Antiferroelectric thin film and preparation method thereof, antiferroelectric capacitor containing same and preparation method thereof

Abstract

The present invention discloses an antiferroelectric thin film and a preparation method thereof, an antiferroelectric capacitor containing the same and a preparation method thereof. The antiferroelectric thin film includes multiple paraelectric-antiferroelectric layers, and each paraelectric-antiferroelectric layer includes multiple paraelectric regions which are diffusely distributed in the antiferroelectric region. The preparation method is as follows: mixing a PbZrO3 precursor solution and an ABO3 precursor solution to obtain a mixed precursor solution; depositing the mixed precursor solution on a substrate material, and obtaining a thin film with at least two paraelectric-antiferroelectric layers through spin coating deposition, baking and pyrolysis, and then performing annealing crystallization treatment to obtain the antiferroelectric thin film; the antiferroelectric capacitor is prepared based on the antiferroelectric thin film, and further includes a single crystal substrate, a conductive electrode layer and a gold electrode, and the antiferroelectric thin film is located between the conductive electrode layer and the gold electrode. The antiferroelectric thin film of the present invention has a frustrated antiferroelectric order structure, which can improve the stability of the antiferroelectric phase, delay the antiferroelectric-ferroelectric transition field and reduce the hysteresis of the electric hysteresis loop.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic materials, and particularly relates to an antiferroelectric thin film, a preparation method thereof, an antiferroelectric capacitor containing the same, and a preparation method thereof. Background Art

[0002] An antiferroelectric capacitor is a capacitor that utilizes an antiferroelectric material. The antiferroelectric material has a special antiparallel polarization configuration. This configuration exhibits paraelectric characteristics at low fields, while at high fields, it will be induced into a ferroelectric phase, resulting in a field-induced antiferroelectric-ferroelectric phase transition. Therefore, it can effectively delay polarization saturation and has good energy storage prospects. At the same time, antiferroelectric materials also have advantages such as fast polarization switching speed and a wide operating temperature range, and are expected to be applied in complex environments and working conditions, and have a very high power density. Currently, the mainstream antiferroelectric material is PbZrO 3 , but it has disadvantages such as a relatively low antiferroelectric-ferroelectric transition field and a large hysteresis, resulting in limited energy storage density of antiferroelectric capacitors.

[0003] In order to solve the above problems existing in the prior art, the present invention comes into being. Summary of the Invention

[0004] To solve the technical problems in the prior art, such as a relatively low antiferroelectric-ferroelectric transition field, a large hysteresis, and limited energy storage density when using PbZrO 3 as an antiferroelectric material, the present invention provides an antiferroelectric thin film, a preparation method thereof, an antiferroelectric capacitor containing the same, and a preparation method thereof. The antiferroelectric thin film has a frustration effect, which can improve the stability of the antiferroelectric phase, delay the antiferroelectric-ferroelectric transition field, and reduce the hysteresis of the electric hysteresis loop.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a preparation method of an antiferroelectric thin film, comprising the following steps:

[0007] Step 1: Mix a PbZrO 3 precursor solution and an ABO 3 paraelectric precursor solution in a set ratio to obtain a mixed precursor solution;

[0008] Step 2: Deposit the mixed precursor solution obtained in Step 1 on a substrate material, and obtain the first-layer paraelectric-antiferroelectric layer through baking and pyrolysis. Repeat the spin coating deposition, baking, and pyrolysis treatment at least once to obtain a thin film with at least two layers of paraelectric-antiferroelectric layers;

[0009] Step 3: Perform annealing crystallization treatment on the thin film obtained in Step 2 to obtain an antiferroelectric thin film.

[0010] Preferably, the ABO 3 type compound is SrTiO 3 , CaTiO 3 , CaZrO 3 , SrZrO 3 , LaScO 3 , LaAlO 3 , LaGaO 3 , KTaO 3 and any one of LnFeO 3 . Only when the ABO 3 type compound is selected as CaZrO 3 or SrZrO 3 , the antiferroelectric thin film contains three metal elements, and the molar ratio of metal element A to metal element B < 1, and the specific ratio is determined according to the volume ratio of the ABO 3 paraelectric precursor solution and the PbZrO 3 precursor solution. While the antiferroelectric thin films prepared with the remaining several raw materials all contain four metal elements, and the molar ratio of metal element A to metal element B is equal to 1.

[0011] Preferably, the concentration of the PbZrO 3 precursor solution is the same as that of the ABO 3 paraelectric precursor solution, and the concentration is 0.1 - 0.4 M, and the volume ratio of the ABO 3 paraelectric precursor solution to the mixed precursor solution is (1:10) - (2:3).

[0012] Preferably, in step 2, the rotation speed of spin coating is 3000 - 6000 revolutions per minute, and the duration is 10 - 60 seconds; the baking temperature is 100 - 500 °C, and the time is 0.5 - 5 min; the pyrolysis temperature is 350 - 550 °C, and the time is 0.5 - 5 min;

[0013] In step 3, the annealing crystallization temperature is 550 - 800 °C, and the time is 3 - 30 min.

[0014] Preferably, the preparation method further includes the preparation of a lead loss prevention layer. The specific method is: spin - coat and deposit a layer of PbO on the surface of each layer of the paraelectric - antiferroelectric layer or the last layer of the paraelectric - antiferroelectric layer, or add a precursor solution containing PbO in a set proportion to the mixed precursor solution when preparing the last layer of the paraelectric - antiferroelectric layer. Lead oxide helps to prevent the loss of lead in the paraelectric - antiferroelectric layer.

[0015] Preferably, the preparation method further includes adding, to the precursor solution in step 1, relative to PbZrO 3 -ABO 3Bismuth nitrate or bismuth acetate with a molar percentage of 3.0% - 7.0% in the whole system. Meanwhile, when preparing each ferroelectric - antiferroelectric layer, control the pyrolysis temperature at 250 - 400 °C.

[0016] The present invention also provides an antiferroelectric thin film prepared by the above - mentioned preparation method, which includes multiple ferroelectric - antiferroelectric layers. Each ferroelectric - antiferroelectric layer includes multiple ferroelectric regions, and the multiple ferroelectric regions are diffusely distributed in the antiferroelectric region; wherein, the ferroelectric region is formed by ABO 3 type compounds, and the antiferroelectric region is formed by PbZrO 3 formed.

[0017] The principle that the antiferroelectric thin film of the present invention can achieve delaying the antiferroelectric - ferroelectric transition field and reducing the hysteresis of the ferroelectric hysteresis loop is as follows: Due to the existence of ferroelectric regions and antiferroelectric regions in the thin film, an antiferroelectric state can be formed in the antiferroelectric region, and a ferroelectric state will be formed in the ferroelectric region. Such a structure will break the long - range antiferroelectric order, which is an antiferroelectric body regulation mechanism based on electrostatic energy and is completed through the bound charges at the antiferroelectric / ferroelectric region interface. Specifically, after applying an electric field, there is an antiferroelectric - ferroelectric field - induced phase transition process in the antiferroelectric region, which will bring a rapid increase in polarization. While the polarization in the ferroelectric region is very small, it will hinder the occurrence of this field - induced phase transition, thereby delaying the phase transition field of the antiferroelectric. After removing the electric field, the polarization in the ferroelectric region will reversibly return to a smaller state, which will drive the antiferroelectric region to undergo an earlier ferroelectric - antiferroelectric reverse transition, thereby reducing the forward and reverse field - induced phase differences and reducing the hysteresis. For the traditional regulation mechanism based on the tolerance factor, although it can increase the field - induced phase transition point, it cannot reduce the hysteresis; or the traditional regulation mechanism based on relaxor antiferroelectrics, although it can reduce the hysteresis, it cannot increase the field - induced phase transition point. The antiferroelectric thin film of the present invention is an antiferroelectric body regulation mechanism based on electrostatic energy, which can not only reduce the hysteresis but also increase the field - induced phase transition point.

[0018] Preferably, the dielectric constant of the ABO 3 type compound is 50 - 200.

[0019] Preferably, the molar ratio of metal element A to metal element B in the ferroelectric - antiferroelectric layer ≤ 1.

[0020] The present invention also provides an antiferroelectric capacitor, which includes the antiferroelectric thin film prepared by the above - mentioned preparation method, and also includes a single - crystal substrate, a conductive electrode layer, and a gold electrode arranged from the inside out. The antiferroelectric thin film is located between the conductive electrode layer and the gold electrode. By using the antiferroelectric thin film, the present invention greatly improves the breakdown electric field and energy storage density, and at the same time realizes improving the relaxivity to weaken the electro - strictive strain and improving the cycling performance.

[0021] Preferably, the single - crystal substrate is LaAlO3 , SrTiO 3 , Pt / Si, DyScO 3 , Nb-doped SrTiO 3 , NaCl or F-doped SnO 2 , In-doped SnO 2 , (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 ; any one of

[0022] The conductive electrode layer is LaNiO 3 conductive electrode layer, SrRuO 3 conductive electrode layer, La 0.7 Sr 0.3 MnO 3 conductive electrode layer; the number of layers of the conductive electrode layer is at least two.

[0023] The present invention also provides a method for preparing an antiferroelectric capacitor, comprising the following steps:

[0024] Step A: Prepare a conductive electrode layer on the surface of a single crystal substrate by spin coating technology;

[0025] Step B: Using the conductive electrode layer of the product obtained in Step A as a substrate material, an antiferroelectric thin film is prepared by the above preparation method;

[0026] Step C: Deposit a gold electrode on the surface of the antiferroelectric thin film through a stainless steel mask to obtain an antiferroelectric capacitor.

[0027] Preferably, in Step A, a first precursor solution is deposited on the surface of the single crystal substrate by spin coating technology, and the first layer of the conductive electrode layer is obtained by baking and pyrolysis in sequence. The spin coating deposition, baking and pyrolysis treatments are repeated at least once to obtain at least two conductive electrode layers, and then annealing crystallization treatment and aging treatment are carried out to obtain the final conductive electrode layer;

[0028] Among them, the first precursor solution is LaNiO 3 precursor solution, SrRuO 3 precursor solution, La 0.7 Sr 0.3 MnO 3 precursor solution; any one of

[0029] Preferably, the baking temperature is 200~230 °C, the pyrolysis temperature is 480~550 °C, and the annealing crystallization temperature is 550~800 °C.

[0030] The beneficial effects of the present invention are:

[0031] (1) The present invention constructs a frustrated antiferroelectric structure by adding an ABO 3 paraelectric precursor into the antiferroelectric material PbZrO 3 and utilizes the polarization discontinuity at the antiferroelectric-paraelectric interface to construct an electrostatic interaction, achieving the effects of delaying the transition field and reducing the hysteresis, and can simultaneously improve the energy storage density and efficiency. In addition, the thin film prepared by the present invention contains several paraelectric regions and antiferroelectric regions, and the antiferroelectric phase stability can be improved through the paraelectric regions and antiferroelectric regions, increasing the breakdown electric field and energy storage density, and the electrostriction is weakened by enhancing the relaxivity, thereby improving the cycling performance.

[0032] (2) The present invention also adopts a variety of measures to prevent element volatilization, such as the preparation of a lead loss prevention layer, and for another example, adding bismuth nitrate or bismuth acetate to the mixed precursor solution. By adding bismuth nitrate or bismuth acetate to the mixed precursor solution, in addition to being able to reduce lead loss, it can also form Bi 2 O 3 according to the reaction. Through the sintering aid effect of Bi 2 O 3 , the temperature of the pyrolysis operation is significantly reduced.

[0033] (3) The preparation method of the present invention has the characteristics of simple operation and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below in conjunction with the drawings and embodiments:

[0035] Figure 1 is the curve of the polarization intensity of the PbZrO 3 -LaScO 3 thin film capacitor disclosed in Example 1 of the present invention changing with the electric field, where a, b, c, d, and e respectively represent the curves of the polarization intensity changing with the electric field when the volume ratio of the LaScO 3 paraelectric precursor solution in the mixed precursor solution is 0 to 0.5;

[0036] Figure 2 is the curve of the breakdown probability of the PbZrO 3 -LaScO 3 thin film capacitor disclosed in Example 1 of the present invention changing with the electric field;

[0037] Figure 3 is the curve of the energy storage density and energy storage efficiency of the PbZrO 3 -LaScO 3 thin film capacitor disclosed in Example 1 of the present invention changing with the electric field;

[0038] Figure 4 is the PbZrO disclosed in Example 1 of the present invention3 -LaScO 3 Variation curves of the energy storage density and energy storage efficiency of the thin film capacitor with the number of cycles;

[0039] Figure 5 It is a distribution diagram of the paraelectric region and the antiferroelectric region in the paraelectric-antiferroelectric layer, where e1 represents the antiferroelectric region and e2 represents the paraelectric region. Specific implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0041] An embodiment of the present invention discloses an antiferroelectric thin film and a preparation method thereof:

[0042] Step 1: Mix a PbZrO 3 precursor solution and an ABO 3 paraelectric precursor solution in a set ratio to obtain a mixed precursor solution; The ABO 3 type compound includes any one of SrTiO 3 , CaTiO 3 , CaZrO 3 , SrZrO 3 , LaScO 3 , LaAlO 3 , LaGaO 3 , KTaO 3 and LnFeO 3 ; the concentrations of the PbZrO 3 precursor solution and the ABO 3 paraelectric precursor solution are the same; the volume ratio of the added amount of the ABO 3 paraelectric precursor solution to the mixed precursor solution is (1:10) to (2:3). Specifically, it is necessary to control that the ABO 3 paraelectric precursor solution does not exceed 2 / 3 of the total volume of the mixed precursor solution and is not less than 1 / 10 of the total volume of the mixed precursor solution.

[0043] Among them, the preparation process of the PbZrO 3 precursor solution is: dissolve lead acetate in a solvent, heat it at 60-150 °C for 0.5-3 hours; after cooling to room temperature, introduce zirconium n-propoxide into the solution, and continuously stir the obtained mixed solution under ambient conditions for 1-3 hours to ensure that zirconium n-propoxide is completely dissolved, and obtain a clear and transparent PbZrO with a concentration of 0.1-0.4 M 3Precursor solution;

[0044] ABO 3 The preparation process of the paraelectric precursor solution is as follows: taking the preparation of SrTiO 3 , LaScO 3 , CaTiO 3 as an example, at a temperature of 60 - 150 °C, equimolar amounts of metal A source and metal B source (strontium acetate and tetrabutyl titanate, lanthanum nitrate and scandium nitrate, or calcium acetate and tetrabutyl titanate) are dissolved in a solvent for 0.5 - 3 hours. The resulting mixture is continuously stirred for 1 - 3 hours until completely dissolved, obtaining a paraelectric ABO 3 precursor solution with a concentration of 0.1 - 0.4 M (SrTiO 3 precursor solution, LaScO 3 precursor solution or CaTiO 3 precursor solution). The solvent used for preparing the precursor solution is one or several of 2 - methoxyethanol, propionic acid, ethylene glycol, and acetic acid. In addition to using nitrates, the metal A source and metal B source for preparing the precursor solution can also use soluble acetates or chlorides.

[0045] Step 2: Spin - coat and deposit the mixed precursor solution obtained in Step 1 on a substrate material, and obtain the first - layer paraelectric - antiferroelectric layer through baking and pyrolysis. Spin - coat deposition, baking, and pyrolysis treatments are repeated at least once to obtain a film with at least two layers of paraelectric - antiferroelectric layers; the thickness of the film can be determined according to user requirements. For example, when preparing a capacitor using an antiferroelectric film, the thickness of the film can be selected to be 100 - 1000 nm.

[0046] Among them, the rotation speed of spin - coating is 3000 - 6000 revolutions per minute, and the duration is 10 - 60 seconds; the baking temperature is 100 - 500 °C, and the time is 0.5 - 5 min to promote the evaporation of the solvent; the pyrolysis temperature is 350 - 550 °C, and the time is 0.5 - 5 min to eliminate the remaining organic substances; further preferably, the baking temperature is 200 - 230 °C, and the pyrolysis temperature is 480 - 550 °C.

[0047] Step 3: Perform annealing crystallization treatment on the film obtained in Step 2 to obtain an antiferroelectric film.

[0048] Among them, the annealing crystallization temperature is 550 - 800 °C, and the time is 3 - 30 min.

[0049] In some improved embodiments, it is also possible to add, relative to PbZrO 3 -ABO 3Bismuth nitrate or bismuth acetate with a molar percentage of 3.0% to 7.0% in the whole system. At the same time, when spin-coating and depositing each layer of paraelectric-antiferroelectric layer, the pyrolysis temperature is controlled at 250 to 400 °C. By adding bismuth nitrate or bismuth acetate to the mixed precursor solution, Bi 2 O 3 can be formed, which has a sintering aid effect and can reduce the heat treatment temperature by about 100 °C, from 350 to 500 °C to 250 to 400 °C. On the one hand, it can reduce the effect of Pb volatilization and loss due to the reduction of pyrolysis temperature, and on the other hand, it can reduce energy consumption and cost.

[0050] In some improved embodiments, a layer of PbO can also be spin-coated and deposited on the surface of each layer of paraelectric-antiferroelectric layer or the last layer of paraelectric-antiferroelectric layer; specifically, a layer of oxide PbO can be deposited on each layer of paraelectric-antiferroelectric layer, and a layer of oxide PbO can also be deposited on the last layer of paraelectric-antiferroelectric layer, which helps to prevent the loss of volatile metal element Pb in the antiferroelectric thin film. In addition, it can also be selected to add a PbO precursor solution to the mixed precursor solution when preparing the last layer of paraelectric-antiferroelectric layer to simplify the process treatment and improve the preparation efficiency. Taking the PbO precursor solution as an example, its preparation process is as follows: Dissolve lead acetate in a solvent and heat it at 60 to 150 °C for 1 to 3 hours to obtain a PbO precursor solution with a concentration of 0.1 to 0.4 M.

[0051] The above antiferroelectric thin film includes multiple layers of paraelectric-antiferroelectric layers, and each layer of the paraelectric-antiferroelectric layer includes multiple paraelectric regions, and the multiple paraelectric regions are diffusely distributed in the antiferroelectric region. Among them, the paraelectric region is formed by ABO 3 type compounds, and the antiferroelectric region is formed by PbZrO 3 , and the molar ratio of metal element A to metal element B in the paraelectric-antiferroelectric layer is ≤1. In order to prevent the loss of lead in the paraelectric-antiferroelectric layer, a layer of lead oxide can also be provided on the surface of each layer of paraelectric-antiferroelectric layer or the last layer of paraelectric-antiferroelectric layer in the multiple layers of paraelectric-antiferroelectric layers.

[0052] The embodiment of the present invention also discloses a high energy storage density antiferroelectric capacitor and its preparation method. The antiferroelectric thin film of the antiferroelectric capacitor is provided with a lead loss prevention layer:

[0053] Step A: Deposit the first precursor solution on the surface of the single crystal substrate by spin coating technology, and sequentially obtain the first layer of conductive electrode layer through baking and pyrolysis. Spin coating deposition, baking and pyrolysis treatment are repeated at least once to obtain at least two conductive electrode layers, and then annealing crystallization treatment and aging treatment are carried out to obtain the final conductive electrode layer; through multiple spin coating deposition treatments in the present invention, the resistivity of the conductive electrode layer can be reduced.

[0054] Among them, the single-crystal substrate is LaAlO 3 、SrTiO 3 、Pt / Si、DyScO 3 、Nb-doped SrTiO 3 、NaCl or F-doped SnO 2 、In-doped SnO 2 、(LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (abbreviation: LSAT) of any one;

[0055] The first precursor solution includes LaNiO 3 precursor solution, SrRuO 3 、La 0.7 Sr 0.3 MnO 3 of any one; The preparation process of the first precursor solution (taking LaNiO 3 as an example) is as follows: at 25~100°C, lanthanum nitrate and nickel acetate are dissolved in a solvent in a molar ratio of 1:1 for 5~30 minutes, and continuously stirred at room temperature for 1~6 hours to obtain a clear and transparent LaNiO 3 precursor solution with a concentration of 0.1~0.4M. Among them, the solvent used is one or several of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid, and the solvent can be completely removed during pyrolysis and annealing crystallization treatment;

[0056] The rotation speed of spin coating is 3000~6000 revolutions per minute, and the duration is 10~60 seconds; the baking temperature is 100~500°C, and the time is 0.5~5 min to promote the evaporation of the solvent; the pyrolysis temperature is 350~550°C, and the time is 0.5~5 min to eliminate the residual organic matter; the annealing crystallization temperature is 550~800°C, and the time is 3~30 min; the aging treatment time is 48 h. Further preferably, the baking temperature is 200~230°C, the pyrolysis temperature is 480~550°C, and the annealing crystallization temperature is 550~800°C.

[0057] Step B: Mix the PbZrO 3 precursor solution and the ABO 3 paraelectric precursor solution according to a set ratio to obtain a mixed precursor solution, spin-coat and deposit the mixed precursor solution on the surface of the conductive electrode layer to obtain an antiferroelectric thin film with multiple paraelectric-antiferroelectric layers, and deposit the PbO precursor solution on the surface of the antiferroelectric thin film through spin-coating technology to obtain a lead-loss prevention layer.

[0058] ABO 3The dielectric constant of the type compound is 50 to 200. The preparation of the antiferroelectric thin film of the paraelectric-antiferroelectric layer is specifically referred to the above-mentioned method for preparing the antiferroelectric thin film.

[0059] Step C: depositing a gold electrode on the surface of the lead loss prevention layer through a stainless steel mask to obtain an antiferroelectric capacitor with high energy storage density.

[0060] The antiferroelectric capacitor comprises a single crystal substrate, a conductive electrode layer and a gold electrode arranged from the inside to the outside, an antiferroelectric film is arranged between the conductive electrode layer and the gold electrode, and a lead loss prevention layer is arranged on the surface of the antiferroelectric film.

[0061] The invention selects the spin coating deposition method to prepare the antiferroelectric film and the high energy storage density antiferroelectric capacitor, the purpose of which is to use the film layer as a conductive electrode on the one hand, and on the other hand, the transition buffer layer makes the antiferroelectric film and the single crystal substrate more compatible.

[0062] Example 1

[0063] This embodiment provides a PbZrO 3 -LaScO 3 An antiferroelectric capacitor of an antiferroelectric film and a preparation method thereof, wherein the preparation method comprises the following steps:

[0064] Step A: LaAlO 3 As a single crystal substrate, LaAlO 3 Preparation of LaNiO on substrate 3 Conductive electrode layer

[0065] (1) LaNiO 3 Preparation of precursor solution: Lanthanum nitrate and nickel acetate were dissolved in a solvent (2-methoxyethanol and propionic acid in a volume ratio of 1:1) at 70°C for 30 minutes and stirred at room temperature for 5 hours to obtain a clear and transparent LaNiO with a concentration of 0.3M. 3 Precursor solution.

[0066] (2) LaNiO 3 Preparation of conductive electrode layer: LaAlO 3 As a single crystal substrate, LaNiO was spin-coated 3The precursor solution is deposited on the surface of a single-crystal substrate at a spin-coating speed of 6000 revolutions per minute for 30 seconds; successively through baking and pyrolysis, the first conductive electrode layer is obtained. The baking temperature is 250 °C, each time for 2.5 min, and the pyrolysis temperature is 400 °C, each time for 5 min; then the spin-coating deposition, baking and pyrolysis processes are repeated once to obtain two conductive electrode layers; annealing crystallization treatment and aging treatment are carried out to obtain the final conductive electrode layer. The annealing crystallization temperature is 680 °C, the time is 15 min, and the aging treatment time is 48 h.

[0067] Step B: Preparation of PbZrO 3 -LaScO 3 antiferroelectric thin film

[0068] (1)Preparation of the mixed precursor solution

[0069] Dissolve lead acetate in a solvent (the volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), and heat it at 85 °C for 2 hours; after cooling to room temperature, introduce zirconium propoxide into the solution, and continuously stir the obtained mixture for 2 hours under ambient conditions to ensure that zirconium propoxide is completely dissolved, obtaining a clear and transparent PbZrO precursor solution with a concentration of 0.3 M. 3 precursor solution.

[0070] Dissolve lanthanum nitrate and scandium nitrate with a molar ratio of 1:1 in a solvent (the volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1) at 85 °C for 1 hour, and continuously stir the obtained mixture for 3 hours until completely dissolved, obtaining a paraelectric precursor solution with a concentration of 0.3 M of LaScO. 3 paraelectric precursor solution.

[0071] Mix the PbZrO 3 precursor solution and the LaScO 3 paraelectric precursor solution according to a set ratio to obtain a mixed precursor solution. The volume ratio of the LaScO 3 paraelectric precursor solution to the volume of the mixed precursor solution is 0, 0.1, 0.2, 0.3, and 0.5 in sequence.

[0072] (2)Spin-coat and deposit the mixed precursor solution on the conductive electrode layer prepared in step A at a spin-coating speed of 6000 revolutions per minute for 30 seconds; then through baking and pyrolysis, the first paraelectric-antiferroelectric layer is obtained. Repeat the spin-coating deposition, baking and pyrolysis processes 9 more times to obtain a film with ten paraelectric-antiferroelectric layers. Among them, the baking temperature is 200 °C, each time for 2 min to promote the evaporation of the solvent, and the pyrolysis temperature is 400 °C, each time for 5 min to eliminate the residual organic matter.

[0073] (3)Preparation of the PbO layer

[0074] Dissolve lead acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), heat at 85 °C for 2 hours, and continuously stir at room temperature for 2 hours to obtain a clear and transparent PbO precursor solution with a concentration of 0.3 M.

[0075] Spin-coat and deposit the PbO precursor solution on the paraelectric-antiferroelectric thin film prepared in step B(2) at a spinning speed of 6000 revolutions per minute for a duration of 30 seconds; then obtain the anti-volatile layer through baking and pyrolysis. Among them, the baking temperature is 200 °C, each time is 2 min to promote the evaporation of the solvent, and the pyrolysis temperature is 400 °C, each time is 5 min to eliminate the residual organic matter.

[0076] (4) Perform annealing crystallization treatment on the thin film obtained in step (3) to obtain an antiferroelectric thin film. Among them, the annealing crystallization temperature is 700 °C and the time is 15 min.

[0077] Step C: Then deposit a gold electrode on the surface of the anti-lead-loss layer through a stainless-steel mask to obtain a high energy storage density antiferroelectric capacitor.

[0078] In this embodiment, a thin film capacitor is obtained by depositing a gold electrode on the surface of the PbO anti-lead-loss layer through a stainless-steel mask. The ferroelectric hysteresis loop, breakdown field strength, energy storage density and efficiency, and cycle stability of the prepared PbZrO 3 -LaScO 3 thin film capacitor are detected. Among them, in the mixed precursor solution for preparing the PbZrO 3 -LaScO 3 antiferroelectric thin film, the volume ratio of the paraelectric precursor solution LaScO 3 precursor solution is defined as x, and at this time the volume ratio of the PbZrO 3 precursor solution is 1 - x, and the value of x is 0, 0.1, 0.2, 0.3, 0.5.

[0079] Figure 1 For the PbZrO 3 -LaScO 3 thin film capacitor, the curve of polarization intensity versus electric field represents the ferroelectric hysteresis loop measured at different electric fields (up to the breakdown electric field). It can be seen from Figure 1 that when the volume ratio of the paraelectric precursor solution LaScO 3 in the mixed precursor solution x = 0.2, the ferroelectric hysteresis loop of the prepared PbZrO 3 -LaScO 3 thin film capacitor has a relatively high phase transition electric field (~1 MV cm -1) and smaller hysteresis.

[0080] Figure 2 is PbZrO 3 -LaScO 3 The breakdown probability variation curve of the thin-film capacitor with respect to the electric field. In the figure, the abscissa is the electric field and the ordinate is the breakdown probability. It can be seen from Figure 2 that in the mixed precursor solution, when the volume fraction 3 of the paraelectric precursor solution LaScO x = 0.2, the prepared PbZrO 3 -LaScO 3 thin-film capacitor has a relatively high breakdown electric field.

[0081] Figure 3 is PbZrO 3 -LaScO 3 The energy storage density and energy storage efficiency variation curves of the PbZrO Figure 3 -LaScO 3 thin-film capacitor with respect to the electric field. In the figure, the abscissa is the electric field, the left ordinate is the energy storage density, and the right ordinate is the energy storage efficiency. And the upper part of the figure shows the energy storage efficiency variation curve with respect to the electric field, and the lower part shows the energy storage density variation curve with respect to the electric field. It can be seen from 3 -LaScO 3 that after adding the paraelectric precursor solution LaScO 3 to the mixed precursor solution, the prepared PbZrO

[0082] Figure 4 -LaScO 3 thin-film capacitor can achieve an energy storage density of up to 190 J / cm 3 and an efficiency of > 80%. 3 -LaScO 3 The energy storage density and energy storage efficiency variation curves of the PbZrO Figure 4 -LaScO 3 thin-film capacitor with respect to the number of cycles, which represents the cycling stability of the PbZrO 3 -LaScO 3 thin-film capacitor. In the figure, the abscissa represents the number of cycles, the left ordinate is the energy storage density, and the right ordinate is the energy storage efficiency. And the upper part of the figure shows the energy storage efficiency variation curve with respect to the number of cycles, and the lower part shows the energy storage density variation curve with respect to the number of cycles. It can be seen from 7 that after adding the paraelectric precursor solution LaScO

[0083] Figure 5Distribution diagram of paraelectric region and antiferroelectric region in paraelectric-antiferroelectric layer, where e1 represents the antiferroelectric region and e2 represents the paraelectric region. As Figure 5 shown, multiple said paraelectric regions are diffusely distributed in the antiferroelectric region.

[0084] Example 2

[0085] This example provides an antiferroelectric capacitor containing a PbZrO 3 -CaZrO 3 antiferroelectric thin film and a preparation method thereof. The preparation method includes the following steps:

[0086] Step A: Using LaAlO 3 as a single crystal substrate, prepare a LaNiO 3 conductive electrode layer on the LaAlO 3 substrate.

[0087] (1) Preparation of LaNiO 3 precursor solution: At 70 °C, dissolve lanthanum nitrate and nickel acetate in a solvent (volume ratio of 2-methoxyethanol to propionic acid is 1:1) at a molar ratio of 1:1 for 30 minutes, and continuously stir at room temperature for 5 hours to obtain a clear and transparent LaNiO 3 precursor solution with a concentration of 0.3 M.

[0088] (2) Preparation of LaNiO 3 conductive electrode layer: Using LaAlO 3 as a single crystal substrate, deposit the LaNiO 3 precursor solution on the surface of the single crystal substrate by spin coating technology. The rotation speed of spin coating is 6000 revolutions per minute, and the duration is 30 seconds; successively bake and pyrolyze to obtain the first-layer conductive electrode layer. The baking temperature is 250 °C, and the time for each time is 2.5 min. The pyrolysis temperature is 400 °C, and the time for each time is 5 min; then repeat the spin coating deposition, baking and pyrolysis treatment once to obtain two conductive electrode layers; perform annealing crystallization treatment and aging treatment to obtain the final conductive electrode layer. The annealing crystallization temperature is 680 °C, the time is 15 min, and the aging treatment time is 48 h.

[0089] Step B: Prepare a PbZrO 3 -CaZrO 3 antiferroelectric thin film

[0090] (1) Preparation of mixed precursor solution

[0091] Dissolve lead acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), heat at 85 °C for 2 hours; after cooling to room temperature, introduce zirconium n-propoxide into the solution, and continuously stir the resulting mixture under ambient conditions for 2 hours to ensure complete dissolution of zirconium n-propoxide, obtaining a clear and transparent precursor solution with a concentration of 0.3 M of PbZrO 3 precursor solution.

[0092] Dissolve calcium acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), heat at 85 °C for 2 hours; after cooling to room temperature, introduce zirconium n-propoxide into the solution, and continuously stir the resulting mixture under ambient conditions for 2 hours to ensure complete dissolution of zirconium n-propoxide, obtaining a clear and transparent precursor solution with a concentration of 0.3 M of CaZrO 3 precursor solution.

[0093] Mix the PbZrO 3 precursor solution and the CaZrO 3 paraelectric precursor solution in a set ratio to obtain a mixed precursor solution. The volume ratio of the CaZrO 3 paraelectric precursor solution to the volume of the mixed precursor solution is 0.1 and 0.2.

[0094] (2) Spin-coat deposit the mixed precursor solution on the conductive electrode layer prepared in step A at a rotation speed of 6000 revolutions per minute for a duration of 30 seconds; then obtain the first paraelectric-antiferroelectric layer through baking and pyrolysis. Repeat the spin-coat deposition, baking, and pyrolysis processes 9 times to obtain a film with ten paraelectric-antiferroelectric layers. Among them, the baking temperature is 200 °C, each time for 2 min to promote the evaporation of the solvent, and the pyrolysis temperature is 400 °C, each time for 5 min to eliminate the residual organic matter.

[0095] (3) Preparation of the PbO layer

[0096] Dissolve lead acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), heat at 85 °C for 2 hours, and continuously stir under ambient conditions at room temperature for 2 hours to obtain a clear and transparent PbO precursor solution with a concentration of 0.3 M.

[0097] Spin-coat deposit the PbO precursor solution on the paraelectric-antiferroelectric thin film prepared in step B(2) at a rotation speed of 6000 revolutions per minute for a duration of 30 seconds; then obtain the anti-volatility layer through baking and pyrolysis. Among them, the baking temperature is 200 °C, each time for 2 min to promote the evaporation of the solvent, and the pyrolysis temperature is 400 °C, each time for 5 min to eliminate the residual organic matter.

[0098] (4) Anneal and crystallize the thin film obtained in step (3) to obtain an antiferroelectric thin film, where the annealing and crystallization temperature is 700 °C and the time is 15 min.

[0099] Step C: Then deposit a gold electrode on the surface of the lead-loss prevention layer through a stainless-steel mask to obtain a high energy storage density antiferroelectric capacitor.

[0100] For the antiferroelectric capacitor prepared in this example, the energy storage density and efficiency under the breakdown electric field are shown in Table 1 below:

[0101] Table 1

[0102]

[0103] Example 3

[0104] This example provides an antiferroelectric capacitor containing a PbZrO 3 -CaZrO 3 antiferroelectric thin film and a preparation method thereof. The preparation method includes the following steps:

[0105] Step A: Use LaAlO 3 as a single crystal substrate, and prepare a LaNiO 3 conductive electrode layer on the LaAlO 3 substrate

[0106] (1) Preparation of the LaNiO 3 precursor solution: At 70 °C, dissolve lanthanum nitrate and nickel acetate in a solvent (volume ratio of 2-methoxyethanol to propionic acid is 1:1) at a molar ratio of 1:1 for 30 minutes, and continuously stir at room temperature for 5 hours to obtain a clear and transparent LaNiO 3 precursor solution with a concentration of 0.3 M.

[0107] (2) Preparation of the LaNiO 3 conductive electrode layer: Use LaAlO 3 as a single crystal substrate, and deposit the LaNiO 3 precursor solution on the surface of the single crystal substrate by spin coating technology. The spin coating speed is 6000 revolutions per minute, and the duration is 30 seconds; successively bake and pyrolyze to obtain the first layer of conductive electrode layer. The baking temperature is 250 °C, and the time for each time is 2.5 min. The pyrolysis temperature is 400 °C, and the time for each time is 5 min; then repeat the spin coating deposition, baking and pyrolysis treatment once to obtain two conductive electrode layers; perform annealing and crystallization treatment and aging treatment to obtain the final conductive electrode layer. The annealing and crystallization temperature is 680 °C, the time is 15 min, and the aging treatment time is 48 h.

[0108] Step B: Prepare PbZrO 3-CaZrO 3 Antiferroelectric thin film

[0109] (1) Preparation of mixed precursor solution

[0110] Dissolve lead acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), and heat it at 85 °C for 2 hours; after cooling to room temperature, introduce zirconium propoxide into the solution, and continuously stir the obtained mixture for 2 hours under ambient conditions to ensure that zirconium propoxide is completely dissolved, obtaining a clear and transparent PbZrO precursor solution with a concentration of 0.3 M. 3 Precursor solution.

[0111] Dissolve calcium acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), and heat it at 85 °C for 2 hours; after cooling to room temperature, introduce zirconium propoxide into the solution, and continuously stir the obtained mixture for 2 hours under ambient conditions to ensure that zirconium propoxide is completely dissolved, obtaining a clear and transparent CaZrO precursor solution with a concentration of 0.3 M. 3 Precursor solution.

[0112] Mix the PbZrO 3 precursor solution and the CaZrO 3 paraelectric precursor solution in a volume ratio of 4:1 to obtain a mixed precursor solution. The volume ratio of the CaZrO 3 paraelectric precursor solution to the volume of the mixed precursor solution is 0.2; then add bismuth nitrate with a molar percentage of 4.0% relative to the entire system of PbZrO 3 -CaZrO 3 to the above mixed precursor solution, and mix and stir evenly.

[0113] (2) Spin-coat and deposit the mixed precursor solution added with bismuth nitrate on the conductive electrode layer prepared in step A at a rotation speed of 6000 revolutions per minute for 30 seconds; then obtain the first-layer paraelectric-antiferroelectric layer through baking and pyrolysis. Repeat the spin-coating deposition, baking, and pyrolysis processes 9 times to obtain a thin film with ten layers of paraelectric-antiferroelectric layers. Among them, the baking temperature is 200 °C, each time for 2 min to promote the evaporation of the solvent, and the pyrolysis temperature is 400 °C, each time for 5 min to eliminate the residual organic matter.

[0114] (3) Preparation of PbO layer

[0115] Dissolve lead acetate in a solvent (volume ratio of 2-methoxyethanol, ethylene glycol, and acetic acid is 1:1:1), heat it at 85 °C for 2 hours, and continuously stir it for 2 hours under room temperature ambient conditions to obtain a clear and transparent PbO precursor solution with a concentration of 0.3 M.

[0116] The PbO precursor solution was spin-coated and deposited on the ferroelectric-antiferroelectric thin film prepared in step B(2) at a rotation speed of 6000 revolutions per minute for a duration of 30 seconds; then, it was baked and pyrolyzed to obtain the anti-volatilization layer. Among them, the baking temperature was 200 °C for 2 min each time to promote the evaporation of the solvent, and the pyrolysis temperature was 400 °C for 5 min each time to eliminate the residual organic matter.

[0117] (4)Annealing and crystallization treatment was performed on the thin film obtained in step (3) to obtain an antiferroelectric thin film. Among them, the annealing and crystallization temperature was 670 °C for 15 min.

[0118] Step C: Then, a gold electrode was deposited on the surface of the lead-loss prevention layer through a stainless steel mask to obtain a high energy storage density antiferroelectric capacitor.

[0119] For the antiferroelectric capacitor prepared in this embodiment, the energy storage density and efficiency under the breakdown electric field are shown in Table 2 below:

[0120] Table 2

[0121]

[0122] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing an antiferroelectric thin film, characterized in that: The following steps are involved: Step 1: Mixing a PbZrO3 precursor solution and an ABO3 paraelectric precursor solution according to a set ratio to obtain a mixed precursor solution; The concentration of the PbZrO3 precursor solution is the same as that of the ABO3 paraelectric precursor solution, which is 0.1-0.4M, and the volume ratio of the ABO3 paraelectric precursor solution to the mixed precursor solution is (1:10)-(2:3); the ABO3 paraelectric precursor is any one of SrTiO3, CaTiO3, CaZrO3, SrZrO3, LaScO3, LaAlO3, LaGaO3, KTaO3 and LnFeO3; Step 2: depositing the mixed precursor solution obtained in step 1 on a substrate material, baking and pyrolyzing to obtain a first paraelectric-antiferroelectric layer, repeating the spin coating deposition, baking and pyrolysis treatment at least once, to obtain a film having at least two paraelectric-antiferroelectric layers; The spin coating speed is 3000-6000 rpm, and the duration is 10-60 seconds; the baking temperature is 100-500°C, and the time is 0.5-5 minutes; the pyrolysis temperature is 350-550°C, and the time is 0.5-5 minutes; Step 3: Perform annealing and crystallization treatment on the film obtained in step 2, the annealing and crystallization temperature is 550~800℃, and the time is 3~30min to obtain an antiferroelectric film.

2. The preparation method according to claim 1, characterized in that: The preparation method also includes the preparation of a lead loss prevention layer, and the specific method is: spin coating and depositing a layer of PbO on the surface of each paraelectric-antiferroelectric layer or the last paraelectric-antiferroelectric layer, or when preparing the last paraelectric-antiferroelectric layer, adding a set proportion of a precursor solution containing PbO to the mixed precursor solution.

3. The preparation method according to claim 1, characterized in that: The preparation method also includes adding 3.0% to 7.0% of bismuth nitrate or bismuth acetate in molar percentage relative to the entire PbZrO3-ABO3 system to the precursor solution in step 1, and controlling the pyrolysis temperature to 250 to 400°C when preparing each paraelectric-antiferroelectric layer.

4. An antiferroelectric thin film, characterized in that: It is prepared by the preparation method described in any one of claims 1-3, comprising multiple paraelectric-antiferroelectric layers, each of the paraelectric-antiferroelectric layers comprising multiple paraelectric regions, and the multiple paraelectric regions are dispersed in the antiferroelectric region; wherein the paraelectric region is formed by an ABO3 paraelectric precursor, and the antiferroelectric region is formed by PbZrO3.

5. An antiferroelectric capacitor, characterized in that: The invention comprises an antiferroelectric film obtained by the preparation method according to any one of claims 1 to 3, and also comprises a single crystal substrate, a conductive electrode layer and a gold electrode arranged from the inside to the outside, wherein the antiferroelectric film is located between the conductive electrode layer and the gold electrode.

6. The antiferroelectric capacitor according to claim 5, characterized in that: The single crystal substrate is LaAlO3, SrTiO3, Pt / Si, DyScO3, Nb-doped SrTiO3, NaCl or F-doped SnO2, In-doped SnO2, (LaAlO3) 0.3 (Sr2TaAlO6) 0.7 Any of the following: The conductive electrode layer is a LaNiO3 conductive electrode layer, a SrRuO3 conductive electrode layer, a La 0.7 Sr 0.3 Any one of the MnO3 conductive electrode layers, wherein the number of the conductive electrode layers is at least two.

7. A method for preparing an antiferroelectric capacitor, characterized in that: The following steps are involved: Step A: preparing a conductive electrode layer on the surface of a single crystal substrate by spin coating technology; Step B: using the conductive electrode layer of the product obtained in step A as a substrate material, and adopting the preparation method described in any one of claims 1 to 3 to prepare an antiferroelectric thin film; Step C: Depositing a gold electrode on the surface of the antiferroelectric film through a stainless steel mask to obtain an antiferroelectric capacitor.

8. The preparation method according to claim 7, characterized in that: In step A, a first precursor solution is deposited on the surface of a single crystal substrate by spin coating technology, and a first conductive electrode layer is obtained by baking and pyrolysis in sequence, and the spin coating deposition, baking and pyrolysis treatments are repeated at least once to obtain at least two conductive electrode layers, and then annealing crystallization treatment and aging treatment are performed to obtain a final conductive electrode layer; Wherein, the first precursor solution is LaNiO3 precursor solution, SrRuO3 precursor solution, La 0.7 Sr 0.3 Any one of the MnO3 precursor solutions.

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