Bismuth ferrite-based ceramic material with low energy consumption and high energy storage and low-temperature rapid sintering preparation method thereof

Abstract

The invention discloses a bismuth ferrite-based ceramic material with low energy consumption and high energy storage and a low-temperature rapid sintering preparation method of the bismuth ferrite-based ceramic material, a flash sintering technology is applied to 0.55 BiFeO3-0. 4SrTiO3-0.05 NaNbO3 (BFST-0. 05NN) ceramic, on one hand, the component of 0.6 BiFeO3-0. 4SrTiO3 is close to a morphotropic phase boundary (MPB) to provide high polarization, and the introduction of NaNbO3 improves the structure disorder and promotes the relaxation behavior, so that the energy storage efficiency is improved; on the other hand, by optimizing the electric field (100-250 V / cm) and the flash sintering time under the fixed current density (40 mA / mm < 2 >), reactive densification can be achieved at the very low temperature and within the ultra-short time, and compared with traditional solid sintering, the furnace temperature is reduced by nearly 500 DEG C; flash sintering can realize densification of the ceramic, inhibit grain growth of the ceramic, refine a grain structure, inhibit volatilization of volatile elements and inhibit leakage conductance current at the same time, the lead-free bismuth ferrite-based ceramic with high breakdown and high energy storage and excellent ferroelectric, piezoelectric and energy storage performance is obtained, and green development and high energy storage are realized at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials and relates to high-energy storage ceramic materials, and specifically relates to a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage and a low-temperature rapid sintering preparation method thereof. Background Art

[0002] As a common energy storage component in pulse power systems, ceramic dielectric capacitors have been widely used in military weapons, aerospace, electric vehicles, and medical equipment due to their advantages of high power density, fast charge and discharge speed, and long cycle life. As electronic devices gradually enter the era of miniaturization and micro-miniaturization, there is an urgent need to improve the energy storage density of dielectric materials. Lead-free bismuth ferrite (BiFeO3, BFO)-based ceramics combine strong ferroelectric polarization (Ps ~ 100μC / cm 2 ) and environmentally friendly properties, providing a compelling solution for the high energy storage needs of dielectric capacitors. However, the traditional sintering method requires long-term high-temperature treatment (>1000℃, 2-10h), and the instability of BiFeO3 will lead to the generation of a large number of impurity phases (Bi2Fe4O9; Bi 25 FeO 40 In addition, traditional sintering technology will also induce irreversible bismuth volatilization, resulting in excessive leakage current and premature dielectric breakdown. Therefore, new sintering strategies are urgently needed to address the limitations of the volatile matrix. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a bismuth ferrite-based ceramic material with low energy consumption and high energy storage and a low-temperature rapid sintering preparation method thereof, and to prepare a bismuth ferrite-based ceramic material with excellent ferroelectric, piezoelectric and energy storage properties through a simple, high-efficiency, low-energy consumption and environmentally friendly preparation method.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage comprises the following steps:

[0006] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials are weighed, and after ball milling, drying and sieving, a mixed powder of uniform size is obtained;

[0007] Step 2: Press the mixed powder into a shape, demould the formed green body to obtain a green body with a perfect shape, drill holes at both ends of the green body, hang the green body on parallel platinum wires through the two holes, connect one end to a power supply, and place the green body and the platinum wire as a whole in a tube furnace;

[0008] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 300-400°C, the current is set at 40mA / mm 2 An electric field of 100 to 250 V / cm is applied at a constant current density of 100 to 250 V / cm. The tube furnace continues to heat up, and then flash burning occurs. The flash burning state is maintained for 90 to 360 seconds, and then the power is cut off. The flash burning ends, and a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage is obtained.

[0009] The present invention also has the following technical features:

[0010] Preferably, the ball milling in step 1 is performed by mixing the raw materials, zirconia balls and deionized water in a mass ratio of 1:5:1 and milling for 8 to 12 hours.

[0011] Preferably, the screening in step 1 is through a 120-200 mesh sieve.

[0012] Preferably, the compression molding in step 2 includes the following steps:

[0013] First, the mixed powder was added into a dog-bone mold to press out a dog-bone sample blank, and finally cold isostatic pressing was performed at a pressure of 200 MPa for 3 minutes.

[0014] The present invention also protects a bismuth ferrite-based ceramic material with low energy consumption and high energy storage, which is prepared by the low-temperature rapid sintering preparation method as described above.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] The present invention applies flash firing technology to 0.55BiFeO3-0.4SrTiO3-0.05NaNbO3 (BFST-0.05NN) ceramics. On the one hand, the 0.6BiFeO3-0.4SrTiO3 composition close to the morphotropic phase boundary (MPB) provides high polarization, while the introduction of NaNbO3 improves structural disorder and promotes relaxation behavior, thereby improving energy storage efficiency; on the other hand, by optimizing the electric field (100-250V / cm) and the current density (40mA / mm 2) under flash sintering time (t), reactive densification can be achieved at a very low temperature (572 ° C) and an ultra-short time (300s). Compared with traditional solid-state sintering, the furnace temperature is reduced by nearly 500 ° C; flash sintering can achieve densification of ceramics while inhibiting their grain growth, refining the grain structure, inhibiting the volatilization of volatile elements and suppressing leakage current, and obtaining high-breakdown and high-energy storage lead-free bismuth ferrite-based ceramics with excellent ferroelectric, piezoelectric and energy storage properties, so that green development and high energy storage can be achieved simultaneously; this method can obtain 4.98 J / cm 3 high energy storage density while suppressing Bi 3+ The volatilization of NH4CO3 establishes a new path for low-energy, high-performance dielectric materials and is an effective means of green industry transformation consistent with global goals.

[0017] The present invention directly dries and sieves Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials without calcination, thereby reducing the heat energy loss required in the process, and has a simple preparation process, high production efficiency, low energy consumption and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Graph showing the relationship between electric field intensity and furnace temperature during the flash firing process of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0019] Figure 2 Graph showing the relationship between current density and furnace temperature during the flash firing process of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0020] Figure 3 XRD patterns of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0021] Figure 4 The dielectric temperature spectrum of the BFST-0.05NN ceramic material prepared in Example 3 and Examples 5-8;

[0022] Figure 5 This is a graph showing the relationship between the electric field strength of the BFST-0.05NN ceramic material prepared in Examples 1-4 and the furnace temperature;

[0023] Figure 6 The relationship between the flash temperature and electric field of the BFST-0.05NN ceramic material prepared in Examples 1-4;

[0024] Figure 7 XRD patterns of the BFST-0.05NN ceramic materials prepared in Examples 1-4;

[0025] Figure 8The complex impedance spectrum of the BFST-0.05NN ceramic material prepared in Examples 1-4;

[0026] Figure 9 (a) and (b) are the SEM images and element distribution diagrams of the BFST-0.05NN ceramic material prepared in Example 3; Figure 9 (c) and (d) are the SEM images and element distribution diagrams of the BFST-0.05NN ceramic material prepared in Comparative Example 1;

[0027] Figure 10 2. Leakage current curves of the BFST-0.05NN ceramic materials prepared in Comparative Example 1 and Example 3;

[0028] Figure 11 is the complex impedance spectrum of the BFST-0.05NN ceramic material prepared in Comparative Example 1 and Example 3;

[0029] Figure 12 PE loops of the BFST-0.05NN ceramic materials prepared in Comparative Example 1 and Example 3 under different electric fields;

[0030] Figure 13 The Wrec, Wtal and η of the BFST-0.05NN ceramic materials prepared in Comparative Example 1 and Example 3 vary with the electric field. DETAILED DESCRIPTION

[0031] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0032] Example 1

[0033] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0034] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 8 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 120-mesh sieve to obtain a mixed powder of uniform size;

[0035] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0036] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 300°C, the flow rate is 40mA / mm 2 An electric field of 100 V / cm was applied at a constant current density of 100 V / cm, the tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 300 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0037] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0038] Example 2

[0039] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0040] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 200-mesh sieve to obtain a mixed powder of uniform size;

[0041] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0042] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2 An electric field of 150 V / cm was applied at a constant current density, the tubular furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 300 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0043] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0044] Example 3

[0045] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0046] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 10 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 150-mesh sieve to obtain a mixed powder of uniform size;

[0047] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0048] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 350°C, the flow rate is 40mA / mm 2 An electric field of 200 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 300 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0049] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0050] Example 4

[0051] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0052] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 160-mesh sieve to obtain a mixed powder of uniform size;

[0053] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0054] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2 An electric field of 250 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 300 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0055] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0056] Example 5

[0057] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0058] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 10 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 120-mesh sieve to obtain a mixed powder of uniform size;

[0059] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0060] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2 An electric field of 200 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 90 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0061] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0062] Example 6

[0063] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0064] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 200-mesh sieve to obtain a mixed powder of uniform size;

[0065] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0066] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2An electric field of 200 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 180 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0067] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0068] Example 7

[0069] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0070] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 120-mesh sieve to obtain a mixed powder of uniform size;

[0071] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0072] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2 An electric field of 200 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 240 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0073] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0074] Example 8

[0075] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0076] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 120-mesh sieve to obtain a mixed powder of uniform size;

[0077] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone-shaped sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes. Demold the formed blank to obtain a well-shaped blank. Drill holes at both ends of the blank, hang the blank on parallel platinum wires through the two holes, connect one end to a power supply, and place the blank and the platinum wire as a whole in a tube furnace;

[0078] Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 400°C, the current is set at 40mA / mm 2 An electric field of 200 V / cm was applied at a constant current density of 100 V / cm. The tube furnace continued to heat up, and then flash burning occurred. After the flash burning state was maintained for 360 seconds, the power was cut off and the flash burning ended, obtaining a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage.

[0079] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished to a thickness of 0.1 to 0.15 mm on both sides with 2000-grit sandpaper. They were ultrasonically cleaned in distilled water for 15 min, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and heated at 580 °C in an air atmosphere. ℃ The dielectric energy storage performance was tested by sintering at a temperature of 20 min.

[0080] Comparative Example 1

[0081] This embodiment provides a low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage, comprising the following steps:

[0082] Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials were weighed, and the raw materials, zirconia balls and deionized water were mixed in a mass ratio of 1:5:1 and ball-milled for 12 hours. The mixture was placed in an oven and dried at 80°C for 10 hours, and passed through a 120-mesh sieve to obtain a mixed powder of uniform size;

[0083] Step 2: First, add the mixed powder into a dog-bone mold to press out a dog-bone sample blank, and finally perform cold isostatic pressing at a pressure of 200 MPa for 3 minutes to obtain a compact blank;

[0084] Step 3: Place the green body in a muffle furnace, heat it to 1100°C at a rate of 5°C / min in an air atmosphere, keep it for 2 hours, then reduce it to 500°C at a rate of 5°C / min, and then cool it to room temperature and sinter it into porcelain to obtain dielectric ceramics;

[0085] The prepared sintered ceramics were first polished to a thickness of 0.3 mm with 240-grit sandpaper, and then polished on both sides with 2000-grit sandpaper to a thickness of 0.1-0.15 mm. They were ultrasonically cleaned in distilled water for 15 minutes, and silver electrode slurry was coated on their surfaces. They were then placed in a muffle furnace and sintered at 580°C for 20 minutes in an air atmosphere to test the dielectric energy storage performance.

[0086] Figure 1 Graph showing the relationship between electric field intensity and furnace temperature during the flash firing process of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0087] Figure 2 Graph showing the relationship between current density and furnace temperature during the flash firing process of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0088] Depend on Figure 1 and Figure 2 It can be seen that with the increase of furnace temperature, the change curves of electric field intensity and current density show typical flash characteristics, indicating that flash occurs at all durations. Under the same conditions, the flash start temperature of samples with different processing times is limited to a narrow ultra-low temperature range (559-573℃), indicating that the sintering start temperature is insensitive to changes in duration. After flash, the resistance of the BFST-0.05NN sample continues to decrease, resulting in a rapid decrease in its power consumption until it reaches a quasi-steady state. The time required to enter this stable state corresponds to the flash duration, confirming the successful preparation of the ceramic sample under the application conditions.

[0089] Figure 3XRD patterns of the BFST-0.05NN ceramic materials prepared in Example 3 and Examples 5-8;

[0090] Figure 4 The dielectric temperature spectrum of the BFST-0.05NN ceramic material prepared in Example 3 and Examples 5-8;

[0091] Depend on Figure 3 and Figure 4 It can be seen that with the increase of furnace temperature, the change curves of electric field intensity and current density show typical flash characteristics, indicating that flash occurs at all durations. Under the same conditions, the flash start temperature of samples with different processing times is limited to a narrow ultra-low temperature range (559-573℃), indicating that the sintering start temperature is insensitive to changes in duration. After flash, the resistance of the BFST-0.05NN sample continues to decrease, resulting in a rapid decrease in its power consumption until it reaches a quasi-steady state. The time required to enter this stable state corresponds to the flash duration, confirming the successful preparation of the ceramic sample under the application conditions.

[0092] Figure 5 Figure 3 is a graph showing the relationship between the electric field strength and furnace temperature of the BFST-0.05NN ceramic materials prepared in Examples 1-4. As the electric field increases from 100 V / cm to 250 V / cm, the flash sintering starting temperature decreases from 671°C to 540°C, indicating an inverse relationship between the two parameters.

[0093] Figure 6 The relationship between the flash sintering temperature and the electric field of the BFST-0.05NN ceramic materials prepared in Examples 1-4; the temperature is reduced (330-560°C lower than traditional sintering) and the processing time is greatly shortened (from 3 hours to 300 seconds), confirming the energy-saving characteristics of the flash sintering technology.

[0094] Figure 7 XRD patterns of the BFST-0.05NN ceramic materials prepared in Examples 1-4; all samples showed a single solid solution, confirming that NaNbO3 was completely dissolved in the 0.60BF-0.40ST matrix, with no structural inhomogeneity or warping, indicating little dependence on the electric field.

[0095] Figure 8 Complex impedance spectra of the BFST-0.05NN ceramic materials prepared in Examples 1-4; characterization shows that the dielectric and electrical properties of the samples sintered at 200 V / cm are enhanced, including lower dielectric loss, higher dielectric constant and higher resistivity, which all contribute to improved breakdown strength.

[0096] Figure 9(a) and (b) are the SEM images and element distribution diagrams of the BFST-0.05NN ceramic material prepared in Example 3; Figure 9 (c) and (d) are the SEM images and element distribution diagrams of the BFST-0.05NN ceramic material prepared in Comparative Example 1; Figure 9 (a) and (b) show that the ceramic sample prepared in Example 3 has a dense microstructure, no obvious pores, and an average grain size of 0.42 μm. Compared with the traditional sintering method ( Figure 9 (c)) Grain growth was suppressed and reduced by nearly two times. In addition, elemental analysis showed that ( Figure 9 (b, d)), the samples prepared by the flash sintering method inhibit the volatilization of Bi and Na elements, which is beneficial to reducing defects and optimizing electrical properties.

[0097] Figure 10 : The leakage current curves of the BFST-0.05NN ceramic materials prepared in Comparative Example 1 and Example 3; Figure 10 It can be clearly seen that the leakage current of the FS-BFST-0.05NN sample is significantly lower than that of the CS-BFST-0.05NN sample, from 3.72×10 -8 A / cm 2 Down to 9.25×10 -9 A / cm 2 .

[0098] Figure 11 This is the complex impedance spectrum of the BFST-0.05NN ceramic material prepared in Example 1 and Example 3; in addition, the resistivity of the FS-BFST-0.05NN sample is significantly higher than that of the CS-BFST-0.05NN ceramic, indicating that its electrical insulation performance is improved, which is beneficial to optimizing the energy storage performance.

[0099] Figure 12 PE loops of the BFST-0.05NN ceramic materials prepared in Comparative Example 1 and Example 3 under different electric fields;

[0100] Figure 13 The Wrec, Wtal, and η of the BFST-0.05NN ceramic materials prepared in Example 1 and Example 3 vary with electric field. Under an ultra-high electric field of 340 kV / cm, the energy storage density of the FS-BFST-0.05NN sample is as high as 4.98 J / cm 3 , showing excellent dielectric energy storage performance. FS-BFST-0.05NN achieves low-temperature ultrafast processing (572°C, 300s) while maintaining excellent energy storage performance, making it highly competitive.

Claims

1. A low-temperature rapid sintering method for preparing bismuth ferrite-based ceramic materials with both low energy consumption and high energy storage, characterized in that: The following steps are involved: Step 1: According to the stoichiometric ratio of 0.55BiFeO3-0.40SrTiO3-0.05NaNbO3, analytically pure Bi2O3, Fe2O3, SrTiO3 and NaNbO3 raw materials are weighed, and after ball milling, drying and sieving, a mixed powder of uniform size is obtained; Step 2: Press the mixed powder into a shape, demould the formed green body to obtain a green body with a perfect shape, drill holes at both ends of the green body, hang the green body on parallel platinum wires through the two holes, connect one end to a power supply, and place the green body and the platinum wire as a whole in a tube furnace; Step 3: Set the tube furnace to a heating rate of 10°C / min. When the tube furnace is heated from room temperature to 300-400°C, the current is set at 40mA / mm 2 An electric field of 100 to 250 V / cm is applied at a constant current density of 100 to 250 V / cm. The tube furnace continues to heat up, and then flash burning occurs. The flash burning state is maintained for 90 to 360 seconds, and then the power is cut off. The flash burning ends, and a bismuth ferrite-based ceramic material with both low energy consumption and high energy storage is obtained.

2. The low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with low energy consumption and high energy storage according to claim 1, characterized in that: The ball milling in step 1 is performed by mixing the raw materials, zirconia balls and deionized water in a mass ratio of 1:5:1 and milling for 8 to 12 hours.

3. The low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with low energy consumption and high energy storage according to claim 1, characterized in that: The screening in step 1 is performed through a 120-200 mesh sieve.

4. The low-temperature rapid sintering method for preparing a bismuth ferrite-based ceramic material with low energy consumption and high energy storage according to claim 1, characterized in that: The compression molding described in step 2 includes the following steps: First, the mixed powder was added into a dog-bone mold to press out a dog-bone sample blank, and finally cold isostatic pressing was performed at a pressure of 200 MPa for 3 minutes.

5. A bismuth ferrite-based ceramic material with low energy consumption and high energy storage prepared by the low-temperature rapid sintering preparation method according to any one of claims 1 to 4.

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