Aurivillius phase ferroelectric thin film prepared in large area and method and use thereof

Abstract

The application discloses Aurivillius phase ferroelectric thin film prepared in a large area and a method and application thereof, and relates to the technical field of ferroelectric thin film. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The Aurivillius phase ferroelectric thin film is prepared by the following steps: step one, preparing a precursor solution of the Aurivillius phase ferroelectric thin film by using ethylene glycol methyl ether as a solvent, and obtaining the precursor solution with Na 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The calculated concentration is 0.08mol / L-0.12mol / L; step two, performing surface pretreatment on a substrate A to obtain a substrate B; step three, coating the precursor solution on the substrate B to form a wet film, and then blowing the wet film flat by using an air knife; step four, annealing the wet film obtained in step three by sequentially passing through a low-temperature drying area, a medium-temperature pyrolysis area and a high-temperature crystallization area; and step five, repeating steps two to four for m times, so that the obtained Aurivillius phase ferroelectric thin film is a Na 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The Aurivillius phase ferroelectric thin film. The Aurivillius phase ferroelectric thin film is prepared in a large area by using the method, and has considerable recoverable energy storage density and efficiency.

Description

Technical Field

[0001] This invention relates to the field of dielectric energy storage technology. Specifically, it relates to a method for fabricating large-area Aurivillius phase ferroelectric thin films and their applications. Background Technology

[0002] With population growth, accelerated industrialization, and the widespread use of electronic devices, the demand for energy and natural resources continues to rise. Faced with the increasing depletion of non-renewable resources such as coal, oil, and natural gas, developing low-cost, pollution-free energy storage devices with high energy density and excellent fast-charging performance has become an urgent need for achieving green intermittent energy storage. Dielectric thin-film capacitors, with their high power density and ultra-fast charging and discharging characteristics, occupy a key position in pulse power systems such as hybrid vehicles, rocket propulsion systems, medical defibrillators, and pacemakers. However, compared to energy storage systems such as electrochemical capacitors and batteries, the energy density of organic energy storage films as dielectric materials is relatively low, severely restricting the integration and precision development of electronic devices.

[0003] Researchers have developed various methods to prepare dielectric thin films with high energy storage performance. Among them, Aurivillius phase Bi-based layered perovskite thin films have attracted much attention in the fields of dielectric energy storage and electronic devices due to their advantages such as large ferroelectric polarization, excellent fatigue characteristics, high Curie temperature, and lead-free environmental friendliness. Their general formula is (Bi₂O₂). 2+ (A n-1 B n O 3n+1 ) 2- (where A is Na) + K + 、Sr 2+ Ba 2+ Bi 3+ Iso-12-coordinated cations, B is Ti 4+ Fe 3+ 、Nb 5+ Ta 5+ Mg 2+ (Eight-coordinated cations, where n is the number of BO6 octahedral layers).

[0004] Although numerous methods exist for preparing such thin films, most are limited to small-scale laboratory preparation and lack effective means for large-area, large-scale preparation. Furthermore, some large-area preparation methods lead to a significant decrease in the ferroelectric properties of the thin films, greatly limiting their application in practical engineering. Therefore, there is an urgent need to develop a technique for preparing Aurivillius phase ferroelectric thin films that can balance large-area preparation with high-performance output. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method and application for large-area preparation of Aurivillius phase ferroelectric thin films, aiming to break through the bottleneck of existing preparation technology of Aurivillius phase ferroelectric thin films and lay the foundation for their large-scale application.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A large-area fabrication of Aurivillius phase ferroelectric thin films, wherein the Aurivillius phase ferroelectric thin films are Na films with an area ranging from centimeters to meters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films.

[0008] A method for large-area preparation of Aurivillius phase ferroelectric thin films includes the following steps:

[0009] Step 1: Prepare a precursor solution for the Aurivillius phase ferroelectric thin film using ethylene glycol methyl ether as a solvent. The prepared precursor solution is then used with Na... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The calculated concentrations are 0.08 mol / L to 0.12 mol / L;

[0010] Step 2: Perform surface pretreatment on substrate A and set aside for later use;

[0011] Step 3: After the precursor liquid is scraped onto the substrate B to form a wet film, it is then smoothed out with an air knife.

[0012] Step 4: The wet film obtained in Step 3 is annealed by sequentially passing it through a low-temperature drying zone, a medium-temperature pyrolysis zone, and a high-temperature crystallization zone.

[0013] Step 5: Repeat steps 2 through 4 m times to obtain an Aurivillius phase ferroelectric thin film with an area ranging from centimeters to meters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films.

[0014] Using ethylene glycol methyl ether as a solvent, ferroelectric thin films of the Aurivillius phase with specific molar ratios of target elements were prepared. A combination of blade coating and air knife techniques was employed, and each film underwent sequential annealing treatment in a low-temperature drying zone, a medium-temperature pyrolysis zone, and a high-temperature crystallization zone. This method not only enables the large-area preparation of Na+ phase ferroelectric thin films with areas ranging from centimeters to meters.0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 It is a phase ferroelectric thin film, and can also ensure that the thin film has good ferroelectric properties, which has broad prospects for engineering applications.

[0015] In the above-mentioned method for preparing large-area Aurivillius phase ferroelectric thin films, the preparation method of the precursor solution in step one is as follows: magnesium source, sodium source and bismuth source are added sequentially to a beaker containing solvent. After they are completely dissolved, tetrabutyl titanate is added dropwise, followed by pentapentine. Stirring is continued until tetrabutyl titanate and pentapentine are completely dissolved, thus obtaining the raw material dispersion. Solvent is added to make up the volume of the raw material dispersion to the required capacity, and the mixture is aged under sealed conditions to obtain the precursor solution.

[0016] The above-described method for large-area preparation of Aurivillius phase ferroelectric thin films employs a sol-gel method, which features low energy consumption, ease of industrialization, and low cost. When preparing Aurivillius phase ferroelectric thin films, the value of m determines the film thickness; when the film is too thick or too thin, its surface morphology and electrical properties will be affected.

[0017] The above-mentioned method for preparing large-area Aurivillius phase ferroelectric thin films uses magnesium acetate, sodium acetate, and bismuth nitrate as magnesium source, sodium acetate, and bismuth nitrate, respectively, in a molar ratio of 1:1:(11~13). More specifically, the molar ratio can be 10:10:121. The excess bismuth nitrate can compensate for the volatilization loss of the Bi source during high-temperature heat treatment, thereby ensuring that the final thin film has the correct stoichiometry, good crystallinity, and excellent ferroelectric properties.

[0018] The above-described method for large-area preparation of Aurivellius phase ferroelectric thin films involves an aging temperature of 15–20 °C and an aging time of 100–140 h. Appropriate aging temperature and time facilitate the full polymerization reaction of the raw materials in the dispersion. The resulting precursor solution contains Na... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The calculated concentration is 0.08 mol / L to 0.12 mol / L. The Na content in the current driving solution... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18When the concentration of the precursor solution is greater than 0.12 mol / L, the viscosity will be high, making it difficult for the precursor solution to be uniformly coated on the substrate surface, thus affecting the uniformity and smoothness of the film, and potentially causing abnormal grain growth during annealing and crystallization. When the concentration of the precursor solution is less than 0.08 mol / L, the final film has insufficient density and poor mechanical properties, which will affect the dielectric properties and long-term stability of the film.

[0019] In the above-mentioned method for large-area preparation of Aurivellius phase ferroelectric thin films, in step two, the substrate A is an LNO / SiO2 / Si(111) substrate or an LNO / SiO2 / Si(110) substrate, and the substrate B is the substrate A after surface pretreatment. LNO serves as a buffer layer, exhibiting better lattice compatibility with the thin film material. Furthermore, this composite substrate provides an excellent interface, reduces defects, and improves the crystal quality of the thin film, thereby optimizing the ferroelectric properties. By changing the orientation of the silicon substrate, LNO (lanthanum nickelate) thin films are prepared, thus affecting the area of ​​Na+ in the centimeter to meter range. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Regarding the ferroelectric properties of ferroelectric thin films, a 110 substrate will cause LNO to grow more towards the 100 orientation, while a 111 substrate will cause LNO to grow towards the 110 orientation.

[0020] In the above-mentioned method for preparing large-area Aurivillius phase ferroelectric thin films, the surface pretreatment method in step two is as follows: the substrate A is placed in an oxygen ion plasma treatment instrument for surface plasma treatment, thereby improving the surface activity of substrate A through surface pretreatment.

[0021] The aforementioned method for large-area preparation of Aurivillius phase ferroelectric thin films utilizes an oxygen ion plasma treatment apparatus with an oxygen pressure of 13–18 Pa, a temperature of 23–28 °C, a radio frequency power of 35–45 W, and a treatment time of 120–240 s. Appropriate oxygen plasma treatment effectively cleans the substrate surface, removes contaminants, and increases roughness, thereby enhancing the adhesion between the thin film and the substrate. Simultaneously, it introduces active oxygen, reduces oxygen vacancies in the thin film, facilitates the formation of a complete crystal structure, and optimizes ferroelectric properties. Furthermore, it improves interfacial electrical properties, reduces leakage current, and overall enhances the quality and stability of the thin film.

[0022] In the above-mentioned method for large-area preparation of Aurivillius phase ferroelectric thin films, the surface pretreatment method in step two can also be: placing substrate A in an annealing furnace and performing rapid annealing treatment under an oxygen atmosphere at a temperature of 500℃~700℃ for 5~10 min, wherein the oxygen beam flow rate is 0.1~0.3 L / min, which is used to improve the surface activity of the substrate while meeting the needs of large-area preparation in the factory.

[0023] In the above-described method for large-area preparation of Aurivillius phase ferroelectric thin films, the amount of precursor solution used in step three is 60-120 μL, which can be adjusted as needed. A reasonable amount of precursor solution can be matched with the doctor blade size and substrate area, avoiding waste due to over-coating or incomplete coating due to insufficient amount. During doctor blade coating, a doctor blade size of 5-20 cm is used, the distance between the doctor blade and substrate A is 100-400 μm, the coating temperature is 20℃-30℃, and the coating speed is 2-20 mm / s. An air knife or nitrogen air knife is used, with a pressure of 0.02-0.1 MPa and a moving speed of 2-20 mm / s. The purpose of using an air knife is twofold: first, to flatten the film; and second, to accelerate film drying, thus accelerating film formation and improving efficiency. An appropriate doctor blade size can flexibly handle substrates of different widths, ensuring coating coverage while balancing operational flexibility and coating efficiency. A suitable doctor blade-substrate distance allows for precise control of the initial wet film thickness, providing a solid foundation for the formation of a uniform film. Furthermore, the distance between the doctor blade and the substrate in this application provides a gravitational effect, resulting in a thinner final film relative to the distance between the doctor blade and the substrate. A suitable coating temperature and a reasonable coating speed work together to ensure stable spreading of the precursor liquid on the substrate surface, reducing problems such as sagging and uneven drying caused by improper temperature or speed imbalances, and ensuring the regularity of the initial film morphology. When using an air knife or nitrogen air knife, if the air pressure is set appropriately and combined with a suitable air knife movement speed, excess liquid on the film surface can be efficiently removed, resulting in good film smoothing. This also avoids damage to the film caused by excessive air pressure or improper movement speed, effectively reducing film defects and ultimately contributing to obtaining a film with excellent uniformity and stable quality.

[0024] In the above-described method for large-area preparation of Aurivillius phase ferroelectric thin films, step four employs a rapid annealing process, placing the wet film in a three-temperature-zone annealing furnace. The three temperature zones correspond to the film's drying, pyrolysis, and crystallization, respectively, with the specific parameters as follows:

[0025] Drying stage: The drying temperature is 260℃~320℃, and the drying time is 2.5~3.5min; this temperature is to dry the film and set its shape, and a reasonable drying temperature and drying time helps to promote the full crystallization of the film during the annealing process;

[0026] Pyrolysis stage: The pyrolysis temperature is 420℃~480℃, and the pyrolysis time is 3~5 min. A reasonable pyrolysis temperature can fully decompose substances such as nitrates and acetates in the film, promote the next crystallization, reduce the defect stress of the film, and avoid uneven cracking of the film caused by direct heating to 650℃~750℃.

[0027] Crystallization stage: The crystallization temperature is 650~750℃, allowing the film to crystallize into a phase. Oxygen is introduced during crystallization (oxygen can be introduced throughout the entire process, but it is introduced only during crystallization to save oxygen, although it is generally introduced earlier for experimental stability). The oxygen beam flow rate is 0.1~0.3L / min. Inappropriate crystallization temperature or time may cause changes in the crystal structure of the film, thereby affecting its dielectric properties and reliability. Too low or too high oxygen pressure will affect the microstructure of the film and introduce defects. Conversely, reasonable control of the oxygen beam flow rate, heat treatment temperature and time can promote the full crystallization of the film, thereby obtaining a film with excellent performance.

[0028] The crystallization time is 4-6 min for the first to the (m-1)th crystallization, and 8-12 min for the mth annealing; the value of m ranges from 8 to 12.

[0029] This invention can also disclose a Na 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The application of ferroelectric thin films, specifically the preparation of Na films with areas ranging from centimeters to meters, is discussed. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films are used in dielectric energy storage materials.

[0030] The technical solution of the present invention achieves the following beneficial technical effects:

[0031] 1. Achieve efficient and uniform coating over large areas

[0032] Currently, the main method for large-area fabrication of energy storage films is organic energy storage films, which have relatively low energy storage density. This application, however, uses a combination of blade coating and air knife leveling, and incorporates Na... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18The calculated concentration of the precursor solution is 0.08~0.12 mol / L. With the help of a doctor blade, the precursor solution is coated onto the substrate surface through gravity and the surface activity of the substrate. Then, a high-speed airflow is used to perform a secondary smoothing of the film surface, which promotes the efficient and uniform spread of the sol on the substrate surface. This avoids the thicker film produced by the slurry coating method in the prior art. It also effectively avoids the problems of cracks and low density caused by uneven stress during the drying process. Moreover, the film thickness deviation is small and the process preparation is highly stable. It solves the bottleneck of the difficulty in scaling up traditional small-size preparation technology and provides possibilities for the practical engineering applications of thin films (such as flexible electronic devices and energy storage devices).

[0033] Furthermore, by combining subsequent low-temperature drying, medium-temperature pyrolysis, and high-temperature crystallization annealing processes, precise control of the pyrolysis of organic matter and the crystallization of the ceramic phase can promote full crystallization of the film, reduce defects such as oxygen vacancies and dislocations, and facilitate the formation of a complete Aurivillius phase layered structure. This improves key properties of the film such as ferroelectric polarization and dielectric constant. Simultaneously, by combining repeated coating and optimizing the crystallization time for each layer, dense interlayer bonding is ensured, avoiding interlayer porosity, thus enhancing the Na produced by this invention. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 While meeting the requirements for large-area (e.g., centimeter-scale to meter-scale) fabrication, ferroelectric thin films can still maintain relatively good ferroelectric properties.

[0034] 2. Precise control of film thickness and composition uniformity

[0035] By adjusting the gap between the doctor blade and the substrate, the airflow pressure of the air knife, and the viscosity of the sol, the thickness of the Aurivillius phase film (from tens of nanometers to several micrometers) can be precisely controlled to meet the specific thickness requirements of different devices. Simultaneously, the uniformity of the airflow reduces localized aggregation of solutes in the sol, avoiding microstructural defects (such as impurities and porosity) caused by component segregation. This ensures the compositional uniformity of the film on a macroscopic scale, laying the foundation for the formation of a stable layered perovskite structure (characteristic of the Aurivillius phase) during subsequent crystallization.

[0036] 3. Reduce thin film defects and stress, and optimize microstructure.

[0037] Compared to physical deposition methods such as sputtering and vapor deposition, air knife coating is a liquid phase coating process. The spreading and drying process of the sol on the substrate surface is gentler, which can reduce lattice damage or stress accumulation caused by high-energy particle bombardment.

[0038] 4. Strong process compatibility and low cost

[0039] Air knife coating equipment has a relatively simple structure and is widely compatible with substrates. It is suitable for both rigid substrates (such as silicon wafers and ceramics) and flexible substrates (such as polyimide films). The raw materials are sol-gel systems (such as organometallic precursors), and the cost is lower than that of high-purity target materials, making it suitable for large-scale industrial production. Attached Figure Description

[0040] Figure 1 Na prepared in Example 1 of this invention 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Phase ferroelectric thin films and Na prepared in Example 2 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 XRD patterns of ferroelectric thin films;

[0041] Figure 2 Na prepared in Example 1 of this invention 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Phase ferroelectric thin films and Na prepared in Example 2 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 PE loop of ferroelectric thin film;

[0042] Figure 3 (a) Na prepared in Example 1 of the present invention 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Phase ferroelectric thin films and Na prepared in Example 2 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The energy storage density of phase ferroelectric thin films;

[0043] Figure 3 (b) Na prepared in Example 1 of the present invention 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Thin film and Na prepared in Example 2 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18The energy storage efficiency of ferroelectric thin films. Detailed Implementation

[0044] Example 1

[0045] Through research and exploration of the air knife coating process, the inventors successfully prepared a large-area Na coating with a centimeter-scale area on a 70*70*0.5mm LNO / SiO2 / Si(111) substrate. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films.

[0046] In this embodiment, a five-layer Na₂O₃ with an area on the centimeter scale was prepared using an air knife coating machine, an oxygen ion plasma treatment instrument, and a three-temperature zone annealing furnace. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films. All chemical reagents used were of analytical grade, with a purity of over 99.9%. The method was as follows:

[0047] (1) 0.5415g magnesium acetate, 0.2071g sodium acetate, and 14.8216g bismuth nitrate were sequentially added to a beaker containing 30 mL of ethylene glycol methyl ether. After the magnesium acetate, sodium acetate, and bismuth nitrate were completely dissolved, 7.7355g tetrabutyl titanate and 3.4132g pentanedione were added dropwise. The mixture was stirred until the tetrabutyl titanate and pentanedione were completely dissolved, thus obtaining the raw material dispersion. Ethylene glycol methyl ether was added to bring the volume of the raw material dispersion to 50 mL, and the mixture was aged at 18°C ​​under sealed conditions for 120 hours. During the aging process, bismuth nitrate, sodium acetate, magnesium acetate, and tetrabutyl titanate underwent a condensation reaction. After aging, Na was obtained. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 A precursor solution with a concentration of 0.1 mol / L;

[0048] (2) The LNO / SiO2 / Si(111) substrate was placed in an oxygen plasma treatment instrument for surface treatment. During the surface plasma treatment, the oxygen pressure in the oxygen ion plasma treatment instrument was 15 Pa, the temperature was 25 °C, the radio frequency power was 40 W, and the treatment time was 180 s;

[0049] (3) Add the precursor liquid obtained in step (1) into the gap between the doctor blade and the LNO / SiO2 / Si(111) substrate obtained in step (2) using a pipette. The amount of precursor liquid added is 90 μL, the doctor blade size is 8 cm, the distance between the doctor blade and the substrate is 300 μm, the coating temperature is 25℃, and the coating speed is 5 mm / s. After the doctor blade has scraped the entire substrate surface, turn on the air knife to blow the wet film flat. The air knife is an air knife with a pressure of 0.05 MPa and a moving speed of 10 mm / s.

[0050] (4) Using the “rapid annealing” process, the wet film obtained in step (3) is placed in a three-temperature zone annealing furnace, and the three temperature zones are dried, pyrolyzed and crystallized respectively. The drying temperature is 280℃ and the drying time is 3min. The pyrolysis temperature is 450℃ and the pyrolysis time is 4min. The crystallization temperature is 700℃ and the crystallization time is 5min. Oxygen is introduced during crystallization, and the flow rate of the oxygen stream is 0.2L / min.

[0051] (5) Repeat steps (2) to (4) 10 times. During the 10th crystallization, anneal at 700℃ for 10 minutes to allow the material to fully crystallize and promote tight bonding between layers, to obtain Na with an area on the order of centimeters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films.

[0052] Example 2

[0053] In this embodiment, the precursor solution from Example 1 was used for coating to prepare a large-area Na substrate with an area on the centimeter scale on a Si-oriented substrate LNO / SiO2 / Si(110) different from that in Example 1. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 A five-layer Na₂Aurivillius phase ferroelectric thin film was prepared using an air knife coating machine, an oxygen ion plasma treatment system, and a three-zone annealing furnace, with a surface area on the order of centimeters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films. The method is as follows:

[0054] (1) The LNO / SiO2 / Si(110) substrate was placed in an oxygen plasma treatment instrument for surface treatment. During the surface plasma treatment, the oxygen pressure in the oxygen ion plasma treatment instrument was 15 Pa, the temperature was 25 °C, the radio frequency power was 40 W, and the treatment time was 180 s;

[0055] (2) The precursor liquid obtained in step (1) of Example 1 was added to the gap between the doctor blade and the LNO / SiO2 / Si(110) substrate obtained in step (1) of Example 2 using a pipette. The amount of precursor liquid added was 90 μL, the doctor blade size was 8 cm, the distance between the doctor blade and the substrate was 300 μm, the coating temperature was 25℃, and the coating speed was 5 mm / s. After the doctor blade had scraped the entire substrate surface, the air knife was turned on to blow the wet film flat. The air knife was an air knife with a pressure of 0.05 MPa and a moving speed of 10 mm / s.

[0056] (3) Using the “rapid annealing” process, the wet film obtained in step (2) is placed in a three-temperature zone annealing furnace, and the three temperature zones are dried, pyrolyzed and crystallized respectively. The drying temperature is 280℃ and the drying time is 3min. The pyrolysis temperature is 450℃ and the pyrolysis time is 4min. The crystallization temperature is 700℃ and the crystallization time is 5min. Oxygen is introduced during crystallization, and the flow rate of the oxygen stream is 0.2L / min.

[0057] (4) Repeat steps (2) to (3) 10 times. During the 10th crystallization, anneal at 700 °C for 10 min to allow the material to fully crystallize and promote tight bonding between layers, to obtain Na with an area on the order of centimeters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films.

[0058] X-ray diffraction was used to analyze Na prepared on different Si-based substrates. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Crystal structure of ferroelectric thin films; measurement of Na₂O₃ prepared on different Si-based substrates using a ferroelectric analyzer. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The PE loop of the ferroelectric thin film is used to convert the voltage into an electric field and calculate the recyclable energy storage density and efficiency of the two films.

[0059] like Figure 1 The image shows a Na+ nanofiber with a surface area on the centimeter scale prepared on LNO / SiO2 / Si(111) in Example 1. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The phase ferroelectric thin film and the centimeter-scale Na film prepared on LNO / SiO2 / Si(110) in Example 2 0.5 Bi 5.5 Ti4.5 Mg 0.5 O 18 XRD patterns of ferroelectric thin films. The figures show Na+ with an area on the order of centimeters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The main peak of the ferroelectric thin film is (1111), indicating that the five-layer Aurivillius phase Na in Examples 1 and 2... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 All phase ferroelectric thin films were successfully prepared.

[0060] like Figure 2 Na₂ with an area on the centimeter scale, prepared in Example 1, are respectively 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The ferroelectric thin film and the Na film with an area on the centimeter scale prepared in Example 2 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The PE loop of the ferroelectric thin film. It can be seen that both embodiments exhibit typical PE loop diagrams of ferroelectric materials.

[0061] like Figure 3 a and Figure 3 b represents the Na+ particles with an area on the centimeter scale prepared in Examples 1 and 2, respectively. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The energy storage density and energy storage efficiency of the phase ferroelectric thin film are shown. It can be seen that both Example 1 and Example 2 have good energy storage performance.

[0062] In practical factory applications, Na+ can be prepared with an area on the order of meters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 When processing ferroelectric thin films, due to the size limitations of the oxygen ion plasma treatment equipment, the following alternative method can be used for surface pretreatment of the substrate: place the substrate in an annealing furnace and perform rapid annealing treatment in an oxygen atmosphere at a temperature of 500℃~700℃ for 5~10min to improve surface activity, wherein the oxygen beam flow rate is 0.1~0.3L / min.

[0063] In summary, this application, through the synergistic effects of substrate surface activity, precursor liquid composition and concentration, low-temperature drying, medium-temperature pyrolysis and high-temperature crystallization annealing process, and the combination of scraping and air knife leveling, can maintain relatively good ferroelectric properties while having stronger large-area continuous production capacity and higher efficiency; higher material utilization and lower cost, with the air knife scraping method achieving a material utilization rate of over 80%, and reducing waste through linear coating; and simple equipment with low investment costs.

[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for large-area preparation of Aurivillius phase ferroelectric thin films, characterized in that, Includes the following steps: Step 1: Prepare a precursor solution for the Aurivillius phase ferroelectric thin film using ethylene glycol methyl ether as a solvent. The prepared precursor solution is then used with Na... 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The calculated concentrations are 0.08 mol / L to 0.12 mol / L; Step 2: Perform surface pretreatment on substrate A to obtain substrate B, which is ready for use. Step 3: After the precursor liquid is scraped onto the substrate B to form a wet film, it is then smoothed out with an air knife. Step 4: The wet film obtained in Step 3 is annealed by sequentially passing it through a low-temperature drying zone, a medium-temperature pyrolysis zone, and a high-temperature crystallization zone. Step 5: Repeat steps 2 through 4 m times to obtain an Aurivillius phase ferroelectric thin film with an area ranging from centimeters to meters. 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films; In step three, the scraper size is 5~20cm, the distance between the scraper and the substrate A is 100~400μm, the scraping temperature is 20℃~30℃, the scraping speed is 2~20mm / s, and the air knife is an air knife or a nitrogen air knife with a pressure of 0.02~0.1MPa and a moving speed of 2~20mm / s. In step four, a rapid annealing process is used, in which the wet film is placed in a three-temperature zone annealing furnace for annealing. The three temperature zones correspond to the drying, pyrolysis, and crystallization of the film, respectively. The specific parameters are as follows: Drying stage: Drying temperature is 260℃~320℃, and drying time is 2.5~3.5min; Pyrolysis stage: The pyrolysis temperature is 420℃~480℃, and the pyrolysis time is 3~5 min; Crystallization stage: The crystallization temperature is 650~750℃. Oxygen is introduced during crystallization, and the flow rate of the oxygen stream is 0.1~0.3L / min. The crystallization time is 4-6 min for the first to the (m-1)th crystallization, and 8-12 min for the mth annealing; the value of m ranges from 8 to 12. In step two, the substrate A is an LNO / SiO2 / Si(111) substrate or an LNO / SiO2 / Si(110) substrate; In step two, the surface pretreatment method is as follows: place substrate A in an oxygen ion plasma treatment instrument for surface plasma treatment or place substrate A in an annealing furnace for rapid annealing in an oxygen atmosphere.

2. The method for large-area preparation of Aurivellius phase ferroelectric thin films according to claim 1, characterized in that, In step one, the preparation method of the precursor liquid is as follows: magnesium source, sodium source and bismuth source are added to a beaker containing solvent in sequence. After they are completely dissolved, tetrabutyl titanate is added dropwise, followed by pentapentine. Stirring is continued until tetrabutyl titanate and pentapentine are completely dissolved to obtain the raw material dispersion. Solvent is added to make up the volume of the raw material dispersion to the required capacity, and the mixture is aged under sealed conditions to obtain the precursor liquid.

3. The method for large-area preparation of Aurivillius phase ferroelectric thin films according to claim 2, characterized in that, The magnesium source, sodium source, and bismuth source are magnesium acetate, sodium acetate, and bismuth nitrate, respectively, with a molar ratio of 1:1:(11~13); the aging temperature is 15~20℃, and the aging time is 100~140h.

4. The method for large-area preparation of Aurivillius phase ferroelectric thin films according to claim 1, characterized in that, The oxygen pressure in the oxygen ion plasma processor is 13-18 Pa, the temperature is 23-28℃, the radio frequency power is 35-45 W, and the processing time is 120-240 s; the annealing temperature is 500℃-700℃, the time is 5-10 min, and the oxygen beam flow rate is 0.1-0.3 L / min. 5.Na 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 The application of ferroelectric thin films is characterized by, Na₂ with an area ranging from centimeters to meters, prepared by any one of claims 1 to 4 0.5 Bi 5.5 Ti 4.5 Mg 0.5 O 18 Ferroelectric thin films are used in dielectric energy storage materials.

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