Doping-regulated lead-lanthanum-zirconium-tin-based anti-ferroelectric film and preparation method and application thereof

Abstract

The invention discloses a lead-lanthanum-zirconium-tin-based anti-ferroelectric film regulated and controlled through doping and a preparation method and application thereof.The preparation method comprises the steps that lead acetate trihydrate, dibutyltin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid are mixed to prepare a mixed solution, and then the mixed solution is heated, stirred and cooled; sequentially adding polyethylene glycol and acetylacetone and stirring at room temperature, then adding zirconium n-propoxide, ethylene glycol monomethyl ether and deionized water and stirring at room temperature, finally adding lactic acid and stirring at room temperature, standing and filtering to obtain a precursor solution; and spin-coating the prepared precursor solution on a Pt (111) / Ti / SiO2 / Si (004) substrate, then carrying out drying treatment and pyrolysis treatment, and respectively carrying out annealing treatment on the first layer of film and the tenth layer of film in an air atmosphere to obtain the lead lanthanum zirconium tin-based anti-ferroelectric film. While a large refrigeration temperature change value is achieved, the electrocaloric refrigeration effect is expanded to a low-temperature area, and more excellent anti-ferroelectric performance is shown.

Description

Technical Field

[0001] The 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 pursuit of quality of life, refrigeration technology has a wide range of applications and prospects in aviation-grade refrigerators, vehicle thermal management systems, wearable devices, etc. 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 type of solid-state refrigeration technology, electrocaloric effect refrigeration has the advantages of high efficiency, low cost, miniaturization and mass production of materials. The basic idea of ​​electrocaloric effect refrigeration is that the polarization state of the material changes under the action of an external electric field, resulting in a change in entropy, which in turn causes the material to change in temperature. Therefore, using an external electric field to change the polarization state of the material can achieve temperature regulation and thus achieve refrigeration. At present, in addition to conventional ferroelectrics and relaxor ferroelectrics, antiferroelectric materials are also very attractive for electrocaloric refrigeration. Unlike conventional ferroelectrics and relaxor ferroelectrics, under the action of an external electric field, the polarization direction of adjacent electric domains of antiferroelectric materials will change from antiparallel to the same direction as the electric field. During the antiferroelectric-ferroelectric phase transition, the polarization changes, which will produce a large electrocaloric cooling effect.

[0004] Antiferroelectric materials represented by lead zirconate have a stable antiferroelectric phase stability zone in the lead lanthanum zirconium tin (PLZS) antiferroelectric system formed by adding lanthanum and tin, which has attracted people's attention. However, in the traditional preparation method, there are still some bottlenecks, such as the low adiabatic temperature change caused by the electrocaloric effect and the high electric field of phase change, which limit its practical application in the field of electronic components. Therefore, in view of the problem of regulating the electrocaloric properties of the antiferroelectric material lead lanthanum zirconium tin film, developing a new doping regulation method to optimize the antiferroelectric properties and electrocaloric refrigeration performance of the film has become a scientific and technological challenge that needs to be solved urgently. This patent proposes a new method of doping regulation modification to prepare lead lanthanum zirconium tin film, thereby significantly improving the antiferroelectric properties and electrocaloric properties of the antiferroelectric film, thereby meeting the needs of high-performance refrigeration microdevices in the future, opening up new ideas for electrocaloric refrigeration of antiferroelectric materials, and promoting further development in related fields. Summary of the invention

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

[0006] The present invention adopts the following technical solutions: A method for preparing a lead lanthanum zirconium tin-based antiferroelectric film by doping regulation comprises the following steps: Lead acetate trihydrate, dibutyltin diacetate, lanthanum nitrate hexahydrate, manganese acetate tetrahydrate and glacial acetic acid are mixed to prepare a mixed solution, and then the mixed solution is heated, stirred and cooled, 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 then filtered after standing to obtain a precursor solution with a concentration of 0.2-0.4 mol / L; The prepared precursor solution was spin-coated on a Pt(111) / Ti / SiO2 / Si(004) substrate, and then dried and pyrolyzed. The first and tenth layers of the film were annealed in an air atmosphere to obtain a lead lanthanum zirconium tin based antiferroelectric film.

[0007] Preferably, 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: (0-0.02): (0.4-0.6), and the lead acetate trihydrate is in excess of 20%.

[0008] Preferably, the mixed solution is heated and stirred at 120-135° C. for 30-60 minutes, cooled to room temperature, polyethylene glycol and acetylacetone are added in sequence, 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, and finally lactic acid is added, stirred for 30-60 minutes, and filtered to obtain a precursor solution after standing for 48-72 hours.

[0009] Preferably, the mass volume ratio of polyethylene glycol to acetylacetone is (0.5-1):(0.5-1), the mass volume ratio of zirconium n-propoxide to 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.

[0010] Preferably, the filter pore size is 0.2-0.4 microns.

[0011] Preferably, the spin coating speed is 2000-2800 rpm, and the spin coating time for each layer is 30-50 seconds.

[0012] Preferably, the drying temperature is 240-260° C., the drying time is 5-15 minutes, the pyrolysis temperature is 500-600° C., the pyrolysis time is 5-10 minutes, and the process is repeated 10 times.

[0013] Preferably, it is characterized in that the temperature of the annealing treatment 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.

[0014] 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%.

[0015] Another technical solution of the present invention is to use the lead lanthanum zirconium tin based antiferroelectric film 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.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: A method for preparing a lead-lanthanum-zirconium-tin-based antiferroelectric film by doping regulation. The colloid preparation process can obtain a stable and uniform colloid by reasonably arranging the order of adding precursor materials, as well as adding catalysts and chelating agents. At the same time, the overall preparation steps are simple and highly repeatable. The solvent is removed by heat treatment, the crystallinity is increased by pyrolysis, and a simple annealing method is used to achieve full crystallization, and finally a film with stable improved antiferroelectric and electrocaloric properties is obtained.

[0017] Furthermore, 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: (0-0.02): (0.4-0.6), wherein the lead acetate trihydrate is in excess of 20%, which can compensate for the loss of lead during annealing and prevent the formation of pyrochlore phase in the film. Glacial acetic acid, as a solvent, is easy to volatilize, has good solubility, and can dissolve a variety of organic matter and inorganic salts. By controlling its molar ratio relative to other raw materials, the concentration of the colloid can be further controlled. Dibutyltin diacetate is inexpensive, making the cost much lower than tin acetate. Lead acetate trihydrate and manganese acetate tetrahydrate are more easily dissolved in glacial acetic acid. Lanthanum nitrate, as one of the precursors, can accelerate the hydrolysis and condensation reactions of the precursor through its catalytic action, thereby shortening the preparation time and improving the purity of the product.

[0018] Further, the mixed solution is heated and stirred at 120-135°C for 30-60 minutes, which can effectively remove the crystal water in the raw material 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, which can 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, and 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. Each step is stirred for 30-60 minutes to make the reaction more complete. Standing for 48-72 hours can facilitate the follow-up, remove impurities, promote sol aging, etc., so as to filter and obtain the desired precursor solution.

[0019] Furthermore, when prepared in this ratio, polyethylene glycol can be used as an emulsifier and surfactant to improve the mechanical properties of the gel film, and acetylacetone can improve the dispersion and stability of the sol, prevent the agglomeration and precipitation of the colloidal particles, and ensure that the final colloidal product has excellent performance. And the configuration of ethylene glycol methyl ether in this ratio can affect the hydrolysis and condensation reaction rates when the PLZS colloid is formed, thereby optimizing the preparation process of the PLZS colloid.

[0020] 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 avoiding their influence on the performance of the membrane.

[0021] 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.

[0022] 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 helps the grain growth and orientation in the film, thereby improving the crystallinity and performance of the film.

[0023] Furthermore, annealing at this temperature is conducive to more complete crystallization of the lead-lanthanum-zirconium-tin based antiferroelectric film. At the same time, the first layer of annealing helps to refine the grains of the material, improve uniformity, and also help to eliminate stress and prevent subsequent film cracking. The last layer of annealing helps to change the surface properties of the material and improve the stability of the film.

[0024] In summary, the method of the present invention has a simple preparation process and strong repeatability. While achieving a large refrigeration temperature change value, it also successfully expands the electrocaloric refrigeration effect to the low temperature region. The preparation process is simple and exhibits more excellent antiferroelectric properties. This innovation enables the device prepared at the same cost to have better performance.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 creative work.

[0027] Figure 1 is a flow chart of the preparation method of the present invention; 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; 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; 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; 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; Figure 3 This is a SEM cross-sectional view of the lead lanthanum zirconium tin based antiferroelectric film provided by the present invention; Figure 4 Provide XRD diagrams of Example 1 and Example 2 and Comparative Example 1 for the present invention; FIG5 (a) is a curve showing the change of polarization intensity with temperature of Comparative Example 1 provided by the present invention; FIG5( b ) is a curve showing the change of polarization intensity with temperature in Example 1 provided by the present invention; FIG5( c ) is a curve showing the change of polarization intensity with temperature in Example 2 provided by the present invention; FIG5( d ) is a curve showing the change of polarization intensity with temperature in Example 3 provided by the present invention; FIG6 (a) is an electrocaloric effect ΔT-T curve of Comparative Example 1 provided by the present invention; FIG6 (b) is an electrocaloric effect ΔT-T curve of Example 1 provided by the present invention; FIG6 (c) is an electrocaloric effect ΔT-T curve of Example 2 provided by the present invention; FIG6 (d) is an electrocaloric effect ΔT-T curve of Example 3 provided by the present invention; FIG. 7 is a graph showing the E values ​​at different temperatures of Comparative Example 1 and Example 1 provided by the present invention. AFE-FE Curve, wherein (a) is Comparative Example 1, and (b) is Example 1. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] 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.

[0030] 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.

[0031] In the present invention, unless otherwise specified, percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0032] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0033] In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "6-22" represents that all real numbers between "6-22" are listed in this document, and "6-22" is just an abbreviation of these numerical combinations.

[0034] The “range” disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0035] 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.

[0036] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0037] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention.

[0038] 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 steam compression refrigeration technology can basically meet the refrigeration needs in many application scenarios, its disadvantages such as high greenhouse gas emissions, large volume 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 defects. The electrocaloric effect refrigeration has the advantages of high efficiency, low cost, miniaturization and batch production of materials. Among them, antiferroelectric materials are ideal materials that meet the needs of modern electronic devices because of the antiferroelectric-ferroelectric phase transition. In this process, polarization changes, causing entropy change, and then a large electrocaloric cooling effect is produced. However, the current existing electrocaloric technology has a low temperature change effect of the prepared material, and the temperature change area is mostly present near the temperature change point, or the antiferroelectric-ferroelectric phase change point is high. Therefore, the present application proposes a preparation method of regulating the electrocaloric effect of lead lanthanum zirconium tin antiferroelectric film by doping, so as to achieve the effect of improving the electrocaloric properties of antiferroelectric materials.

[0039] The present invention provides a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, and a preparation method and application thereof. The PLZS film obtained by doping regulation weakens the antiferroelectric to ferroelectric phase change electric field of PLZS compared with other electrocaloric materials by doping Mn. Under this influence, the PLZS film after Mn doping regulation shows a temperature change range close to room temperature and a higher polarization intensity. At the same time, the greater change of polarization with temperature makes the film have more outstanding electrocaloric temperature change characteristics. The technology provided by the present application significantly improves the electrocaloric performance of the lead lanthanum zirconium tin antiferroelectric film, deeply understands the antiferroelectric electrocaloric principle of the PLZS film, and promotes the development of the new practical antiferroelectric film refrigeration field. The preparation method is simple in process, and while achieving a larger refrigeration temperature change value, the electrocaloric refrigeration effect is also expanded to the low temperature region, and more excellent antiferroelectric performance is exhibited, which will promote the technological progress and industrial upgrading of the future electrocaloric refrigeration market.

[0040] See also Figure 1 The present invention provides a method for preparing a lead lanthanum zirconium tin based antiferroelectric film by doping regulation, comprising the following steps: S1, pre-treating the substrate; 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%.

[0041] 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).

[0042] S2. Heat the mixed solution at 120-135° C. with stirring for 30-60 minutes. After cooling to room temperature, add polyethylene glycol in sequence and stir for 30-60 minutes. Then add zirconium n-propoxide, ethylene glycol methyl ether and deionized water and stir at room temperature for 30-60 minutes. The mass volume ratio of polyethylene glycol to acetylacetone is (0.5-1): (0.5-1). Stir for 30 minutes. S3, adding zirconium n-propoxide and ethylene glycol methyl ether, the mass volume ratio of zirconium n-propoxide and ethylene glycol methyl ether is (0.8~1): (0.8~1), and adding deionized water at a ratio of 1 mol of deionized water to 5 mol of lead, and stirring again for 30~60 minutes; S4. Finally, add lactic acid in a ratio of 1 mol lactic acid to 1 mol lead and stir for 30 to 60 minutes; S5. After standing for 48 to 72 hours, filter it with a filter with a pore size of 0.2 to 0.4 microns to obtain a precursor solution with a concentration of 0.2 to 0.4 mol / L. Evenly drop the filtered precursor solution on a clean Pt(111) / Ti / SiO2 / Si(004) substrate that has been ultrasonically cleaned with alcohol and high-purity water for 5 minutes. S6, spin coating the precursor solution on a spin coater, the spin coating speed is 2000~2800 rpm, and the spin coating time of each layer is 30~50 seconds; after coating, the wet film is dried on a heating table at 240~260°C for 5~15 minutes, and then pyrolyzed in a tube furnace at 500~600°C for 5~10 minutes, and repeated 10 times; S7. Annealing the first and tenth thin films at 700-720° C. for 10-20 minutes respectively in an air atmosphere.

[0043] 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 0.5 O3-x%Mn (0%≤x≤2%), while obtaining a larger refrigeration temperature change value, the electric caloric refrigeration change also approaches low temperature. At the same time, it is simple to prepare and has better antiferroelectric properties.

[0044] The lead lanthanum zirconium tin based antiferroelectric film regulated by gold doping of the present invention can be applied to the manufacture of wearable thermal management devices, in-situ thermal management devices for data center chips, and low-energy consumption thermal management devices for electric vehicles.

[0045] 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, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually 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 in 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.

[0046] Comparative Example 1: By sol-gel method, according to the calculated molar ratio, Figure 1 Step preparation chemical formula Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 After the lead lanthanum zirconium tin film of O3, i.e. PLZS, was evenly dropped onto the cleaned substrate, 10 layers were spin-coated on a spin coater, and the first and tenth layers of the sample were annealed in an air atmosphere at a temperature of 720°C.

[0047] Before the electrical performance test, one corner of the substrate was polished with 2000-grit sandpaper, and a platinum electrode square pattern with a size of 200 μm × 200 μm was manufactured 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.

[0048] Embodiment 1: 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 Pb 0.97 La 0.02 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 uniformly 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 700°C.

[0049] Before the electrical performance test, one corner of the substrate was polished with 2000-grit sandpaper, and a platinum electrode square pattern with a size of 200 μm × 200 μm was manufactured 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.

[0050] Embodiment 2: By 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 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 uniformly 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.

[0051] Before the electrical performance test, one corner of the substrate was polished with 2000-grit sandpaper, and a platinum electrode square pattern with a size of 200 μm × 200 μm was manufactured 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.

[0052] Embodiment 3: 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 Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 The 2%Mn-doped lead lanthanum zirconium tin film of O3-2%Mn, i.e. PLZS-2%Mn, was uniformly dropped onto the cleaned substrate, and then 10 layers were spin-coated on a spin coater. The first and tenth layers of the sample were annealed in an air atmosphere at 710°C.

[0053] Before the electrical performance test, one corner of the substrate was polished with 2000-grit sandpaper, and a platinum electrode square pattern with a size of 200 μm × 200 μm was manufactured 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 -2Pa, substrate rotation speed was 1 rpm, sputtering power was 30 W, and sputtering time was 6 min.

[0054] Data Analysis: 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. The antiferroelectric properties of the film are significantly enhanced.

[0055] 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 crystallized 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 conducive to the application of the film in refrigeration components. At the same time, it can be seen that after adding Mn, the (112) characteristic peak 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), according to the Bragg diffraction formula 2dsinθ=nλ, it means that Mn may occupy the A site.

[0056] The TF Analyzer 2000E standard ferroelectric test system was used to test the hysteresis loop of the sample. The temperature increment was 9K, the measurement frequency was 1000Hz, the measurement started from room temperature, and the measurement temperature range was 295-439K to measure the electrocaloric effect of the PLZS film. The heating rate during the test was 2K / min. After reaching the set temperature, the test was started after 5 minutes of heat preservation. The partial polarization change with temperature and the adiabatic temperature change results obtained by the test are shown in Figures 5 and 6.

[0057] Please refer to Figure 5 (a)-(d), which are the temperature variation curves of the polarization intensity of PLZS, PLZS-0.5%Mn, PLZS-1%Mn and PLZS-2%Mn films, respectively.

[0058] Specifically, we selected the numerical points of external electric field strength of 426kv / cm, 638kv / cm, 745kv / cm and 851kv / cm, and fitted these points to obtain the trend curve of polarization intensity changing with conditions; it can be found that under the electric field of 426kv / cm, the polarization changes with temperature the most and gradually increases, showing the typical trend of antiferroelectric polarization changing with temperature. Figure 6 (a)-(d) are the adiabatic temperature change curves of PLZS, PLZS-0.5%Mn, PLZS-1%Mn and PLZS-2%Mn films, respectively.

[0059] 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 lead to 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, which shows the comparison of the phase transition electric field from antiferroelectric to ferroelectric phase of PLZS and PLZS-0.5%Mn films at different temperatures.

[0060] In summary, the present invention provides a lead lanthanum zirconium tin based antiferroelectric film regulated by doping, and a preparation method and application thereof. 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, a large adiabatic temperature change of more than 10K is produced, and the application scope of electrocaloric refrigeration is successfully expanded 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.

[0061] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 regulation, 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 then the mixed solution is heated, stirred and cooled, 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 then filtered after standing to obtain a precursor solution with a concentration of 0.2-0.4 mol / L; The prepared precursor solution was spin-coated on a Pt(111) / Ti / SiO2 / Si(004) substrate, and then dried and pyrolyzed. The first and tenth layers of the film were annealed in an air atmosphere to obtain a lead lanthanum zirconium tin based antiferroelectric film.

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: (0-0.02): (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 volume ratio of polyethylene glycol and acetylacetone is (0.5~1):(0.5~1), the mass 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; the molar ratio of lactic acid and lead acetate trihydrate is 1:

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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 speed of spin coating preparation was 2000~2800 rpm, and the spin coating time of each layer was 30~50 seconds.

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, the pyrolysis time is 5-10 minutes, and this is repeated 10 times.

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 temperature of the annealing treatment 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.

9. A lead lanthanum zirconium tin based antiferroelectric thin film regulated by doping, characterized in that: Prepared according to any one of claims 1 to 8, the general formula is Pb 0.97 La 0.02 Zr 0.5 Sn 0.5 O3-x%Mn, 0%≤x≤2%.

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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