Antiferroelectric molecular ceramic material, method of preparation and use

Abstract

The present invention relates to antiferroelectric molecular ceramic materials, methods of preparation and use. The antiferroelectric molecular ceramic materials of the present invention have the chemical formula (C7H 16 N)Br x I 1‑x or (C7H 16 N)Br x Cl 1‑x wherein 0

Description

Technical Field

[0001] This invention belongs to the field of functional materials, and mainly relates to an antiferroelectric molecular ceramic material, its preparation method, and its application. Background Technology

[0002] Antiferroelectrics, a special class of dielectric materials, possess antiparallel dipoles in their adjacent crystal lattices. Under an external electric field, these dipoles align in the same direction, macroscopically manifesting as double hysteresis loops. Based on their excellent dielectric, pyroelectric, and ferroelectric properties, antiferroelectrics have attracted widespread attention in applications such as dielectric capacitors, solid-state refrigeration, and ferroelectric memory. Discovered in the 1950s, researchers studying ceramic dielectric materials found that some non-ferroelectric materials exhibited dielectric-temperature characteristics similar to ferroelectrics: the dielectric constant undergoes abrupt changes within a specific temperature range, forming a dielectric peak, and the dielectric temperature change during the transition to the paraelectric phase follows the Curie-Weiss law. To date, researchers have discovered and reported more than 40 antiferroelectric materials, mainly limited to inorganic oxides and molecular crystals, with a significant lack of antiferroelectric materials possessing potential applications.

[0003] Traditional inorganic antiferroelectric ceramics are characterized by their high saturation polarization intensity (P0). s ), near-zero remanent polarization, high Curie temperature (T) c Inorganic antiferroelectric materials are widely used due to their superior properties, such as high-temperature sintering and suitable phase-change electric fields. However, the application of inorganic antiferroelectric materials is often limited by problems such as the need for high-temperature sintering, high cost, and easy phase separation precipitation during their preparation process. At the same time, the synthesis process also involves heavy metal elements such as lead that are harmful to the environment.

[0004] Compared to traditional inorganic materials, molecular antiferroelectrics offer advantages such as mild synthesis conditions, ease of molecular tailoring and structural design, and environmental friendliness. Their molecular structure and composition can be modified through molecular design and crystal engineering, making them viable alternatives or supplements to traditional inorganic antiferroelectric materials. Furthermore, due to their unique advantages in biocompatibility and thin-film fabrication, molecular antiferroelectric materials hold promise as strong candidates for flexible electronic devices. Therefore, molecular antiferroelectrics represent a class of highly promising functional materials, potentially offering new opportunities for innovation in energy storage technologies and the development of electrically ordered materials.

[0005] Compared to single crystals and thin films, ceramics offer a simple and cost-effective manufacturing route and stable properties. Therefore, the fabrication of high-performance antiferroelectric molecular ceramics helps expand the application areas of molecular materials, such as multi-source energy harvesting. However, the development of macroscopic molecular antiferroelectrics in cold-pressed polycrystalline morphologies is still in its early stages, mainly due to the fact that molecular antiferroelectrics often exhibit antiferroelectric properties only in specific crystal orientations.

[0006] In conclusion, the direct preparation of high-performance antiferroelectric molecular ceramics using solid-state sintering has significant practical value. Summary of the Invention

[0007] The purpose of this invention is to provide antiferroelectric molecular ceramic materials, preparation methods, and applications. The antiferroelectric molecular ceramic materials of this invention exhibit saturation polarization intensity and moderate coercivity in both the antiferroelectric and ferroelectric phases, similar to those of single crystals. Moreover, the synthesis method is simple, the conditions are mild, the cost is low, and it is non-toxic and harmless. Therefore, it is a functional material with great development potential and is expected to be applied in the field of energy storage and electric card refrigeration devices.

[0008] This invention is achieved through the following technical solution:

[0009] Option 1)

[0010] An antiferroelectric molecular ceramic material, wherein the chemical formula of the antiferroelectric molecular ceramic material is (C7H 16 N)Br x I 1-x Or (C7H) 16 N)Br x Cl 1-x , of which 0 <x≤1。

[0011] Option 2)

[0012] An antiferroelectric molecular ceramic material, comprising the following scheme:

[0013] 1. The stoichiometric ratio of (1-x):x is given by (C7H) 16 N)Cl and (C7H 16 N)Br or (C7H) 16 N)I and (C7H 16 N)Br was first ground, and during the grinding process, an appropriate amount of anhydrous ethanol and adhesive were added to granulate until the grinding was uniform.

[0014] 2. The mixture powder obtained in step 1 is sintered at a pre-calcination temperature of 50-80℃ for 12-36 hours. Then, the pre-calcined mixture is taken out and ground a second time to obtain powder with a particle size range of 2-5μm.

[0015] 3. Press the powder obtained in step 2 into tablets using a powder tablet press or a hot press molding machine;

[0016] Fourth, finally, place the pressed tablets obtained in step three in a vacuum drying oven and sinter at a temperature of 160-180℃ for 1-3 hours to obtain antiferroelectric molecular ceramics (C7H). 16 N)Br x I 1-x Or (C7H) 16 N)Brx Cl 1-x , where 0 < x ≤ 1.

[0017] Specifically, in Step 1, every 10 g of (C7H 16 N)Cl and (C7H 16 N)Br or (C7H 16 N)I and (C7H 16 N)Br are added to 5 - 10 ml of absolute ethanol and 0.1 - 0.2 g of adhesive.

[0018] Specifically, when tabletting in Step 3, under a pressure of 2 - 5 Mpa, dry - press for 30 - 150 seconds to obtain a wafer with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm.

[0019] Scheme Three

[0020] Application of an antiferroelectric molecular ceramic material in an energy - storage device, where the energy - storage device comprises the antiferroelectric molecular ceramic material.

[0021] Scheme Four

[0022] An energy - storage device comprising the antiferroelectric molecular ceramic material.

[0023] Scheme Five

[0024] Application of an antiferroelectric molecular ceramic material in an electrocaloric refrigeration device, where the electrocaloric refrigeration device comprises the antiferroelectric molecular ceramic material.

[0025] Scheme Six

[0026] An electrocaloric refrigeration device comprising the antiferroelectric molecular ceramic material.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The antiferroelectric molecular ceramic material of the present invention exhibits a saturation polarization intensity similar to that of a single crystal and a moderate coercive field in both the antiferroelectric phase and the ferroelectric phase. Moreover, the synthesis method is simple, the conditions are mild, the cost is low, and it is non - toxic and harmless. Therefore, it is a kind of functional material with great development potential and is expected to be applied in the field of energy storage and electrocaloric refrigeration devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 . Preparation flow chart of antiferroelectric molecular ceramics (C7H 16 N)Br x I 1-x and (C7H 16 N)Br x Cl 1-x (0 < x ≤ 1).

[0030] Figure 2 Scanning electron microscope (SEM) spectra of the antiferroelectric molecular ceramic material in Example 5.

[0031] Figure 3 Dielectric temperature spectra of antiferroelectric molecular ceramic materials in Examples 4-6.

[0032] Figure 4 Hysteresis loop of antiferroelectric molecular ceramic material in Example 5. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] Antiferroelectric molecular ceramics (C7H) 16 N)Br 0.25 I 0.75 Preparation

[0036] An antiferroelectric molecular ceramic material, comprising the following scheme:

[0037] 1. A stoichiometric ratio of 3:1 (C7H) 16 N)I and (C7H 16 N)Br was first ground, and during the grinding process, an appropriate amount of anhydrous ethanol and adhesive were added to granulate until the grinding was uniform.

[0038] 2. The mixture powder obtained in step 1 is sintered at a pre-calcination temperature of 65℃ for 24 hours. Then, the pre-calcined mixture is taken out and ground a second time to obtain powder with a particle size range of 2-5μm.

[0039] 3. Compress the powder obtained in step 2 into tablets using a powder tableting machine;

[0040] Fourth, finally, the pressed tablets obtained in step three are sintered in a vacuum drying oven at 180°C for 1 hour to obtain antiferroelectric molecular ceramics (C7H). 16 N)Br 0.25 I 0.75 .

[0041] Specifically, in step one, every 10g of (C7H) 16 N)I and (C7H 16 Add N)Br to 7 ml of anhydrous ethanol and 0.12 g of adhesive.

[0042] Specifically, in step three, during tablet compression, dry pressing is performed at a pressure of 3 MPa for 30 seconds, producing round tablets with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as follows: Figure 1 As shown.

[0043] Example 2

[0044] Antiferroelectric molecular ceramics (C7H) 16 N)Br 0.5 I 0.5 Preparation

[0045] An antiferroelectric molecular ceramic material, comprising the following scheme:

[0046] 1. A stoichiometric ratio of 1:1 (C7H) 16 N)I and (C7H 16 N)Br was first ground, and during the grinding process, an appropriate amount of anhydrous ethanol and adhesive were added to granulate until the grinding was uniform.

[0047] 2. The mixture powder obtained in step 1 is sintered at a pre-calcination temperature of 50°C for 36 hours. Then, the pre-calcined mixture is taken out and ground a second time to obtain powder with a particle size range of 2-5μm.

[0048] 3. Compress the powder obtained in step 2 into tablets using a powder tableting machine;

[0049] Fourth, finally, the pressed tablets obtained in step three are sintered in a vacuum drying oven at 160°C for 3 hours to obtain antiferroelectric molecular ceramics (C7H). 16 N)Br 0.5 I 0.5 .

[0050] Specifically, in step one, every 10g of (C7H) 16 N)I and (C7H 16 Add N)Br to 5 ml of anhydrous ethanol and 0.1 g of adhesive.

[0051] Specifically, in step three, during tablet compression, dry pressing is performed at a pressure of 2 MPa for 150 seconds to produce round tablets with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as follows: Figure 1 As shown.

[0052] Example 3

[0053] Antiferroelectric molecular ceramics (C7H) 16 N)Br 0.75 I 0.25 Preparation

[0054] An antiferroelectric molecular ceramic material, comprising the following scheme:

[0055] 1. A stoichiometric ratio of 1:3 (C7H) 16 N)Cl and (C7H 16Perform the first grinding on (C7H

[0056] N)Br, and add appropriate amounts of anhydrous ethanol and binder during the grinding process for granulation until the grinding is uniform; then sinter the mixture powder obtained in step one at a pre-sintering temperature of 80°C for 12 hours. Next, take out the pre-sintered mixture for the second grinding to obtain a powder with a particle size range of 2 - 5 μm;

[0057] III. Press the powder obtained in step two using a powder press;

[0058] IV. Finally, place the tablet obtained in step three in a vacuum drying oven and sinter it at a temperature of 170°C for 1 - 3 hours to obtain the antiferroelectric molecular ceramic (C7H 16 N)Br 0.75 I 0.25 .

[0059] Specifically, in step one, for every 10 g of (C7H 16 N)I and (C7H 16 N)Br, add 10 ml of anhydrous ethanol and 0.2 g of binder.

[0060] Specifically, when pressing the tablet in step three, dry-press for 30 seconds under a pressure of 5 Mpa to obtain a round tablet with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as Figure 1 shown.

[0061] Example 4

[0062] Preparation of antiferroelectric molecular ceramic (C7H 16 N)Br 0.25 Cl 0.75 (0 < x ≤ 1)

[0063] An antiferroelectric molecular ceramic material includes the following steps:

[0064] I. Grind (C7H 16 N)Cl and (C7H 16 N)Br with a stoichiometric ratio of 1:3 for the first time, and add appropriate amounts of anhydrous ethanol and binder during the grinding process for granulation until the grinding is uniform;

[0065] II. Sinter the mixture powder obtained in step one at a pre-sintering temperature of 65°C for 24 hours, then take out the pre-sintered mixture for the second grinding to obtain a powder with a particle size range of 2 - 5 μm;

[0066] III. Press the powder obtained in step two using a powder press;

[0067] IV. Finally, place the tablets obtained in Step III in a vacuum drying oven and sinter them at a temperature of 165 °C for 2 hours to obtain the antiferroelectric molecular ceramic (C7H 16 N)Br 0.25 Cl 0.75 .

[0068] Specifically, in Step I, for every 10 g of (C7H 16 N)Cl and (C7H 16 N)Br, add 7 ml of absolute ethanol and 0.12 g of binder.

[0069] Specifically, when pressing the tablets in Step III, dry-press for 30 seconds under a pressure of 3 Mpa to obtain a disc with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as shown in Figure 1 .

[0070] Example 5

[0071] Preparation of antiferroelectric molecular ceramic (C7H 16 N)Br 0.5 Cl 0.5 (0 < x ≤ 1)

[0072] An antiferroelectric molecular ceramic material includes the following steps:

[0073] I. Grind (C7H 16 N)Cl and (C7H 16 N)Br with a stoichiometric ratio of 1:1 for the first time. During the grinding process, add an appropriate amount of absolute ethanol and binder for granulation until the grinding is uniform;

[0074] II. Sinter the mixture powder obtained in Step I at a pre-sintering temperature of 50 °C for 36 h. Then, take out the pre-sintered mixture and conduct the second grinding to obtain a powder with a particle size range of 2 - 5 μm;

[0075] III. Press the powder obtained in Step II into tablets using a powder press;

[0076] IV. Finally, place the tablets obtained in Step III in a vacuum drying oven and sinter them at a temperature of 160 °C for 3 hours to obtain the antiferroelectric molecular ceramic (C7H 16 N)Br 0.5 Cl 0.5 .

[0077] Specifically, in Step I, for every 10 g of (C7H 16 N)Cl and (C7H 16 N)Br, add 5 ml of absolute ethanol and 0.1 g of binder.

[0078] Specifically, during the tabletting in Step 3, dry press for 150 seconds under a pressure of 2 Mpa to obtain a wafer with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as Figure 1 shown.

[0079] Example 6

[0080] Antiferroelectric molecular ceramic (C7H 16 N)Br 0.75 Cl 0.25 (0 < x ≤ 1) Preparation

[0081] An antiferroelectric molecular ceramic material, including the following scheme:

[0082] I. Grind (C7H 16 N)Cl and (C7H 16 N)Br with a stoichiometric ratio of 3:1 for the first time. During the grinding process, add an appropriate amount of absolute ethanol and binder for granulation until the grinding is uniform;

[0083] II. Sinter the mixture powder obtained in Step I at a pre-sintering temperature of 80 °C for 12 h. Then, take out the pre-sintered mixture for the second grinding to obtain a powder with a particle size range of 2 - 5 μm;

[0084] III. Tablet the powder obtained in Step II with a powder tabletting machine;

[0085] IV. Finally, place the tablet obtained in Step III in a vacuum drying oven and sinter at a temperature of 180 °C for 1 hour to obtain the antiferroelectric molecular ceramic (C7H 16 N)Br 0.75 Cl 0.25 .

[0086] Specifically, for every 10 g of (C7H 16 N)Cl and (C7H 16 N)Br in Step I, add 10 ml of absolute ethanol and 0.2 g of binder.

[0087] Specifically, during the tabletting in Step 3, dry press for 30 seconds under a pressure of 5 Mpa to obtain a wafer with a thickness greater than or equal to 0.2 mm and a diameter greater than or equal to 1 cm. The preparation process is as Figure 1 shown.

[0088] Perform a hysteresis loop test on the antiferroelectric molecular ceramic (C7H 16 N)Br 0.5 Cl 0.5 obtained in Example 5, as Figure 4As shown. In the antiferroelectric phase, at a test frequency of 50 Hz, the current density and electric field exhibit obvious antiferroelectric and ferroelectric characteristics, displaying saturation polarization intensity comparable to that of crystalline materials. The releaseable energy density W of the sample was obtained by fitting and calculating the hysteresis loop. re (J / cm 3 The total energy storage density W st (J / cm 3 Energy loss W loss (J / cm 3 The energy storage efficiency η is shown in Table 1, which indicates that the molecular ceramics prepared in this embodiment have potential application value in the field of energy storage.

[0089] like Figure 2 As shown, SEM analysis revealed that the ceramic exhibited uniform grain size and a relatively dense surface morphology. The phase transition temperature of the ceramic was determined using dielectric temperature spectroscopy. Figure 3 The results show that solid solution molecular ceramics can achieve a wide range of adjustable phase transition temperatures.

[0090] Hysteresis loop of antiferroelectric ceramics was tested using a Sawyer-Tower circuit. Figure 4 The results show that the molecular ceramics prepared in this embodiment have potential application value in the field of energy storage.

[0091] The antiferroelectric molecular ceramics prepared in other embodiments also have good saturation polarization intensity and moderate coercivity field.

[0092] Table 1 Performance parameters of the antiferroelectric molecular ceramics prepared in this invention

[0093] Performance parameters <![CDATA[W re (J / cm 3 )]]> <![CDATA[W st (J / cm 3 )]]> <![CDATA[W loss ]]> η Example 1 0.31 0.62 0.31 50％ Example 2 0.40 0.82 0.42 49％ Example 3 0.35 0.75 0.40 47％ Example 4 0.54 0.96 0.42 56％ Example 5 0.55 1.00 0.46 55％ Example 6 0.55 1.05 0.50 52％

[0094] This invention is not limited to the above embodiments. Any substitutions and improvements made based on the principles of this invention are within the scope of protection of this invention.

Claims

1. A method for preparing an antiferroelectric molecular ceramic material, characterized in that: Includes the following steps:

1. A stoichiometric ratio of 1:1 (C7H) 16 N)Cl and (C7H 16 N)Br was mixed and ground for the first time. During the grinding process, an appropriate amount of anhydrous ethanol and adhesive were added to granulate until the grinding was uniform.

2. The mixture powder obtained in step 1 is sintered at a pre-calcination temperature of 50°C for 36 hours. Then, the pre-calcined mixture is taken out and ground a second time to obtain powder with a particle size range of 2-5μm.

3. Compress the powder obtained in step 2 into tablets using a powder tableting machine; Fourth, finally, the pressed tablets obtained in step three are sintered in a vacuum drying oven at 160°C for 3 hours to obtain antiferroelectric molecular ceramics (C7H). 16 N)Br 0.5 Cl 0.5 ; Furthermore, the aforementioned antiferroelectric molecular ceramic material exhibits a saturation polarization intensity in the antiferroelectric phase similar to that of a single crystal, and its energy release density Wre reaches 0.55 J / cm² at a test frequency of 50 Hz. 3 The total energy storage density Wst reaches 1.00 J / cm³. 3 The energy storage efficiency η reaches 55%.

2. The application of an antiferroelectric molecular ceramic material prepared by the method of claim 1 in energy storage devices.

3. The application of an antiferroelectric molecular ceramic material prepared by the method of claim 1 in an electric card refrigeration device.

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