Giant dielectric barium titanate-based ceramic dielectric material as well as preparation method and application thereof

Abstract

The invention relates to a giant dielectric barium titanate-based ceramic dielectric material and a preparation method and application thereof, the giant dielectric barium titanate-based ceramic dielectric material comprises barium titanate and doping elements, and the doping elements are composed of Mg, Ca, RE, Al and Si; the content of barium titanate is 90 to 99.7 mol%, the content of Mg is 0.1 to 4 mol%, the content of Ca is 0.25 to 0.55 mol%, the content of RE is 0.1 to 3.5 mol%, the content of Al is 0.002 to 0.3 mol%, and the content of Si is 0.01 to 4.0 mol%. The ceramic dielectric material provided by the invention has the advantages that the average grain size is small, the room-temperature dielectric constant is greater than 10 < 4 > order of magnitude, the dielectric constant is giant, the dielectric stability in a wide temperature range is good, and the resistivity is greater than 10 < 9 > omega.cm; the traditional solid-phase method process is adopted, and is suitable for large-scale industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic ceramics, and in particular to a giant dielectric barium titanate-based ceramic dielectric material, a preparation method thereof, and applications thereof. Background Art

[0002] With the advent of the 5G era, electronic devices are constantly developing towards integration, miniaturization, environmental protection and high reliability. To adapt to the development of microelectronics technology, multilayer ceramic capacitors (MLCC), as one of the most widely used electronic components, need to have smaller size, higher capacity and higher reliability. Giant dielectric (>10 4 ) Ceramic dielectric materials are the preferred materials for preparing high-capacity capacitors, but most fine-grained giant dielectric barium titanate-based ceramic dielectric materials have poor temperature stability, too large ceramic grain size (>1μm), expensive raw materials, complex synthesis process and poor reliability.

[0003] Currently, while copper calcium titanate or titanium oxide-based giant dielectric ceramics can achieve giant dielectric constants, they are often accompanied by relatively high dielectric losses, large grain sizes, and very low breakdown field strengths. Strontium titanate-based giant dielectric ceramics require relatively high sintering temperatures during the preparation process, and above 1300°C, the ceramic grain size increases abnormally. Therefore, giant dielectric barium titanate-based ceramics are a dielectric material widely used in ceramic capacitors. Existing technologies typically use doping to optimize their performance. For example, using rare earth elements such as Nb, La, Ta, and Sm as single doping elements, the preparation process involves multiple sintering stages at temperatures as high as 1350-1450°C. However, this method's excessively high sintering temperature leads to an increase in grain size and high energy consumption, severely limiting the practical application of giant dielectric ceramics. For example, adding niobium oxide, magnesium oxide, calcium zirconate, etc. to barium titanate can also achieve extremely high dielectric constants, but its dielectric loss is relatively high. The high dielectric loss will inevitably greatly reduce the application value of the corresponding material, and its sintering temperature also reaches 1350°C, which will increase the grain size.

[0004] Therefore, it is necessary to modify the barium titanate-based ceramic dielectric material so that it has a smaller and narrower particle size distribution, while possessing a giant dielectric constant and low dielectric loss. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a giant dielectric barium titanate-based ceramic dielectric material and its preparation method and application. The giant dielectric barium titanate-based ceramic dielectric material of the present invention has a uniform grain size distribution and a small average grain size; the room temperature dielectric constant is greater than 10 at 1kHz. 4 order of magnitude, with a giant dielectric constant, good dielectric stability in a wide temperature range, and a resistivity greater than 10 9Ω·cm; It is prepared by traditional solid-phase method, which is simple, low-cost and suitable for large-scale industrialization.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a giant dielectric barium titanate-based ceramic dielectric material, wherein the giant dielectric barium titanate-based ceramic dielectric material comprises barium titanate and a doping element, wherein the doping element is composed of Mg, Ca, RE, Al and Si;

[0008] In terms of mole percentage, the barium titanate content is 90 to 99.7 mol%, for example, 90 mol%, 90.5 mol%, 91 mol%, 91.5 mol%, 92 mol%, 92.5 mol%, 93 mol%, 93.5 mol%, 94 mol%, 94.5 mol%, 95 mol%, 95.5 mol%, 96 mol%, 96.5 mol%, 97 mol%, 97.5 mol%, 98 mol%, 98.5 mol%, 99 mol%, 99.5 mol% or 99.7 mol%, etc.;

[0009] Mg content is 0.1 to 4 mol%, for example, 0.1 mol%, 0.3 mol%, 0.5 mol%, 0.8 mol%, 1.0 mol%, 1.2 mol%, 1.5 mol%, 1.8 mol%, 2.0 mol%, 2.2 mol%, 2.5 mol%, 2.8 mol%, 3.0 mol%, 3.2 mol%, 3.5 mol%, 3.8 mol% or 4.0 mol%, etc.;

[0010] The Ca content is 0.25 to 0.55 mol%, for example, 0.25 mol%, 0.27 mol%, 0.29 mol%, 0.31 mol%, 0.33 mol%, 0.35 mol%, 0.37 mol%, 0.39 mol%, 0.41 mol%, 0.43 mol%, 0.45 mol%, 0.47 mol%, 0.49 mol%, 0.51 mol%, 0.53 mol% or 0.55 mol%, etc.;

[0011] RE content is 0.1 to 3.5 mol%, for example, 0.1 mol%, 0.3 mol%, 0.5 mol%, 0.7 mol%, 0.9 mol%, 1.1 mol%, 1.3 mol%, 1.5 mol%, 1.7 mol%, 1.9 mol%, 2.1 mol%, 2.3 mol%, 2.5 mol%, 2.7 mol%, 2.9 mol%, 3.1 mol%, 3.3 mol% or 3.5 mol%, etc.;

[0012] The Al content is 0.002 to 0.3 mol%, for example, 0.002 mol%, 0.005 mol%, 0.01 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol%, 0.1 mol%, 0.12 mol%, 0.14 mol%, 0.16 mol%, 0.18 mol%, 0.2 mol%, 0.22 mol%, 0.24 mol%, 0.26 mol%, 0.28 mol% or 0.3 mol%, etc.;

[0013] The Si content is 0.01 to 4.0 mol%, for example, 0.01 mol%, 0.15 mol%, 0.1 mol%, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol% or 4 mol%.

[0014] It should be noted that the "giant dielectric" in the "giant dielectric barium titanate-based ceramic dielectric material" of the present invention refers to a dielectric constant greater than 10 at room temperature at 1kHz. 4 Order of magnitude.

[0015] In the present invention, Mg, Ca, RE, Al and Si are used as doping elements for barium titanate-based ceramic dielectric materials. Mg, Al and Si can synergistically inhibit the growth of barium titanate grains. At the corresponding temperature, they will generate a liquid phase molten state that coats the surface of barium titanate particles, thereby inhibiting further growth of grains. Mg, Ca and RE can replace different A sites (Ba in barium titanate crystals) in the barium titanate crystals. 2+ ) or B position (Ti 4+ ), resulting in lattice defects and free carriers, thereby forming defect dipoles. The defect dipoles will aggregate to form defect clusters, which will produce polarization under the action of the electric field. By utilizing defect chemistry, the dielectric constant can be increased to achieve the effect of giant dielectric constant.

[0016] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0017] Preferably, the RE includes any one or a combination of at least two of Ho, Dy, Y, La, Sm, Er or Ce.

[0018] Preferably, the average grain size of the giant dielectric barium titanate-based ceramic dielectric material is 460-650 nm, for example, 460 nm, 480 nm, 500 nm, 520 nm, 540 nm, 560 nm, 580 nm, 600 nm, 620 nm or 650 nm.

[0019] In a second aspect, the present invention further provides a method for preparing the giant dielectric barium titanate-based ceramic dielectric material according to the first aspect, the preparation method comprising the following steps:

[0020] The Mg source, Ca source, RE source, Al source, Si source and barium titanate are mixed once to obtain an intermediate powder, which is then mixed with a binder solution for a second time, granulated and sintered to obtain a giant dielectric barium titanate-based ceramic dielectric material;

[0021] Among them, in terms of molar percentage, the barium titanate content in the intermediate powder is 90-99.7 mol%, the Mg content is 0.1-4 mol%, the Ca content is 0.25-0.55 mol%, the RE content is 0.1-3.5 mol%, the Al content is 0.002-0.3 mol%, and the Si content is 0.01-4.0 mol%.

[0022] As a preferred technical solution of the present invention, the Mg source, Ca source, RE source, Al source, Si source and barium titanate are mixed once to obtain an intermediate powder comprising:

[0023] (1) First, Mg source, Ca source, RE source and barium titanate are uniformly mixed and pre-sintered to obtain pre-sintered powder;

[0024] (2) The pre-sintered powder is then mixed evenly with an Al source and a Si source to obtain an intermediate powder.

[0025] In the present invention, barium titanate is first mixed with a Mg source, a Ca source, and an RE source. Pre-sintering can pre-control the grain size, provide a basis for obtaining a fine-grained material, and effectively control the diffusion depth of the elements. The obtained pre-sintered powder is then mixed with an Al source and a Si source to further reduce the grain size, so that the grains reach a fine-grained state. After sintering, all the doping elements are further diffused, and the elements in the prepared barium titanate-based ceramic dielectric material are more evenly distributed.

[0026] As a preferred technical solution of the present invention, before the mixing in step (1), a first solvent is added for mixing together, and before the mixing in step (2), a second solvent is added for mixing together.

[0027] Preferably, the first solvent and the second solvent each independently comprise anhydrous ethanol.

[0028] Preferably, the mass ratio of the first solvent to the Mg source, Ca source, RE source and barium titanate in step (1) is (1-3):1, such as 3:1, 2.5:1, 2:1, 1.5:1 or 1:1.

[0029] Preferably, the mass ratio of the second solvent to the pre-sintered powder, Al source and Si source in step (2) is (1-3):1, such as 3:1, 2.5:1, 2:1, 1.5:1 or 1:1.

[0030] Preferably, the mixing comprises ball milling.

[0031] Preferably, the ball mill has a rotation speed of 250 to 1500 r / min, for example, 250 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min or 1500 r / min, etc.

[0032] Preferably, the ball milling time is 2 to 24 hours, for example, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours.

[0033] Preferably, the ball milling method includes any one of planetary ball milling, roller milling or sand milling.

[0034] Preferably, the diameter of the ball milling beads is 0.5 to 3 mm, for example, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm.

[0035] Preferably, the pre-sintering temperature is 900-1100°C, for example, 900°C, 920°C, 950°C, 980°C, 1000°C, 1020°C, 1050°C, 1080°C or 1100°C.

[0036] Preferably, the pre-sintering holding time is 0.5 to 1.5 h, for example, 0.5 h, 0.8 h, 1 h, 1.2 h or 1.5 h.

[0037] Preferably, before the pre-sintering and before obtaining the intermediate powder, drying is further included.

[0038] Preferably, the drying temperature is 80-100°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C.

[0039] Preferably, the drying time is 6 to 24 hours, for example, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours.

[0040] Preferably, the Mg source, Ca source, RE source, Al source and Si source each independently include any one of oxides, hydroxides, chlorides, sulfates, nitrates or carbonates, or a combination of at least two thereof.

[0041] Preferably, the RE in the RE source includes any one of Ho, Dy, Y, La, Sm, Er or Ce, or a combination of at least two of them.

[0042] Preferably, the particle size of the Mg source, Ca source, RE source, Al source and Si source is independently 20 to 150 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, etc.

[0043] Preferably, the particle size of the barium titanate is 50 to 500 nm, for example, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0044] As a preferred technical solution of the present invention, the binder solution includes a polyvinyl alcohol solution or a polyvinyl butyral solution.

[0045] Preferably, the concentration of the binder solution is 2.5-15 wt%, for example, 2.5 wt%, 5 wt%, 7.5 wt%, 10 wt%, 12.5 wt% or 15 wt%.

[0046] Preferably, after the granulation and before the sintering, tableting is further performed to obtain a ceramic green body.

[0047] Preferably, the tabletting pressure is 50-530 MPa, for example, 50 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa or 530 MPa.

[0048] Preferably, the diameter of the ceramic green body is 5 to 10 mm, for example, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0049] Preferably, the thickness of the ceramic green body is 1 to 2 mm, for example, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm or 2 mm.

[0050] As a preferred technical solution of the present invention, the sintering atmosphere includes any one of air, nitrogen, argon or a nitrogen-hydrogen mixture.

[0051] Preferably, the H2 content in the nitrogen-hydrogen mixture is 0.1-8 vol%, for example, 0.1 vol%, 1 vol%, 2 vol%, 3 vol%, 4 vol%, 5 vol%, 6 vol%, 7 vol% or 8 vol%.

[0052] Preferably, the sintering includes one-stage sintering and two-stage sintering.

[0053] In the present invention, the one-stage sintering is a debinding process.

[0054] Preferably, the heating rate of the first stage sintering is 1 to 5°C / min, for example, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or 5°C / min.

[0055] Preferably, the sintering temperature of the first stage sintering is 500-650°C, for example, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C or 650°C, etc.

[0056] Preferably, the holding time of the first sintering stage is 30 to 180 min, for example, 30 min, 60 min, 90 min, 120 min, 150 min or 180 min.

[0057] Preferably, the heating rate of the second-stage sintering is 2 to 10°C / min, for example, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min.

[0058] Preferably, the sintering temperature of the second stage sintering is 1100-1300°C, for example, 1100°C, 1120°C, 1140°C, 1160°C, 1180°C, 1200°C, 1220°C, 1240°C, 1260°C, 1280°C or 1300°C, and preferably 1150-1250°C.

[0059] Preferably, the holding time of the second-stage sintering is 60 to 360 min, for example, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min, 270 min, 300 min, 330 min or 360 min.

[0060] As a preferred technical solution, the preparation method comprises the following steps:

[0061] First, Mg source, Ca source, RE source, barium titanate with a particle size of 50 to 500 nm and a first solvent are ball-milled at a speed of 250 to 1500 r / min for 2 to 24 hours, dried at 80 to 100 ° C for 6 to 24 hours, and pre-sintered at 900 to 1100 ° C for 0.5 to 1.5 hours. Then, the obtained pre-sintered powder is ball-milled with an Al source, a Si source and a second solvent at a speed of 250 to 1500 r / min for 2 to 24 hours, dried at 80 to 100 ° C for 6 to 24 hours to obtain an intermediate powder, which is then mixed with a concentration of The ceramic green body is first heated to 500-650° C. at a rate of 1-5° C. / min, kept at that temperature for 30-180 minutes, and then sintered in a second stage. The ceramic green body is then heated to 1100-1300° C. at a rate of 2-10° C. / min, kept at that temperature for 60-360 minutes, and then sintered in a second stage to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0062] Wherein, in terms of molar percentage, the barium titanate content in the intermediate powder is 90-99.7 mol%, the Mg content is 0.1-4 mol%, the Ca content is 0.25-0.55 mol%, the RE content is 0.1-3.5 mol%, the Al content is 0.002-0.3 mol%, and the Si content is 0.01-4.0 mol%; the mass ratio of the first solvent to the Mg source, Ca source, RE source and barium titanate as a whole in step (1) is (1-3):1; the mass ratio of the second solvent to the pre-sintered powder, Al source and Si source as a whole in step (2) is (1-3):1; the particle sizes of the Mg source, Ca source, RE source, Al source and Si source are each independently 20-150 nm.

[0063] In a third aspect, the present invention also provides an application of a giant dielectric barium titanate-based ceramic dielectric material, wherein the giant dielectric barium titanate-based ceramic dielectric material described in the first aspect, or the giant dielectric barium titanate-based ceramic dielectric material prepared by the preparation method described in the second aspect, is applied to electronic ceramics.

[0064] Compared with the prior art, the present invention has at least the following beneficial effects:

[0065] 1) The giant dielectric barium titanate-based ceramic dielectric material provided by the present invention is a fine-grained ceramic with an average grain size of 460 to 650 nm and a room temperature dielectric constant greater than 10 at 1 kHz. 4 order of magnitude, with a giant dielectric constant, good dielectric stability in a wide temperature range, and a resistivity greater than 10 9 Ω·cm.

[0066] 2) The present invention adopts the traditional solid-phase process, which is simple, low-cost, suitable for large-scale industrialization, and applicable to the preparation of various electronic components. It is widely used in multilayer ceramic capacitors (MLCCs) to meet the development needs of their dielectric layers.

[0067] 3) In the solid-phase process of the present invention, barium titanate is first mixed with a Mg source, a Ca source, and an RE source to obtain a pre-sintered powder, which is then mixed with an Al source and a Si source. This ensures that the prepared ceramic is fine-grained, has a more uniform distribution of doping elements, and has a giant dielectric constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is an SEM image of the giant dielectric barium titanate-based ceramic dielectric material according to Example 1 of the present invention.

[0069] Figure 2 This is a grain size distribution diagram of the giant dielectric barium titanate-based ceramic dielectric material according to Example 1 of the present invention.

[0070] Figure 3 This is the XRD pattern of the giant dielectric barium titanate-based ceramic dielectric material of Example 1 of the present invention.

[0071] Figure 4 This is an SEM image of the giant dielectric barium titanate-based ceramic dielectric material of Example 2 of the present invention.

[0072] Figure 5 This is a grain size distribution diagram of the giant dielectric barium titanate-based ceramic dielectric material according to Example 2 of the present invention.

[0073] Figure 6 This is an SEM image of the giant dielectric barium titanate-based ceramic dielectric material of Comparative Example 1 of the present invention.

[0074] Figure 7 This is a diagram of the dielectric properties of the giant dielectric barium titanate-based ceramic dielectric material according to Example 1 of the present invention.

[0075] Figure 8 This is a diagram of the dielectric properties of the giant dielectric barium titanate-based ceramic dielectric material of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0076] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0077] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0078] Example 1

[0079] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The giant dielectric barium titanate-based ceramic dielectric material, in terms of molar percentage, has a barium titanate content of 94.445 mol%, a Mg content of 0.8 mol%, a Ca content of 0.45 mol%, a Dy content of 1.3 mol%, an Al content of 0.005 mol%, and a Si content of 3 mol%. The preparation method comprises the following steps:

[0080] (1) Weigh 23.3194 g (0.1 mol) of 250 nm barium titanate powder, weigh the corresponding masses of MgO, CaO, Dy2O3, Al2O3 and SiO2 according to the molar percentage content of each element, and ball mill the barium titanate powder, MgO, CaO and Dy2O3 with 35.5 g of anhydrous ethanol at a speed of 480 r / min for 24 h to mix them evenly. The ball milling beads are zirconia beads with a diameter of 3 mm. The mixed slurry is dried in an oven at 80°C for 12 h, and pre-sintered at 1000°C for 1 h. Then, the pre-sintered powder, Al2O3 and SiO2 are ball milled with 35.5 g of anhydrous ethanol at 480 r / min for 24 h, and dried at 80°C for 12 h to obtain an intermediate powder;

[0081] (2) A 6 wt% polyvinyl alcohol solution (12 wt% of the intermediate powder) and the intermediate powder were mixed, granulated, and pressed at a pressure of 300 MPa to obtain a ceramic green body with a diameter of 10 mm and a thickness of 1 mm. The ceramic green body was sintered in a nitrogen-hydrogen mixture with a H2 content of 1.5 vol%. The temperature was first raised to 600°C at a rate of 1.5°C / min and kept at this temperature for 120 minutes to fully debind. The temperature was then raised to 1200°C at a rate of 5°C / min and kept at this temperature for 120 minutes to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0082] Figure 1 The SEM image of the giant dielectric barium titanate-based ceramic dielectric material of Example 1 of the present invention is shown. From the SEM image at a magnification of 10,000, it can be seen that the material is highly dense, has a small grain size, and has no abnormally large grains.

[0083] Figure 2 The grain size distribution diagram of the giant dielectric barium titanate-based ceramic dielectric material of Example 1 of the present invention is shown. As can be seen from the figure, the average grain size of the ceramic material is 485 nm, and the grain size distribution is relatively concentrated.

[0084] Figure 3 The XRD pattern of the giant dielectric barium titanate-based ceramic dielectric material of Example 1 of the present invention is shown. As can be seen from the figure, the ceramic material is a single phase without the presence of other impurity phases.

[0085] Example 2

[0086] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The giant dielectric barium titanate-based ceramic dielectric material, in terms of molar percentage, has a barium titanate content of 93.49 mol%, a Mg content of 1.2 mol%, a Ca content of 0.3 mol%, a Dy content of 1.8 mol%, an Al content of 0.01 mol%, and a Si content of 3.2 mol%. The preparation method comprises the following steps:

[0087] (1) Weigh 23.3194 g (0.1 mol) of 250 nm barium titanate powder, weigh the corresponding mass of MgO, CaO, Dy2O3, Al2O3 and SiO2 according to the molar percentage content of each element, and ball mill the barium titanate powder, MgO, CaO and Dy2O3 with 35.5 g of anhydrous ethanol at a speed of 480 r / min for 18 h to mix them evenly. The ball milling beads are zirconia beads with a diameter of 3 mm. The mixed slurry is dried in an oven at 80°C for 24 h, and pre-sintered at 950°C for 0.8 h. Then, the pre-sintered powder, Al2O3 and SiO2 are ball milled with 40 g of anhydrous ethanol at 480 r / min for 18 h, and dried at 80°C for 24 h to obtain an intermediate powder;

[0088] (2) A polyvinyl alcohol solution with a concentration of 8 wt% (12 wt% of the intermediate powder) and the intermediate powder were mixed, granulated, and pressed into sheets under a pressure of 300 MPa to obtain a ceramic green body with a diameter of 10 mm and a thickness of 1 mm. The ceramic green body was sintered in a nitrogen-hydrogen mixture with a H2 content of 1.0 vol%. The temperature was first raised to 600°C at a rate of 1.5°C / min and kept warm for 120 minutes to fully debind. The temperature was then raised to 1200°C at a rate of 5°C / min and kept warm for 120 minutes to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0089] Figure 4 The SEM image of the giant dielectric barium titanate-based ceramic dielectric material of Example 2 of the present invention is shown. From the SEM image at a magnification of 10,000, it can be seen that the ceramic material is highly dense, has a small grain size, and has no abnormally large grains.

[0090] Figure 5 The grain size distribution diagram of the giant dielectric barium titanate-based ceramic dielectric material of Example 2 of the present invention is shown. As can be seen from the figure, the average grain size of the ceramic material is 590 nm, and the grain size distribution is relatively concentrated.

[0091] Example 3

[0092] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The giant dielectric barium titanate-based ceramic dielectric material, in terms of molar percentage, has a barium titanate content of 94.07 mol%, a Mg content of 1.8 mol%, a Ca content of 0.38 mol%, a Dy content of 2.5 mol%, an Al content of 0.05 mol%, and a Si content of 1.2 mol%. The preparation method comprises the following steps:

[0093] (1) Weigh 23.3194 g (0.1 mol) of 250 nm barium titanate powder, weigh the corresponding mass of MgO, CaO, Dy2O3, Al2O3 and SiO2 according to the molar percentage content of each element, and ball mill the barium titanate powder, MgO, CaO and Dy2O3 with 34.5 g of anhydrous ethanol at a speed of 480 r / min for 24 h to mix them evenly. The ball milling beads are zirconia beads with a diameter of 3 mm. The mixed slurry is dried in an oven at 80°C for 24 h, and pre-sintered at 1050°C for 1.2 h. Then, the pre-sintered powder, Al2O3 and SiO2 are ball milled with 35.5 g of anhydrous ethanol at 480 r / min for 24 h, and dried at 80°C for 24 h to obtain an intermediate powder;

[0094] (2) A 5 wt% polyvinyl alcohol solution (12 wt% of the intermediate powder) was mixed with the intermediate powder, granulated, and pressed into sheets at a pressure of 350 MPa to obtain a ceramic green body with a diameter of 10 mm and a thickness of 1 mm. The ceramic green body was sintered in air by first heating to 600°C at a rate of 1.0°C / min, keeping the temperature for 180 minutes to fully debind, and then heating to 1200°C at a rate of 4°C / min and keeping the temperature for 150 minutes to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0095] Example 4

[0096] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The giant dielectric barium titanate-based ceramic dielectric material, in terms of molar percentage, has a barium titanate content of 92.148 mol%, a Mg content of 0.1 mol%, a Ca content of 0.25 mol%, a Y content of 3.5 mol%, an Al content of 0.002 mol%, and a Si content of 4 mol%. The preparation method comprises the following steps:

[0097] (1) Weigh 23.3194 g (0.1 mol) of 250 nm barium titanate powder, weigh the corresponding masses of MgO, CaO, Y2O3, Al2O3 and SiO2 according to the molar percentage content of each element, and ball mill the barium titanate powder, MgO, CaO and Y2O3 with 35.5 g of anhydrous ethanol at a speed of 1500 r / min for 4 h to mix them evenly. The ball milling beads are zirconia beads with a diameter of 3 mm. The mixed slurry is dried in an oven at 100°C for 24 h, and pre-sintered at 900°C for 1.5 h. Then, the pre-sintered powder, Al2O3 and SiO2 are ball milled with 30.0 g of anhydrous ethanol at 1500 r / min for 4 h, and dried at 100°C for 24 h to obtain an intermediate powder;

[0098] (2) A 6 wt% polyvinyl alcohol solution (12 wt% of the intermediate powder) was mixed with the intermediate powder, granulated, and pressed into sheets at a pressure of 300 MPa to obtain a ceramic green body with a diameter of 10 mm and a thickness of 1 mm. The ceramic green body was sintered in a nitrogen-hydrogen mixture with a H2 content of 5 vol%. The temperature was first raised to 650°C at a rate of 5°C / min and kept at this temperature for 30 minutes to fully debind. The temperature was then raised to 1250°C at a rate of 10°C / min and kept at this temperature for 60 minutes to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0099] Example 5

[0100] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The giant dielectric barium titanate-based ceramic dielectric material, in terms of molar percentage, has a barium titanate content of 95.05 mol%, a Mg content of 4 mol%, a Ca content of 0.55 mol%, a Ce content of 0.1 mol%, an Al content of 0.25 mol%, and a Si content of 0.05 mol%. The preparation method comprises the following steps:

[0101] (1) Weigh 23.3194 g (0.1 mol) of 250 nm barium titanate powder, weigh the corresponding mass of MgO, CaO, CeO2, Al2O3 and SiO2 according to the molar percentage content of each element, and ball mill the barium titanate powder, MgO, CaO and CeO2 with 35.5 g of anhydrous ethanol at a speed of 250 r / min for 12 h to mix them evenly. The ball milling beads are zirconia beads with a diameter of 3 mm. The mixed slurry is dried in an oven at 90°C for 24 h, and pre-sintered at 1100°C for 0.5 h. Then, the pre-sintered powder, Al2O3 and SiO2 are ball milled with 35.5 g of anhydrous ethanol at 250 r / min for 12 h, and dried at 90°C for 24 h to obtain an intermediate powder;

[0102] (2) A 15 wt% polyvinyl alcohol solution (12 wt% of the intermediate powder) and the intermediate powder were mixed, granulated, and pressed into sheets at a pressure of 300 MPa to obtain a ceramic green body with a diameter of 10 mm and a thickness of 1 mm. The ceramic green body was sintered in a nitrogen-hydrogen mixture with a H2 content of 0.5 vol%. The temperature was first raised to 500°C at a rate of 1°C / min and kept at this temperature for 180 minutes to fully debind. The temperature was then raised to 1150°C at a rate of 2°C / min and kept at this temperature for 360 minutes to obtain a giant dielectric barium titanate-based ceramic dielectric material.

[0103] Example 6

[0104] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this embodiment and Example 1 is that in step (1), all raw materials are directly mixed with anhydrous ethanol, that is, barium titanate powder, MgO, CaO, Dy2O3, Al2O3 and SiO2 are mixed with 35.5g of anhydrous ethanol by ball milling at a speed of 480r / min for 24h to mix evenly, the ball milling beads are zirconia beads with a diameter of 3mm, and the mixed slurry is dried in an oven at 80°C for 12h to obtain an intermediate powder. The remaining preparation methods and parameters are consistent with Example 1.

[0105] Example 7

[0106] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this embodiment and Example 1 is that in step (2), the temperature of the second stage sintering is 1300° C., and the remaining preparation methods and parameters are consistent with Example 1.

[0107] Example 8

[0108] This embodiment provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this embodiment and Example 1 is that in step (2), the temperature of the second stage sintering is 1100° C., and the rest of the preparation methods and parameters are consistent with Example 1.

[0109] Comparative Example 1

[0110] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 94.445 mol%, the Mg content is 3.805 mol%, the Ca content is 0.45 mol% and the Dy content is 1.3 mol%, in terms of molar percentage, and Al2O3 and SiO2 are omitted. In step (1), 23.3194 g (0.1 mol) of 250 nm barium titanate powder is weighed, and the corresponding masses of MgO, CaO and Dy2O3 are weighed according to the molar percentage content of the above elements and directly mixed. The remaining preparation methods and parameters are consistent with Example 1.

[0111] Figure 6 The SEM image of the giant dielectric barium titanate-based ceramic dielectric material of Comparative Example 1 of the present invention is shown. From the SEM image at a magnification of 10,000, it can be seen that the average grain size of the ceramic material is large and the grain size is uneven.

[0112] Comparative Example 2

[0113] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 94.445 mol%, the Mg content is 2.0 mol%, the Ca content is 0.55 mol%, the Al content is 0.005 mol% and the Si content is 3 mol%, and Dy2O3 is omitted. In step (1), 23.3194 g (0.1 mol) of 250 nm barium titanate powder is weighed, and the corresponding masses of MgO, CaO, Al2O3 and SiO2 are weighed according to the molar percentage content of the above elements. The remaining preparation methods and parameters are consistent with Example 1.

[0114] Comparative Example 3

[0115] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 94.445 mol%, the Mg content is 1.95 mol%, the Ca content is 0.55 mol%, the Dy content is 0.05 mol%, the Al content is 0.005 mol%, and the Si content is 3 mol%. The remaining preparation methods and parameters are consistent with Example 1.

[0116] Comparative Example 4

[0117] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 92.645 mol%, the Mg content is 0.1 mol%, the Ca content is 0.25 mol%, the Dy content is 4.0 mol%, the Al content is 0.005 mol%, and the Si content is 3 mol%. The remaining preparation methods and parameters are consistent with Example 1.

[0118] Comparative Example 5

[0119] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 93.25 mol%, the Mg content is 0.1 mol%, the Ca content is 0.45 mol%, the Dy content is 1.3 mol%, the Al content is 0.4 mol%, and the Si content is 4.5 mol%. The remaining preparation methods and parameters are consistent with Example 1.

[0120] Comparative Example 6

[0121] This comparative example provides a giant dielectric barium titanate-based ceramic dielectric material and a preparation method thereof. The difference between this comparative example and Example 1 is that, in the giant dielectric barium titanate-based ceramic dielectric material, the barium titanate content is 94.445 mol%, the Mg content is 0.8 mol%, the Ca content is 0.45 mol%, the Ta content is 1.3 mol%, the Al content is 0.005 mol%, and the Si content is 3 mol%. That is, Dy is replaced by Ta, and in step (1), Dy2O3 is replaced by Ta2O3 of the corresponding mass. The remaining preparation methods and parameters are consistent with Example 1.

[0122] The giant dielectric barium titanate-based ceramic dielectric materials of Examples 1 to 8 and Comparative Examples 1 to 6 were polished on both sides and coated with silver. The dielectric properties and room temperature resistivity were tested. The test results are shown in Table 1:

[0123] 1) Dielectric properties

[0124] Test instrument: Dielectric parameter tester (E4980A; Agilent; USA); Test method: At room temperature of 25°C, the driving field was adjusted to 0.5 V / μm and the frequency was 120 Hz, and its basic electrical properties were measured using the dielectric parameter tester.

[0125] 2) Room temperature resistivity

[0126] Test instrument: Semiconductor tester (708B; Keithley; USA). Test method: Set a linear increase in DC voltage from 0 to 2.5 V in 0.05 V steps. Measure the device's insulation resistance vs. voltage curve. Take the average of the last two resistance points as the insulation resistance value. Calculate the resistivity from this resistance value.

[0127] Figure 7 The dielectric properties of the giant dielectric barium titanate-based ceramic dielectric material of Example 1 of the present invention are shown. As can be seen from the figure, the room temperature dielectric constant is 41760 at 1 kHz, the dielectric stability is good in the temperature range of 25 to 200°C, and the dielectric loss is 0.032.

[0128] Figure 8 The dielectric properties of the giant dielectric barium titanate-based ceramic dielectric material of comparative example 2 of the present invention are shown. As can be seen from the figure, the room temperature dielectric constant is 2576 at 1 kHz, and the dielectric stability is poor in the temperature range of 25 to 200°C.

[0129] Table 1

[0130]

[0131]

[0132] The test results show that:

[0133] (1) It can be seen from Examples 1 to 8 that the present invention can obtain fine-grained ceramics with an average grain size of 460 to 650 nm by regulating the type and content of doping elements in the barium titanate-based ceramic dielectric material and combining it with the corresponding preparation process. At the same time, it has a giant dielectric constant, low dielectric loss, and a room temperature resistivity greater than 10 9 Ω·cm, the overall performance is better.

[0134] (2) It can be seen from Examples 1 and 7 to 8 that the present invention further controls the temperature of the secondary sintering, resulting in a smaller average grain size, a higher dielectric constant of the ceramic material, and better dielectric stability over a wide temperature range.

[0135] (3) It can be seen from Example 1 and Comparative Examples 1 to 6 that the present invention can obtain the technical effect of obtaining fine-grained ceramics while having a giant dielectric constant by regulating the type and content of doping elements in the barium titanate-based ceramic dielectric material.

[0136] In Comparative Example 1, when Al2O3 and SiO2 are omitted and only MgO exists, although its liquid molten state can be coated on the surface of barium titanate particles, the effect is limited. When Al and Si elements are added, Mg and Al can jointly reduce the sintering temperature, and at the same time play a corresponding pinning role at the grain boundaries, thereby effectively hindering the movement of grain boundaries and further inhibiting grain growth. Si can also promote the formation of liquid molten state. Therefore, omitting Al2O3 and SiO2 cannot achieve the preparation of fine-grained ceramics, the average grain size of the material is too large, and the corresponding dielectric constant does not meet the standard of giant dielectric constant. The three elements are added together and work synergistically to obtain fine-grained ceramics with giant dielectric constant.

[0137] In Comparative Example 2, when Dy2O3 is omitted, the capacitance effect of the internal barrier layer cannot be generated in the ceramic material, the dielectric constant of the ceramic material is greatly reduced, and the dielectric loss is also greatly increased.

[0138] In Comparative Examples 3 and 4, when the Dy content is too low, fewer defect dipoles are generated in the ceramic material. When the Dy content is too high, an electron pinning effect occurs, which suppresses the capacitance effect of the internal barrier layer. Therefore, whether the content is too low or too high, it will affect the dielectric constant of the ceramic material, causing it to be greatly reduced.

[0139] In Comparative Example 5, when the contents of Si and Al are both too high, more liquid phase is generated, resulting in abnormally large grains, which in turn affects the dielectric constant and dielectric loss of the ceramic material.

[0140] In Comparative Example 6, when Dy is replaced with the non-rare earth element Ta, because the Ta ion radius is slightly larger than the Ti ion, after replacing the titanium (Ti) site, too many defect dipoles are generated, and the capacitance effect of the internal barrier layer cannot be played, so that the dielectric constant and dielectric loss of the ceramic material will be affected.

[0141] In summary, the present invention adopts the traditional solid phase process to prepare the giant dielectric barium titanate-based ceramic dielectric material with a small average grain size; the room temperature dielectric constant is greater than 10 at 1kHz. 4 order of magnitude, with a giant dielectric constant, good dielectric stability in a wide temperature range, and a resistivity greater than 10 9 Ω·cm; the process is simple, the cost is low, and it is suitable for large-scale industrialization.

[0142] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A giant dielectric barium titanate-based ceramic dielectric material, characterized in that: The giant dielectric barium titanate-based ceramic dielectric material includes barium titanate and doping elements, wherein the doping elements are composed of Mg, Ca, RE, Al and Si; in terms of molar percentage, the barium titanate content is 90-99.7 mol%, the Mg content is 0.1-4 mol%, the Ca content is 0.25-0.55 mol%, the RE content is 0.1-3.5 mol%, the Al content is 0.002-0.3 mol%, and the Si content is 0.01-4.0 mol%.

2. The giant dielectric barium titanate-based ceramic dielectric material according to claim 1, characterized in that: The RE includes any one of Ho, Dy, Y, La, Sm, Er or Ce, or a combination of at least two of them.

3. The giant dielectric barium titanate-based ceramic dielectric material according to claim 1 or 2, characterized in that: The average grain size of the giant dielectric barium titanate-based ceramic dielectric material is 460-650 nm.

4. A method for preparing a giant dielectric barium titanate-based ceramic dielectric material according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The Mg source, Ca source, RE source, Al source, Si source and barium titanate are mixed once to obtain an intermediate powder, which is then mixed with a binder solution for a second time, granulated and sintered to obtain a giant dielectric barium titanate-based ceramic dielectric material; Among them, in terms of molar percentage, the barium titanate content in the intermediate powder is 90-99.7 mol%, the Mg content is 0.1-4 mol%, the Ca content is 0.25-0.55 mol%, the RE content is 0.1-3.5 mol%, the Al content is 0.002-0.3 mol%, and the Si content is 0.01-4.0 mol%.

5. The preparation method according to claim 4, characterized in that The Mg source, Ca source, RE source, Al source, Si source and barium titanate are mixed once to obtain an intermediate powder, which includes: (1) First, Mg source, Ca source, RE source and barium titanate are uniformly mixed and pre-sintered to obtain pre-sintered powder; (2) The pre-sintered powder is then mixed evenly with an Al source and a Si source to obtain an intermediate powder.

6. The preparation method according to claim 5, characterized in that Before the mixing in step (1), a first solvent is added for mixing; before the mixing in step (2), a second solvent is added for mixing; Preferably, the mass ratio of the first solvent to the Mg source, Ca source, RE source and barium titanate in step (1) is (1-3):1; Preferably, the mass ratio of the second solvent to the pre-sintered powder, Al source and Si source in step (2) is (1-3):1; Preferably, the mixing comprises ball milling; Preferably, the rotation speed of the ball mill is 250 to 1500 r / min; Preferably, the ball milling time is 2 to 24 hours; Preferably, the pre-sintering temperature is 900-1100°C; Preferably, the pre-sintering holding time is 0.5 to 1.5 hours; Preferably, the Mg source, Ca source, RE source, Al source and Si source each independently include any one or a combination of at least two of oxides, hydroxides, chlorides, sulfates, nitrates or carbonates; Preferably, the RE in the RE source includes any one or a combination of at least two of Ho, Dy, Y, La, Sm, Er or Ce; Preferably, the particle size of the Mg source, Ca source, RE source, Al source and Si source is independently 20 to 150 nm; Preferably, the particle size of the barium titanate is 50 to 500 nm.

7. The preparation method according to any one of claims 4 to 6, characterized in that The binder solution includes a polyvinyl alcohol solution or a polyvinyl butyral solution; Preferably, the concentration of the binder solution is 2.5 to 15 wt%; Preferably, after the granulation and before the sintering, tableting is further performed to obtain a ceramic green body.

8. The preparation method according to any one of claims 4 to 7, characterized in that The sintering atmosphere in step (2) includes any one of air, nitrogen, argon or a nitrogen-hydrogen mixture; Preferably, the sintering includes one-stage sintering and two-stage sintering; Preferably, the heating rate of the first stage sintering is 1-5°C / min; Preferably, the sintering temperature of the first stage sintering is 500-650°C; Preferably, the holding time of the sintering stage is 30 to 180 minutes; Preferably, the heating rate of the second-stage sintering is 2-10°C / min; Preferably, the sintering temperature of the second stage sintering is 1100-1300°C, preferably 1150-1250°C; Preferably, the holding time of the second-stage sintering is 60 to 360 minutes.

9. The preparation method according to claim 4, characterized in that The preparation method comprises the following steps: First, Mg source, Ca source, RE source, barium titanate with a particle size of 50 to 500 nm and a first solvent are ball-milled at a speed of 250 to 1500 r / min for 2 to 24 hours, dried at 80 to 100 ° C for 6 to 24 hours, and pre-sintered at 900 to 1100 ° C for 0.5 to 1.5 hours. Then, the obtained pre-sintered powder is ball-milled with an Al source, a Si source and a second solvent at a speed of 250 to 1500 r / min for 2 to 24 hours, dried at 80 to 100 ° C for 6 to 24 hours to obtain an intermediate powder, which is then mixed with a concentration of The ceramic green body is first heated to 500-650° C. at a rate of 1-5° C. / min, kept at that temperature for 30-180 minutes, and then sintered in a second stage. The ceramic green body is then heated to 1100-1300° C. at a rate of 2-10° C. / min, kept at that temperature for 60-360 minutes, and then sintered in a second stage to obtain a giant dielectric barium titanate-based ceramic dielectric material. Wherein, in terms of molar percentage, the barium titanate content in the intermediate powder is 90-99.7 mol%, the Mg content is 0.1-4 mol%, the Ca content is 0.25-0.55 mol%, the RE content is 0.1-3.5 mol%, the Al content is 0.002-0.3 mol%, and the Si content is 0.01-4.0 mol%; the mass ratio of the first solvent to the Mg source, Ca source, RE source and barium titanate as a whole in step (1) is (1-3):1; the mass ratio of the second solvent to the pre-sintered powder, Al source and Si source as a whole in step (2) is (1-3):1; the particle sizes of the Mg source, Ca source, RE source, Al source and Si source are each independently 20-150 nm.

10. An application of a giant dielectric barium titanate-based ceramic dielectric material, characterized in that: The giant dielectric barium titanate-based ceramic dielectric material according to any one of claims 1 to 3, or the giant dielectric barium titanate-based ceramic dielectric material prepared by the preparation method according to any one of claims 4 to 9, is applied to electronic ceramics.

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