Anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film with high energy storage density and preparation method of anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film

Abstract

The invention provides an anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film with high energy storage density as well as a preparation method and application thereof. The anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film with high energy storage density comprises a substrate layer, a bottom electrode layer and a plurality of stacked relaxation ferroelectric layers, wherein the bottom electrode layer and the multiple stacked relaxation ferroelectric layers are sequentially arranged on the substrate layer; each relaxor ferroelectric layer sequentially comprises a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer comprises LaFeO3, the second functional layer comprises BiFeO3, and the third functional layer comprises SrTiO3. The anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film with the high energy storage density has small electric leakage performance and high polarization value, and more excellent energy storage performance is achieved.

Description

Technical Field

[0001] This invention belongs to the field of dielectric energy storage materials technology, specifically relating to a high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film and its preparation method. Background Technology

[0002] Currently, dielectric capacitors are widely used in energy storage devices and energy conversion systems due to their ultra-high power density, fast charge and discharge speed, long cycle life, and good temperature stability. These include pulse / high-power power systems used in various IoT electronic devices, hybrid vehicles, and weaponry. However, compared to other energy storage devices (such as batteries and electrochemical capacitors), dielectric capacitors have relatively low energy density and efficiency, which has become a major factor restricting their rapid development and large-scale application. Therefore, in recent years, many different types of dielectric capacitor materials have been rapidly developed. Currently, based on the change in polarization state of dielectric energy storage materials with the applied electric field, they can be classified into four types: linear dielectrics (LD), ferroelectrics (FE), antiferroelectrics (AFE), and relaxor ferroelectrics (RFE). Linear dielectrics typically have high energy storage efficiency and breakdown resistance, but their relatively low maximum polarization intensity limits their use in high-energy storage applications. Ferroelectrics possess greater saturation polarization and moderate breakdown strength; however, their large remanent polarization leads to reduced energy storage density and decreased efficiency. Antiferroelectrics have good energy storage density, but their low energy storage efficiency and high heat dissipation have been factors limiting their application and development. Relaxor ferroelectrics exhibit moderate breakdown field strength, large maximum polarization, and low remanent polarization, making them very suitable for high-energy storage.

[0003] Among numerous dielectric materials, bismuth ferrite (BiFeO3, BFO) is a lead-free multiferroic material with excellent performance. It contains no toxic lead and possesses a high Curie temperature (≈850℃) and a large spontaneous polarization intensity (100μC / cm). 2 Bismuth-lanthanum ferrite (BFO) films have received considerable attention in recent years. During the deposition process, the volatilization of bismuth and changes in the valence state of iron often lead to large leakage currents and low breakdown electric fields. Therefore, lanthanum ferrite (LaFeO3, LFO) is often dissolved in BFO films to improve leakage current and breakdown electric field, thereby enhancing the electrical properties of BFO-based films. Furthermore, by controlling the content of BFO and LFO, a novel lead-free antiferroelectric film of bismuth ferrite-lanthanum ferrite (BF-LF) can be synthesized, with a storage density of 30.7 J / cm³. 3 .

[0004] Currently, most relaxor ferroelectric materials are lead-based dielectric energy storage materials. Lead-based dielectric energy storage materials are frequently used in capacitors due to their high energy density, but lead poses significant hazards to the environment and human health. Furthermore, although LBFO solid solutions offer good energy storage controllability, most reported BFO-based ferroelectric thin films still exhibit high remanent polarization and low breakdown field strength, resulting in low energy density and efficiency. Improving energy storage thermal stability and frequency stability also presents challenges. Developing lead-free relaxor ferroelectric ceramic materials based on BFBT that simultaneously possess high energy storage performance and high mechanical properties is a necessary task for the miniaturization, lightweighting, high reliability, and high stability development of energy storage devices and energy conversion systems in the new era. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film with low leakage current and high polarization value, thereby achieving better energy storage performance.

[0006] This invention is achieved through the following technical solution:

[0007] A high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film includes a substrate layer, a bottom electrode layer and a plurality of stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; each relaxor ferroelectric layer sequentially includes a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer includes LaFeO3, the second functional layer includes BiFeO3, and the third functional layer includes SrTiO3.

[0008] This invention provides a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film. Multiple relaxor ferroelectric layers are stacked on the bottom electrode layer. Each relaxor ferroelectric layer sequentially comprises a first functional layer, a second functional layer, and a third functional layer from bottom to top. The first functional layer comprises LaFeO3, the second functional layer comprises BiFeO3, and the third functional layer comprises SrTiO3. The introduction of the first functional layer LaFeO3 can apply interfacial electrostatic boundary conditions to the BiFeO3 of the second functional layer, inducing a metastable Pnma-AFE phase, giving BiFeO3 double hysteresis loop characteristics. It can be reversibly switched to the ferroelectric R3c phase through an electric field, exhibiting high energy density and tunable breakdown field strength. The introduction of the third functional layer SrTiO3 increases the overall dielectric constant while reducing the overall leakage current, which is beneficial for increasing the breakdown electric field and improving energy storage performance. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film provided by the present invention is based on an antiferroelectric system, which has low leakage current and high polarization value, thus achieving better energy storage performance.

[0009] Furthermore, in a single relaxor ferroelectric layer, the thickness of the first functional layer is 0.3-1.05 nm, the thickness of the second functional layer is 1.95-2.7 nm, and the thickness of the third functional layer is 0.1-2 nm. As the thickness of LaFeO3 increases, the ferroelectric domain structure of the second functional layer BiFeO3 exhibits a significant degradation trend, inducing a metastable Pnma-AFE phase, giving BiFeO3 double hysteresis loop characteristics. If the thickness of the first functional layer is too small, interfacial diffusion occurs at the interface, making the metastable Pnma-AFE phase of BiFeO3 unstable. If the thickness of the first functional layer is too large, it leads to excessive structural distortion of the second functional layer BiFeO3, causing the ferroelectric phase to completely disappear.

[0010] Furthermore, the number of relaxor ferroelectric layers is 50-100, and the total thickness of multiple relaxor ferroelectric layers is 150-500 nm. Too few relaxor ferroelectric layers will lead to excessive leakage current, making high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice films easily break down. Too many relaxor ferroelectric layers will lead to a decrease in the overall breakdown electric field. Through material design of the relaxor ferroelectric layers, the thickness of a single relaxor ferroelectric layer can be reduced, and the total thickness of multiple relaxor ferroelectric layers can be 150-420 nm, resulting in a thinner overall thickness, a higher number of relaxor ferroelectric layer cycles, and superior energy storage performance.

[0011] Furthermore, the substrate layer is a rigid SrTiO3 layer with crystal plane orientation

[100] .

[0012] Furthermore, the bottom electrode layer is an SrRuO3 layer with a thickness of 20-25 nm.

[0013] The present invention also provides a method for preparing the above-mentioned high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film, comprising the following steps: depositing the bottom electrode layer on the substrate layer; depositing a plurality of stacked relaxor ferroelectric structures on the bottom electrode layer; sequentially depositing a first functional layer, a second functional layer and a third functional layer, repeating the process multiple times; and cooling to room temperature to obtain the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film.

[0014] Furthermore, multiple stacked relaxor ferroelectric layers are deposited on the bottom electrode layer, followed by the sequential deposition of a first functional layer, a second functional layer, and a third functional layer. This process is repeated multiple times, with a deposition vacuum degree ≤1×10⁻⁶. -7 The deposition parameters were set at 700℃±2℃, oxygen partial pressure 10 Pa, and deposition rate 700℃ / min. By controlling the deposition parameters of the relaxor ferroelectric layer, the high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin films exhibited better energy density and efficiency, as well as better internal structure and compactness.

[0015] The present invention also provides an antiferroelectric energy storage device, comprising the above-mentioned high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film.

[0016] The present invention also provides the application of the above-mentioned high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin films in the field of energy storage.

[0017] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the high energy density antiferroelectric lanthanum ferroferrite, bismuth ferrite and strontium titanate superlattice thin film of Example 1.

[0019] Figure 2 This is a flowchart of the preparation method of the high energy density antiferroelectric lanthanum ferroferrite, bismuth ferrite and strontium titanate superlattice thin film in Example 2.

[0020] Figure 3 This is the XRD pattern of the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film of Example 3.

[0021] Figure 4 The images show the PV diagrams of the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin films prepared in Example 3 and the comparative example.

[0022] Figure 5 The diagram shows the recyclable energy storage density (Wrec) and energy storage efficiency (η) of the high energy storage density antiferroelectric lanthanum ferroferrite, bismuth ferrite and strontium titanate superlattice thin films prepared in Example 3 and the comparative example.

[0023] Figure 6 The breakdown electric field Weibull distribution of the relaxor ferroelectric thin films prepared in Example 3 and the comparative example are shown. Detailed Implementation

[0024] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the embodiments of the present invention, and not all structures.

[0025] Furthermore, the terms "first," "second," "third," etc., used in the specification and claims are only for the purpose of distinguishing the description of the same technical features and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, nor necessarily the order of description or chronological sequence. Where appropriate, the terms are interchangeable. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0026] Similarly, the terms "fixed" and "connected" are used in the specification and claims and should not be construed as limited to a direct connection. Therefore, the expression "device A is connected to device B" should not be limited to device A being directly connected to device B in a device or system; it means that there is a path between device A and device B, which can be a path that includes other devices or tools.

[0027] Example 1

[0028] This embodiment provides a high-energy-density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin film. Figure 1 This is a schematic diagram of the structure of a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film. Please refer to [link / reference]. Figure 1 The high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film includes a substrate layer and a bottom electrode layer and multiple stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; each relaxor ferroelectric layer includes a first functional layer, a second functional layer and a third functional layer sequentially from bottom to top; the first functional layer includes LaFeO3, the second functional layer includes BiFeO3 and the third functional layer includes SrTiO3.

[0029] This embodiment provides a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film. Multiple relaxor ferroelectric layers are stacked on the bottom electrode layer. Each relaxor ferroelectric layer includes a first functional layer, a second functional layer, and a third functional layer from bottom to top. The first functional layer includes LaFeO3, the second functional layer includes BiFeO3, and the third functional layer includes SrTiO3. The introduction of the first functional layer LaFeO3 can apply an interfacial electrostatic boundary condition to the BiFeO3 of the second functional layer, inducing a metastable Pnma-AFE phase, giving BiFeO3 double hysteresis loop characteristics. It can be reversibly switched to the ferroelectric R3c phase through an electric field, exhibiting high energy density and tunable breakdown field strength. The introduction of the third functional layer SrTiO3 increases the overall dielectric constant while reducing the overall leakage current, which is beneficial to increasing the breakdown electric field and improving energy storage performance. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film provided in this embodiment is based on an antiferroelectric system, which has low leakage current and high polarization value, thus achieving better energy storage performance.

[0030] In this embodiment, in a single relaxor ferroelectric layer, the thickness of the first functional layer is 0.3-1.05 nm, the thickness of the second functional layer is 1.95-2.7 nm, and the thickness of the third functional layer is 0.1-2 nm. As the thickness of LaFeO3 increases, the ferroelectric domain structure of the second functional layer BiFeO3 exhibits a significant degradation trend, inducing a metastable Pnma-AFE phase, giving BiFeO3 double hysteresis loop characteristics. If the thickness of the first functional layer is too small, interfacial diffusion occurs at the interface, and the metastable Pnma-AFE phase of BiFeO3 is unstable. If the thickness of the first functional layer is too large, it leads to excessive structural distortion of the second functional layer BiFeO3, and the ferroelectric phase completely disappears.

[0031] In this embodiment, the number of relaxor ferroelectric layers is 50-100, and the total thickness of multiple relaxor ferroelectric layers is 150-500 nm. Too few relaxor ferroelectric layers will lead to excessive leakage current, and high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice films will be easily broken down. Too many relaxor ferroelectric layers will lead to a decrease in the overall breakdown electric field. Through the material design of the relaxor ferroelectric layers, the thickness of a single relaxor ferroelectric layer can be reduced, and the total thickness of multiple relaxor ferroelectric layers is 150-420 nm. The overall thickness is thinner, the number of relaxor ferroelectric layer periods is higher, and the energy storage performance is better.

[0032] In this embodiment, the substrate is a rigid SrTiO3 layer with crystal plane orientation

[100] .

[0033] In this embodiment, the bottom electrode layer is an SrRuO3 layer with a thickness of 20-25 nm.

[0034] Example 2

[0035] This embodiment provides a method for preparing the high energy density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin film of Example 1. Figure 2 This is a flowchart illustrating the preparation method of high-energy-density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin films. Please refer to [link / reference]. Figure 2 A method for producing high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin films includes the following steps:

[0036] Step S1: Deposit a bottom electrode layer on the substrate layer.

[0037] In one embodiment, a rigid SrTiO3 (STO) with a

[001] crystal plane orientation is selected as the substrate layer, and an SrRuO3 layer is used as the bottom electrode layer. A bottom electrode layer with a thickness of 20-25 nm is deposited on the substrate layer using pulsed laser deposition. The deposition vacuum degree of the bottom electrode layer is ≤1×10⁻⁶. -7The deposition temperature was 670℃, the oxygen partial pressure was 15Pa, the laser energy was 60mJ, the pulsed laser frequency was 8Hz, and the deposition rate was 700℃ / min.

[0038] Step S2: Deposit multiple stacked relaxor ferroelectric structures on the bottom electrode layer, and sequentially deposit the first functional layer, the second functional layer and the third functional layer. Repeat this process multiple times, and after cooling to room temperature, obtain a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film.

[0039] In one embodiment, LFO, BFO, and STO targets are placed on three adjacent target sites respectively; the STO substrate layer from step S1 is bonded and placed in the growth cavity of the pulsed laser deposition system, directly above the main target site, with the distance between the STO substrate layer and the target controlled at 55 cm; the LFO target site is switched to the main target site, and the laser is turned on to bombard the LFO target 104 times; the BFO target site is quickly switched to the main target site, and the laser is turned on to bombard the BFO target 203 times; the STO target site is quickly switched to the main target site, and the laser is turned on to bombard the STO target 90 times; the cyclic steps are repeated to obtain the LFO-BFO-STO multi-component relaxor ferroelectric thin film material.

[0040] In step S2, multiple stacked relaxor ferroelectric layers are deposited on the bottom electrode layer, followed by the sequential deposition of a first functional layer, a second functional layer, and a third functional layer. This process is repeated multiple times until cooling to room temperature to obtain a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film. During this step, the deposition vacuum degree is ≤1×10⁻⁶. -7 The deposition parameters were set at 700℃±2℃, oxygen partial pressure 10 Pa, and deposition rate 700℃ / min. By controlling the deposition parameters of the relaxor ferroelectric layer, the high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin films exhibited better energy density and efficiency, as well as better internal structure and compactness.

[0041] In step S2, the prepared multi-component relaxor ferroelectric thin film material is slowly cooled to room temperature at a temperature of 700℃ and an oxygen partial pressure of 10 Pa, with a cooling rate of 5-10℃ / min, to obtain a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film.

[0042] Using the above preparation method, a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film with a superlattice structure was prepared. This relaxor ferroelectric thin film has the advantages of high saturation polarization, low remanent polarization, and high breakdown field strength, and also has excellent energy density and energy storage efficiency.

[0043] This embodiment also provides an antiferroelectric energy storage device, including the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film of Embodiment 1.

[0044] This embodiment also provides an application of the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film of Embodiment 1 in the field of energy storage, such as in the field of pulse power energy storage.

[0045] Example 3

[0046] This embodiment provides a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film, including a substrate layer and a bottom electrode layer and a plurality of stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; each relaxor ferroelectric layer includes a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer includes LaFeO3, the second functional layer includes BiFeO3 and the third functional layer includes SrTiO3.

[0047] The substrate is a rigid SrTiO3 layer with crystal plane orientation

[100] , the bottom electrode layer is an SrRuO3 layer with a thickness of 22 nm. The number of relaxor ferroelectric layers is 70. In a single relaxor ferroelectric layer, the thickness of the first functional layer is 0.9 nm, the thickness of the second functional layer is 2.1 nm, and the thickness of the third functional layer is 0.6 nm.

[0048] The high-energy-density antiferroelectric lanthanum ferroferrite, bismuth ferroferrite, and strontium titanate superlattice thin films of this embodiment have the advantages of high saturation polarization, low remanent polarization, and high breakdown field strength, while also exhibiting excellent energy density and energy storage efficiency. Pt electrodes were fabricated on the relaxor ferroelectric layers and characterized as follows:

[0049] Figure 3 Here are the XRD patterns of the high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin films from Example 3. Please refer to [link / reference]. Figure 3 The diffraction peaks of each component obtained were clear and sharp, with no extra impurity phase peaks.

[0050] Figure 4 These are PV images of the high-energy-density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin films prepared in Example 3 and the comparative example. Figure 4 (a) is the comparative example without STO. Figure 4 (b) is an example; please refer to [link / reference]. Figure 4(a)-(b) The PV curves of the superlattice thin film in this embodiment are slender and the hysteresis loops have the typical polarization characteristics of antiferroelectric double hysteresis loops. That is, as the applied voltage increases, it exhibits a reversible phase transition from antiferroelectric phase to ferroelectric phase, indicating that the coercive field is smaller than that of the comparative example, and the polarization direction is easily reversed under the action of an external electric field. The domain walls are easy to move and flip under the action of an external electric field.

[0051] Figure 5 The diagrams show the recoverable energy storage density (Wrec) and energy storage efficiency (η) of the high energy storage density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin films prepared in Example 3 and the comparative example. Figure 5 (a) is a graph showing the recyclable energy storage density (Wrec) of the high energy storage density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin films prepared in Example 3 and the comparative example. Figure 5 (b) is a graph showing the energy storage efficiency (η) of the high energy storage density antiferroelectric lanthanum ferroferrite, bismuth ferrite, and strontium titanate superlattice thin films prepared in Example 3 and the comparative example. Please refer to [the graph]. Figure 5 The energy storage performance obtained in Example 3 is significantly better than that of the comparative example, exhibiting higher recyclable energy storage density and energy storage efficiency. When the number of relaxor ferroelectric layers reaches 70, the energy storage density can reach 89 J / cm³. 3 The energy storage efficiency can be maintained above 64%, which is conducive to the improvement of energy storage performance.

[0052] Figure 6 The breakdown electric field Weibull distributions of the relaxor ferroelectric thin films prepared in Example 3 and the comparative example are shown. It can be seen that due to the addition of STO, the average breakdown electric field of the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin films in Example 3 is improved.

[0053] Example 4

[0054] This embodiment provides a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film, including a substrate layer and a bottom electrode layer and a plurality of stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; each relaxor ferroelectric layer includes a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer includes LaFeO3, the second functional layer includes BiFeO3 and the third functional layer includes SrTiO3.

[0055] The substrate is a rigid SrTiO3 layer with crystal plane orientation

[100] , the bottom electrode layer is an SrRuO3 layer with a thickness of 20 nm. The number of relaxor ferroelectric layers is 50. In a single relaxor ferroelectric layer, the thickness of the first functional layer is 0.3 nm, the thickness of the second functional layer is 2.7 nm, and the thickness of the third functional layer is 0.1 nm.

[0056] Example 5

[0057] This embodiment provides a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film, including a substrate layer and a bottom electrode layer and a plurality of stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; each relaxor ferroelectric layer includes a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer includes LaFeO3, the second functional layer includes BiFeO3 and the third functional layer includes SrTiO3.

[0058] The substrate is a rigid SrTiO3 layer with crystal plane orientation

[100] , the bottom electrode layer is an SrRuO3 layer with a thickness of 25 nm. The number of relaxor ferroelectric layers is 100. In a single relaxor ferroelectric layer, the thickness of the first functional layer is 1.05 nm, the thickness of the second functional layer is 1.95 nm, and the thickness of the third functional layer is 2 nm.

[0059] This invention is not limited to the above-described embodiments. If any modifications or variations to this invention do not depart from the spirit and scope of this invention, and if such modifications and variations fall within the scope of the claims and equivalent technologies of this invention, then this invention also intends to include such modifications and variations.

Claims

1. A high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film, characterized in that: It includes a substrate layer and a bottom electrode layer and a plurality of stacked relaxor ferroelectric layers sequentially disposed on the substrate layer; Each of the aforementioned relaxor ferroelectric layers, from bottom to top, includes a first functional layer, a second functional layer, and a third functional layer; The first functional layer includes LaFeO3, the second functional layer includes BiFeO3, and the third functional layer includes SrTiO3.

2. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film according to claim 1, characterized in that: In a single relaxor ferroelectric layer, the thickness of the first functional layer is 0.3-1.05 nm, the thickness of the second functional layer is 1.95-2.7 nm, and the thickness of the third functional layer is 0.1-2 nm.

3. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film according to claim 2, characterized in that: The number of relaxor ferroelectric layers is 50-100, and the total thickness of the plurality of relaxor ferroelectric layers is 150-500 nm.

4. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film according to claim 1, characterized in that: The substrate layer includes a rigid SrTiO3 layer with crystal plane orientation [001].

5. The high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film according to claim 1, characterized in that: The bottom electrode layer includes an SrRuO3 layer with a thickness of 20-25 nm.

6. A method for preparing a high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film according to any one of claims 1-5, characterized in that, Includes the following steps: The bottom electrode layer is deposited on the substrate layer; Multiple stacked relaxor ferroelectric structures are deposited on the bottom electrode layer, and a first functional layer, a second functional layer, and a third functional layer are deposited sequentially. This process is repeated multiple times, and after cooling to room temperature, the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film is obtained.

7. The method for preparing high-energy-density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin films according to claim 6, characterized in that: In the process of depositing multiple stacked relaxor ferroelectric structures on the bottom electrode layer, sequentially depositing a first functional layer, a second functional layer, and a third functional layer, and repeating the cooling process to room temperature multiple times to obtain the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite, and strontium titanate superlattice thin film, the deposition vacuum degree is ≤1×10⁻⁶. -7 Pa, deposition temperature is 700℃±2℃, oxygen partial pressure is 10Pa, and deposition rate is 700℃ / min.

8. An antiferroelectric energy storage device, characterized in that: Including the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film as described in any one of claims 1-7.

9. The application of the high energy density antiferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin films according to any one of claims 1-7 in the field of energy storage.

Images