CN113666738A

CN113666738A - Barium titanate-based X9R dielectric material for multilayer ceramic capacitor and preparation method thereof

Info

Publication number: CN113666738A
Application number: CN202111017096.9A
Authority: CN
Inventors: 陈志武; 刘瑞兆; 胡婉兵; 卢振亚
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2021-11-19

Abstract

The invention discloses a barium titanate-based X9R dielectric material for a multilayer ceramic capacitor and a preparation method thereof. The chemical formula of the material is 0.85BT-0.15BNT-0.02Nb₂O₅‑0.02MgO‑xCaZrO₃Wherein x is 1.0 to 3.0 mol%. The preparation method comprises the following steps: preparation of Bi_0.5Na_0.5TiO₃(ii) a Preparation of 0.85BaTiO₃‑0.15Bi_0.5Na_0.5TiO₃(ii) a Putting the raw materials into a ball mill, mixing and ball-milling by a wet ball-milling method, and drying to obtain ceramic powder; grinding, granulating, sieving, and dry-pressing to obtain ceramic green body; and (4) removing the glue and sintering to obtain the product. The dielectric ceramic material prepared by the invention meets the temperature change rate DeltaC/C within the temperature range of-55-200 DEG C_25℃| < 15%, and dielectric constant of 1940 at room temperature,the dielectric loss at room temperature is not more than 2.0%.

Description

Barium titanate-based X9R dielectric material for multilayer ceramic capacitor and preparation method thereof

Technical Field

The invention belongs to the technical field of dielectric ceramics, and particularly relates to a barium titanate-based X9R type dielectric material for a multilayer ceramic capacitor with high-temperature stability and a preparation method thereof.

Background

Dielectric materials have been the focus of research as an important energy storage electronic material. With the research and the technical progress, the development of the lead-free high-performance dielectric capacitor is greatly promoted. In recent years, due to a great increase in energy consumption, there is an increasing global demand for development of environmentally friendly, low-cost renewable energy. One of the key factors for realizing a clean and renewable energy system is a high-performance energy storage device, and the mainstream energy storage devices at present comprise a battery, a dielectric capacitor, a super capacitor and the like. Dielectric capacitors have become one of the most important components in electronic devices due to their ultra-high charge and discharge performance.

The multilayer ceramic capacitor (MLCC) is a parallel chip electronic component formed by alternately arranging dielectric ceramic diaphragms and internal electrodes, mainly plays roles of charging and discharging, blocking direct current and alternating current, bypassing, filtering and the like in a circuit, and has important significance for realizing high performance, multiple functions and high integration of electronic equipment. Modern electronic components are increasingly high in integration level and complexity, and the MLCC has the advantages of low equivalent resistance, small space volume, high specific volume, low dielectric loss, high reliability and the like, so that the MLCC is widely applied to the fields of mobile internet, 5G network, Internet of things, consumer electronics, automatic driving and the like. With the expansion of the application range, the application requirement of the temperature-stable high-temperature capacitor device in special fields such as aerospace, automobile engines, national defense and military industry and the like is more and more urgent. Satisfying American Electronic Industries Association (Electronic Industries Association) X7/8R type (X represents the lowest temperature use temperature of-55 ℃; 7/8 represents the highest temperature of 125/150 ℃; R represents the maximum deviation of the allowable capacitance along with the temperature change and the capacitance value at the room temperature of 25 ℃ is not more than 15%, namely delta C/C_25℃Less than or equal to +/-15 percent). The multilayer ceramic capacitor of the X7/8R standard has not been able to meet the use requirements. Therefore, the X9R type (9 stands for a maximum service temperature of 200 ℃) MLCC is becoming an increasingly hot point of research.

The current large-capacity lead-free temperature stable MLCCs are mainly composed of barium titanate (BaTiO)₃Hereinafter abbreviated as BT) is a typical toolWith perovskite (ABO)₃) A structural room temperature ferroelectric material. The dielectric constant of the material is higher at room temperature and can reach 2000-3000, the dielectric loss is also lower, and meanwhile, the material does not pollute the environment in the production and use processes, so the material is particularly suitable for manufacturing high-performance dielectric materials. However, pure barium titanate has a Curie temperature of about 120 ℃ and a large dielectric constant, and after the temperature is higher or lower than the Curie temperature, the dielectric constant of the pure barium titanate is sharply reduced, and the temperature is within a temperature range of-55 ℃ to 200 ℃ and delta C/C_25℃Less than or equal to +/-15 percent cannot meet the requirement, the Curie temperature needs to be further increased, and meanwhile, the Curie peak is widened to reach the standard.

In the existing research, sodium bismuth titanate is mostly selected as a peak shifting additive. Sodium bismuth titanate (Bi)_0.5Na_0.5TiO₃BNT for short) is a ferroelectric compositely substituted by a-site ions with perovskite structure, which is first synthesized by Smolenskii in the sixties of the last century, and has been widely researched as an important lead-free piezoelectric material system in recent years. Bismuth sodium titanate has a Curie temperature of about 320 ℃ and a rhombohedral phase structure at room temperature

a is 89 degrees 36') and has a large coercive field (73 kV/cm). Although BNT has many disadvantages, if its high Curie point is utilized, it is mixed with BaTiO₃The solid solution with the perovskite structure is compounded, which is very beneficial to improving the Curie temperature and realizing the temperature stability of the dielectric constant at the high temperature end. CaZrO₃Is a common stretching agent and is doped with BaTiO₃After that, the substitution of the ions at the A-and B-positions results in Ti⁴⁺The mobility of the dielectric layer is reduced, thereby generating a non-ferroelectric phase and broadening a curie peak. In fact CaZrO₃Solid solution into BaTiO₃But also acts to increase the curie temperature. CaZrO₃From equimolar CaCO by solid-phase methods₃And ZrO₂And after mixing, calcining at high temperature to synthesize the material, wherein the material is in an orthogonal structure at room temperature. CaZrO₃The most advantage of the dopant is that BaTiO can be treated without changing the A/B ratio of the system₃The ceramics are doped to widen the Curie peak and reduce the CurieThe change rate of the dielectric constant near the point and the improvement of the temperature stability are helpful.

Chinese invention patent CN112110723A discloses a dielectric material satisfying the application requirements of X9R type MLCC and a preparation method thereof, the technical dielectric material is La₂O₃And Bi (Mg)_0.5Ti_0.5)O₃Co-doped BaTiO₃Ceramic composition with molecular formula of 0.75Ba_(1-x)La_2x/3TiO₃-0.25Bi(Mg_0.5Ti_0.5)O₃Wherein x is 0 to 0.2. The dielectric material utilizes the peak shift effect generated by the rare earth element La (the Curie peak is shifted out of the using temperature range by the peak shift effect generated by the peak shifter) and Bi (Mg)_0.5Ti_0.5)O₃The generated ' stretching effect ' (the stretching effect ' brought by the ' stretching agent ' is used for raising two sides of the Curie peak and simultaneously depressing the Curie peak) jointly acts on the BaTiO₃Ceramic to obtain a dielectric material meeting the application requirements of X9R type MLCC. However, the technology has high requirement on the rotating speed of the ball mill, and the dielectric constant of the obtained dielectric material meeting the requirement of X9R is low and is only hundreds, so that the technology is not suitable for preparing the MLCC element with miniaturization, thinness and large capacity.

Disclosure of Invention

The invention aims to solve the technical problem of developing a lead-free environment-friendly novel high-performance medium material for MLCC (multilayer ceramic capacitor) which meets the requirements of EIA X9R standard on wide working temperature range and high temperature stability aiming at the defects in the prior art, can be sintered at lower temperature and has higher anti-reduction performance so as to be suitable for taking base metal nickel and copper as internal electrodes.

The purpose of the invention is realized by the following technical scheme:

a dielectric material for a high dielectric constant X9R type multilayer ceramic capacitor: it is prepared from tetragonal submicron barium titanate BaTiO₃、Bi_0.5Na_0.5TiO₃、Nb₂O₅、MgO、CaZrO₃The chemical formula of the composition is 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0 to 3.0 mol%; the high dielectric constantThe dielectric material for the X9R type multilayer ceramic capacitor meets the temperature change rate DeltaC/C within the temperature range of-55 to 200 DEG C_25℃Less than or equal to 15 percent, dielectric constant of 1940 at room temperature and dielectric loss of not more than 2.0 percent at room temperature;

the Bi_0.5Na_0.5TiO₃Is Bi₂O₃、Na₂CO₃And TiO₂Respectively weighing Bi with a certain mass according to a molar ratio of 1:1: 3.5-1: 1:4.5 as a raw material₂O₃、Na₂CO₃And TiO₂And (3) powder, namely ball-milling the raw materials, drying and presintering to obtain the powder.

In order to further achieve the object of the present invention, preferably, the ball milling is to put the raw materials into a ball mill and mix and ball mill the raw materials by a wet ball milling method; the pre-sintering process comprises the steps of heating to 900-950 ℃ at room temperature at a heating rate of 5 ℃/min, preserving heat for 2.5-3.5 hours, and then naturally cooling along with a furnace; and the drying is carried out for 12-14 h at the temperature of 80-120 ℃.

Preferably, the wet ball milling method adopts zirconia balls and absolute ethyl alcohol as media, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3-1: 2:4, and the wet ball milling method is used for mixing and ball milling for 22-26 hours.

The preparation method of the dielectric material for the high-dielectric-constant X9R type multilayer ceramic capacitor comprises the following steps:

1) preparation of Bi_0.5Na_0.5TiO₃；

2) With BaTiO₃And Bi obtained in step 1)_0.5Na_0.5TiO₃As raw material, controlling BaTiO₃And Bi_0.5Na_0.5TiO₃Putting the prepared raw materials into a ball mill according to a molar ratio of 4: 1-9: 1, mixing and ball-milling by a wet ball-milling method, drying and pre-sintering to obtain BTBNT powder;

3) respectively weighing certain mass of CaCO according to the molar ratio of 1: 1-1: 1.2₃And ZrO₂Putting the prepared raw materials into a ball mill, mixing and ball-milling by a wet ball-milling method, drying and presintering to obtain CaZrO₃Powder material;

4) by Nb₂O₅、MgO、CaZrO₃Step 2) obtaining0.85BT-0.15BNT powder as material and in the chemical expression of 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Proportioning, namely putting the proportioned raw materials into a ball mill, mixing and ball-milling by a wet ball-milling method, and drying to obtain ceramic powder;

5) grinding, granulating and sieving the ceramic powder obtained in the step 4), and then performing dry pressing to obtain a ceramic green body;

6) and (3) placing the ceramic green body obtained in the step 5) in a high-temperature furnace for sintering after glue discharging to obtain the dielectric material with the high dielectric constant of X9R type for the multilayer ceramic capacitor, wherein the sintering temperature is 1150-1190 ℃, and the sintering time is 2-4 hours.

Preferably, in the step 2) and the step 3), the wet ball milling method is to perform mixing ball milling for 22-26 hours, preferably 10-16 hours, by using zirconia balls and absolute ethyl alcohol as media.

Preferably, in the step 2), the pre-sintering is carried out at room temperature and at a heating rate of 5 ℃/min until the temperature rises to 950-1050 ℃, the temperature is kept for 2.5-3.5 hours, and then the product is naturally cooled along with the furnace.

Preferably, in the step 3), the pre-sintering is carried out by heating to 1000-1100 ℃ at a heating rate of 5 ℃/min at room temperature, preserving heat for 2.5-3.5 h, and then naturally cooling along with the furnace.

Preferably, in the step 5), the rubber discharging is that the temperature is raised to 550-600 ℃ at the temperature rise rate of 3 ℃/min at room temperature, the temperature is kept for 1.5-2.5 hours, and then the rubber is naturally cooled along with the furnace.

Preferably, in the step 6), the sintering is carried out by heating to 1150-1190 ℃ at a heating rate of 5 ℃/min at room temperature, preserving heat for 2-4 h, and then naturally cooling along with the furnace.

Preferably, in the step 2), the step 3) and the step 4), the drying is carried out for 12-14 hours at the temperature of 80-120 ℃.

Preferably, in the step 5), the granulation is carried out after polyvinyl alcohol (PVA) accounting for 10-15% of the mass of the ceramic powder is added; and the sieving is to sieve the mixture by a sieve of 60-100 meshes.

In the invention, BaTiO is mixed with₃And Bi_0.5Na_0.5TiO₃、Nb₂O₅MgO and CaZrO₃Burning the raw materials togetherAnd (4) forming ceramic. 0.85BT-0.15BNT powder as basic material mixed with 2.0 mol% Nb₂O₅Acts as a grain growth inhibitor and promotes the formation of a "core-shell" structure. Nb₂O₅Is diffused into BaTiO in the sintering process₃The shell part of (1), namely the shell, is doped and modified (including doping elements such as Nb, Mg and the like) paraelectric phase BaTiO₃The "core" is essentially the pure ferroelectric phase BaTiO₃。

Appropriate amount of Nb in the invention₂O₅The MgO co-doping is based on the following mechanism. Nb₂O₅Is one of the most commonly used dopants in air-sintered barium titanate-based ceramics. Nb⁵⁺Ion introduction into BaTiO₃Lattice substitution of Ti⁴⁺The 'core-shell' structure is formed, and the dielectric constant-temperature curve can be flattened. Nb₂O₅The solid solubility limit in barium titanate is 2.0 wt%. High valence Nb⁵⁺By substitution of lower valence Ti⁴⁺The doping of the donor can generate excessive positive charges, so that the same amount of negative charges need to be generated in the system to balance the electrovalence, and the electroneutrality is realized. The negative charge depends on the formation of defects, and point defects that may introduce negative charge have V ″_BaEmpty bit, V ""_TiEmpty bit, O ""_iInterstitial and free electrons, etc. Specifically, which defect mechanism may vary depending on the sintering system and the Nb content. When the Nb content is low, balancing the valence mainly by generating free electrons causes the barium titanate ceramic to be semiconductive as shown in formula (1):

the ceramic samples of the present invention were all sintered in air and had a higher Nb content, more likely by producing V "", according to formula (2)_TiVacancies to compensate for charge, resulting in a large increase in insulation resistivity, Nb⁵⁺Substituted Ti⁴⁺The crystal lattice constant is changed to cause poor tetragonality, the c/a ratio is reduced, and the peak degrees of (002) and (200) with the diffraction angle 2 theta of about 45 degrees in an XRD diffraction pattern are changedWeak.

Mg with coordination number of 6²⁺Ion radius of

With Ti⁴⁺The ionic radius of the titanium alloy is more approximate, and Ti is more easily replaced in the sintering process⁴⁺Ions. Lower valence Mg²⁺By substitution of higher valence Ti⁴⁺The doping belonging to an acceptor can bring excessive negative charges, and positive charge defects can be generated in the system to balance the charges to achieve electric neutrality, and the defects comprise oxygen vacancies

Electron hole h^·And metal ion interstitials. Which defect mechanism is suitable for the actual sintering process is determined by the MgO content and the sintering system. In the range of 0.85BT-0.15BNT-0.02Nb₂O₅In the system, the sintering atmosphere, the doping content of MgO and Mg are taken into consideration²⁺Should be by formation of oxygen vacancies

To compensate for the charge, the mechanism is shown in equation (3):

because of Nb₂O₅After doping with 0.85BT-0.15BNT, V' is generated_TiAnd too much V ""_TiCan cause the instability of 0.85BT-0.15BNT structure, generate a second phase, and form after being doped with MgO

To balance charge to achieve charge neutrality, which may serve to increase Nb₂O₅Solid solubility in barium titanate latticeThereby reducing the generation of second phases. However, as the Nb/Mg atomic ratio is gradually decreased (i.e., the MgO content is increased), particularly when the Nb/Mg ratio is less than 2:1, the formation of the second phase is started. At this time Nb⁵⁺Substituted Ti⁴⁺Produced by

The positive charge is not enough to balance Mg²⁺Substituted Ti⁴⁺Produced Mg_TiThe charged negative charges can continuously generate oxygen vacancies in the system

To balance the charge for the purpose of charge conservation. Excess oxygen vacancies

The aggregation together causes the perovskite structure to be distorted and simultaneously receives Mg²⁺Because of the addition of Ti⁴⁺Due to the ionic radius difference, the ionic type and the valence factor, the solid solubility of the barium titanate crystal is limited. The introduction of MgO can inhibit the diffusion of Nb element, and liquid phase can be formed in the sintering process, so that a compact outer shell layer is formed to prevent the Nb element from entering the grain core part, thereby achieving the effect of reducing the volume fraction of the shell part. The dielectric constant temperature characteristics of ceramics are also greatly improved because of the relative balance of the volume fractions of the "core-shell" structure. The lattice parameter of the MgO-doped barium titanate sample becomes larger (still is a single phase), when the content of MgO is 2 mol%, the lattice constant gradually approaches to a constant, which shows that the dissolution limit of MgO in the barium titanate lattice is 2 mol%, excessive MgO doping can form a new second phase to cause the temperature characteristic of the dielectric constant of the ceramic to be seriously deteriorated, and the addition amount of MgO is 2 mol%, so that better dielectric property can be obtained.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) adding appropriate Nb₂O₅And CaZrO₃，Nb₂O₅Can help to form a core-shell structure which can play a role in suppressing the width of the mediumThe action of electric peak is favorable for reducing the capacity temperature change rate of the material, CaZrO₃It is helpful to improve the tetragonal rate of barium titanate crystal grains with existing 'core-shell' structure. Meanwhile, MgO is added to effectively change the core-shell volume ratio, so that the core-shell volume ratio is in a balanced state, and Nb is avoided₂O₅Excessive diffusion leads to an excessively large shell volume fraction, an excessively small core volume fraction and an unsatisfactory temperature stability. During sintering, the added MgO forms a liquid phase on a crystal boundary to promote material transmission, the sintering temperature can be obviously reduced, the grain size is reduced, and the added CaZrO₃The density of the dielectric ceramic body can be improved, and the loss is reduced.

(2) The invention is a suitable amount of Nb₂O₅And MgO in appropriate proportions, doping Nb alone can cause the metastable "core-shell" structure of barium titanate-based ceramics to be destroyed by excessive diffusion of Nb, losing the temperature stability of the dielectric constant. Nb⁵⁺Substituted Ti⁴⁺This also causes a change in lattice constant, resulting in poor tetragonality and a small c/a ratio. MgO is 0.85BT-0.15BNT-0.02Nb₂O₅The system also has the similar function of adjusting the volume fraction of the core-shell structure, and proper amount of MgO doping can improve the density of the ceramic and inhibit Nb₂O₅And enters the core of the 0.85BT-0.15BNT ceramic, thereby playing the role of reducing the volume fraction of the shell part of the non-ferroelectric phase and further increasing the volume fraction of the core of the 0.85BT-0.15BNT of the pure ferroelectric phase. However, excessive MgO doping can instead destroy the "core-shell" structure because Mg diffuses faster in the system than Nb, so Nb can suppress Mg diffusion (in fact, the two elements can mutually suppress diffusion during sintering). However, if the content of Mg exceeds the Nb inhibiting ability, the Mg element is excessively diffused into the core of the crystal grain to react with the pure ferroelectric phase therein, so that the core-shell structure is damaged, the elements in the crystal grain are uniformly distributed, and a second phase with a lower dielectric constant is generated, so that the temperature stability of the dielectric constant of the system is completely deteriorated, and the system no longer meets the X9R standard.

(3) The ceramic dielectric material prepared by the invention has low sintering temperature of 1150-1190 ℃, meets the EIA X9R standard requirement, has good dielectric property and lower dielectric loss (less than or equal to 3.42%), wherein the room temperature dielectric constant is about 1940, and the room temperature (25 ℃) dielectric loss is only 1.94%.

(4) The dielectric material of the invention does not contain lead and is harmless to the environment. The ceramic preparation process adopts a solid phase method, and the process flow is simple and easy to operate.

Drawings

FIG. 1 is a graph showing the dielectric constant and dielectric loss as a function of temperature for comparative example 1 and examples 1 to 3;

FIG. 2 is a graph showing the temperature change rate with temperature for comparative example 1 and examples 1 to 3;

FIG. 3 is a graph showing the dielectric constant and dielectric loss as a function of temperature for comparative example 2 and examples 4 to 6;

FIG. 4 is a graph showing the temperature change rate with temperature in comparative example 2 and examples 4 to 6.

Detailed Description

For better understanding of the present invention, the present invention is further illustrated by the following figures and examples, but the embodiments of the present invention are not limited to the following examples, and the purity of the raw materials used in the present invention is analytical.

Comparative example 1

With Bi₂O₃、Na₂CO₃And TiO₂As a starting material, based on Bi₂O₃、Na₂CO₃And TiO₂The raw materials are mixed according to the molar ratio of 1:1:4, and the mixed raw materials are put into a ball mill to be mixed and ball-milled by a wet ball milling method. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 12 hours at the rotating speed of 240 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises the steps of raising the temperature to 900 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving the heat for 3 hours, and naturally cooling along with the furnace to obtain Bi_0.5Na_0.5TiO₃(BNT) powder;

with BaTiO₃And Bi_0.5Na_0.5TiO₃As a raw material, according to BaTiO₃And Bi_0.5Na_0.5TiO₃The raw materials are mixed and ball milled in a wet ball milling method in a ball mill, wherein the molar ratio of the raw materials is 0.85: 0.15. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 24 hours at the rotating speed of 200 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises heating to 1000 deg.C at room temperature at a rate of 5 deg.C/min, maintaining for 3 hr, and naturally cooling to obtain 0.85BaTiO₃-0.15Bi_0.5Na_0.5TiO₃(0.85BT-0.15BNT) powder;

with CaCO₃And ZrO₂As a raw material, according to CaCO₃And ZrO₂The raw materials are mixed according to the molar ratio of 1:1, and the mixed raw materials are put into a ball mill to be mixed and ball-milled by a wet ball milling method. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 4 hours at the rotating speed of 200 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises the steps of raising the temperature to 1050 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving the temperature for 3 hours, and naturally cooling along with the furnace to obtain CaZrO₃Powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 0.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.000g), putting the prepared raw materials into a ball mill, mixing and ball-milling by a wet ball-milling method, wherein ball-milling media are zirconia balls and absolute ethyl alcohol, mixing and ball-milling for 24 hours, and then drying for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. The obtained ceramic green bodyHeating to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for binder removal, then sintering in a high-temperature furnace, wherein the sintering process is that heating to 1190 ℃ at the heating rate of 5 ℃/min at room temperature, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the X9R type multilayer ceramic capacitor with high dielectric constant.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. The specific dielectric property parameters are listed in Table 1, the dielectric constant can reach 1640 at room temperature, and the loss is only 1.97%.

Example 1

with BaTiO₃And Bi_0.5Na_0.5TiO₃As a raw material, according to BaTiO₃And Bi_0.5Na_0.5TiO₃The raw materials are mixed and ball milled in a wet ball milling method in a ball mill, wherein the molar ratio of the raw materials is 0.85: 0.15. The ball milling medium is zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is1:2:3. After being put into a planetary ball mill, the mixture is ball milled for 24 hours at the rotating speed of 200 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises heating to 1000 deg.C at room temperature at a rate of 5 deg.C/min, maintaining for 3 hr, and naturally cooling to obtain 0.85BaTiO₃-0.15Bi_0.5Na_0.5TiO₃(0.85BT-0.15BNT) powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.159g), the prepared raw materials are put into a ball mill and mixed and ball-milled by a wet ball milling method, the ball milling media are zirconia balls and absolute ethyl alcohol, the mixture is ball-milled for 24 hours, and then the mixture is dried for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for binder removal, then sintering in a high-temperature furnace, wherein the sintering process comprises heating to 1190 ℃ at the heating rate of 5 ℃/min at room temperature, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the high-dielectric-constant X9R type medium for the multilayer ceramic capacitorA material.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 1, and the temperature change rate of the ceramic, | Delta C/C_25℃The temperature range of | is-55-200 ℃ and is not more than 15%, and the standard of EIA X9R is met. The dielectric constant can reach 1783 at room temperature, and the loss is only 1.82%.

Example 2

with BaTiO₃And Bi_0.5Na_0.5TiO₃As a raw material, according to BaTiO₃And Bi_0.5Na_0.5TiO₃The raw materials are mixed and ball milled in a wet ball milling method in a ball mill, wherein the molar ratio of the raw materials is 0.85: 0.15. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 24 hours at the rotating speed of 200 rpm/min. After the ball milling is finished, the slurry is put into a drying oven to be dried for 12 hours at the temperature of 80 ℃, and is put into a high-temperature furnace after being ground and sieved by a 80-mesh sieveAnd (6) pre-burning. The pre-sintering process comprises heating to 1000 deg.C at room temperature at a rate of 5 deg.C/min, maintaining for 3 hr, and naturally cooling to obtain 0.85BaTiO₃-0.15Bi_0.5Na_0.5TiO₃(0.85BT-0.15BNT) powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 2.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.359g), putting the prepared raw materials into a ball mill, mixing and ball-milling the raw materials by a wet ball-milling method by using zirconia balls and absolute ethyl alcohol as ball-milling media, mixing and ball-milling the raw materials for 24 hours, and then drying the raw materials for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for removing glue, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1190 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the X9R type multilayer ceramic capacitor with high dielectric constant.

The dielectric ceramic element is obtained by grinding and polishing the two ends of the dielectric material prepared in the embodiment, coating an electrode, drying and burning silver,then the relative dielectric constant epsilon is tested and calculated_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 1, and the temperature change rate of the ceramic, | Delta C/C_25℃The temperature range of | is-55-200 ℃ and is not more than 15%, and the standard of EIA X9R is met. The dielectric constant can reach 1765 at room temperature, and the loss is only 1.65 percent.

Example 3

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 3.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.538g), putting the prepared raw materials into a ball mill, mixing and ball-milling the raw materials by a wet ball-milling method by using zirconia balls and absolute ethyl alcohol as ball-milling media, mixing and ball-milling the raw materials for 24 hours, and then drying the raw materials for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for removing glue, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1190 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the X9R type multilayer ceramic capacitor with high dielectric constant.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constants of example 1ε_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 1, and the temperature change rate of the ceramic, | Delta C/C_25℃The temperature range of | is-55-200 ℃ and is not more than 15%, and the standard of EIA X9R is met. The dielectric constant can reach 1864 at room temperature, and the loss is only 1.44%.

TABLE 1 dielectric Properties of ceramic media of different formulations

Example 4

with BaTiO₃And Bi_0.5Na_0.5TiO₃As a raw material, according to BaTiO₃And Bi_0.5Na_0.5TiO₃The raw materials are mixed and ball milled in a wet ball milling method in a ball mill, wherein the molar ratio of the raw materials is 0.85: 0.15. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 24 hours at the rotating speed of 200 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process is that the temperature is raised to 1 degree centigrade at the room temperature at the rate of 5 degree centigrade per minuteKeeping the temperature at 000 ℃ for 3h, and naturally cooling the mixture along with the furnace to obtain 0.85BaTiO₃-0.15Bi_0.5Na_0.5TiO₃(0.85BT-0.15BNT) powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.159g), the prepared raw materials are put into a ball mill and mixed and ball-milled by a wet ball milling method, the ball milling media are zirconia balls and absolute ethyl alcohol, the mixture is ball-milled for 24 hours, and then the mixture is dried for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for binder removal, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1150 ℃ at the room temperature at a heating rate of 5 ℃/min, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the high-dielectric-constant X9R type multilayer ceramic capacitor.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss ofTan delta consumption and capacity temperature change rate Delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 2, and the temperature change rate of the ceramic, | Delta C/C_25℃The temperature range of | is-55-200 ℃ and is not more than 15%, and the standard of EIA X9R is met. The dielectric constant can reach 1940 at room temperature, and the loss is only 1.94%.

Example 5

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.159g), the prepared raw materials are put into a ball mill and mixed and ball-milled by a wet ball milling method, the ball milling media are zirconia balls and absolute ethyl alcohol, the mixture is ball-milled for 24 hours, and then the mixture is dried for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at the heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for binder removal, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1170 ℃ at the heating rate of 5 ℃/min at room temperature, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the X9R type multilayer ceramic capacitor with high dielectric constant.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 2, and the temperature change rate of the ceramic, | Delta C/C_25℃The dielectric constant can reach 1779 and the loss is only 1.84 percent at room temperature, wherein |, the temperature range of-55 to 200 ℃ is not more than 15 percent and meets the EIA X9R standard.

Example 6

with CaCO₃And ZrO₂As a raw material, according to CaCO₃And ZrO₂Mixing materials at a molar ratio of 1:1, and wet-grinding the mixed materials in a ball millMixing and ball milling by a ball milling method. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, the mixture is ball milled for 4 hours at the rotating speed of 200 rpm/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises the steps of raising the temperature to 1050 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving the temperature for 3 hours, and naturally cooling along with the furnace to obtain CaZrO₃Powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.159g), the prepared raw materials are put into a ball mill and mixed and ball-milled by a wet ball milling method, the ball milling media are zirconia balls and absolute ethyl alcohol, the mixture is ball-milled for 24 hours, and then the mixture is dried for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for removing glue, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1190 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the X9R type multilayer ceramic capacitor with high dielectric constant.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. Specific dielectric property parameters are listed in Table 2, and the temperature change rate of the ceramic, | Delta C/C_25℃The temperature range of | is not more than minus 55 to 200 DEG C15 percent and meets the EIA X9R standard. The dielectric constant can reach 1783 at room temperature, and the loss is only 1.82%.

Comparative example 2

with CaCO₃And ZrO₂As a raw material, according to CaCO₃And ZrO₂The raw materials are mixed according to the molar ratio of 1:1, and the mixed raw materials are put into a ball mill to be mixed and ball-milled by a wet ball milling method. The ball milling medium comprises zirconia balls and absolute ethyl alcohol, wherein the mass ratio of the powder to the absolute ethyl alcohol to the zirconia balls is 1:2: 3. After being put into a planetary ball mill, at 200rpBall milling is carried out for 4 hours at the rotating speed of m/min. And after the ball milling is finished, putting the slurry into a drying oven for drying for 12 hours at the temperature of 80 ℃, grinding the slurry, sieving the ground slurry by using a 80-mesh sieve, and putting the ground slurry into a high-temperature furnace for presintering. The pre-sintering process comprises the steps of raising the temperature to 1050 ℃ at the room temperature at the heating rate of 5 ℃/min, preserving the temperature for 3 hours, and naturally cooling along with the furnace to obtain CaZrO₃Powder;

by Nb₂O₅MgO, 0.85BT-0.15BNT powder obtained in the step (2) and CaZrO powder obtained in the step (3)₃Is prepared from 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0% (BT:19.821g, BNT:3.177g, Nb)₂O₅:0.532g，MgO:0.081g，CaZrO₃0.159g), the prepared raw materials are put into a ball mill and mixed and ball-milled by a wet ball milling method, the ball milling media are zirconia balls and absolute ethyl alcohol, the mixture is ball-milled for 24 hours, and then the mixture is dried for 12 hours at 80 ℃. And grinding the dried ceramic powder, adding PVA accounting for 15% of the mass of the ceramic powder, granulating, sieving by a 80-mesh sieve, and performing dry pressing to obtain a ceramic green body with the diameter of 10mm and the thickness of 1.2 mm. Heating the obtained ceramic green body to 600 ℃ at room temperature at a heating rate of 3 ℃/min, then preserving heat for 2h, then naturally cooling along with the furnace for removing glue, then sintering in a high-temperature furnace, wherein the sintering process is heating to 1210 ℃ at room temperature at a heating rate of 5 ℃/min, preserving heat for 2h, and then naturally cooling along with the furnace to obtain the dielectric material for the high-dielectric-constant X9R type multilayer ceramic capacitor.

Grinding and polishing two ends of the dielectric material prepared in the embodiment, coating electrodes, drying and burning silver to obtain a dielectric ceramic element, and then testing and calculating the relative dielectric constant epsilon of the dielectric ceramic element_rDielectric loss tan delta and capacity temperature change rate delta C/C_25℃. FIGS. 1 and 2 show the dielectric constant ε in example 1_rDielectric loss tan delta and capacity temperature change rate DeltaC/C_25℃Graph of the relationship with temperature change. The specific dielectric property parameters are listed in Table 2, the dielectric constant can reach 2525 at room temperature, and the loss is only 1.02%.

TABLE 2 dielectric properties of ceramic media at different sintering temperatures

It should be noted that the embodiments of the present invention are not limited by the above-mentioned examples, and any other changes, modifications, substitutions, combinations, and simplifications which are made without departing from the spirit and principle of the present invention should be regarded as equivalent substitutions, and are included in the scope of the present invention.

Claims

1. A dielectric material for a high dielectric constant X9R type multilayer ceramic capacitor, characterized in that: it is prepared from tetragonal submicron barium titanate BaTiO₃、Bi_0.5Na_0.5TiO₃、Nb₂O₅、MgO、CaZrO₃The chemical formula of the composition is 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Wherein x is 1.0 to 3.0 mol%; the dielectric material for the high-dielectric-constant X9R multilayer ceramic capacitor meets the temperature change rate DeltaC/C within the temperature range of-55-200 DEG C_25℃Less than or equal to 15 percent, dielectric constant of 1940 at room temperature, and dielectric loss of not more than 2.0 at room temperature.

2. The method for preparing a dielectric material for a multilayer ceramic capacitor having a high dielectric constant of X9R according to claim 1, comprising the steps of:

1) preparation of Bi_0.5Na_0.5TiO₃；

3) by Nb₂O₃、MgO、CaZrO₃The BTBNT powder obtained in the step 2) is used as a raw material and is prepared according to a chemical formula of 0.85BT-0.15BNT-0.02Nb₂O₅-0.02MgO-xCaZrO₃Proportioning, namely putting the proportioned raw materials into a ball mill, mixing and ball-milling by a wet ball-milling method, and drying to obtain ceramic powder;

4) grinding, granulating and sieving the ceramic powder obtained in the step 3), and then performing dry pressing to obtain a ceramic green body;

5) and (3) placing the ceramic green body obtained in the step 4) in a high-temperature furnace for sintering after glue discharging to obtain the dielectric material with the high dielectric constant of X9R type for the multilayer ceramic capacitor, wherein the sintering temperature is 1150-1190 ℃, and the sintering time is 2-4 hours.

3. The method of claim 2, wherein Bi is Bi in the dielectric material for a multilayer ceramic capacitor having a high dielectric constant of X9R_0.5Na_0.5TiO₃Is Bi₂O₃、Na₂CO₃And TiO₂Respectively weighing Bi according to the molar ratio of 1:1: 3.5-1: 1:4.5 as raw materials₂O₃、Na₂CO₃And TiO₂And (3) powder, namely ball-milling the raw materials, drying and presintering to obtain the powder.

4. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 3, wherein the method comprises: the ball milling is to put the raw materials into a ball mill and mix and ball mill the raw materials by a wet ball milling method; the pre-sintering process comprises the steps of heating to 900-950 ℃ at a heating rate of 10 ℃/min at room temperature, preserving heat for 2.5-3.5 hours, and then naturally cooling along with a furnace; and the drying is carried out for 12-14 h at the temperature of 80-120 ℃.

5. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 4, wherein the method comprises: the wet ball milling method adopts zirconia balls and absolute ethyl alcohol as media, and the mixing and ball milling are carried out for 10-16 h.

6. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 2, wherein the method comprises: in the step 2), the pre-sintering is carried out by heating to 900-950 ℃ at room temperature at a heating rate of 5 ℃/min, preserving heat for 2.5-3.5 h, and then naturally cooling along with the furnace.

7. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 2, wherein the method comprises: in the step 5), the pre-sintering is carried out by heating to 950-1050 ℃ at a heating rate of 3 ℃/min at room temperature, preserving heat for 2.5-3.5 h, and then naturally cooling along with the furnace;

the step of removing the glue is that the temperature is raised to 550-600 ℃ at the room temperature at the heating rate of 2 ℃/min, the temperature is kept for 1.5-2.5 hours, and then the glue is naturally cooled along with the furnace.

8. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 2, wherein the method comprises: the temperature rise mode of the sintering is that the temperature is raised to 1150-1190 ℃ from room temperature at the temperature rise rate of 5 ℃/min.

9. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 2, wherein the method comprises: in the step 2) and the step 3), the drying is carried out for 12-14 hours at the temperature of 80-120 ℃.

10. The method for preparing a dielectric material for a high-k X9R multilayer ceramic capacitor according to claim 2, wherein the method comprises: in the step 4), polyvinyl alcohol (PVA) accounting for 10-15% of the mass of the ceramic powder is added for granulation; and the sieving is to sieve the mixture by a sieve of 60-100 meshes.