High energy density dielectric material, capacitor and method of making same
By doping and regulating the Bi3(AnNp)Ti3O12 dielectric material, an amorphous-crystalline dual-phase structure is constructed, which solves the problems of environmental pollution and poor high-temperature resistance of ferroelectric thin film capacitors and realizes the preparation of capacitors with high energy storage density and low electrical loss.
Patent Information
- Application Number
- CN202510977852.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2045-07-16
AI Technical Summary
Existing ferroelectric thin film capacitor materials have problems of environmental pollution and poor high-temperature resistance, which limits their application, especially in fields with high temperature requirements such as aerospace.
A high energy storage density dielectric material with Bi3(AnNp)Ti3O12 as the chemical composition is used. By doping A and N elements, the rotation and crystallization energy of oxygen octahedron are synergistically regulated to construct an amorphous-crystalline two-phase structure and prepare a dielectric thin film capacitor.
The energy storage density and energy storage efficiency of the capacitor are increased, the electrical loss is reduced, the comprehensive performance of the capacitor is improved, and the preparation method is simple and efficient.
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Figure CN120473336B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a high energy storage density dielectric material, a capacitor and a preparation method thereof, and belongs to the technical field of dielectric capacitors. Background Art
[0002] Dielectric capacitors, as a primary passive energy storage device, offer fast charge and discharge rates and ultra-high power density, making them widely used in electronic circuits for functions such as DC blocking and AC passing, coupling, bypassing, filtering, tuning circuits, and energy conversion. Ferroelectric film capacitors, a common dielectric capacitor, boast high dielectric constant and high breakdown field strength. Their compact size, light weight, and ease of integration have attracted extensive research interest. However, currently commercialized ferroelectric film capacitors are manufactured using lead-based materials or organic polymers. Lead is a toxic element, and its volatilization during the preparation of lead-based materials can cause severe environmental pollution and pose a health risk. Organic polymers, while offering extremely high breakdown field strength and thus high energy storage density, suffer from poor high-temperature resistance, significantly limiting their application, particularly in applications requiring high temperatures, such as aerospace. Therefore, the search for environmentally friendly dielectric materials with high dielectric constants, high energy storage density, and excellent temperature stability is imperative. Summary of the Invention
[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a high energy storage density dielectric material, a capacitor and a preparation method thereof, which can improve the energy storage density and energy storage efficiency of the capacitor and reduce electrical loss.
[0004] The first aspect of the present invention relates to a high energy storage density dielectric material, the general chemical formula of which is Bi3(A n N p )Ti3O 12 , where A is selected from at least one of Nd, La, Sm, Eu, Er, and Dy; N is selected from at least one of Ca, Sn, Sr, Cs, Nb, Hf, and Ga; and n+p=1, 0<n<1, 0<p<1. It is worth noting that A and N can be either isovalent or heterovalent. If they are heterovalent, they can form a complex doped oxide and, during this process, form association defects with the generated Bi vacancies. This not only maintains the material's electrical neutrality, but also improves its electrical properties.
[0005] For n, it can be taken from the following ranges, such as 0.01~0.10, 0.10~0.50, 0.50~0.70, 0.70~0.90, 0.90~0.99, etc.
[0006] For p, it can be taken from the following ranges, such as 0.01~0.10, 0.10~0.20, 0.20~0.50, 0.50~0.80, 0.80~0.99, etc.
[0007] Preferably, n≥p.
[0008] A second aspect of the present invention relates to a capacitor comprising a dielectric film made of the above-mentioned high energy storage density dielectric material.
[0009] For some specific embodiments, the total thickness of the dielectric film is 500-600 nm; preferably, the dielectric film is composed of 3-6 dielectric layers, each with a thickness of 90-200 nm.
[0010] A third aspect of the present invention relates to a method for preparing the above-mentioned capacitor, comprising the following steps:
[0011] Precursor preparation steps: According to Bi3(A n N p )Ti3O 12 The chemical composition of the raw materials bismuth source, titanium source, A source and N source are added to the solvent propionic acid and mixed until the raw materials are fully dissolved; then, the precursor solution is obtained by filtering and collecting the filtrate; finally, the precursor solution is aged;
[0012] The dielectric film preparation steps include: applying an aged precursor solution to a substrate via a spin coating process; heating each layer to a first temperature to evaporate and remove propionic acid, then heating to a second temperature to pyrolyze residual organic matter, and finally heat treating to obtain a dielectric layer; after a predetermined number of dielectric layers are formed, annealing is performed to obtain a dielectric film;
[0013] Electrode preparation steps: Electrodes are plated on the surface of the dielectric film to make a capacitor.
[0014] For some specific embodiments, the bismuth source is bismuth acetate, and the mass ratio of bismuth acetate to propionic acid during mixing is 1:(5-8); the titanium source is tetrabutyl titanate, the A source is A acetate, and the N source is N nitrate.
[0015] For some specific embodiments, in the precursor preparation step, the specific operation of the mixing treatment is first stirring at 70-80° C. for 9-13 minutes, and then continuously stirring at room temperature for 5-7 hours.
[0016] For some specific embodiments, in the precursor preparation step, an excess bismuth source is added to the precursor solution before aging to compensate for the volatilization loss of Bi during the heat treatment; preferably, the excess bismuth source accounts for 5% of the mass of the original bismuth source.
[0017] In some specific embodiments, in the precursor preparation step, the precursor solution is aged at room temperature for 40 to 50 hours.
[0018] For some specific implementation schemes, in the dielectric film preparation step, the first temperature ranges from 190 to 220° C., and the heating time is 1 to 3 minutes; the second temperature ranges from 390 to 420° C., and the heating time is 9 to 12 minutes.
[0019] According to some specific embodiments, in the dielectric film preparation step, the heat treatment temperature is 720-820° C. and the time is 5-20 minutes.
[0020] According to some specific implementation schemes, in the dielectric film preparation step, the annealing treatment temperature is 650-780° C. and the time is 100-150 minutes.
[0021] For some specific embodiments, the substrate is a platinum / titanium / silicon dioxide / silicon substrate.
[0022] Compared with the prior art, the present invention has the following technical effects:
[0023] 1) By doping with elements A and N, the rotation and crystallization energy of the oxygen octahedron are synergistically controlled, the magnitude and direction of local lattice distortion are changed, the basic polarization is enhanced, and an amorphous-crystalline dual-phase structure is constructed. The A element mainly breaks the polarization anisotropy, resulting in a higher polarization of the material in the polycrystalline form; the N element mainly enhances the crystallization energy, which is conducive to the formation of a multiphase structure. The synergistic regulation of elements A and N ensures that the manufactured product has high energy storage density and efficiency, low electrical loss, and improves the overall performance of the capacitor.
[0024] 2) The preparation method is simple and the preparation efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 The powder material obtained by calcining the precursor in Example 1 at 900℃ for 2h and Bi4Ti3O 12 X-ray diffraction pattern comparison chart of standard powder materials;
[0026] Figure 2 is the XRD diffraction pattern of the dielectric film in Example 1;
[0027] Figure 3 This is a partial TEM image of the dielectric film in Example 1; the area outside the closed dotted line belongs to region 1, and the area inside the closed dotted line belongs to region 2;
[0028] Figure 4 The hysteresis loop diagrams of the polarization strength of the capacitors prepared in Examples 1 to 4 and Comparative Example 1 as a function of the electric field are shown. DETAILED DESCRIPTION
[0029] The present invention will be described in detail below in conjunction with specific embodiments. Experimental methods without specific conditions specified in the examples were carried out according to conventional methods and conditions.
[0030] Example 1
[0031] This embodiment relates to a layered compound capacitor with high energy storage density, and its preparation process is as follows:
[0032] Step S1: Based on the dielectric material Bi3 (Dy 0.7 Nb 0.3 )Ti3O 12 The chemical composition of the precursor comprises the following steps: adding bismuth acetate as a bismuth source, tetrabutyl titanate as a titanium source, dysprosium acetate as an A source, and niobium nitrate as a N source to propionic acid, with the mass ratio of bismuth source to propionic acid being 1:6; stirring at 73°C for 10 minutes, and then continuously stirring at room temperature for 5.5 hours to achieve full dissolution; then filtering the precursor with a syringe with a pore size of 0.22 μm, taking the filtrate to obtain a clear precursor solution; then adding an excess bismuth source accounting for 5% of the mass of the original bismuth source, and finally aging at room temperature for 43 hours;
[0033] Step S2: The aged precursor solution is applied to a platinum / titanium / silicon dioxide / silicon substrate via a spin coating process. The substrate is first baked at 200°C for 1.5 minutes to rapidly evaporate the propionic acid, and then pyrolyzed at 400°C for 10 minutes to remove residual organic matter. Finally, the substrate is heat treated at 750°C for 10 minutes to adjust the microstructure.
[0034] Step S3: Repeat step S2 until a four-layer structure film with a thickness of 500 nm is obtained, and finally anneal at 670° C. for 120 minutes to obtain a multilayer dielectric film;
[0035] Step S4: using a sputtering apparatus, an electrode with a diameter of 0.5 mm is plated on the surface of the multilayer dielectric film produced in step S3 to obtain a capacitor.
[0036] Example 2
[0037] This embodiment relates to a layered compound capacitor with high energy storage density, and its preparation process is as follows:
[0038] Step S1: Based on the dielectric material Bi3(La 0.6 Ga 0.4 )Ti3O 12The chemical composition of the precursor comprises the following steps: adding bismuth acetate as a bismuth source, tetrabutyl titanate as a titanium source, lanthanum acetate as an A source, and gallium nitrate as an N source to propionic acid, with the mass ratio of bismuth source to propionic acid being 1:6.5; stirring at 75°C for 11 minutes, and then continuously stirring at room temperature for 6 hours to achieve full dissolution; then filtering the precursor with a syringe with a pore size of 0.22 μm, taking the filtrate to obtain a clear precursor solution; then adding an excess bismuth source accounting for 5% of the mass of the original bismuth source, and finally aging at room temperature for 45 hours;
[0039] Step S2: The aged precursor solution is applied to a platinum / titanium / silicon dioxide / silicon substrate via a spin coating process. The substrate is first baked at 200°C for 2 minutes to rapidly evaporate the propionic acid, and then pyrolyzed at 405°C for 10.5 minutes to remove residual organic matter. Finally, the substrate is heat treated at 780°C for 15 minutes to adjust the microstructure.
[0040] Step S3: Repeat step S2 until a four-layer structure film with a thickness of 550 nm is obtained, and finally anneal at 720° C. for 130 minutes to obtain a multilayer dielectric film;
[0041] Step S4: using a sputtering apparatus, an electrode with a diameter of 0.5 mm is plated on the surface of the multilayer dielectric film produced in step S3 to obtain a capacitor.
[0042] Example 3
[0043] This embodiment relates to a layered compound capacitor with high energy storage density, and its preparation process is as follows:
[0044] Step S1: Based on the dielectric material Bi3(Er 0.8 Sr 0.2 )Ti3O 12 The chemical composition of the precursor is as follows: bismuth acetate as a bismuth source, tetrabutyl titanate as a titanium source, erbium acetate as an A source, and strontium nitrate as a N source are added to propionic acid, with the mass ratio of bismuth source to propionic acid being 1:7.5; stirring is carried out at 78°C for 12 minutes, and then stirring is continued at room temperature for 6.5 hours to achieve full dissolution; the precursor is then filtered with a syringe with a pore size of 0.22 μm, and the filtrate is taken to obtain a clear precursor solution; an excess bismuth source accounting for 5% of the mass of the original bismuth source is then added thereto, and finally aging is carried out at room temperature for 48 hours;
[0045] Step S2: The aged precursor solution is applied to a platinum / titanium / silicon dioxide / silicon substrate via a spin coating process. The substrate is first baked at 200°C for 2 minutes to rapidly evaporate the propionic acid, and then pyrolyzed at 415°C for 11 minutes to remove residual organic matter. Finally, the substrate is heat treated at 800°C for 17 minutes to adjust the microstructure.
[0046] Step S3: Repeat step S2 until a four-layer structure film with a thickness of 580 nm is obtained, and finally anneal at 760° C. for 140 minutes to obtain a multilayer structure dielectric film;
[0047] Step S4: using a sputtering apparatus, an electrode with a diameter of 0.5 mm is plated on the surface of the multilayer dielectric film produced in step S3 to obtain a capacitor.
[0048] Example 4
[0049] This embodiment relates to a layered compound capacitor with high energy storage density, and its preparation process is as follows:
[0050] Step S1: Based on the dielectric material Bi3 (Sm 0.9 Sn 0.1 )Ti3O 12 The chemical composition of the precursor comprises the following steps: adding bismuth acetate as a bismuth source, tetrabutyl titanate as a titanium source, samarium acetate as an A source, and tin nitrate as an N source to propionic acid, with the mass ratio of bismuth source to propionic acid being 1:8; stirring at 80°C for 13 minutes, and then continuously stirring at room temperature for 7 hours to achieve full dissolution; then filtering the precursor with a syringe with a pore size of 0.22 μm, taking the filtrate to obtain a clear precursor solution; then adding an excess bismuth source accounting for 5% of the mass of the original bismuth source, and finally aging at room temperature for 50 hours;
[0051] Step S2: The aged precursor solution is applied to a platinum / titanium / silicon dioxide / silicon substrate via a spin coating process. The substrate is first baked at 200°C for 3 minutes to rapidly evaporate the propionic acid, and then pyrolyzed at 420°C for 12 minutes to remove residual organic matter. Finally, the substrate is heat treated at 820°C for 20 minutes to adjust the microstructure.
[0052] Step S3: Repeat step S2 until a four-layer structure film with a thickness of 600 nm is obtained, and finally anneal the film at 780° C. for 150 minutes to obtain a multilayer dielectric film;
[0053] Step S4: using a sputtering apparatus, an electrode with a diameter of 0.5 mm is plated on the surface of the multilayer dielectric film produced in step S3 to obtain a capacitor.
[0054] Comparative Example 1
[0055] The difference between this comparative example and Example 1 is that the material of the multilayer dielectric film is Bi4Ti3O 12 , the film thickness remains unchanged at 500nm.
[0056] In order to further illustrate the beneficial technical effects of the layered compound capacitors with high energy storage density according to the embodiments of the present invention, the electrical performance of the capacitors prepared in Examples 1 to 4 and Comparative Example 1 was tested, wherein:
[0057] Energy storage density and efficiency: Under 10kHz AC, the electric field strength is gradually increased to reach the breakdown electric field, and the following is obtained: Figure 4 The hysteresis loop diagram shown in FIG. 1 is then integrated with respect to the polarization axis through the hysteresis loop of the discharge section to obtain the energy storage density, and the energy storage efficiency is obtained by dividing the energy storage density by the value of integrating the hysteresis loop of the charging section with respect to the polarization axis.
[0058] Dielectric loss: measured using an LCR (Heinrich Lenz-Capacitor-Resistance) meter;
[0059] The electrical performance test results are shown in Table 1.
[0060] Table 1 Performance test table
[0061] Test items <![CDATA[Energy storage density (J / cm 3 )]]> Energy storage efficiency (%) Dielectric loss at 10kHz Example 1 134 85.0 0.030 Example 2 115 86.1 0.025 Example 3 137 86.9 0.023 Example 4 120 87.4 0.022 Comparative Example 1 98 77.6 0.061
[0062] As can be seen from the data in Table 1, the layered compound capacitors prepared in various embodiments of the present invention have better energy storage effect and lower dielectric loss than the comparative example, indicating that the dielectric film prepared in various embodiments of the present invention is a dielectric material with high energy storage density.
[0063] On this basis, combined Figures 1 to 3 , taking Example 1 as an example to analyze the characteristics of the materials in the embodiments of the present invention:
[0064] Compare Figure 1 The X-ray diffraction patterns of the two powders show that the powder prepared based on the precursor material in Example 1 basically maintains the Bi4Ti3O 12 Phase structure; then compare Figure 2 and Figure 1 It can be found that the diffraction peaks of the dielectric film are significantly reduced compared to the powder, which means that some texture has been formed. In addition, the substrate is a single crystal, and a large number of orientation peaks cannot be As shown in the test geometry, the diffraction peak at 23° represents the titanium layer, and the diffraction peak at 48° represents the platinum layer. Due to the limited detection depth of X-rays, the deeper titanium dioxide layer and silicon layer have no effective signal and do not show any diffraction peaks. Figure 3 This shows that the crystallinity of the dielectric film in Example 1 is weakened and it has a two-phase structure, that is, there are Bi3 (Dy 0.7 Nb 0.3 )Ti3O 12 Crystalline phase (region 1, with diffraction points) and amorphous non-crystalline phase (region 2, with only diffuse diffraction rings), and it is the dual-phase structure that brings about improvements in energy storage density, energy storage efficiency and dielectric loss performance.
[0065] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A high energy storage density dielectric material, characterized in that: Its general chemical formula is Bi3(A n N p )Ti3O 12 , wherein A is selected from at least one of Nd, La, Sm, Eu, Er, and Dy; N is selected from at least one of Ca, Sn, Sr, Cs, Nb, Hf, and Ga; n+p=1, 0<n<1, 0<p<1.
2. The high energy storage density dielectric material according to claim 1, characterized in that n≥p.
3. A capacitor, characterized in that: A dielectric film comprising the high energy storage density dielectric material according to claim 1 or 2.
4. The capacitor according to claim 3, wherein The thickness of the dielectric film is 500-600 nm.
5. A method for preparing the capacitor according to claim 3, characterized in that: The following steps are involved: Precursor preparation steps: According to Bi3(A n N p )Ti3O 12 The chemical composition of the raw materials is to add the bismuth source, titanium source, A source and N source into the solvent propionic acid, mix them until the raw materials are fully dissolved; then filter and collect the filtrate to obtain a precursor solution; Finally, the precursor solution is aged; The dielectric film preparation steps include: coating the aged precursor solution on the substrate by spin coating; Each coating layer is first heated to a first temperature to evaporate and remove propionic acid, then heated to a second temperature to pyrolyze residual organic matter, and finally heat-treated to obtain a dielectric layer; After the predetermined number of dielectric layers are all fabricated, annealing is performed to obtain a dielectric film; Electrode preparation steps: Electrodes are plated on the surface of the dielectric film to make a capacitor.
6. The preparation method according to claim 5, characterized in that The bismuth source is bismuth acetate, and the mass ratio of bismuth acetate to propionic acid during mixing is 1:(5-8); the titanium source is tetrabutyl titanate, the A source is A acetate, and the N source is N nitrate.
7. The preparation method according to claim 5, characterized in that In the precursor preparation step, the specific operation of the mixing treatment is to first stir at 70-80° C. for 9-13 minutes, and then continue stirring at room temperature for 5-7 hours.
8. The preparation method according to claim 5, characterized in that In the precursor preparation step, an excess bismuth source is added to the precursor solution before aging.
9. The preparation method according to claim 5, characterized in that In the precursor preparation step, the precursor solution is aged at room temperature for 40 to 50 hours.
10. The preparation method according to claim 5, characterized in that In the dielectric film preparation step, the first temperature ranges from 190 to 220° C., and the heating time is 1 to 3 minutes; the second temperature ranges from 390 to 420° C., and the heating time is 9 to 12 minutes.
11. The preparation method according to claim 5, characterized in that In the dielectric film preparation step, the heat treatment temperature is 720-820° C. and the time is 5-20 minutes.
12. The preparation method according to claim 5, characterized in that In the dielectric film preparation step, the annealing treatment is performed at a temperature of 650 to 780° C. and for a time of 100 to 150 minutes.
Citation Information
Patent Citations
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