A method for preparing a flexible hastelloy substrate multilayer structure antiferromagnetic film

Abstract

The application discloses a preparation method of a flexible Hastelloy substrate multilayer structure antiferromagnetic film, and relates to the technical field of flexible electronic material preparation processes.The specific steps of the process method are as follows: S100, pretreatment of the Hastelloy substrate: cutting the Hastelloy substrate into a proper size, ultrasonic cleaning with anhydrous ethanol and deionized water, and drying and then placing in a muffle furnace for heat treatment to improve the surface wettability; and introducing a lanthanum strontium cobalt oxide (LSCO) buffer layer between the flexible Hastelloy substrate and a lead lanthanum zirconate titanate (PLZT) film, which effectively reduces the lattice mismatch and thermal expansion mismatch between the film and the substrate, and the buffer layer can relieve the stress caused by the difference in the lattice constants and the thermal expansion coefficients of the materials, thereby reducing the internal defects of the film, such as cracks and dislocations, and improving the overall performance and stability of the film.

Description

Technical Field

[0001] This invention relates to the field of flexible electronic material fabrication technology, specifically to a method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate. Background Technology

[0002] With the rapid development of flexible electronics technology, the demand for high-performance flexible electronic materials is constantly increasing. Antiferroelectric materials, as a special type of electronic material, have shown great application potential in the fields of energy storage and pulse power devices due to their unique physical properties, such as high energy density and fast charge and discharge rates. However, when applying antiferroelectric materials to flexible electronic products, traditional antiferroelectric thin film preparation methods have many shortcomings, which limit their widespread application.

[0003] In the traditional process of preparing antiferroelectric thin films, there is often a large lattice mismatch between the thin film and the substrate. Due to the difference in lattice constants between the substrate and the thin film material, the prepared thin film is prone to defects such as cracks and dislocations due to lattice mismatch, which in turn affects the performance and stability of the thin film. This lattice mismatch problem is particularly prominent on flexible substrates, because flexible substrates will generate greater stress changes during deformation, which further aggravates the effect of lattice mismatch.

[0004] However, the traditional methods for preparing antiferroelectric thin films also face serious problems related to thermal expansion mismatch and diffusion of substrate metal elements. During the preparation process, the thin film and substrate materials undergo thermal expansion to varying degrees during the high-temperature heat treatment, resulting in stress inside the thin film. Especially on flexible substrates, metal elements in the substrate diffuse into the thin film, contaminating it and affecting its purity and performance. This limits the improvement of its performance and the expansion of its application range, posing a great challenge to the preparation of high-performance antiferroelectric thin films. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate. By introducing a lanthanum strontium cobalt oxide (LSCO) buffer layer, the lattice mismatch and thermal expansion mismatch between the thin film and the substrate are reduced, while the diffusion of metal elements in the substrate is blocked, thereby improving the crystallinity of the PLZT thin film and giving it better antiferroelectric energy storage characteristics, thus meeting the demand of flexible electronic products for high-performance antiferroelectric materials.

[0006] One objective of this invention is to provide a flexible Hastelloy substrate multilayer antiferroelectric thin film with the following structure:

[0007] The bottom layer is a Hastelloy substrate, and the top layers are LSCO and PLZT layers, respectively.

[0008] The second objective of this invention is to provide a thin-film electrode prepared from the above-mentioned flexible Hastelloy substrate multilayer antiferroelectric thin film, with the following structure:

[0009] The bottom layer is a Hastelloy substrate, and the top layers are LSCO layer, PLZT layer and Au top electrode, respectively.

[0010] The third objective of this invention is to provide a method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate, the method comprising the following two steps:

[0011] S100, Preparation of LSCO thin films;

[0012] S200, Preparation of PLZT thin film;

[0013] in,

[0014] S100 is as follows: LSCO sol is coated on a Hastelloy substrate to form a wet film, then baked to remove organic matter and moisture, and then pre-crystallization heat treatment is performed to obtain an initial LSCO substrate with an LSCO buffer layer. Finally, the initial LSCO substrate is subjected to crystallization heat treatment to obtain an LSCO substrate.

[0015] S200 involves coating a PLZT sol onto the LSCO substrate to form a wet film, then baking to remove organic matter and moisture, followed by a pre-crystallization heat treatment to obtain an initial LSCO / PLZT substrate with a PLZT thin film on the surface and an LSCO buffer layer in the middle. Finally, the initial LSCO / PLZT substrate is subjected to a crystallization heat treatment to obtain an LSCO / PLZT substrate.

[0016] Preferably, step S100 is repeated before step S200 to prepare a substrate with multiple LSCO buffer layers.

[0017] Preferably, step S200 is repeated to prepare an LSCO / PLZT substrate with multiple layers.

[0018] Preferably, the method for preparing the flexible Hastelloy substrate multilayer antiferroelectric thin film further includes at least one of the following technical features:

[0019] A. The baking temperature range is 200–300℃ for 2–3 minutes;

[0020] B. The parameters for the pre-crystallization heat treatment are: 550–600℃, 5 min;

[0021] C. The parameters of the crystallization heat treatment are as follows: first, heat treatment at 650℃~700℃ for 10~30min, followed by low-temperature heat treatment at 350℃ for 1h.

[0022] Preferably, the method for preparing the flexible Hastelloy substrate multilayer antiferroelectric thin film further includes at least one of the following technical features:

[0023] A. The LSCO sol is prepared using lanthanum nitrate, strontium acetate, and cobalt acetate, with a concentration of 0.05–0.5 mol / L.

[0024] B. The PLZT sol is prepared by using lead acetate, lanthanum nitrate, tetrabutyl titanate and zirconium propoxide, with a concentration of 0.05-0.5 mol / L.

[0025] C. The LSCO sol and / or the PLZT sol should be aged for 24 hours before coating.

[0026] The fourth objective of this invention is to provide a method for preparing a thin-film electrode from a flexible Hastelloy substrate multilayer antiferroelectric thin film. The steps of this method are as follows:

[0027] Au element was sputtered onto a multilayer antiferroelectric thin film on a flexible Hastelloy substrate, followed by heat treatment to obtain the thin film electrode.

[0028] Preferably, the parameters for the heat treatment are: 350℃, 30min.

[0029] Compared with existing technologies, this method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate has the following advantages:

[0030] I. This invention introduces a lanthanum strontium cobalt oxide (LSCO) buffer layer between a flexible Hastelloy substrate and a PLZT thin film. This buffer layer can alleviate the stress caused by the difference in lattice constant and thermal expansion coefficient between the materials, effectively reducing the lattice mismatch and thermal expansion mismatch between the thin film and the substrate, thereby reducing defects inside the thin film, such as cracks and dislocations, and improving the overall performance and stability of the thin film.

[0031] Second, the lanthanum strontium cobalt oxide (LSCO) buffer layer used in this invention not only serves as a bridge for lattice matching but also acts as a barrier layer, effectively blocking the diffusion of metal elements in the flexible Hastelloy substrate. This avoids contamination of the PLZT film by metal elements, ensuring the purity and performance of the film. In addition, due to the reduction in metal element diffusion, the reliability and long-term stability of the film are also improved. Attached Figure Description

[0032] Figure 1 This is a bending image of a 6LSCO / 6PLZT thin film on a flexible Hastelloy substrate;

[0033] Figure 2The images show a comparison of the XRD patterns of 6LSCO / 6PLZT thin film samples with and without buffer layers on Hastelloy substrates.

[0034] Figure 3 The dielectric properties of 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films prepared on Hastelloy substrates as a function of frequency at room temperature are shown.

[0035] Figure 4 It is the hysteresis loop (PE curve) of the polarization intensity of 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films prepared on Hastelloy substrates as a function of electric field intensity at room temperature.

[0036] Figure 5 A comparison of the energy storage performance of 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films prepared on Hastelloy substrates. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment aims to describe in detail a method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate. A well-crystallized lead zirconate titanate (Pb) is prepared on a flexible Hastelloy substrate using a sol-gel process. 0.92 La 0.08 (Zr 0.95 Ti 0.05 O3(PLZT) thin film, by introducing lanthanum strontium cobalt oxide (La) between the substrate and the PLZT thin film. 0.5 Sr 0.5 The CoO3 (LSCO) buffer layer blocks the diffusion of metal elements in the substrate, reduces lattice mismatch and thermal expansion mismatch between the film and the substrate, improves the crystallinity of the PLZT film, and enhances the film's crystallinity and antiferroelectric energy storage characteristics.

[0040] S1, Pretreated Hastelloy substrate

[0041] A Hastelloy substrate measuring 15mm × 15mm and 50μm in thickness was cut and preliminarily cleaned with anhydrous ethanol to remove surface oil and impurities. Subsequently, it was ultrasonically cleaned with deionized water to ensure thorough cleaning of the substrate surface. After cleaning, the substrate was dried in an oven at 60℃ to remove residual moisture. The dried substrate was then placed in a muffle furnace and heat-treated at 500℃ for 10 minutes to improve its surface wettability.

[0042] S2. Prepare 50 mL of 0.1 mol / L LSCO sol.

[0043] Analytical grade starting materials (lanthanum nitrate [La(NO3)3·xH2O], strontium acetate [Sr(CH3COO)2·0.5H2O], and cobalt acetate [Co(CH3COO)2·0.5H2O]) were selected. The corresponding starting materials were weighed and mixed according to the molar ratio of the LSCO chemical formula. An appropriate amount of deionized water was added and the mixture was stirred in an oil bath at 60°C for 0.5 h to completely dissolve the solute. Then, the mixture was heated to 90°C and refluxed under stirring for 2 h. After cooling to 70°C, polyvinyl alcohol (polyvinyl alcohol mass was 5% of the total mass of the solute) was added and stirred for 1 h. The mixture was then cooled to 65°C and glacial acetic acid (molar ratio of glacial acetic acid to deionized water was 1:2) was added dropwise and stirred for 12 h. Finally, the mixture was cooled to room temperature and filtered to remove impurities, resulting in a clear and transparent purple-red LSCO sol.

[0044] S3. Prepare 50 mL of 0.4 mol / L PLZT sol.

[0045] Analytical grade initial raw materials (lead acetate trihydrate [Pb(CH3COO)2·3H2O], lanthanum nitrate hydrate [La(NO3)3·xH2O], tetrabutyl titanate [Ti(OC4H9)4], and zirconium propoxide [Zr(OC3H7)4]) were selected. Before use, lead acetate trihydrate was dried at 75℃ for 24h to remove water of crystallization, and the lead source was in excess by 20% to compensate for the volatilization of lead during high-temperature heat treatment. An appropriate amount of ethylene glycol methyl ether was measured as a solvent and divided into two equal portions for ease of operation.

[0046] First, prepare two solutions:

[0047] First, weigh out dehydrated lead acetate and hydrated lanthanum nitrate raw materials according to the required stoichiometric ratio and put them into a round-bottom flask, and add one part of ethylene glycol methyl ether solvent.

[0048] Secondly, stir in an oil bath at 65°C for 1 hour until the two raw materials are completely dissolved. In another flask, dissolve zirconium propoxide and tetrabutyl titanate in another portion of ethylene glycol methyl ether and stir at room temperature for 0.5 hours.

[0049] Then, the solutions in the two flasks were mixed and refluxed under stirring in an oil bath at 90°C for 2 hours. After the reaction was completed, the mixed solution was cooled to room temperature, and a small amount of deionized water and glacial acetic acid were added dropwise (the amount of glacial acetic acid was 3 times that of the metal alkoxide, and the amount of deionized water was 4.5 times that of the metal alkoxide). The solution was then stirred at room temperature for 12 hours, and after filtration, a clear and transparent yellow PLZT sol was obtained.

[0050] S4. Preparation of LSCO thin films

[0051] LSCO sol aged for 24 hours was spin-coated onto a heat-treated Hastelloy substrate using a spin coater at a speed of 3000 r / min for 30 s to form a wet film. The wet film was then placed on a baking tray and baked at 210 °C for 2 min to remove organic matter and moisture from the film. The film was then placed in a muffle furnace and heat-treated at 550 °C for 5 min in air to achieve a pre-crystallization effect. The spin coating and heat treatment process was repeated to obtain a 6-layer LSCO film. Finally, the film was placed in a muffle furnace and heat-treated at 700 °C for 10 min in air to complete the crystallization process and prepare the required 6-layer LSCO buffer layer.

[0052] S5. Preparation of PLZT thin film

[0053] PLZT film was then coated onto a Hastelloy substrate coated with an LSCO buffer layer: PLZT sol aged for 24 hours was spin-coated onto a substrate with 6 LSCO buffer layers. The spin-coating was performed at 3000 r / min for 30 s in an atmospheric environment. The resulting wet film was then baked at 300℃ for 2 min on a baking tray. The dried sample was then placed in a muffle furnace and heat-treated at 600℃ for 5 min. The spin-coating and heat-treatment process was repeated to obtain a 6-layer PLZT film. Finally, the film was heat-treated in a muffle furnace at 650℃ for 30 min to achieve complete crystallization. The crystallized film was then placed in a muffle furnace at 350℃ and held for 1 h to obtain a smooth, crack-free 6-layer PLZT film.

[0054] The prepared sample was labeled as: 6LSCO / 6PLZT.

[0055] Comparative Example

[0056] The preparation process of this comparative example is basically the same as that of the above embodiments. The difference is that the preparation of LSCO sol and film (steps S2 and S4) is omitted, and the PLZT film is directly coated on the heat-treated Hastelloy substrate using step S5.

[0057] The prepared sample was labeled as: 6PLZT.

[0058] Test Analysis:

[0059] I. Macro Overview

[0060] A bending image of a 6LSCO / 6PLZT thin film on a flexible Hastelloy substrate is shown below. Figure 1 As shown, the thin film has a smooth surface, excellent flexibility, and is compatible with MEMS processes, making it a promising candidate for application in the field of flexible electronics.

[0061] II. XRD

[0062] Figure 2 XRD patterns of 6LSCO / 6PLZT thin film samples with and without buffer layers on Hastelloy substrates are shown. It can be seen that the PLZT films crystallized at 650℃ all formed a single perovskite structure without the formation of a second phase. The 6PLZT film without the buffer layer exhibits a preferred orientation in the (110) direction; the (100), (110), and (200) peaks of the 6LSCO / 6PLZT film with the buffer layer are all more intense than those of the 6PLZT sample without the LSCO buffer layer, indicating better crystallinity.

[0063] Furthermore, thin-film electrodes were fabricated using 6LSCO / 6PLZT thin films.

[0064] A mask with a circular aperture of 0.4 mm was used to cover the surface of the thin film prepared by S5, and the film was placed in an ion sputtering instrument to sputter Au as the top electrode of the thin film. Since the Hastelloy substrate has good conductivity, it can be used as the bottom electrode of the thin film. Finally, the sample was placed in a muffle furnace at 350°C and held for 30 min to complete the electrode fabrication.

[0065] like Figure 1 The illustration shows a schematic diagram of a Hastelloy / LSCO / PLZT multilayer flexible antiferroelectric thin film with an Au top electrode.

[0066] Test Analysis:

[0067] I. Dielectric Properties

[0068] Figure 3 The figures show the dielectric properties of 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films as a function of frequency at room temperature, with a test frequency of 10 Hz. 3 ~10 6At 100 Hz, it can be seen that the introduction of the LSCO buffer layer significantly improves the dielectric constant of the PLZT film. At 100 Hz, the dielectric constant of the 6-layer PLZT film with 6 LSCO buffer layers increases from 152 to 306, while the dielectric loss increases slightly. However, this increase can be reduced by adjusting the thickness of the LSCO buffer layer. The introduction of the LSCO buffer layer reduces the lattice mismatch and thermal expansion mismatch between the film material and the substrate, which can alleviate the internal stress of the film, promote grain growth, and contribute to obtaining better dielectric properties.

[0069] II. Ferroelectric properties

[0070] Figure 4 The figure shows the hysteresis loops (PE curves) of polarization intensity as a function of electric field strength for 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films at room temperature. The test frequency was 100 Hz and the test electric field was 2000 kV / cm. As shown in the figure, with the change of electric field strength, the PE curves of both PLZT film samples exhibit the characteristic tilted double hysteresis loop of antiferroelectric materials, indicating a ferroelectric-antiferroelectric phase transition. After introducing the LSCO buffer layer, the maximum polarization value P of the 6LSCO / 6PLZT film... max From 43.1 μC / cm 2 Increased to 72.9 μC / cm 2 Residual polarization value P r From 9.9μC / cm 2 Increased to 19.5 μC / cm 2 ,ΔP(ΔP=P max -P r Increased by 20.2 μC / cm 2 It demonstrates good energy storage potential.

[0071] III. Energy Storage Performance

[0072] Figure 5 A comparison chart of the energy storage performance of 6PLZT antiferroelectric thin films and 6LSCO / 6PLZT antiferroelectric thin films. Figure 5 It is by Figure 4 The results are obtained by integrating the hysteresis loop. It can be seen that after introducing the LSCO buffer layer, the recoverable energy density, total energy density, and energy storage efficiency of the 6LSCO / 6PLZT thin film are all improved, reaching 26.20 J / cm². 3 55.52 J / cm 3 and 47.19%.

[0073] In summary, by implementing the above steps, a flexible Hastelloy substrate multilayer antiferroelectric thin film material was successfully prepared. By introducing an LSCO buffer layer between the Hastelloy substrate and the PLZT film, the diffusion of metal elements in the substrate is blocked, reducing lattice mismatch and thermal expansion mismatch between the film and the substrate, and improving the crystallinity of the PLZT film, thus giving it better dielectric and antiferroelectric energy storage properties. The flexible Hastelloy substrate multilayer antiferroelectric thin film obtained by this method also has excellent deformation capability, showing broad application prospects in flexible electronic products and pulsed power devices.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a multilayer antiferroelectric thin film on a flexible Hastelloy substrate, characterized in that, The method for preparing the antiferroelectric thin film includes the following two steps: S100, Preparation of LSCO thin films; S200, Preparation of PLZT thin film; in, S100 is as follows: LSCO sol is coated on a Hastelloy substrate to form a wet film, then baked to remove organic matter and moisture, and then pre-crystallization heat treatment is performed to obtain an initial LSCO substrate with an LSCO buffer layer. Finally, the initial LSCO substrate is subjected to crystallization heat treatment to obtain an LSCO substrate. S200 is as follows: PLZT sol is coated on the LSCO substrate to form a wet film, then baked to remove organic matter and moisture, and then pre-crystallization heat treatment is performed to obtain an LSCO / PLZT initial substrate with a PLZT thin film on the surface and an LSCO buffer layer in the middle. Finally, the LSCO / PLZT initial substrate is subjected to crystallization heat treatment to obtain an LSCO / PLZT substrate. The parameters for the crystallization heat treatment are as follows: first, heat treatment at 650℃~700℃ for 10~30min, followed by low-temperature holding treatment at 350℃ for 1h.

2. The method according to claim 1, characterized in that, Before step S200, repeat step S100 to prepare a substrate with multiple LSCO buffer layers.

3. The method according to claim 1, characterized in that, Repeat step S200 to prepare an LSCO / PLZT substrate with multiple layers.

4. The method according to claim 1, characterized in that, It also includes at least one of the following technical features: A1. The baking temperature range is 200-300℃ for 2-3 minutes; B1. The parameters for the pre-crystallization heat treatment are: 550-600℃, 5min.

5. The method according to claim 1, characterized in that, It also includes at least one of the following technical features: A2. The LSCO sol is prepared using lanthanum nitrate, strontium acetate, and cobalt acetate, with a concentration of 0.05–0.5 mol / L. B2. The PLZT sol is prepared using lead acetate, lanthanum nitrate, tetrabutyl titanate, and zirconium propoxide, with a concentration of 0.05–0.5 mol / L. C2. The LSCO sol and / or the PLZT sol are aged for 24 hours before coating.

6. The flexible Hastelloy substrate multilayer antiferroelectric thin film prepared by the method according to any one of claims 1 to 5, characterized in that, The structure of the antiferroelectric thin film is as follows: an LSCO layer is provided between the Hastelloy and PLZT layers.

7. The antiferroelectric thin film according to claim 6, characterized in that, It also includes at least one of the following features: A3. The LSCO layer consists of 1 to 10 layers; B3. The PLZT layer consists of 1 to 10 layers.

8. The thin-film electrode prepared from the antiferroelectric thin film according to claim 6 or 7, characterized in that, The structure of the thin film electrode is as follows: an Au top electrode is provided on the multilayer antiferroelectric thin film of the flexible Hastelloy substrate as described in claim 6 or 7, and the Au top electrode is located on the PLZT layer.

9. The method for preparing the thin-film electrode according to claim 8, characterized in that, Au is sputtered onto the PLZT layer of the antiferroelectric thin film according to claim 6 or 7, and then heat-treated to obtain the thin film electrode.

10. The method for preparing a thin-film electrode according to claim 9, characterized in that, The parameters for the heat treatment are: 350℃, 30min.

Images