A PbZrO3-based low remanent polarization strength ceramic with A-site high entropy design and preparation method thereof

Abstract

The present invention discloses a PbZrO3-based low remanent polarization ceramic with A-site high-entropy design and its preparation method, belonging to the technical field of high-entropy ceramic materials. The chemical formula of the high-entropy ceramic material described in the present invention is (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3 (Me = Na, K, Li). The preparation process is to weigh powders of PbO, BaCO3, Bi2O3, SrCO3, ZrO2, Na2CO3 or K2CO3 or Li2CO3 respectively according to the designed stoichiometric ratio, and then carry out wet ball milling, centrifugal spray drying, and pre-sintering. The obtained pre-sintered powder is dry milled, dried, ground, sieved, and pressed. Finally, it is sintered at 1260 °C in air for 2.5 h to obtain (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3 high-entropy ceramic. The breakdown field strength of the (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3 high-entropy ceramic reaches 120 kv / cm at a test frequency of 10 Hz, and the remanent polarization is only 0.06 μC / cm 2 , and it is expected to be a candidate material for low-remanent polarization ceramic capacitors.

Description

Technical Field

[0001] The invention relates to a PbZrO3-based low residual polarization strength ceramic with A-site high entropy design and a preparation method thereof, belonging to the technical field of high entropy ceramic materials. Background Art

[0002] Lead zirconate (PbZrO3) is a typical antiferroelectric ceramic material, which can achieve better results after doping.

[0003] High entropy ceramic materials are multi-principal solid solution ceramics formed by doping five or more elements in equal proportions. In the field of dielectric ceramics, lead zirconate has the advantages of low dielectric loss and high Curie temperature, and is expected to become a candidate material for ceramic capacitors. At present, there has been no design research or report on the high entropy treatment of the A-site of lead zirconate. This patent is a design for the high entropy treatment of the A-site of lead zirconate, in which five elements with similar chemical properties are doped in equal molar ratios into the A-site lattice of lead zirconate. Because the A-site is at the eight corners of the ABO3 model, the high entropy treatment of the A-site can cause the lead zirconate to produce a lattice distortion effect, increase its disorder, increase the maximum polarization strength, increase the breakdown field strength, and thus improve the dielectric properties. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a PbZrO3-based low residual polarization strength ceramic with a high entropy design at the A position, wherein the chemical formula of the ceramic is: (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3(Me=Na, K, Li). The preparation method comprises the following steps:

[0005] (1)(Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3 (Me=Na, K, Li) preparation process is: weigh PbO, BaCO3, Bi2O3, SrCO3, ZrO2, Na2CO3 or K2CO3 or Li2CO3 powders respectively according to the designed stoichiometric ratio.

[0006] (2) placing the above powders in a ball mill for wet ball milling, then centrifugally spray drying and pre-calcining to obtain high entropy ceramic powder, and then dry milling, drying, grinding, sieving, and tableting;

[0007] (3) The pressed unsintered ceramic sheet is placed in a muffle furnace and sintered at 1200-1300°C in air.

[0008] Preferably, the wet milling conditions in step (2) of the present invention are: the ball mill speed is 200-400 rpm, the ball milling time is 12-24 hours, the ball milling medium is anhydrous ethanol and zirconium oxide balls, and the ball: material: ethanol is 5:1:5. The dry milling conditions are: the ball milling time is 24-48 hours, the ball milling medium is zirconium oxide balls, and the zirconium oxide balls are of different sizes. The ball: material: 3:1, the speed is 50-60 rpm.

[0009] Preferably, the drying conditions in step (2) of the present invention are: the air inlet temperature of the centrifugal spray dryer is 240-320° C., and the air outlet temperature is 100-140° C. The atomization speed of the high-speed centrifugal spray dryer is 200-300 Hz, and the feeding speed is 10-15 Hz.

[0010] Preferably, the pre-firing conditions in step (2) of the present invention are: pre-firing at 800-850° C. for 2-3 hours.

[0011] Preferably, the mesh size of the sieving in step (2) of the present invention is 60 to 150 meshes.

[0012] Preferably, the grinding conditions in step (2) of the present invention are: putting the dried mixed powder into a grinding jar and grinding it for 30 to 50 minutes.

[0013] Preferably, the diameter of the mold used for tableting in step (2) of the present invention is 16 to 20 mm, the uniaxial pressure is 200 to 240 MPa, and the holding time is 5 to 15 minutes.

[0014] Preferably, during the sintering process of step (3) of the present invention: the same powder as the ceramic block is added around and on the top of the ceramic for burial firing, the temperature is raised from room temperature to 1200-1300°C at a heating rate of 6°C / min, the heat preservation time in the muffle furnace is 3 hours, and then the ceramic is taken out after cooling to 300-350°C with the furnace.

[0015] Beneficial Effects of the Invention

[0016] (1) The preparation process of the present invention is simple and does not require atmosphere protection. It only needs to use an ordinary muffle furnace for sintering, which has the characteristics of short sintering time, simple process, low production cost, short production cycle, high efficiency, etc.

[0017] (2) The (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3(Me=Na, K, Li) high entropy ceramics do not require the addition of any binder, sintering aid or dispersant.

[0018] (3) The (Pb 0.2 Bi0.2 Ba 0.2 Sr 0.2 Na 0.2 ) The breakdown field strength of ZrO3 high entropy ceramics tested at 10Hz frequency and room temperature using a ferroelectric analyzer is 120kv / cm; the residual polarization intensity is 0.06μC / cm 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 For examples 1 to 3 (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )XRD of ZrO3(Me=Na, K, Li) high entropy ceramics.

[0020] Figure 2 For examples 1 to 3 (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )SEM of ZrO3(Me=Na, K, Li) high entropy ceramics.

[0021] Figure 3 For examples 1 to 3 (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )Hysteresis loop of ZrO3(Me=Na, K, Li) high entropy ceramics under 10Hz frequency test. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. However, the protection scope of the present invention is not limited to the above contents.

[0023] Example 1

[0024] A PbZrO3-based low remanent polarization (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3 high entropy ceramics, the sintering temperature is 1260℃, the specific steps are as follows:

[0025] (1) According to high entropy ceramics (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2) PbO, BaCO3, Bi2O3, SrCO3, ZrO2, and Na2CO3 were weighed according to the chemical formula and stoichiometric ratio of ZrO3. The above powders were put into a ball mill for ball milling and mixing, and ball milling was performed for 12 hours at a ratio of zirconia ball: anhydrous ethanol: powder of 5:5:1, and the ball mill speed was 300 rpm, and then dried by a centrifugal spray dryer. The inlet temperature of the centrifugal spray dryer was 280°C, and the outlet temperature was 130°C. The atomization speed of the high-speed centrifugal spray dryer was 270Hz, and the feeding speed was 11Hz.

[0026] Then put it into a muffle furnace for pre-sintering at 850℃ for 2 hours. Then dry grind it. The dry grinding conditions are: ball milling time 40 hours, rotation speed 50 rpm, ball milling medium is zirconia balls, and the sizes of zirconia balls are different. Ball: material: 3:1. Put the mixed slurry into an oven and dry it at 80℃ for 12 hours. Put the dried powder into a grinding jar and grind it for 30 minutes.

[0027] (2) After grinding, the ground powder was sieved and the ceramic powder was pressed into a ceramic sheet with a diameter of 16 mm under a uniaxial pressure of 200 MPa.

[0028] (3) Powders identical to those of the ceramic block are added around and on the ceramic block for burial firing. The temperature is raised from room temperature to 1260°C at a heating rate of 6°C / min. The ceramic block is kept in a muffle furnace for 2.5 hours and then cooled to 300°C before being taken out.

[0029] Example 2

[0030] A PbZrO3-based low remanent polarization (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 K 0.2 )ZrO3 high entropy ceramics, the sintering temperature is 1270℃, the specific steps are as follows:

[0031] (1) According to high entropy ceramics (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 K 0.2) PbO, BaCO3, Bi2O3, SrCO3, ZrO2, and K2CO3 were weighed according to the chemical formula and stoichiometric ratio of ZrO3. The above powders were put into a ball mill for ball milling and mixing, and the ball milling was carried out for 15 hours at a ratio of zirconia ball: anhydrous ethanol: powder of 5:5:1, and the ball mill speed was 300 rpm, and then dried by a centrifugal spray dryer. The inlet temperature of the centrifugal spray dryer was 290°C, and the outlet temperature was 135°C. The atomization speed of the high-speed centrifugal spray dryer was 280Hz, and the feeding speed was 12Hz.

[0032] Then put it into a muffle furnace for pre-sintering at 830℃ for 2 hours. Then dry grind it. The dry grinding conditions are: ball milling time 28 hours, rotation speed 55 rpm, ball milling medium is zirconia balls, and the sizes of zirconia balls are different. Ball: material: 3:1. Put the mixed slurry into an oven and dry it at 85℃ for 12 hours. Put the dried powder into a grinding jar and grind it for 35 minutes.

[0033] (2) After grinding, the ground powder was sieved and the ceramic powder was pressed into a ceramic sheet with a diameter of 20 mm under a uniaxial pressure of 240 MPa.

[0034] (3) Powders identical to those of the ceramic block are added around and on the ceramic block for burial firing. The temperature is raised from room temperature to 1270°C at a heating rate of 6°C / min. The ceramic block is kept in a muffle furnace for 2.8 hours. The ceramic block is then cooled to 320°C and taken out.

[0035] Example 3

[0036] A PbZrO3-based low remanent polarization (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Li 0.2 )ZrO3 high entropy ceramics, the sintering temperature is 1280℃, the specific steps are as follows:

[0037] (1) According to high entropy ceramics (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Li 0.2) PbO, BaCO3, Bi2O3, SrCO3, ZrO2, and Li2CO3 were weighed according to the chemical formula and stoichiometric ratio of ZrO3. The above powders were put into a ball mill for ball milling and mixing, and ball milling was performed for 18 hours at a ratio of zirconia ball: anhydrous ethanol: powder of 5:5:1, and the ball mill speed was 300 rpm, and then dried by a centrifugal spray dryer. The inlet temperature of the centrifugal spray dryer was 300°C, and the outlet temperature was 138°C. The atomization speed of the high-speed centrifugal spray dryer was 280Hz, and the feeding speed was 13Hz.

[0038] Then put it into a muffle furnace for pre-sintering at 840℃ for 2.5 hours. Then dry grind it. The dry grinding conditions are: ball milling time 30 hours, rotation speed 60 rpm, ball milling medium is zirconia balls, and the sizes of zirconia balls are different. Ball: material: 3:1. Put the mixed slurry into an oven and dry it at 90℃ for 12 hours. Put the dried powder into a grinding jar and grind it for 40 minutes.

[0039] (2) After grinding, the ground powder was sieved and the ceramic powder was pressed into a ceramic sheet with a diameter of 20 mm under a uniaxial pressure of 220 MPa.

[0040] (3) Powders identical to those of the ceramic block are added around and on the ceramic block for burial firing. The temperature is raised from room temperature to 1280°C at a heating rate of 6°C / min. The ceramic block is kept in a muffle furnace for 3 hours. The ceramic block is then cooled to 305°C and taken out.

[0041] Figure 1 The (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )XRD spectrum of ZrO3(Me=Na, K, Li) high entropy ceramics; it can be seen from the figure that the three high entropy ceramics all have a single-phase perovskite structure without other impurity peaks.

[0042] Figure 2 (ac) are the prepared (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3,(Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 K 0.2 )ZrO3,(Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Li 0.2) SEM microstructure of ZrO3 high entropy ceramics. It can be seen from the figure that the three groups of high entropy ceramics have more pores and coarse grains.

[0043] Figure 3 The (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3(Me=Na、K、Li) high entropy ceramic hysteresis loop diagram; It can be seen from the figure that (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )The residual polarization intensity of ZrO3 is 0.06μC / cm 2 , the breakdown field strength is 120kv / cm, and the maximum polarization intensity is 1.06μC / cm 2 . (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 K 0.2 )The residual polarization intensity of ZrO3 is 0.09μC / cm 2 , the breakdown field strength is 72kv / cm, and the maximum polarization intensity is 1.35μC / cm 2 . (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Li 0.2 )The residual polarization intensity of ZrO3 is 0.07μC / cm 2 , the breakdown field strength is 48kv / cm, and the maximum polarization intensity is 1.05μC / cm 2 . (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3 has a smaller residual polarization intensity, a higher maximum polarization intensity, and a higher breakdown field strength. Compared with the PbZrO3 matrix material, after the A-site high entropy treatment, the dielectric properties are improved. These characteristics can increase the energy storage density. 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Na 0.2 )ZrO3 is expected to become a candidate material for the new generation of ceramic capacitors.

Claims

1. A PbZrO3-based low remanent polarization strength ceramic with A-site high entropy design, characterized in that: The low residual polarization strength ceramic is designed with high entropy at the A position, and the chemical formula of the low residual polarization strength ceramic is: (Pb 0.2 Bi 0.2 Ba 0.2 Sr 0.2 Me 0.2 )ZrO3, Me=Na, K, Li.

2. A method for preparing the PbZrO3-based low residual polarization strength ceramic with high entropy design at the A site as claimed in claim 1, characterized in that: The specific steps include: (1) Weigh PbO, BaCO3, Bi2O3, SrCO3, ZrO2, Na2CO3 or K2CO3 or Li2CO3 powders respectively according to the designed stoichiometric ratio; (2) placing the above powders in a planetary ball mill for wet ball milling, followed by centrifugal spray drying, pre-calcination, and then dry milling, drying, grinding, sieving, and tableting; (3) The pressed unsintered ceramic sheet is placed in a muffle furnace and sintered at 1200-1300°C in air.

3. The method for preparing the PbZrO3-based low remanent polarization strength ceramics with high entropy design at the A-site according to claim 2, characterized in that: The conditions for wet ball milling in step (2) are: the speed of the ball mill is 200 to 400 rpm, the ball milling time is 12 to 24 hours, and the ball milling medium is anhydrous ethanol and zirconia balls; the dry milling conditions are: the dry milling time is 24 to 48 hours, the dry milling medium is zirconia balls, and the zirconia balls are of different sizes, and the dry milling speed is 50 to 60 rpm.

4. The method for preparing the PbZrO3-based low remanent polarization strength ceramic with high entropy design at the A-site according to claim 2 or 3, characterized in that: In step (2), the air inlet temperature of the centrifugal spray dryer is 240-320° C., and the air outlet temperature is 100-140° C.

5. The method for preparing the PbZrO3-based low remanent polarization strength ceramics with high entropy design at the A-site according to claim 2, characterized in that: The pre-firing conditions in step (2) are: pre-firing at 800-850° C. for 2-3 hours.

6. The method for preparing the PbZrO3-based low remanent polarization strength ceramics with high entropy design at the A-site according to claim 2, characterized in that: The grinding conditions in step (2) are as follows: the dried mixed powder is placed in a grinding jar and ground for 30 to 50 minutes; the mesh size of the sieve in step (2) is 60 to 150 meshes.

7. The method for preparing the PbZrO3-based low remanent polarization strength ceramics with high entropy design at the A-site according to claim 2, characterized in that: The diameter of the mold used for tableting in step (2) is 16 to 20 mm, the uniaxial pressure is 200 to 240 MPa, and the holding time is 5 to 15 minutes.

8. The method for preparing the PbZrO3-based low remanent polarization strength ceramics with high entropy design at the A-site according to claim 3, characterized in that: During the sintering process of step (3), the same powder as the unsintered ceramic sheet is added around and on the top of the unsintered ceramic sheet for burying and sintering, and the temperature is increased from room temperature to 1200-1300°C at a heating rate of 6°C / min, and the heat preservation time in the muffle furnace is 2-3 hours, and then the unsintered ceramic sheet is cooled to 300-350°C and taken out.

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