A B-site doped perovskite dielectric layer material and its preparation method

Abstract

This invention relates to the field of inorganic non-metallic materials, and discloses a B-site doped perovskite dielectric layer material and its preparation method; the chemical formula of the material is given by [formula missing], where 0.05 ≤ 0.30, the A-site is composed of a multi-principal high-entropy solid solution of five elements (a, b, c, d, s, ...), and the B-site is a tunable doping system composed of [elements missing]. The preparation method includes raw material weighing, ball milling and mixing, pre-sintering, granulation and molding, debinding and sintering steps, with a sintering temperature of 1200-1350℃ and a holding time of 2-4 hours; the high entropy of the A-site increases the lattice mixing entropy and enhances structural stability; the tunable doping of the B-site optimizes the local strain field distribution, achieving a comprehensive balance between dielectric constant, loss and breakdown field strength.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials, specifically to a B-site doped perovskite dielectric layer material and its preparation method. Background Technology

[0002] With the development of high-power electronic devices and high-energy-density capacitors, electronic ceramic dielectric materials need to simultaneously possess high dielectric constant, low dielectric loss, high breakdown field strength, and good temperature stability under strong electric fields and high-frequency operating conditions to meet the requirements of device miniaturization and high reliability. Perovskite ceramics, due to their tunable polarization behavior and good processing adaptability, are widely used as a dielectric material system in research and application.

[0003] Existing dielectric materials mostly employ perovskite ceramics such as BaTiO3 and SrTiO3, and are modulated through doping or solid solution. However, this often presents a contradiction: increased dielectric constant leads to increased loss or decreased breakdown, and the dielectric parameters fluctuate significantly with temperature and frequency. In recent years, multi-principal element solid solution and high-entropy design have been used to improve lattice stability and electric field uniformity. However, most published systems focus on single A-site or B-site modulation, which may still result in significant relaxation polarization, high loss, or insufficient temperature stability. Therefore, we propose a B-site doped perovskite dielectric layer material and its preparation method. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a B-site doped perovskite dielectric layer material and its preparation method, thereby solving the technical problems commonly found in existing dielectric layer materials, such as difficulty in balancing dielectric constant and breakdown field strength, high dielectric loss, and insufficient stability over a wide temperature range.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A perovskite-type dielectric layer material with high entropy at the A-site and tunable doping at the B-site, wherein the dielectric layer material has a perovskite crystal structure and its chemical composition is as follows:

[0007] Where position A is... , , , , Composed of a multi-principal-element high-entropy solid solution with five elements;

[0008] B position is determined by and A tunable doped system composed of elements;

[0009] A stable single-phase solid solution is formed between the A-site and B-site elements.

[0010] Preferably, in position B The mole fraction of an element is denoted as At the same time, it satisfies 0.05≤ ≤0.30.

[0011] Preferably, in position A , , , , The difference in the molar percentage of the five elements shall not exceed ±0.05.

[0012] Preferably, the dielectric layer material, after sintering, has a dense single-phase perovskite crystal structure with an average grain size of 1-5 μm and a volume density of not less than 95% of the theoretical density.

[0013] Preferably, the dielectric constant of the dielectric layer material is... The value measured at 1kHz is not less than 1500, the breakdown field strength measured in air at 25℃ is not less than 35kV / mm, and the dielectric loss is less than or equal to 0.01.

[0014] Preferably, the dielectric layer material is suitable for use as a dielectric layer in high-dielectric capacitors, energy storage elements, or electronic packaging media.

[0015] A method for preparing a high-entropy doped perovskite dielectric layer material includes the following steps: S1: Raw material weighing and mixing: Weighing according to stoichiometric ratio and Raw materials, of which position B The mole fraction of the element is Satisfying 0.05≤ ≤0.30;

[0016] S2: Ball milling: The raw materials weighed in step S1 are mixed with anhydrous ethanol and zirconium oxide balls and ball milled for 8 to 12 hours to obtain a uniform slurry;

[0017] S3: Drying and pre-calcination: After drying the mixed slurry, pre-calcination is carried out at 850-950°C for 2-4 hours to obtain precursor powder;

[0018] S4: Granulation and molding: The precursor powder is sieved, then granulated with a binder, and pressed into a green body in a mold;

[0019] S5: The molded preform is heated to 1200-1350°C in air at a rate of 3-5°C / min and sintered for 2-4 hours to obtain a dielectric layer material with a dense single-phase perovskite structure.

[0020] Preferably, zirconia balls are used as the ball milling medium in the ball milling process, the ball-to-material mass ratio is 3:1 to 5:1, and the ball milling time is 8 to 12 hours.

[0021] The preheating temperature is 850-950℃, and the holding time is 2-4 hours.

[0022] Preferably, 3-6 wt% polyvinyl alcohol solution is added to the precursor powder as a binder before granulation, and then dried at 80-100°C.

[0023] The molding process uses compression molding, with a molding pressure of 150-250 MPa and a holding time of 1-3 minutes.

[0024] Preferably, the sintering process uses an air or oxygen atmosphere, with a heating rate of 3-5°C / min and a holding time of 2-4 hours;

[0025] The sintered samples were polished and annealed at 700–750°C to improve grain uniformity and dielectric stability.

[0026] In summary, the present invention has the following main beneficial effects:

[0027] By introducing at position A , , , , The five elements form a high-entropy solid solution system, significantly improving lattice stability and resistance to stress distortion. The A-site multi-principal structure generates a high mixing entropy effect during sintering. The structure (≈1.6R) effectively suppresses phase separation and defect agglomeration, enabling the system to achieve a dense single-phase perovskite crystal structure within the temperature range of 1200℃ to 1270℃, with a uniform grain size distribution between 1 and 5 μm. This structural design solves the problems of traditional perovskite dielectric ceramics requiring high-temperature sintering or exhibiting poor phase stability, thus achieving low-temperature densification sintering and high structural uniformity.

[0028] By introducing B position A tunable double-doped design was developed, establishing a controllable local strain field and electric dipole perturbation mechanism. Its electronegativity is slightly higher than This causes fine-tuning of the B-O bond length and changes in the B-O-B angle, thereby regulating polarization relaxation behavior at the microscopic level. When the doping concentration x is controlled within the range of 0.10 to 0.15, lattice distortion is minimized and soft mode vibration energy is reduced, keeping the dielectric constant change rate of the material within ±10% in the range of -25 to 125°C. Through this design, the material simultaneously achieves a high dielectric constant (…). ≥1500) and low dielectric loss ( ≤0.01), which solves the problem of high purity in traditional BaTiO3 systems. Despite the challenge of high losses, dielectric stabilization over a wide temperature range was achieved.

[0029] Through the synergistic effect of the high-entropy structure at site A and the tunable doping at site B, this invention forms a dielectric layer material that combines high polarization reversibility and high breakdown field strength. After surface densification and grain boundary homogenization treatments, the breakdown field strength of the sample is increased to over 35 kV / mm, significantly better than the traditional systems listed in Table 1. This synergistic mechanism macroscopically improves the dielectric energy storage density and energy release rate, and microscopically reduces the probability of local electric field concentration and current-carrying path formation, thereby improving the overall electrical breakdown reliability. Through this technical approach, this invention achieves a balance of high dielectric constant, high withstand voltage, and high stability at low sintering temperatures, providing a new material system and implementation method for high-energy-density capacitors and high-frequency dielectric devices. Attached Figure Description

[0030] Figure 1 This invention is different XRD diffraction pattern of the sample containing the specified content;

[0031] Figure 2 This is a flowchart of the method of the present invention.

[0032] Figure label: 1 represents (Sr) 0.25 Ba 0.25 Mg 0.25 Bi 0.125 Na 0.125 (Ti) 0.95 Zr 0.05 X-ray diffraction pattern of O3;

[0033] 2 is (Sr 0.25 Ba 0.25 Mg 0.25 Bi 0.125 Na 0.125 (Ti) 0.9 Zr 0.1 X-ray diffraction pattern of O3;

[0034] 3 is (Sr 0.25 Ba 0.25 Mg 0.25 Bi 0.125 Na 0.125 (Ti) 0.85 Zr 0.15 X-ray diffraction pattern of O3;

[0035] 4 is (Sr 0.25 Ba 0.25 Mg 0.25 Bi 0.125 Na0.125 (Ti) 0.8 Zr 0.2 X-ray diffraction pattern of O3;

[0036] 5 is the X-ray diffraction pattern of the standard card of Bi0.5Na0.5TiO3, PDF#89-3109;

[0037] 6 are the X-ray diffraction patterns of the standard card for MgTiO3, PDF#79-0831;

[0038] 7 is the X-ray diffraction pattern of the standard card for BaTiO3, PDF#79-2263;

[0039] 8 is the X-ray diffraction pattern of the standard card for SrTiO3, PDF#86-0179. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] refer to Figures 1-2 A B-site doped perovskite dielectric layer material and its preparation method, wherein the general chemical formula of the material is: Where position A is... , , , , It consists of a multi-principal high-entropy solid solution composed of five elements, with the B site composed of... and A tunable doped system composed of elements. mole fraction of an element Satisfying 0.05≤ ≤0.30; The high-entropy structure at position A increases the mixed entropy of its components. To improve lattice stability, B-site doping is used to control polarization and breakdown field strength, achieving a comprehensive balance of high dielectric constant, low loss, and high field strength.

[0043] To verify the technical advantages of this invention, different structural systems were selected as comparative groups, and their sintering conditions and performance are shown in Table 1:

[0044] Table 1 Sintering conditions and dielectric properties of zirconium-titanium mineral structure dielectric ceramic materials

[0045]

[0046] Traditional systems often suffer from the contradiction of high dielectric constant but low breakdown voltage or high breakdown voltage but low dielectric constant; this invention overcomes the above trade-off by combining high entropy at the A site with tunable doping at the B site.

[0047] Eight groups of samples were designed based on the general formula, with the A-site component being constant and the B-site component being constant. The content varied from 0.05 to 0.30, and the composition is shown in Table 2:

[0048] Table 2 Sample composition design

[0049]

[0050] Weigh out analytical grade as well as (≥99.9%), its quality composition is shown in Table 3:

[0051] Table 3 Raw Material Weighing and Proportioning

[0052]

[0053] To ensure process reproducibility, each raw material was vacuum dried at 80°C for 4 hours before ball milling, and the weighing accuracy was controlled to within 0.1 mg to prevent molar ratio errors caused by humidity or particle size differences.

[0054] The raw materials, anhydrous ethanol, and zirconium oxide balls were mixed at a ball-to-material ratio of 3:1 to 5:1 and ball-milled for 8 to 12 hours. The resulting slurry was dried at 80 to 100°C. Parameters are shown in Table 4.

[0055] Table 4 Ball milling and drying parameters

[0056]

[0057] The dried powder is pre-calcined in air at 850–950°C for 2–4 hours to form precursor powder, as shown in Table 5.

[0058] Table 5 Heating Rate and Pre-firing Process

[0059]

[0060] After pre-calcination, the resulting precursor powder is cooled to room temperature and sieved to ensure uniform particle distribution.

[0061] The powder then proceeds to the granulation and pressing stage. To improve the powder's flowability and molding density, 3-6 wt% polyvinyl alcohol (PVA) aqueous solution is added to the pre-calcined powder as a binder. After thorough mixing, the powder is dried with hot air at 80-100℃.

[0062] The resulting granulated powder is sieved through a 200-mesh sieve to ensure that the particle size distribution is concentrated in the range of 20 to 80 μm.

[0063] The molding process uses a compression molding process, with pressure controlled at 150-250 MPa and holding time of 1-3 minutes, to obtain a circular blank with dimensions of Φ10×1.0mm.

[0064] The pressure and holding time at this stage have been verified by multiple comparative experiments to significantly improve density without introducing microcracks.

[0065] The degumming stage is carried out in two stages using a programmed temperature increase method.

[0066] The first stage temperature is 200-400℃, with a heating rate of 2-4℃ / min, used to remove organic binders;

[0067] The second stage temperature is 400–650℃, with a heating rate of 3–5℃ / min, to completely remove residual volatiles.

[0068] This process uses an air atmosphere to avoid fluctuations in the valence state of metal ions caused by reducing gases.

[0069] The surface of the degummed blank is smooth, without obvious warping or air holes.

[0070] Sintering is a key step in shaping material properties.

[0071] The degummed green body is placed in a box-type resistance furnace and sintered in an air or oxygen atmosphere.

[0072] The heating stage employs a three-stage control method to prevent stress concentration and abnormal particle growth:

[0073] The first stage heating rate is 3℃ / min to 1000℃;

[0074] The second stage heating rate is 4℃ / min until the target sintering temperature is reached;

[0075] The third stage is the constant temperature insulation stage.

[0076] The holding time and sintering temperature are adjusted according to the doping ratio, and the specific parameters are shown in Table 6:

[0077] Table 6 Sintering process parameters

[0078]

[0079] After sintering, the ceramic sheets are allowed to cool naturally to room temperature. The resulting ceramic sheets are then mechanically polished to a thickness of 0.5 mm and annealed at 700–750 °C for 2 hours to eliminate residual thermal stress.

[0080] The sample surface is smooth and dense. Density measurement results show that its relative theoretical density is over 95%, and the average grain size is 1-5 μm.

[0081] Carbonate decomposition during the pre-calcination stage, and The reaction produces a perovskite precursor phase: Furthermore, the reaction process can proceed through an intermediate phase:

[0082] ;

[0083] The structural refinement results show that with the increase of Zr content, the lattice constant changes linearly, the B-O bond length increases by about 0.004 Å, the lattice distortion decreases, and the polarization behavior becomes more stable.

[0084] Multi-principal A-bit increases mixed entropy The calculation formula is as follows:

[0085]

[0086] in, It is a mixed entropy; It is the gas constant; The mole fraction of each element at position A is given. This formula is used to quantify the degree of mixing entropy of the components at position A, indicating that the high entropy effect can stabilize the perovskite structure and inhibit defect aggregation.

[0087] B-position adjustable hybridization mechanism Co-doping generates a localized strain field, modulating the polarization response; when The strain is most uniform when the dielectric constant is between 0.10 and 0.15, and the dielectric constant and loss are best matched.

[0088] High-entropy random fields and The local strain superposition induced by doping broadens the dielectric peak and stabilizes the dielectric constant, forming a highly stable dielectric layer over a wide temperature range.

[0089] Structural refinement and performance testing results showed that all samples exhibited a single-phase perovskite structure, with no second-phase peaks detected, indicating that the A-site has multiple principal elements and the B-site has a single-phase perovskite structure. Doping within the molar ratio range defined in this invention can form a stable solid solution structure;

[0090] Figure 1 For different The XRD pattern of the sample shows that the content increases with... With increasing content, the diffraction peaks gradually shift to lower angles, indicating an increase in lattice constant. Alternative The resulting lattice expansion is consistent with the expected results. The sharp diffraction peaks of the sample indicate excellent crystal quality and high crystallinity.

[0091] Dielectric property tests were conducted at room temperature and 1 kHz. The results of the dielectric constant, dielectric loss, and breakdown field strength are shown in Table 7.

[0092] Table 7 Differences Dielectric properties of the sample with high content

[0093]

[0094] As can be seen from Table 7, the dielectric constant increases with... The content first increases and then decreases. The optimal dielectric constant is achieved when the dielectric constant is between 0.10 and 0.15, with a peak dielectric constant of approximately 1695, a breakdown field strength of 35–36 kV / mm, and dielectric loss controlled within 0.009–0.010. This indicates that an appropriate dielectric constant is achieved. Doping can optimize the domain strain of the crystal structure and enhance polarization reversibility; however, excessive doping leads to uneven electric field distribution at B sites and enhanced polarization distortion, thereby reducing dielectric properties.

[0095] Table 8 Sample density and grain size

[0096]

[0097] The results show that when When the mole fraction is 0.10 to 0.15, the sample has the highest relative density (≥95%), the most uniform grains and concentrated distribution; this indicates that appropriate doping helps to form a dense structure and improve dielectric energy storage capacity.

[0098] The perovskite dielectric layer material proposed in this invention, with high entropy at the A-site and tunable doping at the B-site, achieves a comprehensive balance between lattice stabilization, polarization optimization, and breakdown field enhancement while maintaining a dense single-phase structure. This system exhibits strong process compatibility, allowing for batch preparation using conventional solid-state methods, and demonstrates excellent reproducibility and industrial application potential.

[0099] Its high dielectric constant, low loss, and high electric field strength characteristics make it widely applicable in:

[0100] High energy density capacitors;

[0101] Insulating layer for power electronic devices;

[0102] Microwave dielectrics and packaging substrate materials.

[0103] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A B-site-doped perovskite dielectric layer material, characterized in that, The dielectric layer material has a perovskite crystal structure and its chemical composition is as follows: Where position A is... , , , , Composed of a multi-principal-element high-entropy solid solution with five elements; B position is determined by and A tunable doped system composed of elements; A stable single-phase solid solution is formed between the A-site and B-site elements; In the B position The mole fraction of an element is denoted as At the same time, it satisfies 0.05≤ ≤0.

30.

2. The B-site doped perovskite dielectric layer material according to claim 1, characterized in that, The dielectric layer material, after sintering, exhibits a dense single-phase perovskite crystal structure with an average grain size of 1–5 μm and a volume density of not less than 95% of the theoretical density.

3. The B-site doped perovskite dielectric layer material according to claim 2, characterized in that, The dielectric constant of the dielectric layer material The value measured at 1kHz is not less than 1500, the breakdown field strength measured in air at 25℃ is not less than 35kV / mm, and the dielectric loss is less than or equal to 0.

01.

4. The B-site doped perovskite dielectric layer material according to claim 3, characterized in that, The dielectric layer material serves as the dielectric layer in high-dielectric capacitors, energy storage elements, or electronic packaging media.

5. A method for preparing a B-site doped perovskite dielectric layer material, applicable to the B-site doped perovskite dielectric layer material according to claim 1, characterized in that, Includes the following steps: S1: Raw material weighing and mixing: Weigh according to stoichiometric ratio and Raw materials, of which position A , , , , The mole fractions were 0.25, 0.25, 0.25, 0.125, and 0.125, respectively; among which, in position B... The mole fraction of the element is Satisfying 0.05≤ ≤0.30; S2: Ball milling: The raw materials weighed in step S1 are mixed with anhydrous ethanol and zirconium oxide balls and ball milled for 8 to 12 hours to obtain a uniform slurry; S3: Drying and pre-calcination: After drying the mixed slurry, pre-calcination is carried out at 850-950°C for 2-4 hours to obtain precursor powder; S4: Granulation and molding: The precursor powder is sieved, then granulated with a binder, and pressed into a green body in a mold; S5: The molded preform is heated to 1200-1350°C in air at a rate of 3-5°C / min and sintered for 2-4 hours to obtain a dielectric layer material with a dense single-phase perovskite structure.

6. The method for preparing a B-site doped perovskite dielectric layer material according to claim 5, characterized in that, Zirconia balls are used as the ball milling medium in the ball milling process, with a ball-to-material mass ratio of 3:1 to 5:1 and a ball milling time of 8 to 12 hours. The preheating temperature is 850-950℃, and the holding time is 2-4 hours.

7. The method for preparing a B-site doped perovskite dielectric layer material according to claim 6, characterized in that, Before granulation, 3-6 wt% polyvinyl alcohol solution is added to the precursor powder as a binder and dried at 80-100℃. The molding process uses compression molding, with a molding pressure of 150-250 MPa and a holding time of 1-3 minutes.

8. The method for preparing a B-site doped perovskite dielectric layer material according to claim 7, characterized in that, The sintering process uses an air or oxygen atmosphere, with a heating rate of 3-5℃ / min and a holding time of 2-4 hours; The sintered samples were polished and annealed at 700–750°C to improve grain uniformity and dielectric stability.

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