A lead lanthanum zirconium tin-based antiferroelectric film regulated by doping and a preparation method and application thereof

Abstract

The application discloses a lead lanthanum zirconium tin-based antiferroelectric film prepared through doping regulation, a preparation method and application thereof, and relates to the technical field of antiferroelectric films. The lead lanthanum zirconium tin-based antiferroelectric film is prepared through the following steps. First, a mixed solution is prepared by mixing lead acetate trihydrate, dibutyl tin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid. Then, the mixed solution is heated and stirred and cooled. Subsequently, polyethylene glycol and acetylacetone are added in sequence and stirred at room temperature. Then, zirconium n-propylate, ethylene glycol methyl ether and deionized water are added and stirred at room temperature. Finally, lactic acid is added and stirred at room temperature. After standing, a precursor solution is obtained through filtration. The precursor solution is prepared on a Pt(111) / Ti / SiO2 / Si(004) substrate through spin coating. Then, the precursor solution is subjected to drying treatment and pyrolysis treatment. The thin film of the first layer and the tenth layer is subjected to annealing treatment in an air atmosphere, so that the lead lanthanum zirconium tin-based antiferroelectric film is obtained. While realizing a larger refrigeration temperature change value, the electric refrigerator refrigeration effect is also expanded to a low-temperature region, and the antiferroelectric performance is more excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of doping regulation, and in particular relates to a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, and a preparation method and application thereof. Background Art

[0002] With the rapid development of science and technology and people's ever-increasing pursuit of quality of life, refrigeration technology has broad applications and prospects in aviation-grade coolers, automotive thermal management systems, and wearable devices. Current refrigeration equipment generally uses volatile refrigerants such as hydrochlorofluorocarbons (HCFCs), which not only consume a lot of energy but also cause the release of greenhouse gases.

[0003] As a new solid-state refrigeration technology, electrocaloric effect cooling offers the advantages of high efficiency, low cost, miniaturization, and mass production of materials. The basic idea behind electrocaloric effect cooling is that under the action of an external electric field, the polarization state of the material changes, leading to a change in entropy and, in turn, a temperature change in the material. Therefore, using an external electric field to change the polarization state of the material can achieve temperature regulation, thereby achieving cooling. Currently, in addition to conventional ferroelectrics and relaxor ferroelectrics, antiferroelectric materials are also attractive for electrocaloric cooling. Unlike conventional ferroelectrics and relaxor ferroelectrics, in antiferroelectric materials, the polarization directions of adjacent domains change from antiparallel to aligned with the direction of the electric field under the action of an external electric field. During the antiferroelectric-ferroelectric phase transition, the polarization changes, resulting in a significant electrocaloric cooling effect.

[0004] Antiferroelectric materials, such as lead zirconate (PLZS), have attracted considerable attention for their stable antiferroelectric phase stability region in the lead lanthanum zirconium tin (PLZS) antiferroelectric system formed by the addition of lanthanum and tin. However, traditional preparation methods still face several bottlenecks, such as the low adiabatic temperature transition caused by the electrocaloric effect and the high electric field required for phase transition, which limit their practical application in electronic components. Therefore, the development of novel doping control methods to optimize the antiferroelectric and electrocaloric cooling properties of antiferroelectric PbLZS thin films has become an urgent scientific and technological challenge. This patent proposes a novel doping control modification method for preparing PbLZS thin films, significantly improving their antiferroelectric and electrocaloric properties, thereby meeting the needs of future high-performance cooling microdevices. This opens new avenues for electrocaloric cooling of antiferroelectric materials and promotes further development in related fields. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, as well as a preparation method and application thereof, to solve the technical problems of poor antiferroelectric properties and electrocaloric cooling performance of the lead lanthanum zirconium tin film.

[0006] The application adopts the following technical solutions:

[0007] A preparation method of a lead lanthanum zirconium tin-based antiferroelectric film prepared by doping regulation, comprising the following steps:

[0008] A mixed solution is prepared by mixing lead acetate trihydrate, dibutyl tin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid, then the mixed solution is heated and stirred and cooled, polyethylene glycol and acetylacetone are sequentially added and stirred at room temperature, then zirconium n-propyl alcohol, ethylene glycol methyl ether and deionized water are added and stirred at room temperature, and finally lactic acid is added and stirred at room temperature, and after standing, a precursor solution with a concentration of 0.2-0.4 mol / L is obtained by filtration.

[0009] The precursor solution prepared by spin coating on a Pt(111) / Ti / SiO2 / Si(004) substrate is then subjected to drying treatment and pyrolysis treatment, and the films of the 1st layer and the 10th layer are respectively subjected to annealing treatment in an air atmosphere, to obtain a lead lanthanum zirconium tin-based antiferroelectric film.

[0010] Preferably, in the mixed solution, the molar ratio of lead acetate trihydrate:dibutyl tin diacetate:lanthanum nitrate hexahydrate:manganese acetate tetrahydrate:glacial acetic acid is (1-1.2):0.5:0.02:(0-0.02):(0.4-0.6), and the lead acetate trihydrate is in excess of 20%.

[0011] Preferably, the mixed solution is heated and stirred at 120-135°C for 30-60 minutes, after cooling to room temperature, polyethylene glycol and acetylacetone are sequentially added and stirred for 30-60 minutes, then zirconium n-propyl alcohol, ethylene glycol methyl ether and deionized water are added and stirred at room temperature for 30-60 minutes, finally lactic acid is added and stirred for 30-60 minutes, and after standing for 48-72 hours, the precursor solution is obtained by filtration.

[0012] Preferably, the mass-volume ratio of polyethylene glycol and acetylacetone is (0.5-1):(0.5-1), the mass-volume ratio of zirconium n-propyl alcohol and ethylene glycol methyl ether is (0.8-1):(0.8-1), the molar ratio of deionized water to lead acetate trihydrate is 1:5, and the molar ratio of lactic acid to lead acetate trihydrate is 1:1.

[0013] Preferably, the filter pore size is 0.2-0.4 microns.

[0014] Preferably, the spin coating preparation speed is 2000-2800 rpm, and the spin coating time of each layer is 30-50 seconds.

[0015] Preferably, the drying treatment temperature is 240-260°C, the drying time is 5-15 minutes, the pyrolysis treatment temperature is 500-600°C, the pyrolysis time is 5-10 minutes, and the process is repeated 10 times.

[0016] Preferably, the annealing process is characterized in that the temperature is 700-720° C., the annealing time of the first layer is 10-20 minutes, and the annealing time of the tenth layer is 10-20 minutes.

[0017] Another technical solution of the present invention is a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, the general formula is Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 O3-x%Mn, 0%≤x≤2%.

[0018] Another technical solution of the present invention is the application of lead lanthanum zirconium tin based antiferroelectric films regulated by doping in wearable thermal management devices, in-situ thermal management devices for data center chips, and low-energy thermal management devices for electric vehicles.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] A method for preparing lead, lanthanum, zirconium, and tin-based antiferroelectric thin films controlled by doping is described. The colloid preparation process utilizes a rational arrangement of the order of precursor addition, as well as the addition of catalysts and chelating agents, ultimately yielding a stable and uniform colloid. The overall preparation process is simple and highly reproducible. Heat treatment removes the solvent, pyrolysis increases crystallinity, and a simple annealing method achieves full crystallization, ultimately yielding a film with consistently enhanced antiferroelectric and electrocaloric properties.

[0021] Furthermore, the molar ratios of lead acetate trihydrate: dibutyltin diacetate: lanthanum nitrate hexahydrate: manganese acetate tetrahydrate: glacial acetic acid in the mixed solution are (1-1.2):0.5:0.02:(0-0.02):(0.4-0.6). A 20% excess of lead acetate trihydrate compensates for lead loss during annealing and prevents the formation of a pyrochlore phase in the film. Glacial acetic acid, as a solvent, is volatile and has good solubility, dissolving a variety of organic compounds and inorganic salts. Controlling its molar ratio relative to the other raw materials further controls the colloid concentration. Dibutyltin diacetate is inexpensive, making its cost significantly lower than that of tin acetate. Lead acetate trihydrate and manganese acetate tetrahydrate are more soluble in glacial acetic acid. Lanthanum nitrate, as a precursor, catalyzes and accelerates the hydrolysis and condensation reactions of the precursors, thereby shortening the preparation time and improving the purity of the product.

[0022] Furthermore, the mixed solution is heated and stirred at 120-135°C for 30-60 minutes to effectively remove the crystallization water in the raw materials and prevent the subsequent hydrolysis of zirconium n-propoxide in water. After cooling to room temperature, polyethylene glycol and acetylacetone are first added and stirred for 30-60 minutes to improve the stability of the sol and prevent agglomeration and precipitation. Zirconium n-propoxide, ethylene glycol methyl ether, and deionized water are then added. If zirconium n-propoxide is added too early, precipitation may occur. Deionized water can adjust the viscosity of the sol, making the sol easier to handle and operate. Lactic acid acts as a catalyst and chelating agent to promote hydrolysis and condensation reactions. Stirring each step for 30-60 minutes can ensure a more complete reaction. Letting it rest for 48-72 hours can facilitate subsequent steps, remove impurities, promote sol aging, etc., and then filter to obtain the desired precursor solution.

[0023] Furthermore, when formulated in this ratio, polyethylene glycol acts as an emulsifier and surfactant, improving the mechanical properties of the gel film. Acetylacetone enhances the dispersion and stability of the sol, preventing the agglomeration and precipitation of the colloidal particles, ensuring the superior performance of the resulting colloidal product. Furthermore, the addition of ethylene glycol methyl ether to this ratio influences the hydrolysis and condensation reaction rates during PLZS colloid formation, thereby optimizing the preparation process of the PLZS colloid.

[0024] Furthermore, a filter with a pore size of 0.2 to 0.4 microns can effectively filter out impurities that may be present in the colloid, thereby preventing them from affecting the performance of the membrane.

[0025] Furthermore, spin coating each layer at a speed of 2000-2800 rpm for 30-50 seconds is not only simple and rapid, but also enables the wet film to be evenly spread on the substrate.

[0026] Furthermore, heat treatment at a temperature range of 240-260°C can effectively evaporate the organic solvent, and pyrolysis treatment at 500-600°C for 5-10 minutes can help the grain growth and orientation in the film, thereby improving the crystallinity and performance of the film.

[0027] Furthermore, annealing at this temperature promotes more complete crystallization of the lead, lanthanum, zirconium, and tin-based antiferroelectric thin film. The first annealing layer helps refine the material's grain size, improving uniformity while also relieving stress and preventing subsequent film cracking. The final annealing layer helps modify the material's surface properties and improve the film's stability.

[0028] In summary, the method of the present invention has a simple preparation process and strong repeatability. While achieving a large cooling temperature range, it also successfully extends the electrocaloric cooling effect to low-temperature regions. Furthermore, its preparation process is simple and exhibits superior antiferroelectric properties. This innovation enables devices with superior performance at the same cost.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a flow chart of the preparation method of the present invention;

[0032] FIG2 (a) is a hysteresis loop diagram of the lead lanthanum zirconium tin antiferroelectric thin film of Comparative Example 1 provided by the present invention;

[0033] FIG2( b ) is a hysteresis loop diagram of the 0.5% Mn-doped lead lanthanum zirconium tin antiferroelectric thin film of Example 1 provided by the present invention;

[0034] FIG2( c ) is a hysteresis loop diagram of the 1% Mn-doped lead lanthanum zirconium tin antiferroelectric thin film of Example 2 provided by the present invention;

[0035] FIG2( d ) is a hysteresis loop diagram of the 2% Mn-doped lead lanthanum zirconium tin antiferroelectric thin film of Example 3 provided by the present invention;

[0036] Figure 3 This is a SEM cross-sectional view of the lead lanthanum zirconium tin based antiferroelectric thin film provided by the present invention;

[0037] Figure 4 Provide the XRD patterns of Example 1 and Example 2 and Comparative Example 1 for the present invention;

[0038] FIG5 (a) is a curve showing the change of polarization intensity with temperature in Comparative Example 1 provided by the present invention;

[0039] FIG5( b ) is a curve showing the change of polarization intensity with temperature in Example 1 provided by the present invention;

[0040] FIG5( c ) is a curve showing the change of polarization intensity with temperature in Example 2 provided by the present invention;

[0041] FIG5( d ) is a curve showing the change of polarization intensity with temperature in Example 3 provided by the present invention;

[0042] FIG6 (a) is an electrocaloric effect ΔT-T curve of Comparative Example 1 provided by the present invention;

[0043] FIG6( b ) is an electrocaloric effect ΔT-T curve of Example 1 provided by the present invention;

[0044] FIG6 (c) is an electrocaloric effect ΔT-T curve of Example 2 provided by the present invention;

[0045] FIG6 (d) is an electrocaloric effect ΔT-T curve of Example 3 provided by the present invention;

[0046] FIG. 7 shows the E values ​​at different temperatures of Comparative Example 1 and Example 1 provided by the present invention. AFE-FE Curves, wherein (a) is Comparative Example 1, and (b) is Example 1. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0049] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0050] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0051] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.

[0052] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0053] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0054] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0055] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0056] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0057] Up to now, cooling technology has been widely integrated into various fields of production and life in modern society, such as food preservation, biomedicine and temperature control management of electrical equipment. Although traditional vapor compression refrigeration technology can basically meet the refrigeration needs in many application scenarios, its disadvantages such as high greenhouse gas emissions, large size and complex structure are increasingly attracting people's deep attention. Therefore, from the perspective of practical application, there is an urgent need for a new cooling technology that can overcome the above-mentioned shortcomings. Electrocaloric effect refrigeration has the advantages of high efficiency, low cost, miniaturization and mass production of materials. Among them, antiferroelectric materials are ideal materials to meet the needs of modern electronic devices because they undergo antiferroelectric-ferroelectric phase transition. In this process, polarization changes, causing entropy change, and then produces a large electrocaloric cooling effect. However, the temperature change effect of the materials prepared by the current existing electrocaloric technology is low, and the temperature change region is mostly located near the temperature change point, or the antiferroelectric-ferroelectric phase transition point is relatively high. Therefore, this application proposes a preparation method for regulating the electrocaloric effect of lead lanthanum zirconium tin antiferroelectric thin films by doping, so as to achieve the effect of improving the electrocaloric properties of antiferroelectric materials.

[0058] The present invention provides a lead lanthanum zirconium tin (PLZS)-based antiferroelectric film regulated by doping, as well as its preparation method and application. Compared to other electrocaloric materials, the Mn-doped PLZS film obtained by doping weakens the antiferroelectric to ferroelectric phase transition electric field of the PLZS. Under this influence, the Mn-doped PLZS film exhibits a temperature variation range closer to room temperature and a higher polarization intensity. At the same time, the greater change in polarization with temperature gives the film more outstanding electrocaloric temperature variation characteristics. The technology provided by this application significantly improves the electrocaloric performance of the lead lanthanum zirconium tin (PLZS) antiferroelectric film, provides a deep understanding of the antiferroelectric electrocaloric principle of the PLZS film, and promotes the development of new practical antiferroelectric film refrigeration. The preparation method is simple in process, and while achieving a large refrigeration temperature change value, it also expands the electrocaloric cooling effect to the low-temperature region and exhibits more excellent antiferroelectric performance, which will promote technological progress and industrial upgrading in the future electrocaloric cooling market.

[0059] See also Figure 1 The present invention provides a method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control, comprising the following steps:

[0060] S1, pre-treating the substrate;

[0061] Lead acetate trihydrate, dibutyltin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid are mixed in a predetermined ratio; in order to compensate for the loss of lead during annealing and prevent the formation of pyrochlore phase in the film, lead acetate trihydrate needs to be in excess of 20%.

[0062] In the mixed solution, the molar ratio of lead acetate trihydrate, dibutyltin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid is (1-1.2):0.5:0.02:(0-0.02):(0.4-0.6).

[0063] S2. Heat the mixed solution at 120-135° C. with stirring for 30-60 minutes. After cooling to room temperature, polyethylene glycol is added in sequence and stirred for 30-60 minutes. Then, zirconium n-propoxide, ethylene glycol methyl ether and deionized water are added and stirred at room temperature for 30-60 minutes. The mass volume ratio of polyethylene glycol to acetylacetone is (0.5-1): (0.5-1), and stirred for 30 minutes.

[0064] S3. Add zirconium n-propoxide and ethylene glycol methyl ether in a mass volume ratio of (0.8-1): (0.8-1), and add deionized water at a ratio of 1 mol deionized water to 5 mol lead, and stir again for 30-60 minutes;

[0065] S4. Finally, add lactic acid in a ratio of 1 mol lactic acid to 1 mol lead and stir for 30 to 60 minutes;

[0066] S5. After standing for 48 to 72 hours, filter the solution with a filter having a pore size of 0.2 to 0.4 μm to obtain a precursor solution with a concentration of 0.2 to 0.4 mol / L. The filtered precursor solution is evenly dropped onto a clean Pt(111) / Ti / SiO2 / Si(004) substrate that has been ultrasonically cleaned with alcohol and high-purity water for 5 minutes.

[0067] S6. Spin-coat the precursor solution on a spin coater at a speed of 2000-2800 rpm and a spin-coating time of 30-50 seconds per layer. After coating, dry the wet film on a heating table at 240-260° C. for 5-15 minutes, and then pyrolyze in a tube furnace at 500-600° C. for 5-10 minutes, repeating 10 times.

[0068] S7. Annealing the first and tenth thin films at 700-720° C. for 10-20 minutes respectively in an air atmosphere.

[0069] A lead lanthanum zirconium tin based antiferroelectric film regulated by doping, the general formula is PLZS-x%Mn, specifically Pb 0.97 La 0.02 Zr 0.5 Sn 0.5O3-x%Mn (0%≤x≤2%), while obtaining a larger refrigeration temperature change value, the electrocaloric refrigeration change also approaches low temperature. At the same time, it is simple to prepare and has better antiferroelectric properties.

[0070] The lead-lanthanum-zirconium-tin based antiferroelectric thin film regulated by gold doping according to the present invention can be used in the manufacture of wearable thermal management devices, in-situ thermal management devices for data center chips, and low-energy thermal management devices for electric vehicles.

[0071] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0072] Comparative Example 1:

[0073] By sol-gel method, according to the calculated molar ratio, Figure 1 Step preparation chemical formula is Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 The lead lanthanum zirconium tin film of O3, i.e. PLZS, was evenly dropped onto the cleaned substrate, and then spun on 10 layers on a spin coater. The first and tenth layers of the sample were annealed in air atmosphere at 720°C.

[0074] Before the electrical performance test, one corner of the substrate was polished with 2000 grit sandpaper. A platinum electrode square pattern with a size of 200 μm × 200 μm was fabricated on the film surface by magnetron sputtering (Q150TS vacuum coater). A shadow mask was used to determine the size of the platinum electrode square. The argon partial pressure was 5.0 × 10 -2 Pa, substrate rotation speed was 1 rpm, sputtering power was 30 W, and sputtering time was 6 min.

[0075] Example 1:

[0076] By the sol-gel method, manganese acetate tetrahydrate was added according to the calculated molar ratio to make the colloid doped with 0.5% Mn. Figure 1 Step preparation chemical formula is Pb 0.97 La0.02 Zr 0.5 Sn 0.5 The 0.5%Mn-doped lead lanthanum zirconium tin film of O3-1%Mn, i.e. PLZS-0.5%Mn, was evenly dropped onto the cleaned substrate, and then spun on 10 layers on a spin coater. The first and tenth layers of the sample were annealed in air atmosphere at 700°C.

[0077] Before the electrical performance test, one corner of the substrate was polished with 2000 grit sandpaper. A platinum electrode square pattern with a size of 200 μm × 200 μm was fabricated on the film surface by magnetron sputtering (Q150TS vacuum coater). A shadow mask was used to determine the size of the platinum electrode square. The argon partial pressure was 5.0 × 10 -2 Pa, substrate rotation speed was 1 rpm, sputtering power was 30 W, and sputtering time was 6 min.

[0078] Example 2:

[0079] By the sol-gel method, manganese acetate tetrahydrate was added according to the calculated molar ratio to make the colloid doped with 1% Mn. Figure 1 Step preparation chemical formula is Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 The 1%Mn-doped lead lanthanum zirconium tin film of O3-1%Mn, i.e. PLZS-1%Mn, was evenly dropped onto the cleaned substrate, and then spun on a spin coater for 10 layers. The first and tenth layers of the sample were annealed in air atmosphere at 720°C.

[0080] Before the electrical performance test, one corner of the substrate was polished with 2000 grit sandpaper. A platinum electrode square pattern with a size of 200 μm × 200 μm was fabricated on the film surface by magnetron sputtering (Q150TS vacuum coater). A shadow mask was used to determine the size of the platinum electrode square. The argon partial pressure was 5.0 × 10 -2 Pa, substrate rotation speed was 1 rpm, sputtering power was 30 W, and sputtering time was 6 min.

[0081] Example 3:

[0082] By the sol-gel method, manganese acetate tetrahydrate was added according to the calculated molar ratio to make the colloid doped with 2% Mn. Figure 1 Step preparation chemical formula is Pb 0.97 La 0.02 Zr 0.5 Sn 0.5The 2%Mn-doped lead lanthanum zirconium tin film of O3-2%Mn, i.e. PLZS-2%Mn, was evenly dropped onto the cleaned substrate, and then spun on a spin coater for 10 layers. The first and tenth layers of the sample were annealed in air atmosphere at a temperature of 710°C.

[0083] Before the electrical performance test, one corner of the substrate was polished with 2000 grit sandpaper. A platinum electrode square pattern with a size of 200 μm × 200 μm was fabricated on the film surface by magnetron sputtering (Q150TS vacuum coater). A shadow mask was used to determine the size of the platinum electrode square. The argon partial pressure was 5.0 × 10 -2 Pa, substrate rotation speed was 1 rpm, sputtering power was 30 W, and sputtering time was 6 min.

[0084] Data Analysis:

[0085] Please refer to Figure 2, from which we can see that the PLZS film has obvious antiferroelectric properties. Under an external electric field of 1.064MV / cm, its maximum polarization P max Reached 28.2μC / cm 2 By comparing Figure 2(a)-(d), it can be seen that after doping with Mn, the polarization is significantly enhanced, and the PLZS-0.5%Mn, PLZS-1%Mn and PLZS-2%Mn films are enhanced to 50.5μC / cm 2 、51.1μC / cm 2 and 50.75μC / cm 2 At the same time, when the Mn doping content is 1%, the applied electric field also increases, and the antiferroelectric properties of the film are significantly enhanced.

[0086] See also Figure 3 , which is a structural SEM characterization of the film. The film shown is relatively flat, and the thickness of the film is 470nm, which meets the needs of current industrial electronic components. Figure 4 The XRD phase structure characterization of the film shows that after doping, the four films are all polycrystalline and all crystallize into pure perovskite phase, showing obvious diffraction peaks such as (101), (111), (002), and (112). All diffraction peaks correspond to the PLZS perovskite structure, and no impurity phase is detected. Therefore, the film prepared in this application is relatively stable and has high repeatability, which is beneficial to the application of the film in refrigeration components. At the same time, it can be seen that after adding Mn, the characteristic peak (112) shifts to a high angle. According to the ionic radius (Mn 2+ =0.096 nm, Pb 2+ =0.119 nm,Zr 4+=0.072 nm), and according to the Bragg diffraction formula 2dsinθ=nλ, it can be seen that Mn may occupy the A site.

[0087] Hysteresis loops of the samples were measured using a TF Analyzer 2000E standard ferroelectric testing system. Measurements were made at a frequency of 1000 Hz, starting from room temperature and covering a temperature range of 295–439 K, to determine the electrocaloric effect of the PLZS film. The temperature was ramped at a rate of 2 K / min, and the test was continued after a 5-minute hold at the desired temperature. The temperature-dependent changes in partial polarization and adiabatic temperature variations are shown in Figures 5 and 6.

[0088] Please refer to Figures 5(a)-(d), which are the temperature-dependent curves of the polarization intensity of PLZS, PLZS-0.5%Mn, PLZS-1%Mn, and PLZS-2%Mn films, respectively.

[0089] Specifically, numerical points with external electric field strengths of 426 kV / cm, 638 kV / cm, 745 kV / cm, and 851 kV / cm were selected and fitted to obtain a trend curve showing the polarization intensity changing with conditions. It can be found that under an electric field of 426 kV / cm, the polarization changes the most with temperature and gradually increases, showing a typical antiferroelectric polarization temperature variation trend. Figures 6 (a)-(d) show the adiabatic temperature variation curves of PLZS, PLZS-0.5% Mn, PLZS-1% Mn, and PLZS-2% Mn films, respectively.

[0090] The results show that under an electric field of 426 kV / cm, the adiabatic temperature changes of PLZS-0.5%Mn, PLZS-1%Mn and PLZS-2%Mn films can reach 11K, 13K and 10K respectively, which are much higher than the adiabatic temperature change of PLZS film of 3K. However, it should be noted that doping with 2%Mn will cause serious leakage under high temperature conditions. At the same time, it can be observed that the temperature change range changes from unstable to gradually approaching low temperature. This may be mainly due to the substitutional doping of Mn, which leads to a decrease in the phase transition electric field from antiferroelectric to ferroelectric phase. As shown in Figure 7, the comparison of the phase transition electric field from antiferroelectric to ferroelectric phase of PLZS and PLZS-0.5%Mn films at different temperatures is shown.

[0091] In summary, the present invention provides a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, and its preparation method and application. By changing the antiferroelectric to ferroelectric phase change electric field of the lead lanthanum zirconium tin based antiferroelectric film through doping regulation, while showing excellent antiferroelectric properties, it produces a large adiabatic temperature change of more than 10K, and successfully expands the application scope of electrocaloric refrigeration to the low temperature field, which is of great significance for improving the electrocaloric refrigeration effect of thin film materials, enhancing the stability of antiferroelectric materials and developing new refrigeration technologies.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control, characterized in that: The following steps are involved: Lead acetate trihydrate, dibutyltin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate, and glacial acetic acid are mixed to prepare a mixed solution, and the mixed solution is heated, stirred, and cooled, and polyethylene glycol and acetylacetone are added in sequence and stirred at room temperature, and then zirconium n-propoxide, ethylene glycol methyl ether, and deionized water are added and stirred at room temperature, and finally lactic acid is added and stirred at room temperature, and the mixture is allowed to stand and then filtered to obtain a precursor solution with a concentration of 0.2 to 0.4 mol / L; The precursor solution was spin-coated on a Pt(111) / Ti / SiO2 / Si(004) substrate. The spin-coating time for each layer was 30 to 50 seconds. The film was then dried and pyrolyzed for 10 times. The first and tenth layers were annealed in air to obtain a lead lanthanum zirconium tin based antiferroelectric film with the general formula of Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 O3-x%Mn, 0.5%≤x≤2%.

2. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 1, characterized in that: In the mixed solution, the molar ratio of lead acetate trihydrate: dibutyltin diacetate: lanthanum nitrate hexahydrate: manganese acetate tetrahydrate: glacial acetic acid is (1-1.2): 0.5: 0.02: (0.005-0.02): (0.4-0.6), and the lead acetate trihydrate is in excess of 20%.

3. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 1, characterized in that: The mixed solution is heated and stirred at 120-135° C. for 30-60 minutes. After cooling to room temperature, polyethylene glycol and acetylacetone are added in sequence and stirred for 30-60 minutes. Then, zirconium n-propoxide, ethylene glycol methyl ether and deionized water are added and stirred at room temperature for 30-60 minutes. Finally, lactic acid is added and stirred for 30-60 minutes. After standing for 48-72 hours, the precursor solution is filtered.

4. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 3, characterized in that: The mass-to-volume ratio of polyethylene glycol and acetylacetone is (0.5-1):(0.5-1), the mass-to-volume ratio of zirconium n-propoxide and ethylene glycol methyl ether is (0.8-1):(0.8-1), the molar ratio of deionized water and lead acetate trihydrate is 1:5; and the molar ratio of lactic acid and lead acetate trihydrate is 1:

1.

5. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 3, characterized in that: The filter pore size is 0.2~0.4 microns.

6. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 1, characterized in that: The spin coating speed was 2000~2800 rpm.

7. The method for preparing a lead lanthanum zirconium tin based antiferroelectric thin film by doping control according to claim 1, characterized in that: The drying temperature is 240-260°C, the drying time is 5-15 minutes, the pyrolysis temperature is 500-600°C, and the pyrolysis time is 5-10 minutes.

8. The lead lanthanum zirconium tin based antiferroelectric thin film regulated by doping and its preparation method and application according to claim 1, characterized in that: The annealing temperature is 700-720° C., the annealing time for the first layer is 10-20 minutes, and the annealing time for the tenth layer is 10-20 minutes.

9. A lead lanthanum zirconium tin based antiferroelectric thin film regulated by doping, characterized in that: Prepared according to the method according to any one of claims 1 to 8.

10. Application of the lead lanthanum zirconium tin based antiferroelectric thin film regulated by doping according to claim 9 in wearable thermal management devices, in-situ thermal management devices for data center chips, and low-energy thermal management devices for electric vehicles.

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