A lanthanum, vanadium and iron co-doped bismuth titanate layered perovskite film, a preparation method and applications thereof

Abstract

The present invention relates to a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, a preparation method, and an application. The method includes the following steps: S1. Mix bismuth nitrate pentahydrate, lanthanum nitrate hexahydrate, tetrabutyl titanate, vanadyl acetylacetonate, iron nitrate nonahydrate, ethylene glycol monomethyl ether, acetic acid, and a chelating agent to obtain a Bi 3.25 La 0.75 Ti 3‑2x V x Fe x O 12 (BLTVF) sol, where 0 < x < 0.5; S2. Coat the BLTVF sol on a substrate to obtain a wet film; S3. Perform pyrolysis and annealing treatment on the wet film in air; S4. Repeat steps S2 and S3 to obtain a lanthanum, vanadium, and iron element co-doped Bi 3.25 La 0.75 Ti 3‑2x V x Fe x O 12 thin film. The present invention has significantly improved the energy storage performance and energy storage efficiency of the thin film on the Pt / Ti / SiO2 / Si substrate; the preparation method is extremely simple, the content of the added elements is flexibly controllable, the success rate of thin film preparation is high, and the repeatability is good; only simple processes and low-cost equipment are required, and the environmental requirements are simple, which is suitable for batch production.

Description

Technical Field

[0001] This invention belongs to the field of microelectronic device technology, specifically relating to a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, its preparation method, and its application. Background Technology

[0002] Dielectric capacitors store electrostatic energy through the polarization of the dielectric material under an external electric field and release this energy through the depolarization process of the dielectric after the electric field is removed. They possess ultra-high power density and fast charge / discharge rates, playing a crucial role in high-pulse power applications in defense, medical, and energy systems. Ferroelectric materials are among the candidate materials for high-energy-density capacitors. One such ferroelectric material is bismuth titanate (Bi₄Ti₃O₄). 12 It has advantages such as high Curie temperature, stable chemical properties, strong resistance to polarization fatigue, good anisotropy of crystal structure, and non-toxicity and lead-free, and has potential applications in dielectric capacitors in high-temperature environments.

[0003] High saturation polarization, dielectric strength, and low remanent polarization are crucial indicators for achieving excellent energy storage performance in dielectric materials. While bismuth titanate possesses high saturation polarization and good stability, its large remanent polarization results in a low recoverable energy density and increased energy loss, severely limiting its further applications. To improve energy storage performance, doping modification studies of bismuth titanate thin films have been conducted. Lanthanum doping significantly reduces remanent polarization and increases recoverable energy density; however, its excessively high leakage current still causes significant energy loss. To further improve the energy storage performance and efficiency of bismuth titanate thin films and ensure their low-loss and high-reliability application in novel microelectronic devices, optimization of film composition and preparation is urgently needed. Summary of the Invention

[0004] To overcome the aforementioned problems in the prior art, the present invention provides a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, its preparation method, and its application, thereby solving the problems existing in the prior art.

[0005] A method for preparing a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, the method comprising the steps of:

[0006] S1. Bi is obtained by mixing bismuth nitrate pentahydrate, lanthanum nitrate hexahydrate, tetrabutyl titanate, vanadium acetylacetone, ferric nitrate nonahydrate, ethylene glycol methyl ether, acetic acid, and a chelating agent. 3.25 La 0.75 Ti 3-2x V x Fe x O 12 Sol, specifically BLTVF sol, in which 0 <x<0.5;

[0007] S2. The BLTVF sol is coated onto the substrate to obtain a wet film;

[0008] S3. The wet film is subjected to pyrolysis and annealing in air;

[0009] S4. Repeat steps S2 and S3 to obtain Bi co-doped with lanthanum, vanadium, and iron elements of a predetermined thickness. 3.25 La 0.75 Ti 3- 2x V x Fe x O 12 film.

[0010] In addition to the aspects and any possible implementations described above, an implementation is further provided, wherein S1 specifically includes:

[0011] S11. Dissolve bismuth nitrate pentahydrate and lanthanum nitrate hexahydrate in a solution of ethylene glycol methyl ether and acetic acid in a certain volume ratio, stir at room temperature for 10-30 min, and dissolve all the solutes until clear, wherein bismuth nitrate pentahydrate is in excess by 5-10%;

[0012] S12. Add an appropriate amount of chelating agent to the solution obtained in S11 and stir at room temperature for 5-15 minutes;

[0013] S13. Add a certain amount of tetrabutyl titanate to the solution obtained in S12 and stir at room temperature for 10-20 minutes;

[0014] S14. Add a certain amount of vanadium acetylacetonate and ferric nitrate nonahydrate to the solution obtained in S13, stir at room temperature until all the solutes are dissolved and clear, then stir for another 4-8 hours, and after aging, obtain BLTVF sol.

[0015] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the chelating agent is acetylacetone.

[0016] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the substrate is a Pt, Ti, SiO2, or Si substrate.

[0017] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the preset thickness is 200–600 nm.

[0018] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the value of x ranges from 0.05 to 0.40.

[0019] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the volume ratio of S11 is 4:1, the mixture is stirred at room temperature for 20 minutes for 20 minutes to completely dissolve the solute until it is clear, and the excess of bismuth nitrate pentahydrate is 5%.

[0020] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the pyrolysis operation step is to hold at 180-220°C for 3-7 minutes, and then raise the temperature to 350-450°C and hold for 3-7 minutes.

[0021] This invention also provides a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, which is prepared by the aforementioned method, and the recoverable energy density of the film is 30-50 J / cm². 3 The energy storage efficiency is 60-80%.

[0022] The present invention also provides an application of the aforementioned thin film in a novel ferroelectric memory.

[0023] Beneficial effects of the present invention

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) Compared with the existing technology, the energy storage performance and energy storage efficiency of thin films on Pt / Ti / SiO2 / Si substrates have been significantly improved.

[0026] (2) The preparation method of the present invention is extremely simple, the content of added elements is flexible and controllable, the success rate of thin film preparation is high, and the repeatability is good.

[0027] (3) The preparation method of the present invention only requires a simple process and inexpensive equipment, and the environmental requirements are simple, making it suitable for mass production. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the thin film of the present invention;

[0030] Figure 3 This is a schematic diagram of the polarization-voltage curves of undoped, lanthanum-doped, and lanthanum, vanadium, and iron co-doped thin films constructed on Pt / Ti / SiO2 / Si substrates according to the comparative examples and embodiments.

[0031] Figure 4 This diagram illustrates the recoverable energy density and energy storage efficiency of undoped, lanthanum-doped, and lanthanum, vanadium, and iron co-doped thin films constructed according to the comparative examples and embodiments on Pt / Ti / SiO2 / Si substrates. Detailed Implementation

[0032] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0033] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0034] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0035] like Figure 1 As shown, this invention discloses a method for preparing a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film. The lanthanum, vanadium, and iron co-doped bismuth titanate (Bi) 3.25 La 0.75 Ti 3-2x V x Fe x O 12 The film, also referred to below as a BLTVF film or simply a film, refers to the film prepared by the method of the present invention, which includes the steps of:

[0036] S1. Bismuth nitrate pentahydrate, tetrabutyl titanate, lanthanum nitrate hexahydrate, vanadium acetylacetonate, and ferric nitrate nonahydrate are dissolved in a mixed solvent of ethylene glycol methyl ether, acetic acid, and a chelating agent in stoichiometric ratio to obtain Bi. 3.25 La 0.75 Ti 3- 2x V x Fe x O 12 Sol, specifically BLTVF sol, in which 0 <x<0.5;

[0037] S2. The BLTVF sol is coated onto the substrate to obtain a wet film;

[0038] S3. The wet film is subjected to pyrolysis and annealing in air;

[0039] S4. Based on step S3, repeat steps S2 and S3 to obtain the Bi of the preset thickness. 3.25 La0.75 Ti 3- 2x V x Fe x O 12 A thin film with an extended last annealing time.

[0040] Preferably, S1 specifically includes:

[0041] S11. Dissolve bismuth nitrate pentahydrate and dopant lanthanum nitrate hexahydrate in a mixed solution of ethylene glycol methyl ether and acetic acid with a certain volume ratio, and stir at room temperature for 10 - 30 min until all solutes are dissolved to clarity. The bismuth nitrate pentahydrate should be in an excess of 5 - 10%, that is, exceeding the stoichiometric ratio by 5 - 10% to compensate for the volatilization of bismuth during the heat treatment. Preferably, the volume ratio is 4:1, 20 min, and an excess of 5%;

[0042] S12. Add an appropriate amount of chelating agent to the solution obtained in S11, and stir at room temperature for 5 - 15 min, preferably 10 min;

[0043] S13. Weigh tetrabutyl titanate according to the stoichiometric ratio (Bi 3.25 La 0.75 Ti 3-2x V x Fe x O 12 , 0 < x < 0.5) and add it to the solution obtained in S12, and stir at room temperature for 10 - 20 min, preferably 15 min;

[0044] S14. Weigh dopants vanadyl acetylacetonate and ferric nitrate nonahydrate according to the stoichiometric ratio (Bi 3.25 La 0.75 Ti 3-2x V x Fe x O 12 , 0 < x < 0.5) and add them to the solution obtained in S13. The doping content is flexibly controllable within this range. Stir at room temperature, and after all solutes are dissolved to clarity, stir for another 4 - 8 h. After aging, a BLTVF sol is obtained, preferably stirring for 6 h.

[0045] Preferably, S2 further includes: ultrasonically cleaning the substrate with acetone and absolute ethanol for 30 min each to remove oil stains and impurities on the substrate surface.

[0046] Preferably, the chelating agent is acetylacetone.

[0047] Preferably, the substrate is a Pt / Ti / SiO2 / Si substrate.

[0048] Preferably, the preset thickness is 200 - 600 nm, and within this thickness range, the leakage current and fatigue resistance are good.

[0049] Preferably, the value of x ranges from 0.05 to 0.40.

[0050] Specifically, the preparation process of the present invention is as follows:

[0051] (1) Dissolve bismuth nitrate pentahydrate and lanthanum nitrate hexahydrate in a solution of ethylene glycol methyl ether and acetic acid in a volume ratio of 4:1, stir at room temperature for 20 min, and dissolve all the solutes until clear. Bismuth nitrate pentahydrate should be in excess by 5%.

[0052] (2) Add an appropriate amount of acetylacetone as a chelating agent to the solution obtained in (1) and stir at room temperature for 10 min;

[0053] (3) Weigh a certain amount of tetrabutyl titanate and add it to the solution obtained in (2), and stir at room temperature for 15 minutes;

[0054] (4) Weigh a certain amount of vanadium acetylacetonate and ferric nitrate nonahydrate into the solution obtained in (3), stir at room temperature until all the solutes are dissolved and the solution is clear, then stir for another 6 hours. After aging, Bi is obtained. 3.25 La 0.75 Ti 3-2x V x Fe x O 12 (BLTVF) sol, where 0 < x < 0.5; the BLTVF sol prepared by the present invention in steps (2)-(3) is stable and does not easily settle compared with other methods;

[0055] (5) Spin-coating the BLTVF sol described above onto a Pt / Ti / SiO2 / Si substrate to obtain a wet film;

[0056] (6) The wet film is subjected to pyrolysis and annealing treatment;

[0057] (7) Based on step (6), repeat steps (5) and (6) to obtain a BLTVF film of a preset thickness, wherein the annealing time of the last layer is extended to 15 min, and the film is a doped dielectric film.

[0058] Preferably, in step (4), the value of x is 0.05-0.40.

[0059] Preferably, in step (4), the aging process of BLTVF sol is carried out at room temperature for 24-72 hours.

[0060] Preferably, in step (4), the concentration of BLTVF sol is 0.05-0.1 mol / L, and the film surface prepared by sol within this concentration range is smoother and flatter.

[0061] Preferably, in step (5), the BLTVF sol is spin-coated at a low speed of 300-500 r / s for 3-8 s to ensure that the sol is tightly bonded to the substrate, resulting in a smoother film. Then, it is spin-coated at a speed of 3500-4500 r / s for 20-30 s to obtain a uniform and smooth wet film, thereby achieving the required thickness for each layer of the film and obtaining the wet film.

[0062] Preferably, between steps (4) and (5), the substrate is cleaned with a suitable solvent to remove oil and impurities from the substrate surface, which facilitates the subsequent spin coating operation.

[0063] Preferably, in step (6), the wet film is subjected to pyrolysis and annealing. The pyrolysis operation steps are to keep the temperature at 180-220℃ for 3-7 minutes, and then raise the temperature to 350-450℃ and keep it for 3-7 minutes. Under the above reaction conditions, the organic matter in the wet film can be completely decomposed, leaving only the required material elements. Then, the film is annealed at 650-750℃ for 1-3 minutes to crystallize the film.

[0064] Preferably, in step (7), the preset thickness of the BLTVF film is 200-600 nm.

[0065] Preferably, in step (7), spin coating and pyrolysis can be repeated 8-16 times to obtain a film of a preset thickness.

[0066] Preferably, in step (7), the film of the preset thickness is annealed at 650-750℃ for 10-20 minutes to make the film have better crystallinity.

[0067] The lanthanum, vanadium, and iron co-doped bismuth titanate (Bi) prepared by the method described in this invention 3.25 La 0.75 Ti 3-2x V x Fe x O 12 Thin films, by doping with lanthanum, vanadium, and iron, and by controlling the doping content, can have their recoverable energy density (35-50 J / cm³) significantly improved. 3 ) and energy storage efficiency (60-75%).

[0068] The above-mentioned thin film structure is as follows Figure 2 As shown. The following is an explanation of the invention Bi. 3.25 La 0.75 Ti 3-2x V x Fe x O 12 (BLTVF) Taking x as 0.1 as an example, compared with undoped Bi4Ti3O 12 (BiT) thin films and Bi only doped with lanthanum 3.25 La 0.75Ti3O 12 (BLT) films are used as a comparison, and specific comparative examples and embodiments are given for illustration.

[0069] Comparative Example 1

[0070] Undoped Bi₄Ti₃O₃ substrate on Pt / Ti / SiO₂ / Si 12 The specific preparation steps for thin film materials are as follows:

[0071] (1) According to the general chemical formula Bi4Ti3O 12 Weigh 2.0579g of bismuth nitrate pentahydrate according to the stoichiometric ratio and dissolve it in a mixed solution of 16ml ethylene glycol methyl ether and 4ml acetic acid. Stir for 20min and wait for the solution to become clear.

[0072] (2) Add 0.1g of acetylacetone as a chelating agent to the solution obtained in (1) and stir at room temperature for 10min;

[0073] (3) Weigh 1.0210 g of tetrabutyl titanate according to the stoichiometric ratio and add it to the solution obtained in (2). Stir at room temperature for 6 h, and after standing for 48 h, obtain Bi4Ti3O. 12 Sol;

[0074] (4) Cut the Pt / Ti / SiO2 / Si substrate into a 10mm*10mm square and clean it with acetone and anhydrous ethanol for 30 minutes respectively to remove oil and impurities from the substrate surface.

[0075] (5) Using a spin coater, mix Bi4Ti3O 12 The sol was spin-coated onto a Pt / Ti / SiO2 / Si substrate at a low speed of 400 r / s and a high speed of 4000 r / s to obtain a wet film.

[0076] (6) Place the wet film in a rapid annealing furnace, dry at 200℃ for 5 min, pyrolyze at 400℃ for 5 min, and anneal at 700℃ for 2 min;

[0077] (7) Based on step (6), repeat steps (5) and (6) 12 times to obtain Bi4Ti3O with a preset thickness of approximately 300 nm. 12 film;

[0078] (8) Anneal the film of the preset thickness at 700℃ for 15 min to obtain Bi4Ti3O with good crystallinity. 12 film;

[0079] (9) A Pt electrode with a diameter of 0.1 mm was sputtered on the thin film surface using a vacuum coating instrument for subsequent electrical performance testing.

[0080] Comparative Example 1 above was not doped with lanthanum, vanadium, or iron, and was used to compare with the examples below.

[0081] Comparative Example 2

[0082] Bi on Pt / T i / S iO2 / Si substrate 3.25 La 0.75 Ti3O 12 The specific preparation steps for thin film materials are as follows:

[0083] (1) According to the general chemical formula Bi 3.25 La 0.75 Ti3O 12 Weigh 1.6720g of bismuth nitrate pentahydrate and 0.3280g of lanthanum nitrate hexahydrate according to the stoichiometric ratio, dissolve them in a mixed solution of 16ml ethylene glycol methyl ether and 4ml acetic acid, stir for 20min, and wait for the solution to become clear.

[0084] (2) Add 0.1g of acetylacetone as a chelating agent to the solution obtained in (1) and stir at room temperature for 10min;

[0085] (3) Weigh 1.0210 g of tetrabutyl titanate according to the stoichiometric ratio and add it to the solution obtained in (2). Stir at room temperature for 6 h, and after standing for 48 h, obtain Bi. 3.25 La 0.75 Ti3O 12 Sol;

[0086] (4) Cut the Pt / Ti / SiO2 / Si substrate into a 10mm*10mm square and clean it with acetone and anhydrous ethanol for 30 minutes respectively to remove oil and impurities from the substrate surface.

[0087] (5) Use a spin coater to coat Bi 3.25 La 0.75 Ti3O 12 The sol was spin-coated onto a Pt / Ti / SiO2 / Si substrate at a low speed of 400 r / s and a high speed of 4000 r / s to obtain a wet film.

[0088] (6) Place the wet film in a rapid annealing furnace, dry at 200℃ for 5 min, pyrolyze at 400℃ for 5 min, and anneal at 700℃ for 2 min;

[0089] (7) Based on step (6), repeat steps (5) and (6) 12 times to obtain Bi with a preset thickness of approximately 300 nm. 3.25 La 0.75 Ti3O 12 film;

[0090] (8) Anneal the film of the preset thickness at 700℃ for 15 min to obtain Bi with good crystallinity. 3.25 La 0.75 Ti3O 12 film;

[0091] (9) A Pt electrode with a diameter of 0.1 mm was sputtered on the thin film surface using a vacuum coating instrument for subsequent electrical performance testing.

[0092] Comparative Example 2 above is doped with only lanthanum and not with vanadium or iron, and is used to compare with the examples below.

[0093] Example

[0094] Bi on Pt / T i / S iO2 / Si substrate 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The specific preparation steps for thin film materials are as follows:

[0095] (1) According to the general chemical formula Bi 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Weigh 1.6720g of bismuth nitrate pentahydrate and 0.3280g of lanthanum nitrate hexahydrate according to the stoichiometric ratio, dissolve them in a mixed solution of 16ml ethylene glycol methyl ether and 4ml acetic acid, stir for 20min, and wait for the solution to become clear.

[0096] (2) Add 0.1g of acetylacetone as a chelating agent to the solution obtained in (1) and stir at room temperature for 10min;

[0097] (3) Weigh 0.9529g of tetrabutyl titanate according to the stoichiometric ratio and add it to the solution obtained in (2), and stir at room temperature for 15min;

[0098] (4) Weigh 0.0359 g of vanadium acetylacetonate and 0.0404 g of ferric nitrate nonahydrate according to the stoichiometric ratio and add them to the solution obtained in (3). Stir at room temperature until all the solutes are dissolved and the solution is clear, then stir for another 6 hours. After standing for 48 hours, Bi is obtained. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 (BLTVF) sol;

[0099] (5) Cut the Pt / Ti / SiO2 / Si substrate into a 10mm*10mm square and clean it with acetone and anhydrous ethanol for 30 minutes respectively to remove oil and impurities from the substrate surface.

[0100] (6) Using a spin coater, apply Bi... 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The sol was spin-coated onto a Pt / Ti / SiO2 / Si substrate at a low speed of 400 r / s and a high speed of 4000 r / s to obtain a wet film.

[0101] (7) Place the wet film in a rapid annealing furnace, dry at 200℃ for 5 min, pyrolyze at 400℃ for 5 min, and anneal at 700℃ for 2 min;

[0102] (8) Based on step (7), repeat steps (6) and (7) 12 times to obtain Bi with a preset thickness of approximately 300 nm. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 film;

[0103] (9) Anneal the film of the preset thickness at 700℃ for 15 min to obtain Bi with good crystallinity. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 film;

[0104] (9) A Pt electrode with a diameter of 0.1 mm was sputtered on the thin film surface using a vacuum coating instrument for subsequent electrical performance testing.

[0105] As can be seen from the examples, Bi can be fabricated on a Pt / Ti / SiO2 / Si substrate. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Thin films such as Figure 2 As shown, the thin film prepared by the method of the present invention is not limited to the above-mentioned vanadium and iron doping content, but may have other contents, all of which are within the protection scope of the present invention.

[0106] in conclusion

[0107] The above embodiments prepared Bi according to the method of the present invention.3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The thin films were characterized for their electrical properties. Polarization-voltage curves were obtained using a ferroelectric testing and analysis instrument, and the recoverable energy density and energy storage efficiency were calculated. Specifically, the prepared thin films were used as samples, and each sample group was tested at least eight times. Larger error data were discarded, and the average of the remaining data was calculated to ensure the reliability of the results. The test results are as follows:

[0108] Figure 2 The Bi prepared in the middle represents 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Thin-film capacitor structure. Figure 3 , 4 Undoped Bi4Ti3O prepared by comparative example is shown. 12 Thin film, Bi doped only with lanthanum 3.25 La 0.75 Ti3O 12 Thin films and lanthanum, vanadium, and iron co-doped Bi prepared in the examples 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Electrical performance test data of the thin film are used to demonstrate the effect of lanthanum, vanadium, and iron co-doping on the performance of the thin film.

[0109] Figure 3 The diagram shows a comparison of the polarization-voltage curves for Comparative Example 1, Comparative Example 2, and the Example on a Pt / Ti / SiO2 / Si substrate. The results indicate that the co-doping of lanthanum, vanadium, and iron significantly affects the energy storage performance of the thin film. Specifically, Comparative Example 1 uses undoped Bi4Ti3O2. 12 The thin film has very low dielectric strength but very high remanent polarization, resulting in a very low recoverable energy density and low energy storage efficiency; Comparative Example 2: Bi only doped with lanthanum 3.25 La 0.75 Ti3O 12 The thin film significantly enhances the dielectric strength and drastically reduces the remanent polarization, resulting in a substantial increase in recoverable energy density and energy storage efficiency compared to Comparative Example 1. However, the larger leakage current leads to higher energy loss. Example: Lanthanum, vanadium, and iron co-doped Bi 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O12 Based on Comparative Example 2, the thin film achieved a finer hysteresis loop by suppressing leakage current, further significantly improving the recoverable energy density and energy storage efficiency. Specifically, Comparative Example 1 uses undoped Bi4Ti3O... 12 The dielectric strength of the thin film is only 655 kV / cm, and the maximum polarization intensity is 42.9 μC / cm. 2 The remanent polarization intensity is as high as 23.8 μC / cm. 2 This is very detrimental to energy storage; ratio 2 only doped with lanthanum Bi 3.25 La 0.75 Ti3O 12 The dielectric strength of the thin film reaches 2639 kV / cm, and the remanent polarization is 10.6 μC / cm. 2 Maximum polarization 50.5 μC / cm 2 However, its high leakage current results in a wide hysteresis loop, leading to relatively low energy storage efficiency; Example: Bi co-doped with lanthanum, vanadium, and iron. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The dielectric strength of the thin film is basically the same as that of Comparative Example 2, with a maximum polarization of 54.9 μC / cm. 2 Residual polarization 9.4 μC / cm 2 Compared to Comparative Example 2, this represents a slight improvement, but its finer hysteresis loop significantly enhances energy storage efficiency. Therefore, it indicates that lanthanum, vanadium, and iron co-doped Bi... 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The thin film significantly improves the ferroelectric properties of the prepared thin film.

[0110] Figure 4 This comparison examines the recoverable energy density and energy storage efficiency of Comparative Examples 1, 2, and the Example on a Pt / Ti / SiO2 / Si substrate. The results show that Comparative Example 1, with undoped Bi4Ti3O2, exhibits superior recovery. 12 The recoverable energy density of the thin film is only 4.29 J / cm². 3 The energy storage efficiency was only 35.5%; Comparative Example 2, Bi doped only with lanthanum 3.25 La 0.75 Ti3O 12 The thin film has a recoverable energy density of 38.72 J / cm². 3 However, the energy storage efficiency of 57.3% is still relatively low; Example: Bi co-doped with lanthanum, vanadium, and iron. 3.25 La 0.75 Ti 2.8 V 0.1 Fe0.1 O 12 The recoverable energy density of the thin film further reaches 44.83 J / cm². 3 With an energy storage efficiency of up to 71.8%, it boasts the highest recoverable energy density and energy storage efficiency, exhibiting the best energy storage performance.

[0111] The above conclusions indicate that the co-doping of lanthanum, vanadium, and iron greatly improves the energy storage performance of bismuth titanate films. Therefore, the lanthanum, vanadium, and iron co-doped bismuth titanate (Bi) prepared in this invention... 3.25 La 0.75 Ti 3-2x V x Fe x O 12 Thin films are beneficial for structural optimization and performance improvement when applied to dielectric capacitors.

[0112] This invention provides a bismuth titanate (Bi) co-doped with lanthanum, vanadium, and iron. 3.25 La 0.75 Ti 3-2x V x Fe x O 12 The thin film was prepared using the method described in this invention. The lanthanum, vanadium, and iron co-doped bismuth titanate (Bi) film... 3.25 La 0.75 Ti 3-2x V x Fe x O 12 Thin films improve recoverable energy density and energy storage efficiency.

[0113] This invention also provides bismuth titanate (Bi) co-doped with lanthanum, vanadium, and iron. 3.25 La 0.75 Ti 3-2x V x Fe x O 12 The application of thin films in dielectric capacitors, as demonstrated by the foregoing embodiments, shows that the thin films prepared using the method of the present invention have excellent energy storage performance. Therefore, the bismuth titanate (Bi) of the present invention... 3.25 La 0.75 Ti 3-2x V x Fe x O 12 The thin film is used in a new type of high-performance dielectric capacitor. The high recoverable energy density of the thin film can effectively improve the energy stored / released by the dielectric capacitor under the same process. The improved energy storage efficiency can effectively reduce energy dissipation and heat generation during the use of the dielectric capacitor, thereby improving its service life.

[0114] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing a lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, characterized in that, The method includes the following steps: (1) According to the general chemical formula Bi 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Weigh 1.6720g of bismuth nitrate pentahydrate and 0.3280g of lanthanum nitrate hexahydrate according to the stoichiometric ratio, dissolve them in a mixed solution of 16ml ethylene glycol methyl ether and 4ml acetic acid, stir for 20min, and wait for the solution to become clear. (2) Add 0.1g of chelating agent to the solution obtained in (1) and stir at room temperature for 10min. The chelating agent is acetylacetone. (3) Weigh 0.9529g of tetrabutyl titanate according to the stoichiometric ratio and add it to the solution obtained in (2), and stir at room temperature for 15min; (4) Weigh 0.0359 g of vanadium acetylacetonate and 0.0404 g of ferric nitrate nonahydrate according to the stoichiometric ratio and add them to the solution obtained in (3). Stir at room temperature until all the solutes are dissolved and the solution is clear, then stir for another 6 hours. After standing for 48 hours, Bi is obtained. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Sol; (5) Cut the Pt / Ti / SiO2 / Si substrate into a 10mm*10mm square and clean it with acetone and anhydrous ethanol for 30 minutes respectively to remove oil and impurities from the substrate surface. (6) Using a spin coater, apply Bi... 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 The sol was spin-coated onto a Pt / Ti / SiO2 / Si substrate at a low speed of 400 r / s and a high speed of 4000 r / s to obtain a wet film. (7) Place the wet film in a rapid annealing furnace, dry at 200℃ for 5 min, pyrolyze at 400℃ for 5 min, and anneal at 700℃ for 2 min; (8) Based on step (7), repeat steps (6) and (7) 12 times to obtain Bi with a preset thickness of 300 nm. 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 film; (9) Anneal the film of the preset thickness at 700℃ for 15 min to obtain Bi 3.25 La 0.75 Ti 2.8 V 0.1 Fe 0.1 O 12 Thin film, having energy storage properties and high recoverable energy density, is used in dielectric capacitors; (10) A Pt electrode with a diameter of 0.1 mm was sputtered onto the surface of the thin film using a vacuum deposition apparatus for subsequent electrical performance testing. The recoverable energy density of the thin film was 30-50 J / cm². 3 The energy storage efficiency is 60-80%.

2. A lanthanum, vanadium, and iron co-doped bismuth titanate layered perovskite thin film, characterized in that, The thin film was prepared using the preparation method described in claim 1.

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