Non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic materials and preparation method

Abstract

The present invention discloses a non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material, whose structural formula is (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6, where M is one of Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 , Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 , Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 , Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 . The present invention also discloses a preparation method of the high-entropy ferroelectric energy storage ceramic material, which includes weighing precursor raw materials, ball milling, drying, pre-sintering the obtained mixture, granulating the pre-sintered powder, sieving, pressing, debinding, and sintering. The high-entropy ferroelectric energy storage ceramic material of the present invention is not broken down under the action of an external electric field of 550 kV / cm, has a high energy storage density and energy storage efficiency, and meets the requirements of advanced pulsed power capacitors.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic material preparation, and specifically relates to a non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material, and also relates to a preparation method of the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material. Background Art

[0002] Advanced lead-free ferroelectric ceramics play an indispensable role in the next-generation pulsed power capacitor market. Due to the polarization configuration of ferroelectric ceramic materials, dielectric ceramic capacitors formed based on this have advantages such as ultra-fast charge and discharge speeds, high power density, excellent temperature and mechanical stability, etc., and have received extensive attention and applications in the fields of electromagnetic weapons, medical treatment, and communication. The traditional phase boundary construction strategy is not flexible enough in regulating the polarization configuration, and the performance improvement is limited, and it has increasingly been unable to meet the requirements of device miniaturization and integration.

[0003] Similar to high-entropy alloys, high-entropy ferroelectrics are an important class of materials with excellent comprehensive energy storage performance, that is, ceramic solid solutions formed by five or more components. Due to their unique "high-entropy effect" and superior performance, they have become a hot spot in the field of dielectric capacitors in recent years. The high-entropy design concept can effectively achieve multi-faceted regulation including breakdown field strength, polarization efficiency, and polarization saturation behavior from multiple angles such as composition, microstructure, and local structure, showing excellent adjustability, diversity, and practicality.

[0004] The tungsten bronze structure is the second largest dielectric material after perovskite, and the composition general formula is (A1)2(A2)4C4(B1)2(B2)8O 30 , and due to its relatively high structural tolerance, more cations can be added, and by increasing the configurational entropy of the system (△S config ≥1.61R, R = 8.314 J / mol·K), a single-phase solid solution can be formed. At the same time, different metal cations selectively occupy 5 non-equivalent crystallographic interstitial positions of A1, A2, B1, B2, and C positions according to their radii and valences. Adjusting the filling of the crystallographic interstitial positions can induce flexible and variable structural and functional characteristics. The C position is generally empty. When the A1 and A2 positions are all filled, it is called a full-filled tungsten bronze structure, while when the A1 and A2 positions are partially filled and the C position is vacant, it is called a non-full-filled tungsten bronze structure, and its general formula is (A1,A2)B2O6. Therefore, based on the complex crystal structure of tungsten bronze and the flexibility of composition design, introducing the concept of high-entropy design into the tungsten bronze structure provides new ideas for the design and research and development of dielectric ceramic materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material, which has a relatively high energy storage density and energy storage efficiency.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material.

[0007] The technical solution adopted by the present invention is that the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material has a structural formula of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6, where M is Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 , Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 , Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 , Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 any one of; Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 , Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 , Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 , Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 The configurational entropy △S config of the B-site is 1.61R, 1.686R, 1.74R, and 1.74R respectively, where R is the ideal gas constant.

[0008] Another technical solution adopted by the present invention is a method for preparing the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material, specifically:

[0009] Step 1, according to (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5Weigh BaCO3, SrCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, ZrO2, TiO2, HfO2 and SnO2 with a purity of over 99.95% respectively according to the stoichiometric ratio of O6, mix them thoroughly by ball milling, and dry to obtain a raw material mixture;

[0010] Step 2: Pre-calcine the raw material mixture to obtain a pre-calcined powder;

[0011] Step 3: Granulate the pre-calcined powder under the action of a binder, screen it, press it by cold isostatic pressing, remove the binder, and sinter it to obtain a non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material.

[0012] The features of the present invention also lie in that,

[0013] In step 1, the ball milling medium is anhydrous ethanol, the ball milling speed is 400 revolutions per minute; the ball milling time is 16 - 24 hours, the drying temperature is 80 - 100 °C, and the drying time is 12 - 24 hours.

[0014] In step 2, the pre-calcination temperature is 1000 - 1200 °C, the pre-calcination time is 2 - 6 hours, and the heating rate during pre-calcination is not higher than 5 °C per minute.

[0015] In step 3, the sintering temperature is 1300 - 1340 °C, and the sintering time is 2 - 6 hours.

[0016] The beneficial effect of the present invention is that: by introducing different ions at the B-site into (Sr 0.5 Ba 0.47 Gd 0.02 )Nb2O6, the obtained high-entropy non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material has a stable single-phase structure. The complex arrangement of B-site atoms generates strong compositional fluctuations and chemical disorder, significantly enhancing the relaxation characteristics of the material system, enabling the strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material not to be broken down under the action of an external electric field of 550 kV / cm, not only obtaining a high energy storage density, but also significantly improving its energy storage efficiency, meeting the actual requirements of advanced pulsed power capacitors. Description of the Drawings

[0017] Figure 1 is the X-ray diffraction pattern of the B-site high-configurational entropy non-full-filled strontium barium niobate-based ferroelectric energy storage ceramic material in Example 1;

[0018] Figure 2a is the cross-sectional micrograph of the B-site high-configurational entropy non-full-filled strontium barium niobate-based ferroelectric energy storage ceramic material in Example 2;

[0019] Figure 2b is the cross-sectional micrograph of the B-site high-configurational entropy non-full-filled strontium barium niobate-based ferroelectric energy storage ceramic material in Example 3;

[0020] Figure 2c It is the microscopic morphology diagram of the B-site high configurational entropy non-perovskite strontium barium niobate-based ferroelectric energy storage ceramic material of Example 2;

[0021] Figure 2d It is the microscopic morphology diagram of the B-site high configurational entropy non-perovskite strontium barium niobate-based ferroelectric energy storage ceramic material of Example 3;

[0022] Figure 3 It is the ferroelectric hysteresis loop diagram of the B-site high configurational entropy non-perovskite strontium barium niobate-based ferroelectric energy storage ceramic material of Example 2. Detailed implementation manners

[0023] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The non-perovskite strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material of the present invention has a structural formula of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6, where M is Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 any one of them; by simultaneously introducing multiple ions with different valence states and radii at the B-site of non-perovskite (Sr 0.5 Ba 0.47 Gd 0.02 )Nb2O6, strong compositional fluctuations and chemical disorder are generated, the relaxation characteristics are enhanced, and the energy storage performance of the material system is improved.

[0025] According to the formula where R is the ideal gas constant, x i is the molar concentration of each component at the same position, and N is the number of components, it is calculated that in the (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6 ceramic, M corresponds to Ta 1 / 3Sb 1 / 3Hf 1 / 3 、Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 、Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 、Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 The configurational entropies of

[0026] The preparation method of the non-full-filled barium strontium niobate-based high-entropy ferroelectric energy storage ceramic material of the present invention is specifically as follows:

[0027] Step 1, Weigh BaCO3, SrCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, ZrO2, TiO2, HfO2 and SnO2 with a purity of more than 99.95% respectively according to the stoichiometric ratio of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6, mix and ball-mill them fully for 16 - 24 hours, and dry them for 12 - 24 hours under the condition of 80 - 100 °C to obtain a raw material mixture;

[0028] The ball-milling medium is anhydrous ethanol, and the rotation speed is 400 revolutions per minute;

[0029] Step 2, Pre-sinter the raw material mixture at 1000 - 1200 °C for 2 - 6 hours to obtain a pre-sintered powder;

[0030] Preferably, pre-sinter the raw material mixture at 1100 °C for 2 hours; the pre-sintering heating rate is not higher than 5 °C / min;

[0031] Step 3, Granulate the pre-sintered powder under the action of a binder, sieve it, press it into tablets under cold isostatic pressure of 200 MPa for 1 min, then raise the temperature to 600 °C at a rate of 1 °C / min to remove the binder, and sinter it at 1300 - 1340 °C for 2 - 6 hours to obtain a B-site high-configurational-entropy non-full-filled barium strontium niobate-based high-entropy ferroelectric energy storage ceramic material;

[0032] The binder is an aqueous solution of polyvinyl alcohol with a mass fraction of 5wt%; when sieving, the mesh number of the sieve is 60 meshes;

[0033] Preferably, sinter it at 1330 °C for 2 hours.

[0034] In the present invention, by introducing ions with various valence states and radii simultaneously at the B-site of non-filled (Sr 0.5 Ba 0.47 Gd 0.02 )Nb2O6, the abnormal growth of non-equiaxed grains of tungsten bronze structure ceramics is inhibited, a dense ferroelectric energy storage material is formed, and the energy dissipation under an electric field is reduced. In addition, the ceramic composition does not involve elements such as Bi, Na, and K that are prone to volatilization during high-temperature sintering, which is conducive to the integration of devices, has simple operation, low requirements for equipment, manpower, and site, and the high performance of this B-site high configurational entropy non-filled strontium barium niobate-based ferroelectric energy storage ceramic material can realize the miniaturization of pulsed power devices.

[0035] Example 1

[0036] Step 1, Weigh SrCO3, BaCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, and HfO2 powders with a purity of more than 99.95% respectively according to the stoichiometric ratio of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 ) 0.5 O6, and weigh accurately to 0.001 g. Mix the weighed raw material powders and put them into a ball mill. Use zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium, ball mill at 40 revolutions per minute for 16 hours, place them in a drying oven and dry at 80 °C for 15 hours, and grind with a mortar for 30 minutes to obtain a raw material mixture;

[0037] Step 2, Place the raw material mixture in an alumina crucible and put it in a resistance furnace. Under an air atmosphere, heat it at a heating rate of 3 °C per minute to 1100 °C, pre-sinter for 4 hours, cool naturally to room temperature, grind with a mortar for 10 minutes, and pass through a 120-mesh sieve to obtain a pre-sintered powder;

[0038] Step 3, Add an aqueous solution of polyvinyl alcohol with a mass fraction of 5% (the mass of the aqueous solution of polyvinyl alcohol is 50% of the mass of the pre-sintered powder) to the pre-sintered powder, granulate, pass through a 60-mesh sieve to make spherical powder particles, put the spherical powder particles into a stainless steel mold with a diameter of 15 mm, and use cold isostatic pressing to press them into a cylindrical blank with a thickness of 1.5 mm under a pressure of 200 MPa. Place the cylindrical blank on a zirconia flat plate, place the zirconia flat plate in an alumina sealed crucible, first heat it at a heating rate of 1 °C per minute to 600 °C, keep it warm for 2 hours to remove the binder, cool to room temperature, then heat it at a heating rate of 5 °C per minute to 1000 °C, and then heat it at a heating rate of 3 °C per minute to 1330 °C, sinter for 2 hours, and cool naturally to room temperature with the furnace to obtain (Sr0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 ) 0.5 O6 tungsten bronze structure ferroelectric ceramic materials.

[0039] Example 2

[0040] In step 1 of this example, according to the stoichiometry of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 ) 0.5 O6, the batching calculation is carried out. The raw materials used are SrCO3, BaCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, TiO2 and ZrO2 powders with a purity of more than 99.95%. The other steps are the same as those in Example 1, and (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 ) 0.5 O6 tungsten bronze structure ferroelectric energy storage ceramic materials.

[0041] Example 3

[0042] In step 1 of this example, according to the stoichiometry of (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 ) 0.5 O6, SrCO3, BaCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, TiO2, HfO2 and ZrO2 powders with a purity of more than 99.95% are weighed respectively. The other steps are the same as those in Example 1, and (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.2 Sb 0.2 Ti 0.2 Zr0.2 Hf 0.2 ) 0.5 O6 tungsten bronze structure ferroelectric energy storage ceramic material.

[0043] Example 4

[0044] In step 1 of this example, according to (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 ) 0.5 O6 stoichiometry, SrCO3, BaCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, TiO2, SnO2 and ZrO2 powders with a purity of more than 99.95% were weighed respectively. Other steps were the same as in Example 1, and (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 (Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 ) 0.5 O6 tungsten bronze structure ferroelectric energy storage ceramic material.

[0045] The ceramic materials prepared in the above Examples 1-4 were respectively tested by XRD using a D / max-2200X diffractometer (produced by Rigaku Corporation, Japan), and their ferroelectric properties were tested using a ferroelectric workstation and a connected temperature control device (THMS600), and their energy storage characteristics and temperature stability were evaluated. From Figure 1 It can be seen that the obtained ceramic of Example 1 has no impurity phase, is consistent with the standard PDF#73-0487, and belongs to the tetragonal tungsten bronze structure. From Figures 2a - 2d It can be seen that the cross-sections of the ceramics obtained in Examples 2 and 3 are dense, the surface is equiaxed grains, and no abnormally large rod-shaped grains appear.

[0046] The surfaces of the ceramic materials prepared in Examples 1-4 were polished to a thickness of 0.1 mm with 320-mesh, 800-mesh, and 1500-mesh sandpapers in sequence, and then a layer of platinum electrode was sprayed on the upper and lower surfaces of the ceramics using a small magnetron sputtering instrument. The single-pole hysteresis loop of Example 2 was obtained using a P-PMF ferroelectric workstation of Radiant Technologies, and the results are shown in Figure 3 . From Figure 3 it can be known that the ceramic obtained has a slender hysteresis loop, a breakdown field strength of 625 kV / cm, and a maximum polarization intensity of 34.41 μC / cm2 , the energy storage density is 7.78 J / cm 3 , and the energy storage efficiency is 93.5%.

[0047] In summary, the preparation process of the embodiment of the present invention is simple. By simultaneously introducing ions with different valence states and radii at the B-site of non-full-type (Sr 0.5 Ba 0.47 Gd 0.02 )Nb2O6, strong compositional fluctuations and chemical disorder are generated, inducing distortion of the polarization unit BO6 octahedron, disordered ion distribution, and the formation of local electric fields and elastic fields, which are easy to break the long-range distribution of ferroelectric domains, form nano-polarization micro-domains, significantly improve the breakdown strength of the material, that is, achieve high energy storage density and energy storage efficiency, and have the potential to meet the actual needs of advanced pulsed power capacitors.

Claims

1. A non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material, characterized in that, Its structural formula is (Sr 0.5 Ba 0.47 Gd 0.02 )Nb 1.5 M 0.5 O6, where M is Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 , Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 , Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 , Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 any one of them.

2. The non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material according to claim 1, wherein The Ta 1 / 3 Sb 1 / 3 Hf 1 / 3 , Ta 0.25 Sb 0.25 Ti 0.25 Zr 0.25 , Ta 0.2 Sb 0.2 Ti 0.2 Zr 0.2 Hf 0.2 , Ta 0.2 Sb 0.2 Sn 0.2 Zr 0.2 Hf 0.2 B-site configurational entropy △S config are 1.61R, 1.686R, 1.74R, and 1.74R respectively, where R is the ideal gas constant.

3. The preparation method of the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material according to claim 1, characterized in that Specifically: Step 1, according to (Sr 0.5 Ba 0.47 G 0.02 )Nb 1.5 M 0.5 BaCO3, SrCO3, Gd2O3, Nb2O5, Ta2O5, Sb2O5, ZrO2, TiO2, HfO2 and SnO2 with a purity of more than 99.95% are weighed respectively, fully mixed and ball-milled, and dried to obtain a raw material mixture; Step 2: Pre-sinter the raw material mixture to obtain a pre-sintered powder; Step 3: Granulate the pre-sintered powder under the action of a binder, sieve it, press it under cold isostatic pressure, remove the binder, and sinter it to obtain a non-full-type strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material.

4. The preparation method of the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material according to claim 3, characterized in that, In the said Step 1, the ball-milling medium is anhydrous ethanol, the ball-milling speed is 400 revolutions per minute; the ball-milling time is 16 to 24 hours, the drying temperature is 80 to 100 °C, and the drying time is 12 to 24 hours.

5. The preparation method of the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material according to claim 3, wherein In the said Step 2, the pre-sintering temperature is 1000 to 1200 °C, the pre-sintering time is 2 to 6 hours, and the heating rate during pre-sintering is not higher than 5 °C per minute.

6. The preparation method of the non-full-filled strontium barium niobate-based high-entropy ferroelectric energy storage ceramic material according to claim 3, characterized in that, In the said Step 3, the sintering temperature is 1300 to 1340 °C, and the sintering time is 2 to 6 hours.

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