curve is shown in FIG. 90, the electric field-current density measurement results are shown in FIG. 91, the first unipolar characteristics are shown in FIG. 92, and the second unipolar characteristics are shown in FIG. 93.

[0128] The change in slope of the hysteresis curve with the electric field suggests a reversible phase transition between a ferroelectric crystal with space group P4mm and a ferrielectric crystal with space group P4bm in response to the electric field.

[0129] In addition, the electric field-current density measurement results showed that E T1 and E T2 indicates the pulse current observed during polarization reversal. This pulse current suggests that multi-stage polarization reversal occurs in response to changes in the electric field.

[0130] Furthermore, if the difference between the first and second unipolar properties is small, this suggests that the phase transition occurs reversibly in response to the change in electric field.

[0131] (4) Leakage current Sample BKLT-Ca20, which has the same composition as samples A4 to A10, and sample BKLT-Sr20, which has the same composition as samples A32 to A39, were prepared.

[0132] The leakage currents generated in the samples BKLT-Ca20 and BKLT-Sr20 were measured as follows.

[0133] Sample BKLT-Ca20: Measured using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in leakage current measurement mode under the following conditions: voltage range 0 to 1200 V, voltage step 20 V, step time 10 seconds, delay time 9.5 seconds.

[0134] Sample BKLT-Sr20: Measured using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation under the following conditions: voltage range 0 to 1400 V, voltage step 24 V, step time 10 seconds, delay time 9.5 seconds.

[0135] Furthermore, for comparison, a dielectric material (sample BNT-BT) having a composition of (Bi,Na)TiO-BaTiO3 was also produced, and the leakage current of this sample BNT-BT was measured in the same manner as above.

[0136] These results are shown in Figure 94. In Figure 94, ▲ indicates the results for sample BKLT-Ca20, ◆ indicates the results for sample BKLT-Sr20, and ■ indicates the results for sample BNT-BT. Also, Figure 95 shows the results for sample BKLT-Ca20 only on a semi-logarithmic graph, and Figure 96 shows the results for sample BKLT-Sr20 only on a semi-logarithmic graph.

[0137] As can be seen from these results, the leakage current values ​​for samples BKLT-Ca20 and BKLT-Sr20 were comparable to those for sample BNT-BT, indicating that samples BKLT-Ca20 and BKLT-Sr20 have high electrical insulation properties comparable to that of sample BNT-BT.

[0138] (5) Capacitor Samples having the same composition as samples A4 to A10 were applied to dielectric layer 4 of capacitor 1 and evaluated as follows.

[0139] A disk-shaped dielectric layer 4 was fabricated from the sintered sample, having two circular main surfaces, an outer diameter of 6 mm, and a thickness of 0.2 mm. The method for fabricating the dielectric layer 4 was as described in "3. Dielectric substance and method for fabricating dielectric material" in the detailed description of the invention.

[0140] The first electrode 2 and the second electrode 3 were fabricated so that they overlapped the two main surfaces of the dielectric layer 4, i.e., so that the dielectric layer 4 was interposed between the first electrode 2 and the second electrode 3. Each of the first electrode 2 and the second electrode 3 was formed by applying a resin silver paste consisting of silver particles, thermoplastic resin, and organic solvent to the main surface of the dielectric layer 4 using a screen mask, and then evaporating the organic solvent by heating and drying. In this way, the capacitor 1 for evaluation was fabricated.

[0141] Using an LCR meter, the relative permittivity of the dielectric layer 4 in the capacitor 1 and the capacitance of the capacitor 1 were measured under conditions of a measurement frequency of 1 kHz and a measurement voltage of 0.5 Vrms while applying a DC bias voltage.

[0142] Table 4 below shows the values ​​of the DC bias voltage, the values ​​of the electric field (electric field) to which the dielectric layer 4 is exposed, the measurement results of the dielectric constant of the dielectric layer 4, and the measurement results of the capacitance of the capacitor 1.

[0143] [Table 4]

[0144] As shown in these results, the dielectric layer 4 has a high dielectric constant, and the capacitor 1 has a high capacitance. Furthermore, the changes in the dielectric constant and capacitance that occur when the electric field to which the dielectric layer 4 is exposed changes are both gradual.

[0145] [Example 2] 1. Sample Preparation Bi (1+δ) / 2 K (1-p-x)(1-3δ) / 2 Li x(1-3δ) / 2 Ag p(1-3δ) / 2 □ δ Ti 1-z R z A dielectric material represented by the formula O3 was produced. The method for producing the dielectric material is as described in "3. Method for producing dielectric material and dielectric material" in the detailed description of the invention.

[0146] The values ​​of x, p, and z, which relate to the atomic occupancy in the dielectric material samples described below, were determined from the results of analysis using ICP optical emission spectroscopy and X-ray fluorescence analysis. The value of δ, which relates to the vacancy occupancy, was determined by Rietveld analysis. Furthermore, the results of X-ray diffraction measurements of each sample confirmed that each sample had a perovskite structure.

[0147] 2. Exam (1) Measurement of effective relative permittivity For samples C1 to C27 of the dielectric material shown in Table 5, PE curves were measured in the electric field range from 0 kV / cm to the maximum electric field shown in Table 1 using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in hysteresis measurement mode at a frequency of 1 Hz. The PE curve for sample C5 is shown in Figure 97, the PE curve for sample C14 in Figure 98, and the PE curve for sample C23 in Figure 99. The area of ​​the hatched region in each PE curve corresponds to the stored energy. These PE curves show that the stored energy of the dielectric material is increasing.

[0148] From the PE curve, Δp, the maximum value of polarization (maximum polarization), and the effective relative dielectric constant were determined, and the results are shown in Table 5 below.

[0149] [Table 5]

[0150] It was confirmed that samples C1 to C27 had high effective relative dielectric constants, and it was determined that in any case, an effective relative dielectric constant of 1000 or more could be achieved if the maximum electric field was 100 kV / cm.

[0151] Furthermore, based on the above results, the changes in effective relative permittivity and maximum polarization with respect to changes in the maximum electric field (maximum electric field strength) are shown in Figures 100 to 102. Of these, Figure 100 shows the results for samples C2 to C9. Figure 102 shows the results for samples C10 to C18. Figure 102 shows the results for samples C19 to C27.

[0152] As shown in the results, the effective relative permittivity changes with the change in the maximum electric field, but no sudden changes are observed. Furthermore, the rate of change in the effective relative permittivity is within approximately 20% in the maximum electric field range from 40 kV / cm to 80 kV / cm.

[0153] (2) Measurement of hysteresis curves, electric field-current density, and unipolar characteristics Bi (1+δ) / 2 K (1-p-x)(1-3δ) / 2 Li x(1-3δ) / 2 Ag p(1-3δ) / 2 □ δ Ti 1-z R z Samples D1 to D3 were prepared, each having R, x, p, δ, and z in the composition formula of O3 as shown in Table 6 below.

[0154] [Table 6]

[0155] For each of Samples D1 to D3, a PE curve (hysteresis curve) was measured using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in a hysteresis measurement mode at a frequency of 1 Hz.

[0156] In addition, for each of samples D1 to D3, the current density of the current flowing through the dielectric material when the electric field was swept was measured in hysteresis measurement mode using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation at a frequency of 1 Hz.

[0157] In addition, for each of samples D1 to D3, the first PE curve (first unipolar characteristic) and the second PE curve (second unipolar characteristic) were measured in hysteresis measurement mode using a ferroelectric characteristic evaluation system FCE manufactured by Toyo Corporation, when an electric field was applied from 0 to the maximum electric field at a frequency of 1 Hz.

[0158] For sample D1, the hysteresis curve is shown in FIG. 103, the electric field-current density measurement results are shown in FIG. 104, the first unipolar characteristics are shown in FIG. 105, and the second unipolar characteristics are shown in FIG.

[0159] For sample D2, the hysteresis curve is shown in FIG. 107, the electric field-current density measurement results are shown in FIG. 108, the first unipolar characteristics are shown in FIG. 109, and the second unipolar characteristics are shown in FIG.

[0160] For sample D3, the hysteresis curve is shown in FIG. 111, the electric field-current density measurement results are shown in FIG. 112, the first unipolar characteristics are shown in FIG. 113, and the second unipolar characteristics are shown in FIG.

[0161] The change in slope of the hysteresis curve with the electric field suggests a reversible phase transition between a ferroelectric crystal with space group P4mm and a ferrielectric crystal with space group P4bm in response to the electric field.

[0162] In addition, the electric field-current density measurement results showed that E T1 and E T2 indicates the pulse current observed during polarization reversal. This pulse current suggests that multi-stage polarization reversal occurs in response to changes in the electric field.

[0163] Furthermore, if the difference between the first and second unipolar properties is small, this suggests that the phase transition occurs reversibly in response to the change in electric field.

[0164] [Example 3] 1. Sample Preparation Bi (1-q)(1+δ) / 2 K (1-q)(1-x)(1-3δ) / 2 Li (x(1-q)(1-3δ) / 2)+q □ δ Ti (1-q-z) Nb q R z A dielectric material sample E1 was produced, which is represented by the composition formula O3, where R, x, q, δ, and z in the composition formula are as shown in Table 7 below. The method for producing the dielectric material is as described in "3. Dielectric material and method for producing dielectric material" in the detailed description of the invention.

[0165] The values ​​of x, q, and z, which relate to the atomic occupancy in the dielectric material, were determined from the results of analysis using ICP atomic emission spectroscopy and X-ray fluorescence analysis. The value of δ, which relates to the vacancy occupancy, was determined by Rietveld analysis. Furthermore, the results of X-ray diffraction measurement of sample E1 confirmed that sample E1 has a perovskite structure.

[0166] 2. Exam For sample E1, the PE curves were measured in the electric field range from 0 kV / cm to the maximum electric field (80±3 kV / cm) shown in Table 1 using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in hysteresis measurement mode at a frequency of 1 Hz. The PE curves are shown in Figure 115. The area of ​​the hatched region in the PE curve corresponds to the stored energy. From the PE curve, it can be seen that the stored energy of the dielectric material is increasing.

[0167] From the PE curve, Δp, the maximum value of polarization (maximum polarization), and the effective relative dielectric constant were determined, and the results are shown in Table 7 below.

[0168] [Table 7]

[0169] It was confirmed that sample E1 had a high effective relative dielectric constant, and it was determined that an effective relative dielectric constant of 1000 or more would be achieved if the maximum electric field was 100 kV / cm.

[0170] For sample E1, the PE curve (hysteresis curve) was measured in the electric field range of -80±3 to 80±3 kV / cm using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in the hysteresis measurement mode at a frequency of 1 Hz.

[0171] Furthermore, for sample D1, the current density of the current flowing through the dielectric material in the electric field range of -80±3 to 80±3 kV / cm was measured in the hysteresis measurement mode using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation at a frequency of 1 Hz.

[0172] The hysteresis curve and the measurement results of the electric field-current density are shown in FIG.

[0173] [Aspect] The dielectric material of the first embodiment has a perovskite structure represented by ABX3. The A represents an A site at a vertex position, the B represents a B site at a body-centered position, and the X represents an X site at a face-centered position. Atoms occupying the A site include Bi, Li, and K. Atoms occupying the B site include Ti. Atoms occupying the X site include O.

[0174] According to this embodiment, the dielectric material has a high relative dielectric constant, and the change in the relative dielectric constant of the dielectric material due to a change in the electric field can be suppressed.

[0175] In the second embodiment, in the first embodiment, the occupancy rate of Bi at the A site is 35% or more and 50% or less, the occupancy rate of Li is more than 0% and 6% or less, and the occupancy rate of K is 29% or more and 50% or less.

[0176] In a third embodiment, in the first or second embodiment, the occupancy rate of Ti at the B site is 98% or more and 100% or less.

[0177] In a fourth embodiment, the dielectric material of the first embodiment is Bi 1 / 2 K (1-x) / 2 Li x / 2It is expressed by the formula TiO3, where x is greater than 0.0 and equal to or less than 0.11.

[0178] In a fifth aspect, in any one of the first to third aspects, a vacancy is contained in the A site.

[0179] In this manner, the dielectric material may have a higher dielectric constant.

[0180] In a sixth aspect, the dielectric material of the first aspect is Bi (1+δ) / 2 K (1-x)(1-3δ) / 2 Li x(1-3δ) / 2 □ δ It is expressed by the composition formula TiO3, where □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, and δ is greater than 0.0 and not greater than 0.025.

[0181] In this manner, the dielectric material may have a higher dielectric constant.

[0182] In a seventh aspect, in any one of the first to third and fifth aspects, a divalent metal ion is further contained in the A site.

[0183] In this manner, the dielectric material may have a higher dielectric constant.

[0184] In an eighth aspect, the dielectric material of the first aspect is Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 M y It is represented by the composition formula TiO3, where M is a divalent metal ion, x is greater than 0.0 and not greater than 0.11, and y is greater than 0.0 and not greater than 0.3.

[0185] In this manner, the dielectric material may have a higher dielectric constant.

[0186] In a ninth aspect, in any one of the first to third, fifth and seventh aspects, the divalent metal ions include at least one selected from the group consisting of Ba, Ca and Sr.

[0187] In a tenth aspect, the dielectric material of the first aspect is Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Ba y TiO3 composition formula, Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Ca y TiO3 composition formula or Bi (1-y) / 2 K (1-x-y) / 2 Li x / 2 Sr y In each of the composition formulas, x is greater than 0.0 and less than 0.11, and y is greater than 0.0 and less than 0.3.

[0188] In this manner, the dielectric material may have a higher dielectric constant.

[0189] In an eleventh aspect, in any one of the first to third, fifth, seventh and ninth aspects, the A site further contains a vacancy and a divalent metal ion.

[0190] In this manner, the dielectric material may have a higher dielectric constant.

[0191] In a twelfth aspect, in the first aspect, the dielectric material is Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ M y It is represented by the composition formula TiO3, where □ is a vacancy, M is a divalent metal ion, x is greater than 0.0 and less than or equal to 0.11, y is greater than 0.0 and less than or equal to 0.3, and δ is greater than 0.0 and less than or equal to 0.0025.

[0192] In this manner, the dielectric material may have a higher dielectric constant.

[0193] In a thirteenth aspect, in the eleventh or twelfth aspect, the divalent metal ion includes at least one selected from the group consisting of Ba, Ca, and Sr.

[0194] In a fourteenth aspect, in the first aspect, the dielectric material is Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Ba y TiO3 composition formula, Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Ca y TiO3 composition formula or Bi (1-y)(1+δ / (1-y)) / 2 K (1-x-y)(1-3δ / (1-y)) / 2 Li x(1-3δ / (1-y)) / 2 □ δ Sr y In each of the composition formulas, □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, y is greater than 0.0 and not greater than 0.3, and δ is greater than 0.0 and not greater than 0.025.

[0195] In this manner, the dielectric material may have a higher dielectric constant.

[0196] In a fifteenth aspect, in any one of the first to third, fifth, seventh, ninth, eleventh, and thirteenth aspects, the atoms occupying the A site further include Ag.

[0197] In a sixteenth aspect, in the first aspect, the dielectric material is Bi (1+δ) / 2 K (1-p-x)(1-3δ) / 2 Li x(1-3δ) / 2 Ag p(1-3δ) / 2 □ δ It is represented by the composition formula TiO3, where □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, δ is greater than 0.0 and not greater than 0.025, and p is greater than 0 and not greater than 0.3.

[0198] In a seventeenth aspect, in any one of the first to third, fifth, seventh, ninth, eleventh, thirteenth and fifteenth aspects, the atoms occupying the B site further include Nb.

[0199] In an eighteenth aspect, in the first aspect, the dielectric material is Bi (1-q)(1+δ) / 2 K (1-q)(1-x)(1-3δ) / 2 Li (x(1-q)(1-3δ) / 2)+q □ δ Ti (1-q) Nbq O3, where □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, δ is greater than 0.0 and not greater than 0.025, and q is greater than 0 and not greater than 0.02.

[0200] In a nineteenth aspect, in any one of the first to third, fifth, seventh, ninth, eleventh, thirteenth, fifteenth, and seventeenth aspects, the atoms occupying the B site further include at least one selected from the group consisting of Cu and Mn.

[0201] In this manner, leakage current in the dielectric material can be suppressed.

[0202] In a twentieth aspect, in the fourth, sixth, eighth, tenth, twelfth, fourteenth, sixteenth, or eighteenth aspect, a portion of Ti in the composition formula is substituted with at least one selected from the group consisting of Cu and Mn.

[0203] In this manner, leakage current in the dielectric material can be suppressed.

[0204] A dielectric material according to a twenty-first embodiment contains the dielectric substance according to any one of the first to twentieth embodiments.

[0205] A capacitor (1) according to a 22nd embodiment includes a first electrode (2), a second electrode (3), and a dielectric layer (4) interposed between the first electrode (2) and the second electrode (3). The dielectric layer (4) contains the dielectric material according to the 21st embodiment.

Claims

1. ABX ３ wherein the A represents an A site at a vertex position, the B represents a B site at a body-center position, and the X represents an X site at a face-center position, Atoms occupying the A site include Bi, Li, and K; The atoms occupying the B site include Ti, The atoms occupying the X site include O. Dielectric material.

2. the occupancy rate of Bi in the A site is 35% or more and 50% or less, the occupancy rate of Li is more than 0% and 6% or less, and the occupancy rate of K is 29% or more and 50% or less; The dielectric material of claim 1 .

3. the occupancy rate of Ti in the B site is 98% or more and 100% or less; The dielectric material of claim 1 .

4. Bi １／２ K （１－ｘ）／２ Li ｘ／２ TiO ３ It is represented by the composition formula: In the composition formula, x is greater than 0.0 and not greater than 0.

11. The dielectric material of claim 1 .

5. A vacancy is contained in the A site. The dielectric material of claim 1 .

6. Bi （１＋δ）／２ K （１－ｘ）（１－３δ）／２ Li ｘ（１－３δ）／２ □ δ TiO ３ It is represented by the composition formula: In the composition formula, □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, and δ is greater than 0.0 and not greater than 0.

025. The dielectric material of claim 1 .

7. The A site further contains a divalent metal ion. The dielectric material of claim 1 .

8. Bi （１－ｙ）／２ K （１－ｘ－ｙ）／２ Li ｘ／２ M ｙ TiO ３ It is represented by the composition formula: In the composition formula, M is a divalent metal ion, x is more than 0.0 and not more than 0.11, and y is more than 0.0 and not more than 0.

3. The dielectric material of claim 1 .

9. The divalent metal ion includes at least one selected from the group consisting of Ba, Ca, and Sr.

9. The dielectric material according to claim 7 or 8.

10. Bi （１－ｙ）／２ K （１－ｘ－ｙ）／２ Li ｘ／２ Ba ｙ TiO ３ The composition formula is Bi （１－ｙ）／２ K （１－ｘ－ｙ）／２ Li ｘ／２ Ca ｙ TiO ３ or Bi （１－ｙ）／２ K （１－ｘ－ｙ）／２ Li ｘ／２ Sr ｙ TiO ３ The composition formula is represented by In each of the above composition formulas, x is greater than 0.0 and less than 0.11, and y is greater than 0.0 and less than 0.

3. The dielectric material of claim 1 .

11. The A site further contains a vacancy and a divalent metal ion. The dielectric material of claim 1 .

12. Bi （１－ｙ）（１＋δ／（１－ｙ））／２ K （１－ｘ－ｙ）（１－３δ／（１－ｙ））／２ Li ｘ（１－３δ／（１－ｙ））／２ □ δ M ｙ TiO ３ It is represented by the composition formula: In the composition formula, □ represents a vacancy, M represents a divalent metal ion, x is greater than 0.0 and not greater than 0.11, y is greater than 0.0 and not greater than 0.3, and δ is greater than 0.0 and not greater than 0.0025. The dielectric material of claim 1 .

13. The divalent metal ion includes at least one selected from the group consisting of Ba, Ca, and Sr.

13. The dielectric material according to claim 11 or 12.

14. Bi （１－ｙ）（１＋δ／（１－ｙ））／２ K （１－ｘ－ｙ）（１－３δ／（１－ｙ））／２ Li ｘ（１－３δ／（１－ｙ））／２ □ δ Ba ｙ TiO ３ The composition formula is Bi （１－ｙ）（１＋δ／（１－ｙ））／２ K （１－ｘ－ｙ）（１－３δ／（１－ｙ））／２ Li ｘ（１－３δ／（１－ｙ））／２ □ δ Ca ｙ TiO ３ or Bi （１－ｙ）（１＋δ／（１－ｙ））／２ K （１－ｘ－ｙ）（１－３δ／（１－ｙ））／２ Li ｘ（１－３δ／（１－ｙ））／２ □ δ Sr ｙ TiO ３ The composition formula is shown as follows: In each of the above composition formulas, □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, y is greater than 0.0 and not greater than 0.3, and δ is greater than 0.0 and not greater than 0.

025. The dielectric material of claim 1 .

15. The atoms occupying the A site further include Ag. The dielectric material of claim 1 .

16. Bi （１＋δ）／２ K （１－ｐ－ｘ）（１－３δ）／２ Li ｘ（１－３δ）／２ Ag ｐ（１－３δ）／２ □ δ TiO ３ It is represented by the composition formula: In the composition formula, □ represents a vacancy, x is greater than 0.0 and not greater than 0.11, δ is greater than 0.0 and not greater than 0.025, and p is greater than 0.0 and not greater than 0.

3. The dielectric material of claim 1 .

17. The atoms occupying the B site further include Nb. The dielectric material of claim 1 .

18. Bi （１－ｑ）（１＋δ）／２ K （１－ｑ）（１－ｘ）（１－３δ）／２ Li （ｘ（１－ｑ）（１－３δ）／２）＋ｑ □ δ Ti （１－ｑ） Nb ｑ O ３ It is represented by the composition formula: In the composition formula, □ represents a vacancy, x is greater than 0.0 and less than or equal to 0.11, δ is greater than 0.0 and less than or equal to 0.025, and q is greater than 0.0 and less than or equal to 0.

02. The dielectric material of claim 1 .

19. the atoms occupying the B site further include at least one selected from the group consisting of Cu and Mn; The dielectric material of claim 1 .

20. 19. The dielectric material according to claim 4, 6, 8, 10, 12, 14, 16 or 18, A part of Ti in the composition formula is substituted with at least one selected from the group consisting of Cu and Mn. Dielectric material.

21. A dielectric material comprising the dielectric material of claim 1. Dielectric material.

22. A first electrode; A second electrode; a dielectric layer interposed between the first electrode and the second electrode, The dielectric layer comprises the dielectric material of claim 21. Capacitor.

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