CN114956817A - Silver-sodium niobate based lead-free antiferroelectric ceramic material with high energy storage density and preparation method thereof - Google Patents

Abstract

The invention discloses a high energy storage density silver sodium niobate based lead-free antiferroelectric ceramic material and a preparation method thereof, wherein Ag is prepared by ₂ O，Nb ₂ O ₅ ，Ta ₂ O ₅ And NaCO ₃ Drying, grinding and sieving the mixed powder subjected to the mixed ball milling treatment in sequence; presintering the sieved mixed powder, naturally cooling to room temperature, adding a PVA solution into the sieved powder, and uniformly mixing to obtain granulated powder; naturally drying the granulated powder, then weighing a certain amount of powder, putting the powder into a mould, and pressing the powder into a blank; sintering the blank under the condition of pure oxygen, cooling after sintering, and discharging to obtain a sintered ceramic wafer; and polishing and airing the sintered ceramic plate to obtain the silver-sodium niobate-based antiferroelectric ceramic material with high energy storage density.The invention has simple components and process steps. The method is easy to operate, has good repeatability, can be applied to dielectric capacitors and high-power pulse dielectric energy storage devices with high requirements on energy storage density and energy effectiveness, and has high economic value.

Description

A kind of high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material and preparation method thereof

technical field

The invention belongs to the technical field of lead-free dielectric energy storage materials, in particular to a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density and a preparation method thereof.

Background technique

With the rapid development of science and technology and economy, people's quality of life has been improved, but there have also been problems such as insufficient energy and environmental pollution. At present, our production and life still rely on fossil fuels, but their limited total amount and non-renewability are a major problem that needs to be solved urgently in front of human society. Therefore, the development momentum of new energy is very rapid. Energy storage places higher demands.

At present, electrical energy storage devices mainly include chemical batteries, electrochemical capacitors and dielectric capacitors. Compared with the other two, dielectric capacitors have the characteristics of higher power density, very long cycle times, and fast charging and discharging speed, which meet the requirements of ultra-high power electronic systems. Therefore, based on the above advantages, dielectric capacitors are expected to be used in electronic circuits, microwave communications, 3C electronic production, new energy vehicles, and military equipment such as: electrothermal excitation guns, rail guns, laser fusion systems, etc., and medical equipment such as cardiac defibrillators. , laser surgery and other aspects have broad application prospects.

However, with the increasing miniaturization of electronic products, it is urgent to find a dielectric material with high storage density. Due to its unique double hysteresis loop, high saturation polarization and near-zero remanent polarization, dielectric capacitors of antiferroelectric materials are more capable of achieving high energy storage density and high power density. Advantage. Therefore, it is expected to break through the energy storage bottleneck of some polymer capacitors currently restricted.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material and a preparation method thereof, with simple components and process steps. It is easy to operate and has good repeatability, and can be applied to dielectric capacitors and high-power pulsed dielectric energy storage devices that have high requirements on energy storage density and energy efficiency, and has high economic value.

The present invention adopts the following technical solutions:

A silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density, the chemical composition of the silver sodium niobate-based lead-free antiferroelectric ceramic material is: (Ag _0.5 Na _0.5 )(Nb _1-x Ta _x )O ₃ , x is the mole percentage of (Nb _1-x Ta _x )O ₃ , and 0.2<x≦0.5.

A method for preparing a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density, comprising the following steps:

S1. Weigh Ag ₂ O and Nb ₂ O ₅ according to the calculated mass of the chemical composition (Ag _0.5 Na _0.5 ) (Nb _1-x Ta _x )O ₃ when x=0.2, 0.3, 0.4 and 0.5. , Ta ₂ O ₅ and NaCO ₃ powder;

S2. The Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ powders weighed in step S1 are mixed and then subjected to a first ball milling treatment to obtain a mixed powder, and the mixed powder is sequentially dried, ground and Sieving, pre-sintering the sifted mixed powder, performing a second ball milling treatment after natural cooling, taking out the powder and drying to obtain a prefabricated powder;

S3, grinding the prefabricated powder obtained in step S2, sieving to obtain a screening powder, then adding a PVA solution with a concentration of 3% to 6% to the screening powder, and mixing uniformly to obtain a granulated powder;

S4, pressing the granulated powder obtained in step S3 into an embryo body, then sintering the embryo body, and naturally cooling to obtain a sintered ceramic sheet;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.1-0.15 mm, and naturally drying to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

Specifically, in step S2, the rotational speed of the first ball milling treatment and the second ball milling treatment are both 400 to 450 rpm, the time of the first ball milling treatment is greater than or equal to 12 hours, and the second ball milling treatment time is 4 to 450 rpm. 5 hours.

Further, the solvent used in the ball milling treatment is absolute ethanol or water, and the ball milling medium is zirconia balls or alumina balls.

Specifically, in step S2, the drying temperature after the first ball-milling treatment is 65-70°C, the screen mesh after the sieving treatment is 80-100 mesh, and the drying temperature after the second ball-milling treatment is 65-70°C .

Specifically, in step S2, the temperature of the pre-firing treatment is 800-900° C., the holding time is 4-6 hours, and the atmosphere is pure oxygen.

Specifically, in step S3, the particle size of the screening powder is 80-100 mesh.

Specifically, in step S3, the addition amount of the PVA solution is 5% to 10% of the mass of the screening powder.

Specifically, in step S4, the pressure for pressing the embryo body is 20-25 MPa.

Specifically, in step S4, the sintering process is as follows:

Heat up to 600-700°C at a rate of 3-5°C/min, keep warm for 2-3 hours, continue to heat up to 1230-1280°C and keep for 6-7 hours, cool down to a temperature lower than 500°C, and cool down naturally with the furnace to room temperature.

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

The present invention is a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density. The material composition can be prepared and synthesized by a solid-phase method, and a high density silver sodium niobate-based antiferroelectric ceramic material is obtained. . In this material system, when the chemical composition of the material is x≤0.5, the ceramic material shows the highest effective energy storage density of 5.548J/ ^cm3 at the voltage of 383.34KV cm ^-1 , and when the chemical composition is 0.2<x≤0.5 , the ceramic material shows the highest total energy storage density of 8.35J/ ^cm3 at the voltage of 383.34KV cm ^-1 , while the chemical composition of the material falls within the range of 0.2<x≤0.5, the ceramic material shows a higher energy efficiency in Between 83.26% and 96.605%.

The invention provides a method for preparing a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density. The raw materials of Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ are respectively weighed according to their chemical compositions; Carry out the first ball milling treatment; then carry out drying, grinding and sieving treatment in sequence; the mixed powder is subjected to pre-sintering treatment, after natural cooling, the second ball milling treatment is carried out, and the raw materials are mixed evenly through two ball milling treatments. , the second ball milling is used to reduce the size of the powder after pre-sintering, take out the powder and dry it to obtain the pre-fabricated powder; grind the pre-fabricated powder, sieve the powder to obtain fine and uniform powder, and then put the powder into the powder. PVA solution with a mass concentration of 3-6% is added to the powder, and the granulated powder is obtained after mixing evenly; the granulated powder is pressed and weighed as an embryo; Silver sodium niobate-based ceramic sample; the single-phase silver sodium niobate-based ceramic sample is polished to a thickness of 0.1-0.15mm, and naturally dried to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density. The whole process The steps are simple, easy to operate, and reproducible.

Further, the rotational speed of the first ball milling treatment and the second ball milling treatment is 400 to 450 rpm, the time of the first ball milling treatment is greater than or equal to 12 hours, and the time of the second ball milling treatment is 4 to 5 hours. If the rotation speed is lower than 400 rpm, the rotation speed is too low, and the ball milling is uneven. If the rotation speed is greater than 450 rpm, it may cause damage to the ball mill tank. Therefore, set the ball milling speed to 400-450 rpm. The purpose of the first ball milling is to mix the raw materials evenly, so the ball milling time is longer, and the second ball milling is to reduce the size of the powder after pre-sintering, so the ball milling time is shorter, and the choice of anhydrous ethanol as the solvent has two advantages , First of all, the surface energy of the powder surface can be reduced, so the powder will not agglomerate. Second, the addition of alcohol is easy to volatilize and will not increase the water content of the powder too much. The function of the ball milling medium is to refine the powder while avoiding the agglomeration of the powder.

Further, the ignition point of anhydrous ethanol is 75°C. If the temperature is higher than this, the sample will burn, so choose 65-70°C for drying; choose 80-100 mesh screen to ensure that the obtained powder is fine and uniform.

Further, high-quality pure-phase tantalum silver sodium niobate powder samples can be synthesized from the raw materials after ball milling in an oxygen atmosphere. The pre-sintering temperature is 800-900°C, and the holding time is 4-6 hours to obtain pure-phase powder samples.

Further, the screen mesh for screening the powder is 80-100 mesh, which can ensure that the size of the granulated powder is uniform.

Further, the added amount of the PVA solution is 5-10% of the mass of the screening powder. The addition amount is 5-10% of the mass of the screening powder, which can make the powder fully and uniformly mix with PVA.

Further, the green embryo pressed under the pressure of 20-25 MPa for pressing the embryo body is well formed.

Further, heat up to 600-700°C at a rate of 3-5°C/min, keep warm for 2-3 hours, continue to heat up to 1230-1280°C and keep the temperature for 6-7 hours, cool down to less than 500°C, naturally Cool to room temperature. Keep the temperature at 600-700℃ for 2-3 hours in order to fully discharge the PVA in the embryo body, sintering at 1230-1280℃ and keeping the temperature for 6-7 hours can reach the ceramic forming conditions.

To sum up, the composition and process steps of the present invention are simple, easy to operate, and have good repeatability, and can be applied to dielectric capacitors and high-power pulsed dielectric energy storage devices that have higher requirements on energy storage density and energy efficiency. Has superior economic value.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

1 is a schematic diagram of the total energy storage density, the effective energy storage density and the energy availability of the ANNTx ceramic sample of the present invention under the maximum electric field that increases with the content of doped Ta;

2 is a schematic diagram of the effective energy storage density and energy availability of the same component of the ANNTx ceramic sample of the present invention at x=0.2;

3 is a schematic diagram of the effective energy storage density and energy efficiency of the same component of the ANNTx ceramic sample of the present invention at x=0.3;

4 is a schematic diagram of the effective energy storage density and energy availability of the same component of the ANNTx ceramic sample of the present invention at x=0.4;

FIG. 5 is a schematic diagram of the effective energy storage density and energy efficiency of the same component of the ANNTx ceramic sample of the present invention at x=0.5.

Detailed ways

The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form new technical solutions.

In the present invention, unless otherwise specified, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

In the present invention, unless otherwise specified, percentage (%) or part refers to the weight percentage or weight part of the composition.

In the present invention, unless otherwise specified, the involved components or their preferred components can be combined with each other to form a new technical solution.

In the present invention, unless otherwise stated, the numerical range "a～b" represents an abbreviated representation of any combination of real numbers between a and b, wherein both a and b are real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" have been listed in this document, and "6-22" is just an abbreviated representation of the combination of these numerical values.

A "range" disclosed herein may be in the form of a lower limit and an upper limit, which may be one or more lower limits, and one or more upper limits, respectively.

In the present disclosure, the term "and/or" as used herein refers to and including any and all possible combinations of one or more of the associated listed items.

In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in sequence. Preferably, the reaction methods herein are performed sequentially.

Unless otherwise defined, professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods or materials similar or equivalent to those described can also be used in the present invention.

The invention provides a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density. The chemical composition of the silver sodium niobate-based lead-free antiferroelectric ceramic material is: (Ag _0.5 Na _0.5 ) (Nb _{1 -x} Ta _x )O ₃ , x is the mole percent of (Nb _1-x Ta _x )O ₃ , and 0.2<x≦0.5.

Is there an optimal solution within the above range? Please add

A method for preparing a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density of the present invention comprises the following steps:

S1. Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ powder

S2. The Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ powders weighed in step S1 are mixed and then subjected to a first ball milling treatment to obtain a mixed powder, and the mixed powder is sequentially dried, ground and processed. Sieving treatment, pre-sintering the mixed powder after sieving, performing a second ball milling treatment after natural cooling, taking out the powder and drying to obtain a prefabricated powder;

Among them, the ball milling solvent used in the ball milling treatment is anhydrous ethanol or water, the ball milling medium is zirconia balls or alumina balls, the ball milling speed is 400-450 rpm, the first ball milling time is greater than or equal to 12 hours, and the second ball milling The time is 4 to 6 hours, the drying temperature after the first ball milling treatment is 65 ~ 70 ℃, the screen mesh after sieving treatment is 80 ~ 100 mesh, and the drying temperature after the second ball milling treatment is 65 ~ 70 ℃ .

The pre-burning treatment is as follows:

Put the mixed powder in a tube furnace and pass flowing oxygen, in a pure oxygen atmosphere, pre-fire at 800-900 ° C for 4-5 hours, after natural cooling, carry out the second ball milling treatment, ball milling for 4-6 hours After one hour, take out the powder and dry it in an oven at 65-70° C. to obtain a calcined powder.

S3. The prefabricated powder obtained in step S2 is ground and sieved to obtain 80-100 mesh screening powder, and then a PVA solution accounting for 5% to 10% of the mass of the screening powder is added to the screening powder, and the quality of the PVA solution is The concentration is 3% to 6%, and the granulated powder is obtained after mixing evenly;

S4. The granulated powder obtained in step S3 is allowed to stand until the powder is dry, and 0.5-0.55 g of the dry powder is weighed and placed into a mold with a diameter of 11-12 mm, and pressed into an embryo under a uniaxial pressure of 20-30 MPa ; Put the embryo body into an Al ₂ O ₃ porcelain boat, put it into a tube furnace, carry out sintering treatment under pure oxygen conditions, heat up to 600-700 ℃ at a rate of 3-5 ℃/min, and keep the temperature for 2-3 After an hour, continue to heat up to 1230-1280°C and keep the temperature for 6-7 hours, after cooling to less than 500°C, naturally cool to room temperature with the furnace, and take out the furnace to obtain sintered ceramic sheets;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.1-0.15 mm, and naturally drying to obtain a silver sodium niobate-based antiferroelectric ceramic material with high energy storage density.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

A silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, the chemical composition of which is expressed by the following formula: (Ag _0.5 Na _0.5 )(Nb _0.8 Ta _0.2 )O ₃ .

A preparation method of a silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, comprising the following steps:

S1. Weigh Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ raw materials according to the chemical composition of the silver sodium niobate-based antiferroelectric ceramic material;

S2, the raw materials weighed in step S1 are mixed and subjected to a ball milling, the solvent used in the ball milling treatment is dehydrated alcohol, the ball milling medium is zirconia balls, the ball milling speed is 400 rpm, and the ball milling time is 12 hours; The powder was dried in an oven at 65°C, and after grinding, the powder was sieved with an 80-mesh sieve; the mixed powder was placed in a tube furnace and introduced into flowing oxygen, in a pure oxygen atmosphere, at 800 Pre-fired at ℃ for 4 hours, after natural cooling, the second ball milling treatment was performed, and after ball milling for 4 hours, the powder was taken out and dried in an oven at 65 ° C to obtain the pre-fired powder;

S3, grinding the pre-fired powder obtained in step S2 and passing through an 80-mesh sieve to obtain a sun-dried powder, then adding a 3% PVA solution to the sun-dried powder, and mixing uniformly to obtain a granulated powder;

S4, take out 0.5 g of the granulated powder obtained in step S3 after drying and place it in a mold with a diameter of 11 mm, and press it into an embryo body under a uniaxial pressure of 20 MPa; place the embryo body in an Al ₂ O ₃ porcelain boat, put Sintered in a tube furnace under pure oxygen conditions, heated to 600°C at a rate of 3°C/min, kept for 2 hours, continued to heat up to 1230°C and kept for 6 hours, cooled to less than 500°C, and cooled to room temperature with the furnace , sintered ceramic sheets are obtained after natural cooling;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.15 mm, and naturally drying to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

The effective energy storage density and efficiency of the ceramic material prepared in Example 1 were calculated. The results are shown in Figure 2. Under the electric field of 252KV/cm, the energy storage density of the obtained ceramic material was 2.73638J/cm ³ . The efficiency is 44.113%. The effective energy storage density increases gradually with the increase of the electric field.

Example 2

A silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, the chemical composition of which is expressed by the following formula: (Ag _0.5 Na _0.5 )(Nb _0.7 Ta _0.3 )O ₃ .

A preparation method of a silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, comprising the following steps:

S1. Weigh Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ raw materials according to the chemical composition of the silver sodium niobate-based antiferroelectric ceramic material;

S2, the raw materials weighed in step S1 are mixed and subjected to a ball milling, the solvent used in the ball milling treatment is dehydrated alcohol (or water), the ball milling medium is zirconia balls (or alumina balls), and the ball milling speed is 425 rpm, The ball milling time is 12 hours; the obtained mixed powder is dried in an oven at 70°C, and after grinding, the powder is sieved with a 100-mesh screen; the obtained mixed powder is placed in a tube furnace and passed through. Enter flowing oxygen, pre-sinter at 850°C for 4 hours in a pure oxygen atmosphere, and perform a second ball milling treatment after natural cooling. body;

S3, the pre-burned powder obtained in step S2 is ground and passed through an 80-mesh sieve to obtain a sun-dried powder, and then 5% PVA solution is added to the sun-dried powder, and the granulated powder is obtained after mixing uniformly;

S4, take out 0.55 g of the granulated powder obtained in step S5 after drying and place it in a mold with a diameter of 11.9 mm, and press it into an embryo body under a uniaxial pressure of 20 MPa; place the obtained embryo body in an Al ₂ O ₃ porcelain boat , put it into a tube furnace for sintering under pure oxygen conditions, heat it up to 600 °C at a rate of 5 °C/min, keep it for 2 hours, continue to heat it up to 1250 °C and keep it for 6 hours, cool it down to less than 500 °C, with the furnace After cooling to room temperature, the sintered ceramic sheet is obtained after natural cooling;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.13 mm, and naturally drying to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

The effective energy storage density and energy storage efficiency of the ceramic material obtained in Example 2 are calculated, and the results are shown in Figure 3. Under the electric field of 323KV/cm, the effective energy storage density of the obtained ceramic material is 3.999J/cm ³ , and the energy storage efficiency is 64.857%. The effective energy storage density increases with the increase of the electric field.

Example 3

A silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, the chemical composition of which is expressed by the following formula: (Ag _0.5 Na _0.5 )(Nb _0.6 Ta _0.4 )O ₃ .

A preparation method of a silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, comprising the following steps:

S1. Weigh Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ raw materials according to the chemical composition of the silver sodium niobate-based antiferroelectric ceramic material;

S2, the raw materials weighed in step S1 are mixed and subjected to a ball milling, the solvent used in the ball milling treatment is dehydrated alcohol (or water), the ball milling medium is zirconia balls (or alumina balls), and the ball milling speed is 425 rpm, The ball milling time is 12 hours; the obtained mixed powder is dried in an oven at 70°C, and after grinding, the powder is sieved with a 100-mesh screen; the obtained mixed powder is placed in a tube furnace and passed through. Enter flowing oxygen, pre-sinter at 850°C for 4 hours in a pure oxygen atmosphere, and perform a second ball milling treatment after natural cooling. body;

S3, the pre-burned powder obtained in step S4 is ground and passed through an 80-mesh sieve to obtain a sun-dried powder, and then 5% PVA solution is added to the sun-dried powder, and the granulated powder is obtained after mixing uniformly;

S4, take out 0.55 g of the granulated powder obtained in step S5 after drying and place it in a mold with a diameter of 11.9 mm, and press it into an embryo body under a uniaxial pressure of 20 MPa; place the embryo body in an Al ₂ O ₃ porcelain boat, Put it into a tube furnace for sintering under pure oxygen conditions, heat it up to 600 °C at a rate of 5 °C/min, keep it for 2 hours, continue to heat up to 1280 °C and keep it for 6 hours, cool it to less than 500 °C, and cool it down to 500 °C with the furnace. At room temperature, the sintered ceramic sheet is obtained after natural cooling;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.12 mm, and naturally drying to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

The effective energy storage density and energy storage efficiency of the ceramic material obtained in Example 3 are calculated. The results are shown in the figure. Under the electric field of 383.339KV/cm, the effective energy storage density of the obtained ceramic material is 5.5477J/cm ³ , and the energy storage efficiency is 66.4613%. The resulting effective energy storage density has a significant increase over the first two components, and the efficiency is >65%.

Example 4

A silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, the chemical composition of which is expressed by the following formula: (Ag _0.5 Na _0.5 )(Nb _0.5 Ta _0.5 )O ₃ .

A preparation method of a silver sodium niobate-based antiferroelectric ceramic material with high energy storage density, comprising the following steps:

S1. Weigh Ag ₂ O, Nb ₂ O ₅ , Ta ₂ O ₅ and NaCO ₃ raw materials according to the chemical composition of the silver sodium niobate-based antiferroelectric ceramic material;

S2, the raw materials weighed in step S1 are mixed and subjected to a ball milling, the solvent used in the ball milling treatment is dehydrated alcohol (or water), the ball milling medium is zirconia balls (or alumina balls), and the ball milling speed is 450 rpm, The ball milling time is more than 12 hours; the obtained mixed powder is dried in an oven at 70 °C, and the powder is sieved with a 100-mesh sieve after grinding; the sieved mixed powder is placed in a tube furnace Flow oxygen is introduced into it, pre-fired at 900 °C for 5 hours in a pure oxygen atmosphere, and then subjected to a second ball milling treatment after natural cooling. After ball milling for 5 hours, take out the powder and dry it in an oven at 70 °C. Pre-fired powder;

S3, the pre-burned powder obtained in step S2 is ground and passed through an 80-mesh sieve to obtain a sun-dried powder, and then 6% PVA solution is added to the sun-dried powder, and the granulated powder is obtained after mixing uniformly;

S4, take out 0.55 g of the granulated powder obtained in step S3 after drying and place it in a mold with a diameter of 12 mm, and press it into an embryo body under a uniaxial pressure of 25 MPa; place the embryo body in an Al ₂ O ₃ porcelain boat, put Sintered in a tube furnace under pure oxygen conditions, heated to 700°C at a rate of 5°C/min, kept for 2 hours, continued to heat up to 1280°C and kept for 7 hours, cooled to less than 500°C, and cooled to room temperature with the furnace , sintered ceramic sheets are obtained after natural cooling;

S5, grinding the sintered ceramic sheet obtained in step S4 to a thickness of 0.1 mm, and naturally drying to obtain a silver sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

The effective energy storage density and energy storage efficiency of the ceramic material obtained in Example 4 are calculated, and the results are shown in Figure 5. Under the electric field of 404.9877KV/cm, the effective energy storage density of the obtained ceramic material is 4.32487J/cm ³ , and the energy storage The efficiency is 83.263%. With the increase of the electric field, the energy storage efficiency increases, although the energy storage efficiency decreases, but the minimum efficiency is also above 80%. High energy storage density and energy storage efficiency make silver sodium niobate-based lead-free antiferroelectric ceramic materials have broad prospects in the field of dielectric energy storage.

Test the properties of the polarization intensity of the samples obtained in the above examples as a function of electric field, and then calculate their energy storage density W _store , effective energy storage density W _rec and energy availability η by formulas (1), (2) and (3) respectively. .

Among them, W _store is the total energy storage density; W _rec is the effective energy storage density; E is the electric field intensity; P is the polarization intensity; P _max is the maximum polarization intensity; P _r is the remanent polarization intensity.

Referring to Figure 1, it can be seen from Figure 1 that when x=0.4, the ceramic sample has a maximum total energy storage density of 8.35 J/cm ³ . Meanwhile, when x=0.4, the ceramic sample has the maximum effective energy storage density of 5.548J/cm ³ . When 0<x≤0.5, the energy availability of ceramic samples increases with the increase of Ta content, and when x=0.5, it can reach 83.263%.

Please refer to Figure 2, Figure 3, Figure 4 and Figure 5, respectively x = 0.2, 0.3, 0.4, 0.5, the effective energy storage density and energy efficiency of the same component at different voltages, it can be seen from the figure, with As the voltage increases, the effective energy storage density also increases.

When x=0.2, the voltage at 230KV cm ^-1 energy efficiency drops below 80%, with the increase of Ta content, when x=0.3, 0.4, the voltage is at 315KV cm ^-1 and 337KV cm ^-1 energy efficiency, respectively Sex dropped below 80%.

When x=0.5, it shows high energy efficiency, and the energy efficiency is still more than 83% when the voltage is above 400KV cm ^-1 . It exhibits high storage density as well as high energy efficiency.

To sum up, the present invention has a high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material and a preparation method thereof, which have simple components and process steps, easy operation and good repeatability, and can be applied to energy storage It has superior economic value in dielectric capacitors and high-power pulsed dielectric energy storage devices that require high density and energy efficiency.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (10)

1. The silver-sodium niobate based lead-free antiferroelectric ceramic material with high energy storage density is characterized by comprising the following chemical components: (Ag) _0.5 Na _0.5 )(Nb _1-x Ta _x )O ₃ X is (Nb) _1-x Ta _x )O ₃ And 0.2 mol% of<x≤0.5。

2. The method for preparing the silver-sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density as claimed in claim 1, characterized by comprising the following steps:

s1, chemical composition (Ag) _0.5 Na _0.5 )(Nb _1-x Ta _x )O ₃ The mass of Ag measured when the stoichiometric ratio x in (1) is 0.2, 0.3, 0.4 and 0.5 ₂ O，Nb ₂ O ₅ ，Ta ₂ O ₅ And NaCO ₃ Powder;

s2, weighing Ag in the step S1 ₂ O，Nb ₂ O ₅ ，Ta ₂ O ₅ And NaCO ₃ Mixing the powder, performing first ball milling treatment to obtain mixed powder, and sequentially drying, grinding and passing the mixed powderScreening, pre-burning the screened mixed powder, naturally cooling, performing secondary ball milling, taking out the powder and drying to obtain prefabricated powder;

s3, grinding the prefabricated powder obtained in the step S2, sieving to obtain screened powder, adding a PVA solution with the concentration of 3% -6% into the screened powder, and uniformly mixing to obtain granulated powder;

s4, pressing the granulation powder obtained in the step S3 into a blank, sintering the blank, and naturally cooling to obtain a sintered ceramic wafer;

s5, polishing the sintered ceramic wafer obtained in the step S4 to a thickness of 0.1-0.15 mm, and naturally drying to obtain the silver-sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density.

3. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in step S2, the rotation speed of the first ball milling treatment and the second ball milling treatment is 400-450 rpm, the time of the first ball milling treatment is greater than or equal to 12 hours, and the time of the second ball milling treatment is 4-5 hours.

4. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material as claimed in claim 3, wherein the solvent used in the ball milling treatment is absolute ethanol or water, and the ball milling medium is zirconia balls or alumina balls.

5. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in step S2, the drying temperature after the first ball milling is 65-70 ℃, the screen mesh after the screening is 80-100 mesh, and the drying temperature after the second ball milling is 65-70 ℃.

6. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in step S2, the pre-sintering treatment temperature is 800-900 ℃, the holding time is 4-6 hours, and the atmosphere is pure oxygen.

7. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in step S3, the particle size of the screened powder is 80-100 mesh.

8. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in step S3, the amount of PVA solution added is 5% -10% of the mass of the screened powder.

9. The preparation method of the high energy storage density silver sodium niobate-based lead-free antiferroelectric ceramic material according to claim 2, wherein in the step S4, the pressure for pressing the blank is 20-25 MPa.

10. The method for preparing the silver-sodium niobate-based lead-free antiferroelectric ceramic material with high energy storage density as claimed in claim 2, wherein in step S4, the sintering treatment specifically comprises:

heating to 600-700 ℃ at the speed of 3-5 ℃/min, keeping the temperature for 2-3 hours, continuing to heat to 1230-1280 ℃, keeping the temperature for 6-7 hours, cooling to the temperature lower than 500 ℃, and naturally cooling to the room temperature along with the furnace.

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