CN109020541B

CN109020541B - High-performance environment-friendly capacitor dielectric and preparation method thereof

Info

Publication number: CN109020541B
Application number: CN201810797027.6A
Authority: CN
Inventors: 曾敏; 高贤禄; 陆旭兵; 高兴森; 刘俊明
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2018-07-19
Filing date: 2018-07-19
Publication date: 2021-10-08
Anticipated expiration: 2038-07-19
Also published as: CN109020541A

Abstract

The invention relates to a high-performance environment-friendly capacitor dielectric medium and a preparation method thereof, wherein the high-performance environment-friendly capacitor dielectric medium is prepared by hot-pressing and sintering a ferroelectric material, the ferroelectric material is samarium-scandium co-doped bismuth ferrite, and the chemical composition of the ferroelectric material is Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃. The preparation method comprises the following steps: sm and Sc codoped BiFeO prepared by ball milling method₃Powder material; drying and grinding the powder, then pre-sintering, and carrying out secondary ball milling after pre-sintering; then carrying out hot-pressing sintering to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃And cutting, grinding and polishing the ceramic to obtain the high-performance environment-friendly capacitor dielectric. The high-performance environment-friendly capacitor dielectric effectively improves pure BiFeO₃The voltage resistance is poor, the leakage current is large, the energy storage density and the energy storage efficiency of the capacitor dielectric medium are greatly improved, and the energy storage density and the energy storage efficiency are respectively 2.21J/cm³76 percent of the total weight of the alloy, and the performance of the alloy is superior to that of other lead-free BiFeO₃The preparation method of the base energy storage material has the advantages of simple process, high production efficiency and easy control.

Description

High-performance environment-friendly capacitor dielectric and preparation method thereof

Technical Field

The invention relates to the field of capacitors, in particular to a high-performance environment-friendly capacitor dielectric and a preparation method thereof.

Background

Energy storage materials play an important role in modern electronic and electrical systems, and are widely used for various energy storage components, such as dielectric capacitors, electrochemical capacitors, batteries (lithium ion batteries, fuel cells) and the like. The three types of elements have the characteristics that the battery has the highest energy storage density, but the charging and discharging speed is low, the power density is lowest, and the three types of elements are suitable for equipment for providing durable and stable electric energy; the dielectric capacitor has the highest power density among the three, can be charged instantly, and is suitable for pulse high-power electric energy equipment; the electrochemical capacitor is between the two. However, most of the energy storage materials used commercially at present are mainly lead-containing compounds (such as lead zirconate titanate, abbreviated as PZT), and the raw material of lead monoxide (or lead tetraoxide) used in such materials accounts for about 70% of the total mass of the raw materials, and they are easy to volatilize in the high-temperature production process, so that the content of "lead" in the atmosphere is increased, and the health of human beings and the environment depending on survival are greatly damaged. Research and development of lead-free dielectric functional materials has been the focus of attention of scientists and engineers worldwide. The research on the novel lead-free dielectric material is not only beneficial to environmental protection, but also beneficial to improving the energy storage density of the dielectric material and enduring higher voltage, thereby realizing the miniaturization and the convenience of the capacitor and expanding the application range of the capacitor.

In recent years, research into novel lead-free capacitor materials has been extensive, mainly involving doping with BaTiO₃(BT) -based ceramics and thick film research, lead-free BiFeO₃Base solid solution relaxor ferroelectric dielectrics have been investigated, but each has its limitations. Wherein, BaTiO is used₃(BT) -based ceramics are taken as an example, the highest energy storage density of the materials reported at present is only 1.2J/cm³The efficiency is not high, and the pressure resistance and the energy storage efficiency are bottlenecks in the development.

Disclosure of Invention

Based on the above, the invention aims to overcome the defects of the prior art, optimize process conditions, respond to green life calls and provide a high-performance environment-friendly capacitor dielectric and a preparation method thereof, wherein the high-performance environment-friendly capacitor dielectric has the advantages of high energy storage density and energy storage efficiency, good voltage resistance, small leakage current and better performance than other lead-free BiFeO₃Base energy storage materialThe preparation method has the advantages of simple process, high production efficiency and easy control.

The technical scheme adopted by the invention is as follows:

the high-performance environment-friendly capacitor dielectric is prepared by hot-pressing and sintering a ferroelectric material, wherein the ferroelectric material is samarium-scandium co-doped bismuth ferrite, and the chemical composition of the ferroelectric material is Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃。

The high-performance environment-friendly capacitor dielectric is made of ferroelectric material bismuth ferrite (BiFeO)₃) The rare earth doped Sm-Sm alloy is prepared by hot-pressing sintering of rare earth elements Sm-Sm and Sc. Sm and Sc are doped and modified with pure bismuth ferrite, so that with the increase of the content of rare earth elements, the pure bismuth ferrite is slowly converted from obvious ferroelectric property to paraelectric phase, and paraelectric material has high voltage resistance, and paraelectric layer plays a role in isolating charges, thereby obtaining high breakdown strength. The lead-free high-performance environment-friendly BiFeO₃Based on the dielectric material of the capacitor, the pure BiFeO is effectively improved₃The voltage resistance is poor, the leakage current is large, the energy storage density and the energy storage efficiency of the capacitor dielectric medium are greatly improved, and the energy storage density and the energy storage efficiency are respectively 2.21J/cm ³76 percent of the total weight of the alloy, and the performance of the alloy is superior to that of other lead-free BiFeO₃Based on an energy storage material.

The preparation method of the high-performance environment-friendly capacitor dielectric comprises the following steps:

step one, bismuth trioxide (Bi)₂O₃) Samarium oxide (Sm)₂O₃) Iron oxide (Fe)₂O₃) And dicris (Sc)₂O₃) Is used as a raw material to prepare Bi through ball milling_0.83Sm_0.17Fe_0.95Sc_0.05O₃Powder material;

presintering the powder obtained in the step one at 860 ℃ for 5 minutes, and then carrying out secondary ball milling on the presintered powder;

step three, carrying out hot-pressing sintering on the powder obtained in the step two at 820-860 ℃ for 5 minutes to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃And cutting, grinding and polishing the ceramic to obtain the high-performance environment-friendly capacitor dielectric.

In the preparation step, step one is to prepare Bi by ball milling_0.83Sm_0.17Fe_0.95Sc_0.05O₃The powder is simple in process and easy to realize; the target powder with more uniform components and finer particles can be obtained by performing secondary ball milling on the powder after the two pairs of pre-sintering in the step, so that the pressure resistance of subsequent ceramics can be improved and the microstructure can be optimized; and in the rapid hot-pressing sintering process of the third step, the ceramic can be well phase-formed and internal stress is released by keeping the temperature at 820-860 ℃ for five minutes.

Compared with the traditional solid phase sintering and rapid liquid phase sintering, the ceramic sintered by the rapid hot pressing sintering method has the advantages that the structure is more compact, the components are more uniform, and simultaneously, impure phases are basically not generated, so that the relaxation ferroelectric property and the voltage resistance are very excellent, the energy storage density is higher, the process is simple, the production efficiency is high, and the generation of the ceramic structure is easy to control.

Further, the first step is specifically as follows: adding bismuth trioxide, samarium trioxide, ferric oxide and scandium trioxide into a ball milling tank according to the proportion, adding zirconia grinding balls as grinding media, adding alcohol as grinding solvents, and performing ball milling at the rotating speed of 300-500 rpm for 12-36 hours to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃And (3) powder lot.

Further, the second step is specifically as follows: and (3) drying the powder obtained in the step one, grinding, presintering in a tube furnace at 860 ℃ for 5 minutes, grinding again, performing secondary ball milling, and drying and grinding after the secondary ball milling. Through ball milling for many times and grinding after drying each time, target powder with more uniform components and finer particles can be obtained, and the ceramic powder is beneficial to ensuring that the finally obtained ceramic powder has a more compact structure and more uniform components.

Further, the third step is specifically: putting the powder obtained in the step two into a hot pressing die, carrying out rapid hot pressing sintering under the conditions of 0.8 MPa of pressure and 860 ℃,keeping the temperature for 5 minutes to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃And cutting, grinding and polishing the ceramic to obtain the high-performance environment-friendly capacitor dielectric. The material structure is very compact by sintering under the pressure of 0.8 MPa, no hollow exists basically, and the crystal grains are clear and uniform in size, so that the ceramic with excellent properties is obtained, and the performance of the ceramic prepared at the sintering temperature of 860 ℃ is optimal.

Further, in the rapid hot-pressing sintering process of the third step, the temperature is rapidly increased to 860 ℃ at the rate of 200 ℃ per minute. The temperature is rapidly increased at the temperature increasing rate, so that the influence of impurities generated in the hot-pressing sintering process on the performance of the ceramic can be avoided.

Further, in the third step, the cutting is Bi obtained by hot pressing sintering by using a cutting machine_0.83Sm_0.17Fe_0.95Sc_0.05O₃And cutting a thin sheet with the thickness of less than or equal to 1mm from the middle part of the ceramic, wherein the polishing is to polish the thin sheet to a thickness of 0.1-0.5 mm by using metallographic abrasive paper, and the thickness of the ceramic thin sheet is selected according to actual requirements.

Further, the method also comprises the fourth step of: and (4) respectively plating a bottom electrode and a top electrode on two surfaces of the ceramic sheet obtained in the step three by adopting a sputtering process.

For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 is a comparison of XRD diffraction patterns of a BSFSO ceramic sample and a pure BFO ceramic sample;

FIG. 2 is a SEM cross-sectional representation of a BSFSO ceramic sample;

FIG. 3 is a graph of hysteresis loop and energy storage performance of BSFSO ceramic samples at different voltages;

wherein, fig. 3(a) is a hysteresis loop diagram of the BSFSO ceramic sample under different voltages, and fig. 3(b) is a energy storage performance diagram of the BSFSO ceramic sample under different voltages;

FIG. 4 is a graph of hysteresis loop and energy storage performance of BSFSO ceramic samples at different temperatures;

wherein, fig. 4(a) is a hysteresis loop diagram of the BSFSO ceramic sample at different temperatures, and fig. 4(b) is a graph of energy storage performance of the BSFSO ceramic sample at different temperatures;

FIG. 5 is a plot of hysteresis loop and energy storage performance of BSFSO samples at different frequencies;

wherein, fig. 5(a) is a hysteresis loop diagram of the BSFSO ceramic sample at different frequencies, and fig. 5(b) is a plot of the energy storage performance of the BSFSO ceramic sample at different frequencies;

FIG. 6 is a plot of hysteresis loop and energy storage performance of BSFSO ceramic samples obtained at different sintering temperatures;

wherein, fig. 6(a) is a hysteresis loop diagram of BSFSO ceramic samples obtained at different sintering temperatures, and fig. 6(b) is a comparison graph of energy storage performance of BSFSO ceramic samples obtained at different sintering temperatures;

FIG. 7 is an EDS map and data for BSFSO ceramic samples;

wherein the left graph is an EDS map of a BSFSO ceramic sample, and the right graph is an experimental value and a theoretical value of atomic percentage of four elements of Bi, Sm, Fe, Sc and O;

FIG. 8 is dielectric constant, loss and leakage current data for BSFSO ceramic samples;

fig. 8(a) is a graph showing the change of dielectric constant with the test frequency of the BSFSO ceramic sample, fig. 8(b) is a graph showing the change of loss with the test frequency of the BSFSO ceramic sample, and fig. 8(c) is a graph showing the change of leakage current value with the electric field strength of the BSFSO ceramic sample.

Detailed Description

Example 1

The preparation method of the dielectric of the high-performance environment-friendly capacitor comprises the following steps:

the method comprises the following steps: preparation of Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃(BSFSO) powder.

In this example, when the total amount of the BSFSO powder obtained is 0.08mol, the preparation raw materials of the BSFSO powder are shown in table 1:

TABLE 1 preparation of BSFSO powder

Name of medicine	Molecular weight	Purity of the drug	Experimental proportions	Stoichiometric number	Weighing mass
						Bismuth oxide	465.96	0.9999	1	0.83	15.4714g
Samarium oxide	348.7	0.9999	1	0.17	2.3714g
						Ferric oxide	159.69	0.999	1	0.95	6.0742g
Scandium oxide	137.91	0.999	1	0.05	0.2760g

The method comprises the following specific steps:

1) weighing the raw materials according to the weighing mass in the table 1;

2) adding the weighed raw materials into a nylon ball milling tank, adding zirconia grinding balls as grinding media, adding alcohol as a grinding solvent, and mixing and carrying out primary ball milling. Wherein, the mass ratio of the grinding medium to the raw material is controlled to be 1: 1 or so; the grading of grinding balls used by the grinding medium is controlled to be about 1:2:3 in large: medium: small; the rotation speed of the ball mill is 418 r/min, and the ball milling time is 24 hours.

Step two: and (6) pre-burning. The method comprises the following specific steps:

1) and (3) after the primary ball milling is finished, pouring the obtained powder into a culture dish, and putting the culture dish into an oven for drying until all the alcohol is dried. Scraping the dried powder into an agate mortar by using a medicine spoon, grinding the powder for 30 minutes by using an agate rod, then sending the powder into a tube furnace to pre-burn the powder for 5 minutes at 860 ℃, then adding the powder into the agate mortar again, and grinding the powder for 20 minutes by using the agate rod for secondary ball milling.

2) And (3) performing secondary ball milling on the pre-sintered powder, pouring the obtained powder into a culture dish after the secondary ball milling is finished, drying the powder in an oven until all alcohol is dried, grinding the powder in an agate mortar by using an agate rod to be more uniform and finer to obtain BSFSO target powder, and sealing and storing the BSFSO target powder in a muffle furnace. And the conditions of the secondary ball milling are the same as those of the primary ball milling in the step one.

Step three: preparation of Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃(BSFSO) ceramics. The method comprises the following specific steps:

1) and (3) weighing about 4.5g of BSFSO powder prepared in the step two, filling the BSFSO powder into a graphite die for hot-pressing sintering, and isolating the powder from upper and lower gaskets of the graphite die by using high-temperature-resistant carbon paper coated with boron nitride so as to prevent carbon elements in the graphite die from permeating into an experimental sample and further influencing the performance of the sample. A cylindrical inner cavity for placing a sample in the graphite mold needs to be wrapped by a layer of high-temperature-resistant carbon paper, so that the permeation of carbon elements in the graphite mold to a sample area is reduced.

2) The graphite mould filled with BSFSO powder is coated with a layer of high-temperature-resistant heat-insulating asbestos, so that the loss of the graphite mould in the high-temperature hot-pressing sintering process is reduced, and the graphite mould can be recycled for multiple times. A layer of high-temperature resistant asbestos is also padded above the graphite mould, and then the graphite mould is placed into a rapid direct-current hot press, and the pressure of the upper graphite plate and the lower graphite plate is increased to 0.8 MPa.

3) The circulating cooling water of the rapid direct-current hot press is started, and a large amount of heat is generated in the high-temperature hot-pressing sintering process, so that the temperature needs to be reduced in time; a ventilation system of a laboratory is started, so that dust generated in the experiment process is discharged, and the physical health of an experimenter is prevented from being injured; the thermocouple is inserted into a small hole of the graphite mold for measuring the sintering temperature, and the temperature display screen is opened, so that the temperature of the sample can be conveniently checked at any time, and the rigor and the correctness of the experiment can be ensured. After the preparation work before the test is done, the hot-pressing sintering test can be formally carried out.

4) In order to ensure that the test is carried out smoothly, two experimenters are required to cooperate to complete the test. One person is responsible for controlling the temperature rise instrument panel of the rapid direct-current hot press, and the indication of the thermocouple temperature display screen is closely noticed, so that the sintering temperature is prevented from exceeding the preset test temperature. The other person is responsible for controlling the pressure applied to the two ends of the sample in the hot-pressing test, because the pressure is lower than the preset pressure value after the sample is burned in the high-temperature sintering process, the sample needs to be pressurized in time, and the pressure is always maintained at 0.8 MPa. In the experimental process, two experimenters cooperate to quickly raise the sintering temperature to 860 ℃ at the temperature rise rate of 200 ℃ per minute under the pressure of 0.8 MPa, and then the temperature is kept for 5 minutes, so that the internal stress of the sample is released. And after the heat preservation is finished, closing the hot press, naturally cooling the sample, and still keeping the pressure applied to the two ends of the sample at 0.8 MPa before the temperature of the sample is reduced to 600 ℃ so as to prevent the sample from generating cracks and air holes in the cooling process.

5) And when the temperature of the sample is reduced to room temperature, taking the sample out of the graphite die to obtain a cylindrical BSFSO ceramic wafer with the thickness of 4mm, cutting a slice with the thickness of about 0.6mm from the middle part of the ceramic wafer by using a cutting machine, and grinding and polishing the slice to the BSFSO ceramic wafer with the thickness of 0.17mm by using metallographic abrasive paper so as to perform related tests on the next plated electrode.

Step four: and plating electrodes on two surfaces of the BSFSO ceramic sheet respectively. The method comprises the following specific steps:

1) and plating a bottom electrode on the BSFSO ceramic sheet, wherein the bottom electrode is a surface electrode. Putting the ceramic wafer into a small ion sputtering instrument, loading gold target material into the small ion sputtering instrument, turning on a power supply, and vacuumizing to 2 × 10^-3After Pa and below, the apparatus was started to be supplied with high-purity (99.99%) argon as an ionizing medium. Before starting sputtering, the current is ensured to be between 6 and 8mA (which can be adjusted by a needle valve of the instrument), because the instrument can be damaged by the excessively high current. The sputtering time is 40s each time, the operation is repeated for 4 times, the interval is 20s each time, after the operation is finished, the air valve for introducing the argon gas is closed, then the power supply of the instrument is closed, and the cavity is opened for sampling. After the sample is taken out, the sample is baked for about 6 minutes at 90 ℃ on a heating table, so that the sputtered gold electrode is better adhered to the bottom surface of the ceramic chip.

2) And plating a top electrode on the BSFSO ceramic sheet, wherein the top electrode is a point electrode. And putting the ceramic wafer into a small ion sputtering instrument, covering a mask plate on the ceramic wafer, wherein the diameter of a hole on the mask plate is 1.5 mm. Step 1) in the step four of the process for plating the top electrode, after a sample is taken out, the sample is baked for about 6 minutes at 90 ℃ on a heating table, so that the sputtered gold electrode is better adhered to the surface of the ceramic chip. Therefore, the BSFSO ceramic chip plated with the bottom electrode and the top electrode is obtained, and the BSFSO ceramic chip is the dielectric medium of the high-performance environment-friendly capacitor.

Example 2

The preparation method of the dielectric of the high-performance environment-friendly capacitor in the embodiment is basically the same as that in the embodiment 1, and the difference is that the following two points are adopted:

in the hot-pressing sintering process of the step 4) in the third step, through the cooperation of two experimenters, the sintering temperature is respectively increased to three different temperatures of 860 ℃, 840 ℃ and 820 ℃, then the temperature is respectively preserved for 5 minutes, and three BSFSO ceramic samples prepared at different sintering temperatures are obtained after temperature reduction.

And step 2) of the fourth step, when the top electrode is plated, the diameter of the hole on the adopted mask is 1 mm.

Example 3

The performance of the high-performance environment-friendly capacitor dielectric prepared in example 1 and example 2, namely, the BSFSO ceramic (samarium-scandium co-doped BFO ceramic), was tested and characterized:

(1) XRD diffraction measurement

Referring to fig. 1, which is a comparison of XRD diffractograms of BSFSO ceramic samples and pure BFO ceramic samples, curve 1 is the XRD diffractogram of BSFSO ceramic and curve 2 is the XRD diffractogram of pure BFO ceramic. The test results were obtained by testing the BSFSO ceramics obtained in example 1 with an X-ray diffractometer (X' Pert PRO, PANalytical). As can be seen from FIG. 1, the BSFSO ceramic can be independently phase-formed without other impurity phases.

(2) SEM Cross section characterization

Referring to fig. 2, which is a SEM cross-sectional representation and a partial enlarged view of a BSFSO ceramic sample, the test results were obtained by testing the BSFSO ceramic prepared in example 1 by a scanning electron microscope (ZEISS Gemini 500). It can be seen from fig. 2 that the BSFSO ceramic has a very dense structure, a distinct crystalline phase, no voids, defects and impurities.

(3) Analysis of hysteresis loop and energy storage performance

The BSFSO ceramics after the four-plated bottom and top electrodes of examples 1 and 2 were electrically tested by a Ferroelectric Tester (radial Technology Ferroelectric Tester).

The test results are shown in fig. 3-6, wherein fig. 3(a), fig. 4(a) and fig. 5(a) are hysteresis curves of BSFSO ceramic samples obtained in example 1 at different voltages, different temperatures and different frequencies, respectively; FIGS. 3(b), 4(b) and 5(b) are graphs comparing the energy storage values and the energy storage efficiencies of BSFSO ceramic samples obtained in example 1 at different voltages, different temperatures and different frequencies, respectively, wherein the two curves in each graph correspond to the energy storage values or the energy storage efficiency curves, respectively, according to the ordinate pointed by the arrows enclosed by ellipses; fig. 6(a) is a graph of the hysteresis loop of BSFSO ceramic samples obtained at different sintering temperatures in example 2, and fig. 6(b) is a graph of the energy storage value and energy storage efficiency comparison of BSFSO ceramic samples obtained at different sintering temperatures in example 2.

As can be seen from FIG. 3, the BSFSO ceramic has a field strength as high as 230kV/cm, a relatively slender ferroelectric hysteresis loop, and a corresponding energy storage value and efficiency of 2.21J/cm³And 76% better than the currently reported 1.66J/cm³The maximum energy storage density and the energy storage efficiency of 75%.

As can be seen from fig. 4, the BSFSO ceramic has good temperature stability, achieving the best performance at 120 ℃.

As can be seen from fig. 5, the BSFSO ceramic has excellent frequency stability, achieving optimum performance at 1 Hz.

As can be seen from fig. 6, the BSFSO ceramic has the best performance under the 860 ℃ hot pressing condition.

The excellent characteristics show that the BSFSO ceramic (samarium-scandium co-doped BFO ceramic) can be applied to high-speed and high-temperature energy density dielectric capacitors.

(4) EDS data analysis

Please refer to fig. 7, which is EDS data for BSFSO ceramic samples. The test results were obtained by testing the BSFSO ceramic prepared in example 1 by a field emission scanning electron microscope (ZEISS Gemini 500). As can be seen from fig. 7, the experimental values of all the elements are substantially consistent with the theoretical values, indicating that Sm and Sc co-doping and rapid hot-pressing sintering methods can inhibit the volatilization of the Bi element.

(5) Dielectric behavior and leakage current analysis

Referring to fig. 8, dielectric constant, loss and leakage current data of BSFSO ceramic samples were obtained by testing BSFSO ceramic prepared in example 1 using a Ferroelectric Tester (radial Technology Ferroelectric Tester). As can be seen from FIG. 8(a), the dielectric constant of the BSFSO ceramic sample decreases with the increase of the test frequency, the value is between 200 and 260, which indicates that the BSFSO ceramic sample has excellent properties, and as can be seen from FIG. 8, the dielectric loss and the leakage current value are both very small, which indicates that the insulation property of the sample is very good, and the relevant data tested above are intrinsic values, and the test result is scientific and reliable.

Compared with the prior art, the samarium-scandium co-doped BFO ceramic (BSFSO) sintered by the rapid hot-pressing sintering method is more compact, has more uniform components and basically generates no impurity phase compared with the traditional solid-phase sintering and rapid liquid-phase sintering, so that the samarium-scandium co-doped BFO ceramic has excellent relaxor ferroelectric property and pressure resistance property, thereby obtaining higher energy storage density. The experimental results show that the high-performance environment-friendly BSFSO ceramic effectively overcomes the defects of poor BFO voltage resistance and large leakage current, and improves the energy storage density and energy storage efficiency of the capacitor dielectric medium.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A high performance environmentally friendly capacitor dielectric, characterized by: is prepared by hot-pressing and sintering a ferroelectric material, wherein the ferroelectric material is samarium-scandium co-doped bismuth ferrite, and the chemical composition of the ferroelectric material is Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃The preparation method comprises the following steps:

step one, taking bismuth trioxide, samarium trioxide, ferric oxide and scandium trioxide as raw materials, and preparing Bi by ball milling_0.83Sm_0.17Fe_0.95Sc_0.05O₃Powder material;

step three, the powder obtained in the step two is filled into a hot-pressing diePerforming rapid hot-pressing sintering under the conditions that the pressure is 0.8 MPa and the temperature is 860 ℃, and preserving the heat for 5 minutes to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃Cutting, grinding and polishing the ceramic to obtain the high-performance environment-friendly capacitor dielectric; in the process of rapid hot-pressing sintering, the temperature is rapidly increased to 860 ℃ at the rate of 200 ℃ per minute, then the temperature is preserved for 5 minutes, the temperature is naturally reduced after the temperature preservation is finished, and the pressure is kept at 0.8 MPa before the temperature is reduced to 600 ℃.

2. The method of preparing a high performance environmentally friendly capacitor dielectric as defined in claim 1, wherein: the method comprises the following steps:

step three, the powder obtained in the step two is loaded into a hot pressing die, the rapid hot pressing sintering is carried out under the conditions that the pressure is 0.8 MPa and the temperature is 860 ℃, and the heat preservation is carried out for 5 minutes to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃Cutting, grinding and polishing the ceramic to obtain the high-performance environment-friendly capacitor dielectric; in the process of rapid hot-pressing sintering, the temperature is rapidly increased to 860 ℃ at the rate of 200 ℃ per minute, then the temperature is preserved for 5 minutes, the temperature is naturally reduced after the temperature preservation is finished, and the pressure is kept at 0.8 MPa before the temperature is reduced to 600 ℃.

3. The method of claim 2, wherein the step of preparing the dielectric material comprises: the first step is specifically as follows: adding bismuth trioxide, samarium trioxide, ferric oxide and scandium trioxide into a ball milling tank according to the proportion, adding zirconia grinding balls as grinding media, adding alcohol as grinding solvents, and performing ball milling at the rotating speed of 300-500 rpm for 12-36 hours to obtain Bi_0.83Sm_0.17Fe_0.95Sc_0.05O₃And (3) powder lot.

4. The method of claim 2, wherein the step of preparing the dielectric material comprises: the second step is specifically as follows: and (3) drying the powder obtained in the step one, grinding, presintering in a tube furnace at 860 ℃ for 5 minutes, grinding again, performing secondary ball milling, and drying and grinding after the secondary ball milling.

5. The method of claim 2, wherein the step of preparing the dielectric material comprises: in the third step, the cutting is Bi obtained by hot-pressing sintering by using a cutting machine_0.83Sm_0.17Fe_0.95Sc_0.05O₃And cutting a thin sheet with the thickness of less than or equal to 1mm from the middle part of the ceramic, wherein the polishing is to polish the thin sheet to a ceramic thin sheet with the thickness of 0.1-0.5 mm by using metallographic abrasive paper.

6. The method of claim 5, wherein the step of preparing the dielectric material comprises: the method also comprises the following four steps: and (4) respectively plating a bottom electrode and a top electrode on two surfaces of the ceramic sheet obtained in the step three by adopting a sputtering process.