A plastic enhanced zirconium tin lead lanthanum titanate antiferroelectric ceramic and method of making same

Abstract

The application relates to a plasticity-enhanced lead lanthanum zirconate titanate stannate-based antiferroelectric ceramic and a preparation method thereof. The chemical formula of the lead lanthanum zirconate titanate stannate-based antiferroelectric ceramic is (Pb 0.975‑x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein 0 < x <= 0.10; the plasticity-enhanced lead lanthanum zirconate titanate stannate-based antiferroelectric ceramic is prepared by adopting a flash sintering technology; wherein, the initial electric field intensity is 100-300 V / cm, the heating rate of a flash sintering furnace body is 5-15 DEG C / min; when the current detection meter reading reaches the order of muA, the electric field intensity is increased to 200-500 V / cm; when the current density value reaches 10-30 mA / mm 2 After 90-200 s of stable current density, the heating rate of the flash sintering furnace body is preferably 8-12 DEG C / min.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional material research and technical development, and particularly relates to a plasticity-enhanced lead lanthanum zirconate titanate antiferroelectric ceramic material and a preparation method thereof. BACKGROUND

[0002] As an energy storage element of pulse power supply, the capacitor accounts for a large proportion in the whole energy storage device and is a very important key component. Improving the energy storage density of the capacitor plays an important role in increasing the power of the pulse power supply, reducing the weight and volume of the device, and meeting the development of miniaturization and high power. Therefore, developing high-performance pulse capacitors has become the research focus and urgent task in the current pulse power technology field.

[0003] Compared with linear medium materials and ferroelectric materials, the antiferroelectric material has the advantages of high energy storage density and fast charging and discharging, and has become a very important candidate material in the application of high-performance pulse capacitors and is favored. High-performance antiferroelectric multilayer capacitors are one of the key development directions of pulse power capacitors at home and abroad, and can meet the development requirements of miniaturization and high power of components, but there is a high technical barrier.

[0004] The antiferroelectric-ferroelectric phase transition of the antiferroelectric material brings high energy storage and also accompanies a large volume strain (about 0.5%), and when the large volume change occurs in nanoseconds, a large internal stress will be generated in the ceramic, which is easy to make cracks quickly generate and expand, so that the ceramic is broken down and fails, resulting in short charging and discharging life. At present, the charging and discharging life is prolonged by reducing the working electric field (about the turning electric field) and sacrificing part of the energy storage density, and the high energy storage density advantage is not fully played. SUMMARY

[0005] In view of the above problems, the present application aims to provide a plasticity-enhanced lead lanthanum zirconate titanate antiferroelectric ceramic and a preparation method thereof. The prepared lead lanthanum zirconate titanate ceramic material has a moderate Curie temperature, and the plasticity and dislocation density are improved, so that the charging and discharging life can be prolonged.

[0006] In one aspect, the present application provides a plasticity-enhanced lead lanthanum zirconate titanate antiferroelectric ceramic, the chemical formula of the lead lanthanum zirconate titanate antiferroelectric ceramic is (Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975O3, wherein 0 < x ≤ 0.10; the plastic enhanced zirconium tin titanate lanthanum lead-based antiferroelectric ceramic is prepared by sintering with flash burning technology; wherein the initial electric field intensity is set to 100-300 V / cm, the flash burning furnace body heating rate is 5-15 ℃ / min; when the current detection meter reading reaches the order of μA, the electric field intensity is increased to 200-500 V / cm; when the current density value reaches 10-30 mA / mm 2 After that, the stable current density is maintained for 90-200 s; preferably, the flash burning furnace body heating rate is 8-12 ℃ / min.

[0007] The application uses the flash burning technology to prepare the plastic enhanced zirconium tin titanate lanthanum lead-based antiferroelectric ceramic. The antiferroelectric material mainly uses the electric field induced antiferroelectric-ferroelectric phase transition to store energy, however, the phase transition not only produces high energy storage density, but also is accompanied by large volume strain (about 0.4%) caused by cell difference. When the ceramic has such a large volume change in nanosecond time, great local stress is generated, which seriously damages the internal structure of the ceramic, and the cracking failure phenomenon is easy to occur after multiple charge and discharge. Therefore, the short charge and discharge life is the main bottleneck that the antiferroelectric material cannot be widely applied. The previous research found that there are a large number of dislocations in the PbZrO3-based antiferroelectric ceramic, and the dislocation is closely related to the grain size. The flash burning of the application can obviously reduce the grain size and increase the number of dislocations. The stress field and internal electric field around the dislocation can affect the crack propagation mode, and can occur under the action of stress. Therefore, the local stress can be successfully relieved through dislocation slip or dislocation emission, the average hardness and modulus of the sample are reduced, the sample plasticity is improved, the crack initiation and propagation are inhibited, and the charge and discharge life is prolonged.

[0008] Preferably, 0.016 ≤ x ≤ 0.064.

[0009] Preferably, the average hardness of the zirconium tin titanate lanthanum lead-based antiferroelectric ceramic is 6-7 MPa; and the average modulus of the zirconium tin titanate lanthanum lead-based antiferroelectric ceramic is 160-175 MPa.

[0010] The application takes the zirconium tin titanate lanthanum lead ceramic as the matrix material, and through strontium element doping, the material is converted from the initial ferroelectric phase to the antiferroelectric phase, and with the increase of the strontium doping amount, the electric hysteresis of the antiferroelectric material is gradually reduced.

[0011] In another aspect, the application provides a preparation method of the plastic enhanced zirconium tin titanate lanthanum lead-based antiferroelectric ceramic, comprising:

[0012] (1) taking Pb3O4 powder, La2O3 powder, SrCO3 powder, ZrO2 powder, TiO2 powder and SnO2 powder as raw materials, and according to the chemical formula (Pb 0.975-x La 0.02 Sr x(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3weigh and mix, ball mill, dry, to get the first ceramic powder;

[0013] (2) the resulting ceramic powder is pressed into a block, and then calcined to obtain a ceramic block;

[0014] (3) the resulting ceramic block is ground and broken, and then subjected to secondary ball milling, drying, sieving, and then granulated by adding a binder, and then pressed into a ceramic green body; the resulting ceramic green body is aged, and then subjected to secondary grinding and breaking to obtain a second ceramic powder;

[0015] (4) an appropriate amount of the second ceramic powder is pressed into a first green body; the resulting first green body is plastic encapsulated, cold isostatic pressed, and then plastic is removed to obtain a second green body;

[0016] (5) the plastic reinforced lead lanthanum zirconate titanate antiferroelectric ceramic is prepared by flash sintering.

[0017] Preferably, in step (1), the ball milling is wet ball milling, zirconia balls are used as the ball milling medium, and deionized water / absolute ethanol is used as the ball milling agent; the ball milling is carried out at a ratio of 1:(3.5-5):(1.2-1.5) of the mixed powder:zirconia balls:water / absolute ethanol, the rotation speed is 120-180 r / min, and the ball milling time is 8-12 h.

[0018] Preferably, in step (2), the pressure for pressing into a block is 100-300 MPa, and the time is 5-30 s.

[0019] The calcination temperature is 800-900℃, the time is 2-4 h, and the environmental atmosphere is air.

[0020] Preferably, in step (3), the secondary ball milling is wet ball milling, zirconia balls are used as the ball milling medium, and deionized water / absolute ethanol is used as the ball milling agent; the ball milling is carried out at a ratio of 1:(3.5-5):(1.2-1.5) of the mixed powder:zirconia balls:water / absolute ethanol, the rotation speed is 120-180 r / min, and the ball milling time is 18-24 h.

[0021] Preferably, in step (3), the binder is at least one of PVA and PVB; the concentration of the binder is 5-10 wt%; and the amount of the binder added is 5-8 wt% of the mass of the sieved ceramic powder.

[0022] Preferably, in step (3), the aging temperature is room temperature, and the time is 18-24 h.

[0023] Preferably, in step (4), the second ceramic powder has a mass of 2.5-3.2 g.

[0024] Preferably, in step (4), the pressing pressure is 50-200 MPa and the pressing time is 3-10 s.

[0025] The cold isostatic pressing pressure is 200-300 MPa and the pressing time is 3-5 min.

[0026] The plastic removal temperature is 650-800℃ and the time is 2-3 h.

[0027] Preferably, the first green body is cylindrical, has a diameter of 6 mm, and a length of 1.6-2.4 cm.

[0028] Preferably, in step (5), the flash firing technique comprises:

[0029] The two end regions of the obtained second green body are uniformly coated with silver-palladium conductive paste, and after drying at 100-120℃, platinum wires are wound around the two end regions of the second green body coated with electrodes, and the second green body is placed in a flash firing furnace; preferably, the width of the silver-palladium conductive paste coated on the two end regions of the second green body is 3-5 mm.

[0030] The two ends of the platinum wires are connected to the positive and negative electrodes of a direct current power source outside the furnace body, and a current detector is connected in series in the circuit.

[0031] First, the direct current power source is in voltage control mode, and the initial electric field strength is set to 100-300 V / cm, and the furnace body heating rate is 5-15℃ / min; preferably, the initial electric field strength is 100-150 V / cm, and the furnace body heating rate is 8-12℃ / min.

[0032] When the current detector reading reaches the order of μA, the electric field strength is increased to 200-500 V / cm.

[0033] When the current density value reaches 10-30 mA / mm 2 Then, the direct current power source is switched to current control mode.

[0034] After maintaining a stable current density for 90-200 s in current control mode, the direct current power source switch is turned off, and the flash firing furnace is removed after cooling to room temperature, to obtain the plastic-reinforced zirconium-tin-titanium-lead lanthanum-based antiferroelectric ceramic.

[0035] Preferably, the preparation method further comprises cutting the obtained plastic-reinforced zirconium-tin-titanium-lead lanthanum-based antiferroelectric ceramic and sputtering silver and gold electrodes.

[0036] In the present application, the powder is granulated and isostatic pressed, etc., to ensure that the flash-burning green body has good density, and the current in the flash-burning process can pass through the sample as evenly as possible, thereby improving the sintering quality.

[0037] The present application adopts the flash-burning technology to prepare the plasticity-enhanced lead lanthanum zirconate titanate antiferroelectric ceramic material, realizes the plasticity enhancement of the antiferroelectric ceramic material, makes it bear greater volume stress, improves its charge and discharge life, thereby solving the working failure problem of the antiferroelectric ceramic under high electric field (>turning electric field), improving the energy storage density, and providing guidance for promoting the wide application of the antiferroelectric ceramic.

[0038] Beneficial effects:

[0039] (1) The present application obtains the antiferroelectric material with high phase transition electric field, low electric hysteresis and high energy storage efficiency by flexibly regulating the Sr ion doping amount in the ceramic base material; the antiferroelectric material has moderate dielectric constant, low dielectric loss and excellent energy storage performance;

[0040] (2) Compared with the prior art, the present application adopts the flash-burning technology to regulate the composition and structure gradient of the antiferroelectric ceramic, effectively reduces the sintering temperature, reduces the holding time, and the grain size also becomes small and uniform through SEM and grain size characterization, and the ceramic has high density;

[0041] (3) Compared with the prior art, the present application adopts the flash-burning technology, can obtain the dense ceramic with controllable composition and structure gradient, small and uniform grain size, and the dislocation density is improved, the domain size is reduced, the average hardness and modulus are reduced, and the plasticity is enhanced;

[0042] (4) The preparation method of the present application is simple and easy to operate, has low cost, low sintering temperature, saves energy, short preparation time, good repeatability, good practicability, and has very important application value for realizing the plasticity enhancement of the antiferroelectric ceramic. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is the size diagram of the sample obtained from the embodiment 1 of the present application and the schematic diagram of the conductive paste coating area;

[0044] Figure 2 It is the cross-sectional SEM diagram of the antiferroelectric ceramic sample prepared in the embodiment 1;

[0045] Figure 3 It is the cross-sectional SEM diagram of the antiferroelectric ceramic sample prepared in the comparative example 1;

[0046] Figure 4 It is the dislocation structure and domain schematic diagram of the antiferroelectric ceramic sample prepared in the embodiment 1;

[0047] Figure 5Domain schematic diagram of the antiferroelectric ceramic sample prepared for Comparative Example 1;

[0048] Figure 6 Charge-discharge curves of the antiferroelectric ceramic sample prepared for Example 1 at different test times;

[0049] Figure 7 Charge-discharge curves of the antiferroelectric ceramic sample prepared for Comparative Example 1 at different test times;

[0050] Figure 8 Dielectric temperature spectrum of the antiferroelectric ceramic sample prepared for Example 1;

[0051] Figure 9 Dielectric temperature spectrum of the antiferroelectric ceramic sample prepared for Comparative Example 1;

[0052] Figure 10 Electric hysteresis loop of the antiferroelectric ceramic sample prepared for Example 1;

[0053] Figure 11 Electric hysteresis loop of the antiferroelectric ceramic sample prepared for Comparative Example 1;

[0054] Figure 12 Electric hysteresis loop of the antiferroelectric ceramic sample prepared for Comparative Example 3;

[0055] Figure 13 Electric hysteresis loop of the antiferroelectric ceramic sample prepared for Comparative Example 4. DETAILED DESCRIPTION

[0056] To further illustrate the gist, features and practical effects of the present application, the present application will be described in detail below with reference to the examples. It should be noted that the modification method of the present application is not limited to these specific embodiments. Equivalent substitutions and modifications made by those skilled in the art on the basis of the content of the present application without departing from the spirit and essence of the present application are also within the scope of the present application. Unless otherwise specified, each percentage content refers to mass percentage content.

[0057] Firstly, the present application provides a plasticity-enhanced zirconium-tin-titanate-lead-lanthanum-based antiferroelectric ceramic, which has a chemical formula of (Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein 0 < x ≤ 0.10. If x is too large, the antiferroelectricity of the material will be weakened and the polarization intensity will be reduced; if x is too small, the material matrix will exhibit ferroelectric phase, which does not meet the electrical performance characteristics of antiferroelectric materials.

[0058] The strontium ion has a smaller ion radius, and is equivalent substitution, avoids additional effects caused by uneven charge, and is beneficial to directly and effectively adjust the stability of the anti-ferroelectric phase. The doping of the strontium element can improve the stability of the anti-ferroelectric phase, improve the transition electric field from the anti-ferroelectric phase to the ferroelectric phase, and thus improve the energy storage density. In addition, the doping of the strontium ion can reduce the electric hysteresis, so that the energy storage efficiency is improved.

[0059] In the present application, the flash firing technology can significantly reduce the grain size and increase the number of dislocations. The stress field and internal electric field around the dislocation can affect the crack propagation mode and can climb and decompose under stress. Therefore, local stress can be successfully relieved by dislocation slip or dislocation emission, reducing the average hardness and modulus of the sample and improving the plasticity of the sample, thereby inhibiting crack initiation and propagation and prolonging the charge and discharge life.

[0060] The inventors found that there are dislocations in the lead-based anti-ferroelectric ceramic through theoretical research and multiple tests, and thus hope to take advantage of the large number of dislocations in the lead-based anti-ferroelectric ceramic to relieve the stress concentration caused by the anti-ferroelectric to ferroelectric phase transition through dislocation slip or dislocation emission, thereby improving the plasticity, inhibiting crack initiation and propagation. Based on this, the flash firing technology is creatively applied to the zirconium tin titanate lead lanthanum-based anti-ferroelectric ceramic material.

[0061] In the present application, the plasticity-enhanced zirconium tin titanate lead lanthanum-based anti-ferroelectric ceramic is prepared by combining solid-phase synthesis and flash firing technology. The following exemplary preparation method of the plasticity-enhanced zirconium tin titanate lead lanthanum-based anti-ferroelectric ceramic provided by the present application is described.

[0062] Pb3O4 powder, La2O3 powder, SrCO3 powder, ZrO2 powder, TiO2 powder, and SnO2 powder are selected as raw materials, and are weighed and mixed according to the chemical formula (Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, ball-milled and dried to obtain a first ceramic powder.

[0063] In an optional embodiment, the ball-milling is wet ball-milling, zirconium oxide balls are used as the ball-milling medium, deionized water / absolute ethanol is used as the ball-milling agent, the ball-milling is performed at a ratio of 1:(3.5-5):(1.2-1.5) of the mixed powder:zirconium oxide balls:water / absolute ethanol, the rotation speed of the ball-milling is 120-180 r / min, and the ball-milling time is 8-12 h.

[0064] After the obtained ceramic powder is pressed into a block, the block is calcined to obtain a ceramic block.

[0065] In an alternative embodiment, the pressure for the pressing into blocks is 100-300 MPa, and the time is 5-30 s.

[0066] In an alternative embodiment, the parameters for the calcination include: a temperature of 800-900 ℃, and a time of 2-4 h; and the calcination atmosphere is air.

[0067] The obtained ceramic block is ground and crushed, and then is subjected to secondary ball milling, drying, and sieving, and then is granulated by adding a binder, and is subjected to pressing to obtain a ceramic green body; the obtained ceramic green body is aged, and then is ground and crushed to obtain a second ceramic powder.

[0068] In an alternative embodiment, the secondary ball milling is wet ball milling, and zirconium oxide balls are used as the ball milling medium, and deionized water / anhydrous ethanol is used as the ball milling agent, and the ball milling is performed at a ratio of 1:(3.5-5):(1.2-1.5) of the mixed powder:zirconium oxide balls:water / anhydrous ethanol, and the rotation speed is 120-180 r / min, and the ball milling time is 18-24 h.

[0069] In an alternative embodiment, the binder is at least one of PVA and PVB; the concentration of the binder is 5-10 wt% (for example, 7 wt%); the amount of the binder added is 5-8 wt% of the mass of the ceramic powder after sieving; and preferably, the amount of the binder added is 5-6 wt% of the mass of the ceramic powder after sieving.

[0070] In an alternative embodiment, the diameter of the ceramic green body is 8-12 cm; for example, 10 cm.

[0071] In an alternative embodiment, the temperature for the aging is room temperature, and the time is 18-24 h.

[0072] An appropriate amount of the second ceramic powder is subjected to pressing to obtain a first green body; the obtained first green body is plastic encapsulated, and then is subjected to cold isostatic pressing and plastic removal to obtain a second green body.

[0073] In an alternative embodiment, the mass of the second ceramic powder is 2.5-3.2 g.

[0074] In an alternative embodiment, the first green body is cylindrical, and the diameter is 6 mm, and the length is 1.6-2.4 cm.

[0075] In an alternative embodiment, the pressure for the pressing is 50-200 MPa, and the time is 3-10 s; the pressure for the cold isostatic pressing is 200-300 MPa (for example, 200 MPa), and the time is 3-5 min; and the temperature for the plastic removal is 650-800 ℃, and the time is 2-3 h.

[0076] The plasticity enhanced zirconium tin titanate lead lanthanum based antiferroelectric ceramic is prepared by sintering with flash burning technology. Specifically, the silver palladium conductive paste is uniformly coated on the two end regions of the obtained second green compact, and after drying at 100-120 DEG C, the platinum wire is wound on the two end regions of the second green compact coated with electrodes, and placed in a flash burning furnace. The two ends of the platinum wire are connected to the positive and negative poles of a direct current power supply outside the furnace body, and a current detection meter is connected in series in the circuit. First, the direct current power supply adopts voltage control mode, and the initial electric field strength is set to 100-300 V / cm, and the furnace body heating rate is 5-15 DEG C / min. When the current detection meter reading reaches the order of mu A, the electric field strength is increased to 200-500 V / cm. When the current density value reaches 10-30 mA / mm 2 Then, the direct current power supply is switched to current control mode. After maintaining stable current density for 90-200 s in the current control mode, the direct current power supply switch is turned off, and the flash burning furnace is cooled to room temperature to obtain the plasticity enhanced zirconium tin titanate lead lanthanum based antiferroelectric ceramic.

[0077] The obtained plasticity enhanced zirconium tin titanate lead lanthanum based antiferroelectric ceramic is cut, processed, sputtered with silver and gold electrodes for performance testing.

[0078] In an optional embodiment, the silver includes printed electrodes and fired electrodes; the temperature of the fired electrodes is 700-800 DEG C, and the time is 10-30 min.

[0079] In an optional embodiment, the obtained plasticity enhanced zirconium tin titanate lead lanthanum based antiferroelectric ceramic is cut and processed into a sheet with a thickness of 0.1-1 mm.

[0080] The present application can obtain a dense ceramic with small and uniform grain size and plasticity enhancement at a lower temperature by using flash burning technology, and has low dielectric loss and high breakdown field strength. In addition, the plasticity of the antiferroelectric ceramic is significantly enhanced, and the enhancement amplitude can reach up to about 15%, which is due to the changes in grain size reduction, dislocation density increase and domain shape reduction caused by flash burning technology.

[0081] The obtained zirconium tin titanate lead lanthanum based antiferroelectric ceramic is tested for mechanical properties by nanoindentation method. The average hardness of the zirconium tin titanate lead lanthanum based antiferroelectric ceramic is 6-7 MPa; and the average modulus of the zirconium tin titanate lead lanthanum based antiferroelectric ceramic is 160-170 MPa.

[0082] The following further illustrates the embodiments in detail. It should also be understood that the following embodiments are only used to further illustrate the present application and cannot be understood as limiting the scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application are within the scope of the present application. The specific process parameters and the like described below are only one example in the appropriate range, i.e. those skilled in the art can make appropriate selection within the range according to the description herein, and are not limited to the specific values of the following examples.

[0083] Example 1

[0084] The preparation method of the zirconium tin lead lanthanum titanate-based antiferroelectric ceramic ((Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x = 0.016) in this embodiment 1 includes:

[0085] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition and is prepared according to the composition ratio. Pb3O4 (111.7718 g), La2O3 (1.6468 g), SrCO3 (1.1992 g), ZrO2 (31.1226 g), TiO2 (5.2647 g), and SnO2 (28.2956 g) are taken. The wet ball milling method is used at a rotation speed of 120 r / min for 12 h to mix the components uniformly. After drying, the first ceramic powder is obtained;

[0086] (2) The obtained first ceramic powder is pressed into a block under a pressure of 150 MPa, and then calcined in an air atmosphere at a temperature of 900°C for 2h to obtain a ceramic block;

[0087] (3) The obtained ceramic block is ground and crushed, and then ball milled for 24 h. After the powder is dried and sieved, 6wt% of PVA (concentration of 7wt%) is added, and the powder is mixed uniformly and then pressed into a ceramic green body with a diameter of about 10 cm;

[0088] (4) The obtained ceramic green body is aged for 24 h, then ground and crushed to obtain a second ceramic powder;

[0089] (5) Weigh 3g of the second ceramic powder, and press form under a pressure of 80 MPa, with a pressure maintaining time of 5s, to obtain an elongated cylindrical first green body; the obtained first green body is plastic sealed, and then cold isostatic pressed under a pressure of 200 MPa, with a pressure maintaining time of 5min; then heated to 700℃ at a heating rate of 2℃ / min, and kept for 2h to perform plastic removal, to obtain a second green body, with a size of diameter φ=6mm and length L=2cm;

[0090] (6) The silver-palladium conductive paste is uniformly coated on a 3mm area at each end of the second green body, and dried at a temperature of 120℃; the platinum wire is wound around the two end areas of the second green body coated with the electrode, and placed in a flash firing furnace; the two ends of the platinum wire are connected to the positive and negative poles of a direct current power source outside the furnace body, and an ammeter is connected in series in the circuit; first, the direct current power source adopts a voltage control mode, and the initial electric field strength is set to 100V / cm, and the furnace body is heated at a rate of 10℃ / min; when the current value reaches the order of μA, the electric field strength is increased to 150V / cm. When the current density value reaches the pre-set value of 10.61mA / mm 2 , the direct current power source is switched to a current control mode; the direct current power source maintains a stable current density in the current control mode, and after the current is maintained for 150s, the direct current power source switch is turned off, and the sample is taken out after the flash firing furnace is cooled to room temperature;

[0091] (7) The sample is cut to process thin slices with a thickness of 1mm (for dielectric property test) and 0.1mm (for ferroelectric property test), and the silver (silver firing temperature 750℃, holding time 30min) and gold electrodes are sputtered as needed, and then the dielectric property and ferroelectric property tests are performed.

[0092] Example 2

[0093] The preparation method of the zirconium tin lead lanthanum titanate-based antiferroelectric ceramic ((Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x=0.064) in this example 2 comprises:

[0094] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition, and the components are prepared according to the composition ratio, Pb3O4 (107.9969g), La2O3 (1.6745g), SrCO3 (4.8780g), ZrO2 (31.6470g), TiO2 (5.3534g), SnO2 (28.7724g) are taken, and the wet ball milling method is used to mix for 12h at a speed of 120r / min, so that the components are uniformly mixed, and the first ceramic powder is obtained after drying;

[0095] (2) The obtained first ceramic powder was pressed into a block under a pressure of 150 MPa, and then calcined in an air atmosphere at a temperature of 900°C for 2h to obtain a ceramic block;

[0096] (3) The obtained ceramic block was ground and crushed, and then subjected to secondary ball milling for 24h. After the powder was dried and sieved, 6wt% of PVA (concentration of 7wt%) was added and mixed uniformly with the powder, and then the ceramic green body with a diameter of about 10cm was pressed;

[0097] (4) The obtained ceramic green body was aged for 24h, and then ground and crushed to obtain a second ceramic powder;

[0098] (5) 3g of the second ceramic powder was weighed and pressed into a shape under a pressure of 80MPa for 5s to obtain an elongated cylindrical first green body. The obtained first green body was plastic encapsulated and then cold isostatic pressed under a pressure of 200MPa for 5min. Then, the temperature was increased to 700°C at a rate of 2°C / min, and the plastic was removed by keeping the temperature for 2h to obtain a second green body with a size of diameter φ=6mm and length L=2cm;

[0099] (6) Silver-palladium conductive paste was uniformly coated on the 4mm area at both ends of the second green body, and then dried at a temperature of 120°C. Platinum wires were wound around the two end areas of the second green body coated with electrodes, and placed in a flash furnace. The two ends of the platinum wires were connected to the positive and negative electrodes of a direct current power supply outside the furnace body, and an ammeter was connected in series in the circuit. First, the direct current power supply was set to voltage control mode, and the initial electric field strength was set to 100V / cm, and the furnace body was heated at a rate of 10°C / min. When the current value reached the order of μA, the electric field strength was increased to 150V / cm. When the current density value reached the pre-set value of 10.61mA / mm 2 , the direct current power supply was switched to current control mode. The direct current power supply maintained a stable current density in current control mode. After 150s of current retention, the direct current power supply switch was turned off, and the sample was taken out after the flash furnace cooled to room temperature;

[0100] (7) The sample was cut and processed into a thickness of 1mm and 0.1mm, and then sputtered with silver (sintering temperature of silver 750°C, holding time of 30min) and gold electrodes as needed for testing of dielectric properties and ferroelectric properties.

[0101] Comparative Example 1

[0102] In this comparative example 1, a zirconium tin titanium lead lanthanum-based antiferroelectric ceramic ((Pb 0.975 - x La 0.02 Sr x )(Zr0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x = 0.016), including:

[0103] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition and is prepared according to the composition ratio. Pb3O4 (111.7718 g), La2O3 (1.6468 g), SrCO3 (1.1992 g), ZrO2 (31.1226 g), TiO2 (5.2647 g), SnO2 (28.2956 g) are taken. The components are mixed uniformly by wet ball milling at a speed of 120 r / min for 12 h. After drying, a first ceramic powder is obtained;

[0104] (2) The obtained first ceramic powder is pressed into a block under a pressure of 150 MPa, and then calcined in an air atmosphere at a temperature of 900°C for 2 h to obtain a ceramic block;

[0105] (3) The obtained ceramic block is ground and crushed, and then subjected to secondary ball milling for 24 h. After drying, the powder is sieved and 6wt% PVA (concentration 7wt%) is added. After mixing uniformly, the ceramic green body with a diameter of about 10 cm is pressed;

[0106] (4) The obtained ceramic green body is aged for 24 h, then ground and crushed to obtain a second ceramic powder;

[0107] (5) 3 g of the second ceramic powder is weighed and pressed into a shape under a pressure of 80 MPa for 5 s to obtain an elongated cylindrical first green body. The obtained first green body is plastic encapsulated and then cold isostatic pressed under a pressure of 200 MPa for 5 min. Then, the temperature is raised to 700°C at a rate of 2°C / min and held for 2 h for plastic removal to obtain a second green body with a size of diameter φ = 6 mm and length L = 2 cm;

[0108] (6) The second green body is placed in an alumina crucible and covered with a filler of the same composition to prevent volatilization of the lead component. After covering the crucible cover, the temperature is raised to 1320°C at a rate of 2°C / min and held for 2 h to obtain a traditional sintered antiferroelectric ceramic material;

[0109] (7) The sample is cut to a thickness of 1 mm and 0.1 mm, and silver (silvering temperature 750°C, holding time 30 min) and gold electrodes are sputtered as needed for dielectric and ferroelectric property testing.

[0110] Comparative Example 2

[0111] In this comparative example 2, a zirconium tin titanate lanthanum lead-based antiferroelectric ceramic ((Pb0.975 - x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x = 0.064), including:

[0112] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition and is prepared according to the composition ratio. Pb304 (111.7718g), La203 (1.6468g), SrCO3 (1.1992g), ZrO2 (31.1226g), TiO2 (5.2647g), and SnO2 (28.2956g) are taken. The components are mixed uniformly by wet ball milling at a speed of 120 r / min for 12 h. After drying, a first ceramic powder is obtained;

[0113] (2) The first ceramic powder is pressed into a block under a pressure of 150 MPa, and then calcined in an air atmosphere at a temperature of 900°C for 2 h to obtain a ceramic block;

[0114] (3) The ceramic block is ground and crushed, and then subjected to secondary ball milling for 24 h. After drying, the powder is sieved and 6wt% PVA (concentration 7wt%) is added. After mixing uniformly, the ceramic green body with a diameter of about 10 cm is pressed;

[0115] (4) The ceramic green body is aged for 24 h, ground and crushed to obtain a second ceramic powder;

[0116] (5) 3g of the second ceramic powder is weighed and pressed under a pressure of 80 MPa for 5s to obtain an elongated cylindrical first green body. The first green body is plastic encapsulated and then cold isostatic pressed under a pressure of 200 MPa for 5 min. Then, the temperature is increased to 700°C at a rate of 2°C / min and held for 2 h to remove the plastic and obtain a second green body with a size of diameter φ = 6 mm and length L = 2 cm;

[0117] (6) The second green body is placed in an alumina crucible and covered with filler of the same composition to prevent volatilization of the lead component. After covering the crucible cover, the temperature is increased to 1320°C at a rate of 2°C / min and held for 2 h to obtain a traditional sintered antiferroelectric ceramic material;

[0118] (7) The sample is cut to a thickness of 1 mm and 0.1 mm, and silver (silvering temperature 750°C, holding time 30 min) and gold electrodes are sputtered as needed for dielectric and ferroelectric property testing.

[0119] Comparative Example 3

[0120] The preparation method of the zirconium tin lead lanthanum titanate-based antiferroelectric ceramic ((Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x = 0) in the present comparative example 3 comprises:

[0121] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition, and the components are prepared according to the composition ratio. Pb3O4 (113.0025 g), La2O3 (1.6377 g), ZrO2 (30.9517 g), TiO2 (5.2358 g), and SnO2 (28.1402 g) are mixed uniformly by wet ball milling at a speed of 120 r / min for 12 h. After drying, a first ceramic powder is obtained;

[0122] (2) The obtained first ceramic powder is pressed into a block under a pressure of 150 MPa, and then calcined in air at a temperature of 900 °C for 2 h to obtain a ceramic block;

[0123] (3) The obtained ceramic block is ground and crushed, and then subjected to secondary ball milling for 24 h. After drying, the powder is sieved and 6 wt% of PVA (concentration of 7 wt%) is added. After mixing uniformly, the powder is pressed into a ceramic green body with a diameter of about 10 cm;

[0124] (4) The obtained ceramic green body is aged for 24 h, then ground and crushed to obtain a second ceramic powder;

[0125] (5) 1.2 g of the second ceramic powder is weighed and pressed into a disc-shaped first green body under a pressure of 100 MPa for 10 s. Then, the temperature is increased to 700 °C at a rate of 2 °C / min, and the plastic is removed by holding for 2 h to obtain a second green body with a size of φ = 13 mm in diameter;

[0126] (6) The second green body is placed in an alumina crucible and covered with a filler of the same composition to prevent the volatilization of lead components. After covering the crucible cover, the temperature is increased to 1320 °C at a rate of 2 °C / min, and the antiferroelectric ceramic material sintered by the conventional method is obtained after holding for 2 h;

[0127] (7) The sample is processed to a thickness of 1 mm and 0.1 mm, and silver (silvering temperature is 750 °C, holding time is 30 min) and gold electrodes are sputtered as needed, and then the dielectric properties and ferroelectric properties are tested.

[0128] Comparative Example 4

[0129] The preparation method of the zirconium tin lead lanthanum titanate-based antiferroelectric ceramic ((Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, wherein x=0.12) in the present comparative example 4 comprises:

[0130] (1) The mass of each component in the powder raw material is calculated according to the chemical formula composition, and the components are prepared according to the composition ratio. Pb3O4 (103.4289 g), La2O3 (1.7081 g), SrCO3 (9.3297 g), ZrO2 (32.2816 g), TiO2 (5.4608 g), and SnO2 (29.3492 g) are taken. The components are mixed uniformly by wet ball milling at a speed of 120 r / min for 12 h. After drying, the first ceramic powder is obtained;

[0131] (2) The obtained first ceramic powder is pressed into a block under a pressure of 150 MPa, and then calcined in an air atmosphere at a temperature of 900°C for 2 h to obtain a ceramic block;

[0132] (3) The obtained ceramic block is ground and crushed, and then subjected to secondary ball milling for 24 h. After drying, the powder is sieved and 6 wt% of PVA (concentration of 7 wt%) is added. After mixing the powder and PVA uniformly, a ceramic green body with a diameter of about 10 cm is prepared;

[0133] (4) The obtained ceramic green body is aged for 24 h, then ground and crushed to obtain a second ceramic powder;

[0134] (5) 1.2 g of the second ceramic powder is weighed and pressed into a disc-shaped first green body under a pressure of 100 MPa for 10 s. Then, the temperature is increased to 700°C at a rate of 2°C / min, and the plastic is removed by keeping the temperature for 2 h to obtain a second green body with a size of φ=13 mm in diameter;

[0135] (6) The second green body is placed in an alumina crucible and covered with a filler of the same composition to prevent the volatilization of lead components. After covering the crucible with a lid, the temperature is increased to 1320°C at a rate of 2°C / min, and the temperature is kept for 2 h to obtain an antiferroelectric ceramic material sintered by a conventional method;

[0136] (7) The sample is processed to a thickness of 1 mm and 0.1 mm, and silver (silvering temperature is 750°C, and holding time is 30 min) and gold electrodes are sputtered as needed. The dielectric properties and ferroelectric properties are tested.

[0137] The samples prepared in Examples 1-2 and Comparative Examples 1-2 were subjected to nanoindentation mechanical property tests under the following conditions: maximum indentation depth of 2000 nm, surface indentation speed of 10 nm / s, and holding time of 10 s. Table 1 lists the mechanical properties of the samples prepared in Examples 1-2 and Comparative Examples 1-2.

[0138] Table 1:

[0139] Average Hardness (MPa) Average Modulus (MPa) Example 1 6.397 163.3 Example 2 6.763 174.2 Comparative Example 1 7.530 183.4 Comparative Example 2 6.915 176.3 .

[0140] As shown in Table 1, the average hardness and modulus of the ceramic samples of the examples obtained by the preparation method of the present application are lower than those of the comparative examples. The percentage reduction in average hardness and modulus of Example 1 compared to Comparative Example 1 is 15.0% and 11.0%, respectively, and the percentage reduction in average hardness and modulus of Example 2 compared to Comparative Example 2 is 1.77% and 1.19%, respectively. This shows that the use of the flash technology in the present application improves the plasticity of the antiferroelectric ceramic.

[0141] The samples prepared in Examples 1-2 and Comparative Examples 1-4 were subjected to dielectric temperature spectrum and electric hysteresis loop tests at 250 kV / cm. Table 2 lists the dielectric properties and ferroelectric properties of the samples prepared in Examples 1-2 and Comparative Examples 1-4.

[0142] Table 2:

[0143]

[0144]

[0145] As shown in Table 2, the room temperature dielectric constant and Curie temperature of the ceramic samples of the examples (Examples 1-2) obtained by the preparation method of the present application are basically consistent with those of the comparative examples (Comparative Examples 1-2) of the same composition. However, the positive turning field of the examples (Examples 1-2) is significantly improved compared to the comparative examples (Comparative Examples 1-2) of the same composition. This also helps to improve the energy storage density and energy storage efficiency, so under the same composition and the same test conditions, the energy storage efficiency of the examples (Examples 1-2) is increased compared to the comparative examples (Comparative Examples 1-2). Comparative Examples 1-4 correspond to ceramic samples sintered with different Sr contents by the traditional method. When the strontium content is 0, the room temperature dielectric constant and Curie temperature of Comparative Example 3 are both high, and the energy storage density and energy storage efficiency are both low. With the increase of Sr content, the room temperature dielectric constant and Curie temperature of the ceramic samples decrease, while the energy storage density, energy storage efficiency and positive turning field increase. However, when the strontium content is too high (x = 0.12), the room temperature dielectric constant and Curie temperature of Comparative Example 4 are low. This shows that the strontium content needs to be controlled within a suitable range to ensure the excellent comprehensive performance of the ceramic material in this system.

[0146] Figure 2 and Figure 3 are cross-sectional SEM images of the antiferroelectric ceramic samples prepared in Example 1 and Comparative Example 1, respectively. As can be seen from the images, the dense ceramic samples are successfully prepared by flash sintering, and the grain size is reduced compared to the traditional sintering.

[0147] Figure 4 is a schematic diagram of dislocation structure and domain of the antiferroelectric ceramic sample prepared in Example 1; Figure 5 is a schematic diagram of domain of the antiferroelectric ceramic sample prepared in Comparative Example 1. As can be seen from the image, Figure 4 the number of dislocations (short black lines in the image) in the flash sintered sample of Example 1 is increased, and the dislocations also affect the shape of the domain. The domain shape in the flash sintered sample is a blocky domain with a size of several hundred nanometers. As can be seen from the image, Figure 5 the antiferroelectric ceramic sample prepared in Comparative Example 1 by the traditional method does not have obvious dislocation structure, and the domain shape is a classic long strip-shaped layered domain, and the domain size is larger than that of the flash sintered sample. Therefore, it can be seen that the changes in the microstructure of the ceramic sample after flash sintering together achieve the beneficial effects of the present application.

[0148] Figure 6 and Figure 7 are charge-discharge curves of the antiferroelectric ceramic samples prepared in Example 1 and Comparative Example 1, respectively, indicating the change of discharge current with discharge time during the discharge process. As can be seen from the images, the complete discharge interval of Comparative Example 1 and Example 1 is 500-800 ns, and the discharge period is about 300 ns. Under an electric field of 30 kV / cm, the charge-discharge times of the ceramic sample of Example 1 can reach more than 4200 times, while the charge-discharge times of the ceramic sample of Comparative Example 1 are only more than 350 times. Moreover, the discharge current of Example 1 is slightly improved. This indicates that the prolongation of charge-discharge life can be achieved by improving plasticity.

[0149] Figure 8 and Figure 9 are dielectric temperature spectra of the antiferroelectric ceramic samples prepared in Example 1 and Comparative Example 1, respectively, indicating the change trend of dielectric constant and loss tangent with temperature. As can be seen from the images, the dielectric constant value of Example 1 at room temperature is 1145, and the Curie temperature is 137℃; the dielectric constant value of Comparative Example 1 at room temperature is 1148, and the Curie temperature is 136℃. The change trend of the dielectric constant of Example 1 with temperature is more gentle than that of Comparative Example 1, and the sharpness of the Curie peak is reduced.

[0150] Figure 10 and Figure 11The hysteresis loops of the antiferroelectric ceramic samples prepared by Example 1 and Comparative Example 1, respectively, represent the changes of polarization and current with electric field. As can be seen from the figures, both Example 1 and Comparative Example 1 have sharp double current peaks, indicating that both of them exhibit obvious strong antiferroelectric characteristics. The positive turning field (the electric field corresponding to the positive current peak value) of Example 1 is 37.6 kV / cm, which is higher than that of Comparative Example 1 (34.9 kV / cm), which is beneficial to the improvement of the energy storage density.

[0151] Figure 12 and Figure 13 The hysteresis loops of the antiferroelectric ceramic samples prepared by Comparative Example 3 and Comparative Example 4, respectively. As can be seen from the figures, when no strontium element is doped (Comparative Example 3), only one complete current peak is shown, and the remanent polarization is large, indicating that it is in the ferroelectric phase and cannot play the high energy storage density characteristics of antiferroelectric materials. When the strontium element is doped too much (Comparative Example 4), the current peak becomes flat, indicating that the antiferroelectricity of the material is weakened, and the polarization decreases significantly.

Claims

1. A plasticity-enhanced lead zirconium tin titanate lanthanum-based antiferroelectric ceramic, characterized in that: The chemical formula of the lead lanthanum zirconate stannate-based antiferroelectric ceramic is (Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3, where 0 < x ≤ 0.10; the plastic-enhanced lead lanthanum zirconate stannate-based antiferroelectric ceramic is prepared by sintering using the flash sintering technique; wherein, the initial electric field strength is set to 100 - 300 V / cm, and the heating rate of the flash furnace body is 5 - 15 °C / min; when the reading of the current detector reaches the μA order of magnitude, the electric field strength is increased to 200 - 500 V / cm; when the current density value reaches 10 - 30 mA / mm 2 after that, a stable current density is maintained for 90 - 200 s.

2. The lead lanthanum zirconium tin titanate based antiferroelectric ceramic according to claim 1, characterized in that: The flash furnace heating rate is 8-12℃ / min.

3. The lead lanthanum zirconium tin titanate based antiferroelectric ceramic according to claim 1, characterized in that Set the initial electric field strength to 100-150 V / cm. When the current detector reading reaches the μA level, increase the electric field strength to 200-300 V / cm.

4. The lead lanthanum zirconium tin titanate based antiferroelectric ceramic according to claim 1, wherein: The average hardness of the zirconium tin lead titanate lanthanum based antiferroelectric ceramic is 6-7 MPa; the average modulus of the zirconium tin lead titanate lanthanum based antiferroelectric ceramic is 160-175 MPa.

5. A method for preparing the lead lanthanum zirconium tin titanate based antiferroelectric ceramic according to any one of claims 1 to 4, characterized in that: include: (1) Using Pb3O4 powder, La2O3 powder, SrCO3 powder, ZrO2 powder, TiO2 powder and SnO2 powder as raw materials, according to the chemical formula (Pb 0.975-x La 0.02 Sr x )(Zr 0.5 Sn 0.37 Ti 0.13 ) 0.9975 O3 is weighed and mixed, ball-milled, and dried to obtain a first ceramic powder; (2) Pressing the obtained ceramic powder into blocks and calcining them to obtain ceramic blocks; (3) grinding and crushing the obtained ceramic block, performing secondary ball milling, drying, and screening, adding a binder to granulate, and pressing to obtain a ceramic green body; aging the obtained ceramic green body, and then performing secondary grinding and crushing to obtain a second ceramic powder; (4) Taking an appropriate amount of the second ceramic powder and pressing it to obtain a first green body; sealing the obtained first green body and then cold isostatic pressing and plastic removal to obtain a second green body; (5) The plasticity-enhanced lead zirconium tin titanate lanthanum-based antiferroelectric ceramic is prepared by sintering using a flash sintering technique.

6. The preparation method according to claim 5, wherein In step (1), the ball milling method is wet ball milling, using zirconia balls as the ball milling medium and deionized water / anhydrous ethanol as the ball milling agent, and the ball milling is carried out in a ratio of mixed powder: zirconia balls: water / anhydrous ethanol of 1: (3.5-5): (1.2-1.5), the ball milling speed is 120-180 r / min, and the ball milling time is 8-12 h.

7. The preparation method according to claim 5, wherein In step (2), the pressing pressure is 100-300 MPa and the time is 5-30 s; The calcination temperature is 800-900 o C, time is 2 to 4 h, and the ambient atmosphere is air.

8. The preparation method according to claim 5, wherein In step (3), the secondary ball milling is performed by wet ball milling, using zirconia balls as the ball milling medium and deionized water / anhydrous ethanol as the ball milling agent, and the ball milling is performed in a ratio of mixed powder: zirconia balls: water / anhydrous ethanol of 1: (3.5-5): (1.2-1.5), the ball milling speed is 120-180 r / min, and the ball milling time is 18-24 h; The binder is at least one of PVA and PVB; the concentration of the binder is 5 to 10 wt%; the amount of the binder added is 5 to 8 wt% of the mass of the sieved ceramic powder; The aging temperature is room temperature and the aging time is 18 to 24 hours.

9. The preparation method according to claim 5, wherein In step (4), the mass of the second ceramic powder is 2.5 to 3.2 g; The compression molding process is performed at a pressure of 50 to 200 MPa and a time of 3 to 10 s. The cold isostatic pressing pressure is 200-300 MPa and the time is 3-5 min; The temperature of the plastic removal is 650-800° C., and the time is 2-3 h.

10. The preparation method according to claim 5, characterized in that In step (5), the flash firing technology includes: uniformly coating silver-palladium conductive paste on both end regions of the obtained second blank, drying at 100-120° C., wrapping platinum wire around both end regions of the second blank coated with electrodes, and placing the resultant in a flash firing furnace.

11. The preparation method according to claim 10, characterized in that The width of the silver-palladium conductive paste coated on both end areas of the second blank is 3 to 5 mm.

12. The preparation method according to claim 5, characterized in that The preparation method further comprises: cutting, processing, and sputtering the obtained plasticity-enhanced lead lanthanum zirconium tin titanate-based antiferroelectric ceramic with silver and gold electrodes.

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