Dielectric substance, dielectric material, and capacitor

Abstract

The present disclosure addresses the problem of providing a dielectric substance which has a high relative permittivity and in which a change in relative permittivity due to a change in an electric field is suppressed. The dielectric substance has a perovskite structure represented by the formula: ABX3. In the formula, A represents a site A at a vertex position, B represents a site B at a body-centered position, and X represents a site X at a face-centered position. Atoms occupying the site A include Bi, Li, and K. Atoms occupying the site B include Ti. Atoms occupying the site X include O.

Description

Dielectric substance, dielectric material and capacitor

[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 substance or a dielectric layer containing the dielectric material.

[0002] Patent Document 1 describes a (Bi,Na)TiO-BaTiO exhibiting a polarization twist, characterized in that the concentration of anion X-site vacancies introduced by A-site vacancies resulting from the absence of metals arranged at the A-sites of each vertex of a cubic or pseudocubic crystal having a perovskite-type structure ABX3 is 1% or less, and the octahedra of anions present in the perovskite-type structure are arranged by rotating at an angle ω with respect 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. ３ Dielectric materials such as

[0003] International Publication No. 2020 / 004670

[0004] BaTiO as a dielectric material in capacitors etc. ３ However, in order to make capacitors smaller and with higher capacitance, the relative permittivity of the dielectric material is being improved as in Patent Document 1.

[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 a capacitor.

[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.

[0007] The dielectric material of one embodiment of the present disclosure is ABX ３The 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 aspect of the present disclosure includes a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode, wherein the dielectric layer contains the dielectric substance or the dielectric material.

[0010] FIG. 1 is an explanatory diagram showing a unit cell of a perovskite structure. FIG. 2 is a schematic cross-sectional view showing a capacitor. FIG. 3 is an electric field-polarization curve for sample A1 of Example 1. FIG. 4 is an electric field-polarization curve for sample A2 of Example 1. FIG. 5 is an electric field-polarization curve for sample A3 of Example 1. FIG. 6 is an electric field-polarization curve for sample A4 of Example 1. FIG. 7 is an electric field-polarization curve for sample A5 of Example 1. FIG. 8 is an electric field-polarization curve for sample A6 of Example 1. FIG. 9 is an electric field-polarization curve for sample A7 of Example 1. FIG. 10 is an electric field-polarization curve for sample A8 of Example 1. FIG. 11 is an electric field-polarization curve for sample A9 of Example 1. FIG. 12 is an electric field-polarization curve for sample A10 of Example 1. FIG. 13 is an electric field-polarization curve for sample A11 of Example 1. FIG. 14 is an electric field-polarization curve for Sample A12 of Example 1. FIG. 15 is an electric field-polarization curve for Sample A13 of Example 1. FIG. 16 is an electric field-polarization curve for Sample A14 of Example 1. FIG. 17 is an electric field-polarization curve for Sample A15 of Example 1. FIG. 18 is an electric field-polarization curve for Sample A16 of Example 1. FIG. 19 is an electric field-polarization curve for Sample A17 of Example 1. FIG. 20 is an electric field-polarization curve for Sample A18 of Example 1. FIG. 21 is an electric field-polarization curve for Sample A19 of Example 1. FIG. 22 is an electric field-polarization curve for Sample A20 of Example 1. FIG. 23 is an electric field-polarization curve for Sample A21 of Example 1. FIG. 24 is an electric field-polarization curve for Sample A22 of Example 1. FIG. 25 is an electric field-polarization curve for sample A23 of Example 1. FIG. 26 is an electric field-polarization curve for sample A24 of Example 1. FIG. 27 is an electric field-polarization curve for sample A25 of Example 1. FIG. 28 is an electric field-polarization curve for sample A26 of Example 1. FIG. 29 is an electric field-polarization curve for sample A27 of Example 1. FIG. 30 is an electric field-polarization curve for sample A28 of Example 1. FIG. 31 is an electric field-polarization curve for sample A29 of Example 1.FIG. 32 is an electric field-polarization curve for Sample A30 of Example 1. FIG. 33 is an electric field-polarization curve for Sample A31 of Example 1. FIG. 34 is an electric field-polarization curve for Sample A32 of Example 1. FIG. 35 is an electric field-polarization curve for Sample A33 of Example 1. FIG. 36 is an electric field-polarization curve for Sample A34 of Example 1. FIG. 37 is an electric field-polarization curve for Sample A35 of Example 1. FIG. 38 is an electric field-polarization curve for Sample A36 of Example 1. FIG. 39 is an electric field-polarization curve for Sample A37 of Example 1. FIG. 40 is an electric field-polarization curve for Sample A38 of Example 1. FIG. 41 is a graph showing the change in effective dielectric constant and maximum polarization with change in maximum electric field based on Samples A4 to A10 of Example 1. Fig. 42 is a graph showing the change in effective dielectric constant and maximum polarization with respect to the change in maximum electric field for samples A11 to A17 of Example 1. Fig. 43 is a graph showing the change in effective dielectric constant and maximum polarization with respect to the change in maximum electric field for samples A18 to A24 of Example 1. Fig. 44 is a graph showing the change in effective dielectric constant and maximum polarization with respect to the change in maximum electric field for samples A31 to A37 of Example 1. Fig. 45 is a graph showing the change in effective dielectric constant and maximum polarization with respect to the change in maximum electric field for samples A18 to A24 of Example 1. （１－ｘ＋δ）／２ Na （１－ｘ－３）／２ Ba ｘ □ δ TiO ３(where x=0.07, δ=0.015). FIG. 46 is an electric field-polarization curve (hysteresis curve) for sample B1 of Example 1. FIG. 47 is an electric field-current density graph for sample B1 of Example 1. FIG. 48 is a first electric field-polarization curve (first unipolar characteristic) for sample B1 of Example 1 when an electric field is applied from zero to the maximum electric field. FIG. 49 is a second electric field-polarization curve (second unipolar characteristic) for sample B1 of Example 1 when an electric field is applied from zero to the maximum electric field. FIG. 50 is an electric field-polarization curve (hysteresis curve) for sample B2 of Example 1. FIG. 51 is an electric field-current density graph for sample B2 of Example 1. FIG. 52 shows a first electric field-polarization curve (first unipolar characteristic) for Sample B2 of Example 1 when an electric field is applied from zero to the maximum. FIG. 53 shows a second electric field-polarization curve (second unipolar characteristic) for Sample B2 of Example 1 when an electric field is applied from zero to the maximum. FIG. 54 shows an electric field-polarization curve (hysteresis curve) for Sample B3 of Example 1. FIG. 55 shows an electric field-current density graph for Sample B3 of Example 1. FIG. 56 shows a first electric field-polarization curve (first unipolar characteristic) for Sample B3 of Example 1 when an electric field is applied from zero to the maximum. FIG. 57 shows a second electric field-polarization curve (second unipolar characteristic) for Sample B3 of Example 1 when an electric field is applied from zero to the maximum. FIG. 58 shows an electric field-polarization curve (hysteresis curve) for Sample B4 of Example 1. FIG. 59 is a graph of the electric field-current density for sample B4 of Example 1. FIG. 60 is a graph of the first electric field-polarization curve (first unipolar characteristic) for sample B4 of Example 1 when an electric field is applied from zero to the maximum. FIG. 61 is a graph of the second electric field-polarization curve (second unipolar characteristic) for sample B4 of Example 1 when an electric field is applied from zero to the maximum. FIG. 62 is a graph of the electric field-polarization curve (hysteresis curve) for sample B5 of Example 1. FIG. 63 is a graph of the electric field-current density for sample B5 of Example 1.FIG. 64 shows a first electric field-polarization curve (first unipolar characteristic) for sample B5 of Example 1 when an electric field is applied from zero to the maximum. FIG. 65 shows a second electric field-polarization curve (second unipolar characteristic) for sample B5 of Example 1 when an electric field is applied from zero to the maximum. FIG. 66 shows an electric field-polarization curve (hysteresis curve) for sample B6 of Example 1. FIG. 67 shows a graph of electric field-current density for sample B6 of Example 1. FIG. 68 shows a first electric field-polarization curve (first unipolar characteristic) for sample B6 of Example 1 when an electric field is applied from zero to the maximum. FIG. 69 shows a second electric field-polarization curve (second unipolar characteristic) for sample B6 of Example 1 when an electric field is applied from zero to the maximum. FIG. 70 shows an electric field-polarization curve (hysteresis curve) for sample B7 of Example 1. FIG. 71 is a graph of the electric field-current density for Sample B7 of Example 1. FIG. 72 is a graph of the electric field-polarization curve (first unipolar characteristic) for Sample B7 of Example 1, obtained when an electric field ranging from zero to the maximum is applied. FIG. 73 is a graph of the electric field-polarization curve (second unipolar characteristic) for Sample B7 of Example 1, obtained when an electric field ranging from zero to the maximum is applied. FIG. 74 is a graph of the electric field-polarization curve (hysteresis curve) for Sample B8 of Example 1. FIG. 75 is a graph of the electric field-current density for Sample B8 of Example 1. FIG. 76 is a graph of the electric field-polarization curve (first unipolar characteristic) for Sample B8 of Example 1, obtained when an electric field ranging from zero to the maximum is applied. FIG. 77 is a graph of the electric field-polarization curve (second unipolar characteristic) for Sample B8 of Example 1, obtained when an electric field ranging from zero to the maximum is applied. FIG. 78 is an electric field-polarization curve (hysteresis curve) for Sample B9 of Example 1. FIG. 79 is a graph of electric field-current density for Sample B9 of Example 1. FIG. 80 is a first electric field-polarization curve (first unipolar characteristic) for Sample B9 of Example 1 when an electric field is applied from zero to the maximum. FIG. 81 is a second electric field-polarization curve (second unipolar characteristic) for Sample B9 of Example 1 when an electric field is applied from zero to the maximum.FIG. 82 is an electric field-polarization curve (hysteresis curve) for Sample B10 of Example 1. FIG. 83 is a graph of the electric field-current density for Sample B10 of Example 1. FIG. 84 is a first electric field-polarization curve (first unipolar characteristic) for Sample B10 of Example 1 when an electric field is applied from zero to the maximum. FIG. 85 is a second electric field-polarization curve (second unipolar characteristic) for Sample B10 of Example 1 when an electric field is applied from zero to the maximum. FIG. 86 is an electric field-polarization curve (hysteresis curve) for Sample B11 of Example 1. FIG. 87 is a graph of the electric field-current density for Sample B11 of Example 1. FIG. 88 is a first electric field-polarization curve (first unipolar characteristic) for Sample B11 of Example 1 when an electric field is applied from zero to the maximum. FIG. 89 is a second electric field-polarization curve (second unipolar characteristic) for sample B11 of Example 1 when an electric field is applied from zero to the maximum. FIG. 90 is an electric field-polarization curve (hysteresis curve) for sample B12 of Example 1. FIG. 91 is a graph of electric field-current density for sample B12 of Example 1. FIG. 92 is a first electric field-polarization curve (first unipolar characteristic) for sample B12 of Example 1 when an electric field is applied from zero to the maximum. FIG. 93 is a second electric field-polarization curve (second unipolar characteristic) for sample B12 of Example 1 when an electric field is applied from zero to the maximum. 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. FIG. 95 is a semi-logarithmic graph showing leakage current versus electric field for sample BKLT-Ca20 in Example 1. FIG. 96 is a semi-logarithmic graph showing leakage current versus electric field for sample BKLT-Sr20 in Example 1. FIG. 97 is an electric field-polarization curve for sample C1 in Example 2. FIG. 98 is an electric field-polarization curve for sample C17 in Example 2. FIG. 99 is an electric field-polarization curve for sample C23 in Example 2. FIG. 100 is a graph showing the change in effective relative permittivity versus the change in maximum electric field based on samples C2 to C9 in Example 2.FIG. 101 is a graph showing the change in effective dielectric constant with respect to the change in maximum electric field for samples C10 to C18 of Example 2. FIG. 102 is a graph showing the change in effective dielectric constant with respect to the change in maximum electric field for samples C19 to C27 of Example 2. FIG. 103 is an electric field-polarization curve (hysteresis curve) for sample D1 of Example 2. FIG. 104 is an electric field-current density graph for sample D1 of Example 2. FIG. 105 is a first electric field-polarization curve (first unipolar characteristic) for sample D1 of Example 2 when an electric field is applied from zero to the maximum electric field. FIG. 106 is a second electric field-polarization curve (second unipolar characteristic) for sample D1 of Example 2 when an electric field is applied from zero to the maximum electric field. FIG. 107 is an electric field-polarization curve (hysteresis curve) for sample D2 of Example 2. FIG. 108 is a graph of the electric field-current density for Sample D2 of Example 2. FIG. 109 is a graph of the electric field-polarization curve (first unipolar characteristic) for Sample D2 of Example 2 when an electric field is applied from zero to the maximum. FIG. 110 is a graph of the electric field-polarization curve (second unipolar characteristic) for Sample D2 of Example 2 when an electric field is applied from zero to the maximum. FIG. 111 is a graph of the electric field-polarization curve (hysteresis curve) for Sample D3 of Example 2. FIG. 112 is a graph of the electric field-current density for Sample D3 of Example 2. FIG. 113 is a graph of the electric field-polarization curve (first unipolar characteristic) for Sample D3 of Example 2 when an electric field is applied from zero to the maximum. FIG. 114 is a graph of the electric field-polarization curve (second unipolar characteristic) for Sample D3 of Example 2 when an electric field is applied from zero to the maximum. Fig. 115 is an electric field-polarization curve for sample E1 of Example 3. Fig. 116 is a graph of the electric field-polarization curve (hysteresis curve) and electric field-current density for sample E1 of Example 3. Fig. 117 is a graph of Bi in Example 1. １／２ K （１－ｘ）／２ Li ｘ／２ TiO ３ 1 is an electric field-polarization curve for a sample in which x in the composition formula is 0.08.

[0011] 1. Overview Below, embodiments of the present disclosure will be described. Note that 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 is 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. While the following may describe the mechanism of action of the embodiments, the description of the mechanism of action may be based on speculation, and the present disclosure is not bound by the following description of the mechanism of action.

[0012] 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.

[0013] The dielectric material of the embodiment is ABX ３ 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.

[0014] The dielectric material of embodiments may have a high dielectric constant.

[0015] In addition, (Bi,Na)TiO—BaTiO described in Patent Document 1 ３ Dielectrics such as these have ferrielectricity and can have a high relative permittivity, but the relative permittivity changes significantly in response to changes in the electric field, and can have a high relative permittivity only within a narrow electric field range.

[0016] In contrast, the dielectric constant of the dielectric material of the embodiment changes little even when the electric field changes, and therefore the dielectric material of the embodiment can be effectively applied to the dielectric layer 4 of the capacitor 1.

[0017] The relative permittivity of a dielectric material can be evaluated by its effective relative permittivity. The effective relative permittivity is calculated from the stored energy obtained by measuring the polarization (dielectric polarization moment) of the dielectric material under an electric field sweep and deriving the stored energy from the electric field (electric field)-polarization (dielectric polarization moment) curve (hereinafter also referred to as a P-E curve). The higher the effective relative permittivity, the higher the relative permittivity of the dielectric material is evaluated to be. Furthermore, the degree of change in the relative permittivity in response to a change in the electric field can be evaluated by the degree of change in the effective relative permittivity when the sweep range of the electric field is changed. The smaller the degree of change in the effective relative permittivity, the smaller the degree of change in the relative permittivity in response to a change in the electric field is evaluated to be.

[0018] 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.

[0019] In the dielectric substance of the embodiment, atoms occupying X sites at face-center positions include O as described above. The atoms occupying the X sites are, for example, only O. "Only O" means that atoms other than O are not observed occupying the X sites.

[0020] In the dielectric material of the embodiment, atoms occupying the A sites at the vertices include Bi, Li, and K as described above.

[0021] 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 that this occupancy rate be 40% or less.

[0022] The occupancy rate of Li in the A site is preferably more than 0% and not more than 6%. 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 rate is more preferably 5% or less, and even more preferably 4% or less.

[0023] 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.

[0024] 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.

[0025] The A site may further contain vacancies (vacancy sites). 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 vacancies are contained in the A site, the occupancy of the vacancies 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.

[0026] 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.

[0027] When divalent metal ions are contained in the A site, the occupancy of the divalent metal ions in the A site is preferably more than 0.0% and not more than 30%, more preferably 10% or more, and even more preferably 15% or more, more preferably 25% or less, and even more preferably 20% or less.

[0028] The atoms occupying the A site may further include Ag. In this case, the dielectric material can still have a high relative permittivity. An advantage of Ag is that it can be used in material design by only substituting monovalent atoms without reducing the amount of Bi with lone pairs. Since Bi is not reduced, it is expected that polarization will be increased. Furthermore, by substituting with K, the average ionic radius of A can be reduced. Furthermore, sintering is relatively easy. When Ag is included in the atoms occupying the A site, it is preferable that the occupancy rate of Ag in the A site is more than 0.0% and not more than 15%.

[0029] In the dielectric material of the embodiment, the atoms occupying the body-centered B site include Ti as described above.

[0030] 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 a perovskite structure contained in the dielectric material is easily obtained. This occupancy rate is more preferably 99.9% or more.

[0031] The atoms occupying the B site may further include at least one 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 rate of Cu and the like in the B site is preferably 0.001% or more and 1% or less. This occupancy rate is more preferably 0.1% or more.

[0032] The atoms occupying the B site may further contain Nb. In this case, the dielectric material can also have a high relative dielectric constant. 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.

[0033] The dielectric material of the embodiment is, for example, Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti （１－ｚ） R ｚ O ３ The composition formula is 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 O ３ or Bi(1-q)(1+δ) / 2K （１－ｑ）（１－ｘ）（１－３δ）／２ Li(x(1-q)(1-3δ) / 2)+q□ δ Ti （１－ｑ－ｚ) Nb ｑ R ｚ O ３ It is represented by the following composition formula:

[0034] □ is a vacancy. M is a divalent metal ion. M is, for example, at least one selected from the group consisting of Ba, Ca, and Sr. R is at least one selected from the group consisting of Cu and Mn. x is, for example, more than 0.0 and 0.11 or less. y is, for example, 0.0 or more and 0.3 or less. δ is, for example, 0.0 or more and 0.025 or less. p is, for example, 0.0 or more and 0.3 or less. q is, for example, more than 0.0 and 0.02 or less. z is, for example, 0.0 or more and 0.01 or less.

[0035] In the case where the dielectric material contains a vacancy (□) at the A site, δ is, for example, greater than 0.0 and not greater than 0.025.

[0036] In the dielectric substance, when the atoms occupying the A site include a divalent metal ion (M), y is, for example, greater than 0.0 and 0.3 or less.

[0037] In the dielectric substance, when the atoms occupying the B site include at least one element (R) selected from the group consisting of Cu and Mn, z is, for example, greater than 0.0 and 0.01 or less.

[0038] 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.

[0039] 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 restrictions on the materials of the first electrode 2 and the second electrode 3, as long as they are conductive.

[0040] 2. Embodiments of Dielectric Material More specific embodiments of the dielectric material will be described below.

[0041] 2.1. First embodiment The dielectric material of the first embodiment is Bi. １／２ K （１－ｘ）／２ Li ｘ／２ TiO ３ This dielectric material is expressed by the formula (1-x)Bi １／２ K １／２ TiO ３ -xBi １／２ Li １／２ TiO ３ , or the like. That is, this dielectric material is Bi １／２ K １／２ TiO ３ and Bi １／２ Li １／２ TiO ３and in the ratio (1-x):x.

[0042] In the composition formula, x is preferably greater than 0 and less than or equal to 0.2. In this case, the dielectric substance can have a higher relative dielectric constant, and the change in relative dielectric constant due to a change in electric field can be more suppressed. One of the reasons for this is presumably that the dielectric substance is likely to have a structure of the space group P4bm, which makes it easy to exhibit ferrielectricity, and even if a phase transition occurs when an electric field is applied to the dielectric substance, the phase transition is reversible, that is, when the electric field is removed, the state before the phase transition is easily restored. x is more preferably 0.08 or more, and even more preferably 0.10 or more. x is more preferably 0.11 or less.

[0043] 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 TiO ３ It is represented by the formula:

[0044] The square represents a vacancy at the A site (vacancy site).

[0045] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0046] In the composition formula, δ is preferably greater than 0.0 and less than 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, and in this 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.

[0047] The first embodiment can be said to be the case where δ is 0 in the second embodiment.

[0048] 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 TiO ３ It is represented by the formula:

[0049] In this composition formula, M is a divalent metal ion.

[0050] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0051] In the composition formula, y is preferably greater than 0.0 and less than or equal to 0.3. In this case, the dielectric substance can have a higher relative dielectric constant. 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.

[0052] 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.

[0053] The dielectric material of the third embodiment is, for example, 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 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.

[0054] The first embodiment can be said to be the case where y is 0 in the third embodiment.

[0055] 2.4. Fourth embodiment The dielectric material of the fourth embodiment is Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ TiO ３ It is represented by the formula:

[0056] In this composition formula, □ represents a vacancy (vacancy site), and M represents a divalent metal ion.

[0057] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0058] The preferred range of y in the composition formula and the reasons for it are the same as those in the third embodiment.

[0059] The preferred range of δ in the composition formula and the reasons for it are the same as those in the second embodiment.

[0060] 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.

[0061] The dielectric material of the fourth embodiment is, for example, Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ Ba ｙ TiO ３ The compositional formula of Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ Ca ｙ TiO ３ Or Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ Sr ｙ TiO ３ The composition formula is represented by the following formula: In each composition formula, the preferred ranges of x, y and δ and the reasons therefor are as described above.

[0062] 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.

[0063] 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 TiO ３ It is represented by the formula:

[0064] In this composition formula, squares represent vacancies (vacancy sites).

[0065] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

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

[0067] 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.

[0068] 2.6. Sixth embodiment The dielectric material of the sixth embodiment is Bi(1-q)(1+δ) / 2K. （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 formula:

[0069] In this composition formula, squares represent vacancies (vacancy sites).

[0070] The preferred range of x in the composition formula and the reasons for it are the same as those in the first embodiment.

[0071] The preferred range of δ in the composition formula and the reasons for it are the same as those in the second embodiment.

[0072] 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.

[0073] 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 element 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 the Ti is substituted with at least one element 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.

[0074] 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 material is, for example, Bi. １／２ K （１－ｘ）／２ Li ｘ／２ Ti １－ｚ R ｚ O ３ It is represented by the formula:

[0075] 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 material is, for example, Bi. （１＋δ）／２ K （１－ｘ）（１－３δ）／２ Li ｘ（１－３δ）／２ □ δ Ti １－ｚ R ｚ O ３ It is represented by the formula:

[0076] 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 material is, for example, Bi. （１－ｙ）／２ K （１－ｘ－ｙ）／２ Li ｘ／２ M ｙ Ti １－ｚ R ｚ O ３ It is represented by the formula:

[0077] 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)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti １－ｚ R ｚ O ３ It is represented by the formula:

[0078] 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 material 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 O ３ It is represented by the formula:

[0079] 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) / 2K （１－ｑ）（１－ｘ）（１－３δ）／２ Li(x(1-q)(1-3δ) / 2)+q□ δ Ti （１－ｑ－ｚ) Nb ｑ R ｚ O ３ It is represented by the formula:

[0080] 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.

[0081] 2.8. Modifications 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.

[0082] 3. Dielectric Substances and Methods for Producing Dielectric Materials A method for producing dielectric substances and dielectric materials containing the dielectric substances will be described.

[0083] 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.

[0084] 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 source material containing Bi, a source material containing K, and a source material containing Li. The source material containing Bi is, for example, Bi. ２ The raw material containing K is, for example, K ２ CO ３ The raw material containing Li is, for example, Li ２ CO ３ The first source material may further contain at least one selected from the group consisting of a source material containing a divalent metal ion and a source material containing Ag. An example of the source material containing a divalent metal ion is BaCO ３ , CaCO ３ , and SrCO ３ Examples of raw materials containing Ag include Ag ２ Contains O.

[0085] The second source material includes, for example, a compound selected from the group consisting of oxides and carbonates of atoms occupying the B site. The second source material includes a source material containing Ti. The source material containing Ti is, for example, TiO ２ The second 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 the raw material containing Cu includes CuO. An example of the raw material containing Mn includes MnO. ２ , Mn２ O ３ and Mn ３ O ４ Examples of raw materials containing Nb include Nb ２ O ５ Includes:

[0086] The mixture containing the first and second raw materials is pre-baked by heating it in an air atmosphere.

[0087] During the calcination, for example, the first and second raw materials are first weighed and then mixed. ２ CO ３ is weighed in a nitrogen atmosphere, then heated in air at a heating temperature of 240°C for 4 hours with a heating / cooling rate of 300°C / h, and then mixed with other raw materials. ２ CO ３ is weighed in a nitrogen atmosphere, then heated in air at a heating temperature of 450°C for 1 hour at a heating / cooling rate of 300°C / h, and then mixed with other raw materials.

[0088] 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.

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

[0090] Next, the mixture is pre-baked by heating in an air atmosphere at a heating temperature of 900° C. for 4 hours at a heating / cooling rate of 300° C. / h.

[0091] 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.

[0092] 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.

[0093] Next, the zirconia balls are separated from the mixture, and the mixture is dried in an evaporator, and then heated in a vacuum dryer at 200° C. for 1 hour or more.

[0094] Next, 1 part by mass of polymethyl methacrylate powder is added to the mixture as a binder relative to 24 parts by mass of the mixture, and the mixture is passed through a polyethylene mesh with 177 μm openings to separate coarse particles.

[0095] Next, the mixture is uniaxially pressed at a pressure of 120 MPa for a pressing time of 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 a pressing time of 1 hour.

[0096] Next, the compact is subjected to main firing by heating in air at a heating temperature of 1050 to 1060° C. for 4 hours at a heating / cooling rate of 300° C. / h.

[0097] As a result, a pellet-shaped dielectric material containing the dielectric substance is obtained.

[0098] The 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.

[0099] 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.

[0100] 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 Ti ４ O １５ and Bi ４ Ti ３ O １２ This suggests that it contains the following:

[0101] Specific examples of the present disclosure will be presented below, but the present disclosure is not limited to the following examples.

[0102] [Example 1] 1. Sample preparation Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti （１－ｚ） R ｚ O ３ The dielectric substance was produced by the method described in "3. Method for producing dielectric substance and dielectric material" in the detailed description of the invention.

[0103] In the dielectric material samples described below, the x value relating to the Li occupancy, the y value relating to the M occupancy, and the z value relating to the R occupancy were determined from the analysis results by ICP optical emission spectroscopy and X-ray fluorescence analysis. The δ value relating to the vacancy occupancy was determined by Rietveld analysis. Furthermore, the X-ray diffraction measurement results of each sample confirmed that each sample had a perovskite structure.

[0104] 2. Test (1) Measurement of Effective Relative Dielectric Constant For samples A1 to A38 of the dielectric material shown in Table 1, P-E 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 P-E curves for each of samples A1 to A38 are shown in Figures 3 to 40. The area of ​​the hatched region in each P-E curve corresponds to the stored energy. From these P-E curves, it can be seen that the stored energy is increased in samples A2 to A38 by including Li, compared to sample A1, where x is 0.00.

[0105] 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.

[0106] 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 was determined that an effective relative dielectric constant of 1000 or more was achieved when the maximum electric field was 100 kV / cm.

[0107] 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.

[0108] Furthermore, based on the above results, the changes in effective dielectric constant and maximum polarization with respect to changes in 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.

[0109] As shown in this result, the effective relative dielectric constant 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 dielectric constant is within approximately 20% in the range of the maximum electric field value from 40 kV / cm to 80 kV / cm. （１－ｘ＋δ）／２ Na （１－ｘ－３）／２ Ba ｘ □ δ TiO ３ (where x = 0.07, δ = 0.015), the change in effective relative dielectric constant with respect to the change in maximum electric field (maximum electric field strength) is also shown. In this case, the rate of change in effective relative dielectric constant is approximately 55%. Therefore, it can be evaluated that the change in relative dielectric constant with respect to the degree of change in electric field is small for the above sample. The rate of change in effective relative dielectric constant is the percentage ratio of the minimum effective relative dielectric constant to the maximum effective relative dielectric constant.

[0110]

[0111] (2) Relationship between the application of an electric field and the crystal structure Bi １／２ K （１－ｘ）／２ Li ｘ／２ TiO ３Dielectric material samples were prepared in which x in the composition formula was varied between 0.00 and 0.11. For each sample, the P-E curve (hysteresis curve) was measured in an 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 P-E curve (hysteresis curve) obtained when x was 0.08 is shown in Figure 117.

[0112]

[0113] According to these results, the inclusion of Li in the dielectric material tends to cause the space group of the crystal structure of the dielectric material to become P4bm, and furthermore, the space group of the crystal structure tends to remain P4bm even after the dielectric material is exposed to an electric field.

[0114] Furthermore, Figure 117 shows that there are areas where the waveform of the P-E 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 dielectric material undergoes a phase transition between a phase whose crystalline structure has a space group of P4bm (the region between the two dashed lines) and a phase whose crystalline structure has a space group of P4mm (the region outside each dashed line) in response to a change in 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.

[0115] (3) Measurement of hysteresis curve, electric field-current density, and unipolar characteristics Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti （１－ｚ） R ｚ O ３ In the composition formula, samples B1 to B11 were prepared in which M, R, x, y, z, and δ are as shown in Table 3 below.

[0116]

[0117] 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.

[0118] Furthermore, 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 the hysteresis measurement mode using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation at a frequency of 1 Hz.

[0119] Furthermore, for each of samples B1 to B11, a ferroelectric property evaluation system FCE manufactured by Toyo Corporation was used in a hysteresis measurement mode to measure the first P-E curve (first unipolar characteristic) and the second P-E curve (second unipolar characteristic) when an electric field was applied from 0 to the maximum electric field at a frequency of 1 Hz.

[0120] For sample B1, the hysteresis curve is shown in FIG. 46, the measurement results of electric field-current density are shown in FIG. 47, the first unipolar characteristic is shown in FIG. 48, and the second unipolar characteristic is shown in FIG.

[0121] 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.

[0122] For sample B3, the hysteresis curve is shown in FIG. 54, the measurement results of electric field-current density are shown in FIG. 55, the first unipolar characteristics are shown in FIG. 56, and the second unipolar characteristics are shown in FIG.

[0123] 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.

[0124] 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. 65.

[0125] For sample B6, the hysteresis curve is shown in FIG. 66, the measurement results of electric field-current density are shown in FIG. 67, the first unipolar characteristics are shown in FIG. 68, and the second unipolar characteristics are shown in FIG. 69.

[0126] 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.

[0127] 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.

[0128] 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. 81.

[0129] 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.

[0130] 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.

[0131] For sample B12, the hysteresis curve is shown in FIG. 90, the measurement results of electric field-current density are shown in FIG. 91, the first unipolar characteristics are shown in FIG. 92, and the second unipolar characteristics are shown in FIG. 93.

[0132] The change in slope of the hysteresis curve with the change in 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 change in electric field.

[0133] 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.

[0134] Furthermore, if the difference between the first unipolar characteristic and the second unipolar characteristic is small, this suggests that a phase transition occurs reversibly in response to the change in electric field.

[0135] (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.

[0136] The leakage currents generated in the samples BKLT-Ca20 and BKLT-Sr20 were measured as follows.

[0137] Sample BKLT-Ca20: Measured using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation in leakage current measurement mode under the conditions of a voltage range of 0 to 1200 V, a voltage step of 20 V, a step time of 10 seconds, and a delay time of 9.5 seconds.

[0138] Sample BKLT-Sr20: Measured using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation under the conditions of a voltage range of 0 to 1400 V, a voltage step of 24 V, a step time of 10 seconds, and a delay time of 9.5 seconds.

[0139] For comparison, (Bi,Na)TiO-BaTiO ３ A dielectric material (sample BNT-BT) having the composition was also produced, and the leakage current of this sample BNT-BT was measured in the same manner as above.

[0140] 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 in a semi-logarithmic graph, and Figure 96 shows the results for sample BKLT-Sr20 only in a semi-logarithmic graph.

[0141] As can be seen from these results, the leakage current values ​​for sample BKLT-Ca20 and sample BKLT-Sr20 were equivalent to that of sample BNT-BT, which indicates that sample BKLT-Ca20 and sample BKLT-Sr20 have high electrical insulation properties equivalent to that of sample BNT-BT.

[0142] (5) Capacitor Samples having the same composition as Samples A4 to A10 were applied to the dielectric layer 4 of Capacitor 1 and evaluated as follows.

[0143] 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.

[0144] 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, a thermoplastic resin, and an 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, a capacitor 1 for evaluation was fabricated.

[0145] Using an LCR meter, the relative dielectric constant 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.

[0146] 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.

[0147]

[0148] 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.

[0149] [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 O ３ A dielectric substance represented by the following composition formula was produced. The method for producing the dielectric substance is as described in "3. Method for producing dielectric substance and dielectric material" in the detailed description of the invention.

[0150] The values ​​of x, p, and z, which relate to the atomic occupancy in the dielectric material samples described below, were determined from the analysis results 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. The X-ray diffraction measurement results of each sample confirmed that each sample had a perovskite structure.

[0151] 2. Test (1) Measurement of Effective Dielectric Constant For samples C1 to C27 of the dielectric material shown in Table 5, P-E 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 P-E curve for sample C5 is shown in Figure 97, the P-E curve for sample C14 is shown in Figure 98, and the P-E curve for sample C23 is shown in Figure 99. The area of ​​the hatched region in each P-E curve corresponds to the stored energy. These P-E curves show that the stored energy of the dielectric material is increasing.

[0152] 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.

[0153]

[0154] It was confirmed that samples C1 to C27 had a high effective relative dielectric constant, and in any case, it was determined that an effective relative dielectric constant of 1000 or more was achieved when the maximum electric field was 100 kV / cm.

[0155] 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 Figs. 100 to 102. Of these, Fig. 100 shows the results for samples C2 to C9. Fig. 102 shows the results for samples C10 to C18. Fig. 102 shows the results for samples C19 to C27.

[0156] As shown in the results, the effective dielectric constant changes with the change in the maximum electric field, but no sudden change is observed. Furthermore, the rate of change in the effective dielectric constant is within approximately 20% in the range of maximum electric field values ​​from 40 kV / cm to 80 kV / cm.

[0157] (2) Measurement of hysteresis curve, 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 Rｚ O ３ In the composition formula, R, x, p, δ, and z are as shown in Table 6 below, and samples D1 to D3 were prepared.

[0158]

[0159] For each of Samples D1 to D3, the PE curve (hysteresis curve) was measured in hysteresis measurement mode using a ferroelectric property evaluation system FCE manufactured by Toyo Corporation at a frequency of 1 Hz.

[0160] 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.

[0161] Furthermore, for each of samples D1 to D3, a ferroelectric property evaluation system FCE manufactured by Toyo Corporation was used in a hysteresis measurement mode to measure the first P-E curve (first unipolar characteristic) and the second P-E curve (second unipolar characteristic) when an electric field was applied from 0 to the maximum electric field at a frequency of 1 Hz.

[0162] For sample D1, the hysteresis curve is shown in FIG. 103, the measurement results of electric field-current density are shown in FIG. 104, the first unipolar characteristics are shown in FIG. 105, and the second unipolar characteristics are shown in FIG.

[0163] 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. 110.

[0164] 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.

[0165] The change in slope of the hysteresis curve with the change in 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 change in electric field.

[0166] 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.

[0167] Furthermore, if the difference between the first unipolar characteristic and the second unipolar characteristic is small, this suggests that a phase transition occurs reversibly in response to the change in electric field.

[0168] [Example 3] 1. Sample preparation Bi(1-q)(1+δ) / 2K （１－ｑ）（１－ｘ）（１－３δ）／２ Li(x(1-q)(1-3δ) / 2)+q□ δ Ti （１－ｑ－ｚ) Nb ｑ R ｚ O ３ A dielectric material sample E1 was produced, which is represented by the following composition formula, 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. Method for producing dielectric material and dielectric material" in the detailed description of the invention.

[0169] The values ​​of x, q, and z, which relate to the atomic occupancy in the dielectric material, were determined from the analysis results 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 X-ray diffraction measurement results of sample E1 confirmed that sample E1 has a perovskite structure.

[0170] 2. Test For sample E1, the P-E curve was 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 P-E curve is shown in Figure 115. The area of ​​the hatched region in the P-E curve corresponds to the stored energy. From the P-E curve, it can be seen that the stored energy of the dielectric material is increasing.

[0171] 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.

[0172]

[0173] 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 could be achieved if the maximum electric field was 100 kV / cm.

[0174] For sample E1, the P-E 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.

[0175] Furthermore, for sample D1, the current density of the current flowing through the dielectric material in an electric field range of −80±3 to 80±3 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.

[0176] The hysteresis curve and the measurement results of the electric field-current density are shown in FIG.

[0177] [Aspect] The dielectric material of the first aspect is ABX ３ The perovskite structure is represented by the formula: where A represents an A site at a vertex position, B represents a B site at a body-centered position, and 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.

[0178] 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.

[0179] In the second aspect, in the first aspect, 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.

[0180] In a third aspect, in the first or second aspect, the occupancy rate of Ti in the B site is 98% or more and 100% or less.

[0181] In a fourth aspect, in any one of the first to third aspects, a vacancy is contained in the A site.

[0182] In this manner, the dielectric material may have a higher dielectric constant.

[0183] In a fifth aspect, in any one of the first to fourth aspects, a divalent metal ion is further contained in the A site.

[0184] In this manner, the dielectric material may have a higher dielectric constant.

[0185] In a sixth aspect, in any one of the first to fourth aspects, the A site further contains a vacancy and a divalent metal ion.

[0186] In this manner, the dielectric material may have a higher dielectric constant.

[0187] In a seventh aspect, in the fifth or sixth aspect, the divalent metal ion includes at least one selected from the group consisting of Ba, Ca, and Sr.

[0188] In an eighth aspect, in any one of the first to seventh aspects, the atoms occupying the A site further include Ag.

[0189] In a ninth aspect, in any one of the first to eighth aspects, the atoms occupying the B site further include Nb.

[0190] In a tenth aspect, in any one of the first to ninth aspects, the atoms occupying the B site further include at least one selected from the group consisting of Cu and Mn.

[0191] In this manner, leakage current in the dielectric material can be suppressed.

[0192] In an eleventh aspect, in any one of the first to tenth aspects, the dielectric substance is Bi(1-y)(1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti （１－ｚ） R ｚ O ３ It is represented by the composition formula: In the composition formula, □ represents a vacancy. M represents a divalent metal ion. R represents at least one selected from the group consisting of Cu and Mn. x is greater than 0.0 and equal to or less than 0.11. y is equal to or greater than 0.0 and equal to or less than 0.3. δ is equal to or greater than 0.025 and equal to or less than 0.01.

[0193] In a twelfth aspect, in any one of the first to ninth aspects, the dielectric substance is 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 O ３ In the composition formula, □ represents a vacancy. x is greater than 0.0 and equal to or less than 0.11. δ is equal to or greater than 0.025. p is equal to or greater than 0 and equal to or less than 0.3. z is equal to or greater than 0.0 and equal to or less than 0.01.

[0194] In a thirteenth aspect, in any one of the first to ninth aspects, the dielectric substance is Bi(1-q)(1+δ) / 2K （１－ｑ）（１－ｘ）（１－３δ）／２ Li(x(1-q)(1-3δ) / 2)+q□ δ Ti （１－ｑ－ｚ) Nb ｑ R ｚ O ３In the composition formula, □ represents a vacancy. R represents at least one element selected from the group consisting of Cu and Mn. x is greater than 0.0 and less than or equal to 0.11. δ is greater than or equal to 0.025 and less than or equal to 0.02. q is greater than 0 and less than or equal to 0.02. z is greater than or equal to 0.0 and less than or equal to 0.01.

[0195] In a fourteenth aspect, in any one of the eleventh to thirteenth aspects, in the composition formula, δ is greater than 0.0 and 0.025 or less.

[0196] In this manner, the dielectric material may have a higher dielectric constant.

[0197] In a fifteenth aspect, in any one of the eleventh to fourteenth aspects, in the composition formula, y is greater than 0.0 and 0.3 or less.

[0198] In this manner, the dielectric material may have a higher dielectric constant.

[0199] In a sixteenth aspect, in any one of the eleventh to fifteenth aspects, in the composition formula, M is at least one selected from the group consisting of Ba, Ca, and Sr.

[0200] In this manner, the dielectric material may have a higher dielectric constant.

[0201] In a seventeenth aspect, in any one of the eleventh to fifteenth aspects, in the composition formula, z is greater than 0.0 and equal to or less than 0.01.

[0202] In this manner, leakage current in the dielectric material can be suppressed.

[0203] The dielectric material of the eighteenth aspect contains the dielectric substance of any one of the first to seventeenth aspects.

[0204] A capacitor (1) according to a nineteenth aspect 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 substance according to any one of the first to seventeenth aspects or the dielectric material according to the eighteenth aspect.

Claims

1. ABX ３ A dielectric material having a perovskite structure represented by the formula: wherein A in said formula represents an A site at a vertex position, B in said formula represents a B site at a body-centered position, and X in said formula represents an X site at a face-centered position, atoms occupying said A sites include Bi, Li, and K, atoms occupying said B sites include Ti, and atoms occupying said X sites include O.

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

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

4. The dielectric material according to claim 1, wherein the A site contains a vacancy.

5. The dielectric material according to claim 1, further comprising a divalent metal ion in the A site.

6. The dielectric material according to claim 1, wherein the A site further contains vacancies and divalent metal ions.

7. The dielectric material according to claim 5 or 6, wherein the divalent metal ions include at least one selected from the group consisting of Ba, Ca and Sr.

8. The dielectric material according to claim 1, wherein the atoms occupying the A sites further include Ag.

9. The dielectric material according to claim 1, wherein the atoms occupying the B site further include Nb.

10. The dielectric material according to claim 1, wherein the atoms occupying the B site further include at least one selected from the group consisting of Cu and Mn.

11. Bi(1-y) (1+δ / (1-y)) / 2K(1-x-y)(1-3δ / (1-y)) / 2Lix(1-3δ / (1-y)) / 2□ δ M ｙ Ti （１－ｚ） R ｚ O ３ 2. The dielectric material according to claim 1, which is represented by the following composition formula: wherein in the composition formula, □ represents a vacancy, M represents a divalent metal ion, R represents at least one selected from the group consisting of Cu and Mn, x is greater than 0.0 and equal to or less than 0.11, y is equal to or greater than 0.0 and equal to or less than 0.3, δ is equal to or greater than 0.025, and z is equal to or greater than 0.0 and equal to or less than 0.

01.

12. 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 O ３ 2. The dielectric material according to claim 1, which is represented by a composition formula: wherein in the composition formula, □ represents a vacancy, R represents at least one element selected from the group consisting of Cu and Mn, x is greater than 0.0 and equal to or less than 0.11, δ is equal to or greater than 0.0 and equal to or less than 0.025, p is equal to or greater than 0.0 and equal to or less than 0.3, and z is equal to or greater than 0.0 and equal to or less than 0.

01.

13. Bi(1-q)(1+δ) / 2K （１－ｑ）（１－ｘ）（１－３δ）／２ Li(x(1-q)(1-3δ) / 2)+q□ δ Ti （１－ｑ－ｚ) Nb ｑ R ｚ O ３ 2. The dielectric material according to claim 1, which is represented by the following composition formula: wherein in the composition formula, □ represents a vacancy, R represents at least one element selected from the group consisting of Cu and Mn, x is greater than 0.0 and less than or equal to 0.11, δ is 0.0 or greater and 0.025 or less, q is greater than 0.0 and 0.02 or less, and z is 0.0 or greater and 0.01 or less.

14. The dielectric material according to any one of claims 11 to 13, wherein in the composition formula, δ is greater than 0.0 and not greater than 0.

025.

15. The dielectric material according to claim 11, wherein in the composition formula, y is greater than 0.0 and not greater than 0.

3.

16. The dielectric material according to claim 11, wherein in the composition formula, M is at least one element selected from the group consisting of Ba, Ca, and Sr.

17. The dielectric material according to any one of claims 11 to 13, wherein z in the composition formula is greater than 0.0 and equal to or less than 0.

01.

18. A dielectric material containing the dielectric substance according to claim 1.

19. A capacitor comprising: a first electrode; a second electrode; and a dielectric layer interposed between the first electrode and the second electrode, wherein the dielectric layer contains the dielectric substance according to claim 1 or the dielectric material according to claim 18.

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