Antiferromagnetic material, method for preparing the same, and thin film capacitor

Abstract

The application provides a kind of antiferromagnetic material and its preparation method, thin film capacitor, the chemical formula of the antiferromagnetic material is Pb 1‑ x Sr x ZrO3, wherein 0.4<=x<=0.6;The antiferromagnetic material has the characteristics of dipole disordered arrangement.The dipole arrangement of the technical scheme of the application near the interface of the antiferromagnetic material is completely disordered, and the chaotic dipole arrangement can effectively reduce the lattice distortion of the antiferromagnetic PbZrO3, reduce the defect density, can effectively inhibit the leakage current and reduce the dielectric loss, greatly improve the intrinsic breakdown field of the film.The thin film capacitor prepared by using the antiferromagnetic material has higher breakdown field strength (up to 6.5MV / cm), energy storage density and efficiency, and the maximum energy storage density can reach 125J / cm 3 , the efficiency is 83%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic devices, and in particular to a kind of antiferroelectric material and its preparation method, thin film capacitor. BACKGROUND

[0002] Antiferroelectric material is an important dielectric material, and has good application prospect in high energy density dielectric capacitor, pulse power device, electric refrigerator and the like. Among them, pulse power capacitor is widely used in laser, transportation, mining, energy recovery, medical treatment and military fields. Compared with other energy storage devices, dielectric capacitor has excellent characteristics such as large charge-discharge power density (up to 10 8 W / kg), fast charge-discharge speed (~ ns), good fatigue resistance (> 10 6 Cycles) and the like. The unique electric phase transition characteristics of antiferroelectric material make it have the characteristics of near-zero residual polarization, double hysteresis loop and large saturation polarization intensity at zero electric field. Thanks to the unique double hysteresis loop structure, antiferroelectric material was proposed to be suitable for preparing pulse power capacitor as early as the 1960s. And because it is a solid dielectric energy storage capacitor, it avoids the risk of leakage and explosion, and is more safe and durable. However, due to the low breakdown field strength and high hysteresis loss, the energy storage performance of antiferroelectric material has not been fully explored, and the energy storage density of most antiferroelectric capacitors is less than 100 J / cm 3 As a prototype of antiferroelectric material, PbZrO3 has wide application prospect in the field of energy storage, but it is also limited by low breakdown field strength and hysteresis loss. At present, people mainly regulate the energy storage performance of PbZrO3 film through domain structure regulation, nanocrystalline structure, multilayer film strategy and introduction of second phase. These means can effectively improve the energy storage performance of PbZrO3-based film. However, at present, there is still a lack of effective means to regulate the intrinsic breakdown field strength of single crystal antiferroelectric PbZrO3, which greatly hinders the application of antiferroelectric PbZrO3 material in high-power capacitor. SUMMARY

[0003] In view of the above technical problems, the present application discloses an antiferroelectric material and its preparation method, thin film capacitor, which has a dipole disordered arrangement characteristic in microstructure. The thin film capacitor prepared by using the antiferroelectric material has higher intrinsic breakdown field strength and better energy storage characteristics.

[0004] To this end, the technical scheme adopted by the present application is as follows:

[0005] An antiferroelectric material, whose chemical formula is Pb 1-x Sr xZrO3, wherein 0.4<=x<=0.6, the anti-ferroelectric material has a microscopically disordered arrangement of dipole structures. In a wide range, the polarization directions of the dipoles are mutually compensating, and the whole does not exhibit polarity.

[0006] By adopting the technical scheme, the design idea of a traditional high-density anti-ferroelectric capacitor is broken through, the disordered anti-ferroelectric material is constructed through an anti-ferroelectric-ferroelectric phase interface engineering, and the microscopically disordered arrangement of dipoles is achieved. The intrinsic breakdown field strength of the anti-ferroelectric material is greatly improved, and the thin film capacitor prepared by using the material has super-high energy storage density and efficiency.

[0007] The application further discloses a preparation method of the anti-ferroelectric material.

[0008] In step S1, PbO, SrCO3 and ZrO2 are respectively taken according to the molar ratio of 11(1-x):10x:10, mixed with a solvent and ball milled to obtain a ball milling slurry.

[0009] In step S2, the ball milling slurry is vacuum dried, ground into powder, and sintered by heat preservation at 800-900 DEG C, and then secondarily ball milled and dried after cooling.

[0010] In step S3, polyvinyl alcohol (PVA) glue is added to the powder obtained in step S2, uniformly mixed, pressed into a sheet, heated to remove glue, then sintered by heating to 1200-1300 DEG C, cooled to 400 DEG C at a rate of 3-6 DEG C / min, and finally naturally cooled to room temperature to obtain the anti-ferroelectric material.

[0011] As a further improvement of the application, the ball milling time in step S1 is 6-10h. Further, the ball milling time is 8h.

[0012] As a further improvement of the application, the sintering temperature in step S2 is 850 DEG C.

[0013] As a further improvement of the application, the heating rate in step S2 is 3-8 DEG C / min, and the heat preservation sintering time is 4-6h. Further, the heating rate is 5 DEG C / min, and the heat preservation sintering time is 5h.

[0014] As a further improvement of the application, the heating temperature in step S3 is 600-700 DEG C. Further, the heating temperature is 650 DEG C. Further, the heating temperature is 650 DEG C at a rate of 2-4 DEG C / min. Further, the heating temperature is 650 DEG C at a rate of 3 DEG C / min.

[0015] As a further improvement of the application, the sintering temperature in step S3 is 1250 DEG C.

[0016] The application discloses a kind of antiferroelectric thin film, using the following steps to prepare obtain:

[0017] Step S10, (001) orientation SrTiO3 substrate is used as base, fixed on heating support;

[0018] Step S20, the heating support is put into the cavity of pulsed laser deposition equipment, vacuum to 10 -3 Pa below, temperature is raised to 680-720 DEG C, switch strontium ruthenate target material, deposit 2min under oxygen atmosphere;Subsequently, temperature is reduced to 580-620 DEG C, oxygen pressure is adjusted to 8-12Pa, switch strontium zirconate target material, deposit 20min under oxygen atmosphere, finally temperature is reduced, and annealing under oxygen atmosphere;Wherein the strontium zirconate target material is antiferroelectric material as described above.

[0019] The application discloses a kind of thin film capacitor, including antiferroelectric thin film as described above and top electrode, the top electrode is deposited on the antiferroelectric thin film.

[0020] As a further improvement of the application, the top electrode is Pt electrode.

[0021] As a further improvement of the application, the top electrode is prepared using the following steps: top electrode pattern transfer is carried out by photolithography, a layer of Pt is plated on the antiferroelectric thin film as top electrode using magnetron sputtering, and finally the photoresist is removed.

[0022] As a further improvement of the application, the thickness of the top electrode is 40-60nm.Further, the thickness of the top electrode is about 50nm.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] The technical scheme of the application is based on the method of antiferroelectric-paraelectric phase boundary, and the dipole arrangement near the phase boundary of the antiferroelectric material is completely disordered. Such chaotic dipole arrangement can effectively reduce the large lattice distortion of the antiferroelectric PbZrO3 itself. The reduction of lattice distortion is beneficial to reduce the generation of defects, effectively suppresses the generation of thin film leakage current, and further reduces the Joule heat generated by the leakage current. At the same time, the dielectric loss of the thin film is reduced, thereby further improving the intrinsic breakdown field of the thin film. The thin film capacitor prepared by using the antiferroelectric material has higher breakdown field strength, energy storage density and efficiency, and the maximum energy storage density can reach 125J / cm 3 , and the efficiency is 83%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Pb 0.6 Sr 0.4ZrO3 material hysteresis loop diagram.

[0026] Figure 2 is a XRD θ-2θ line scanning comparison diagram of the thin films of the embodiments 1-3 and the comparative examples of the present application; wherein (a) and (b) are the results of different 2θ, respectively.

[0027] Figure 3 is a X-ray reciprocal space scanning diagram of the thin films of the embodiments 1-3 and the comparative examples of the present application, wherein (a) is a PbZrO3 thin film, (b) is a Pb 0.8 Sr 0.2 ZrO3 thin film of the comparative example 2, (c) is a Pb 0.6 Sr 0.4 ZrO3 thin film of the embodiment 1, (d) is a Pb 0.9 Sr 0.1 ZrO3 thin film of the comparative example 1, (e) is a Pb 0.7 Sr 0.3 ZrO3 thin film of the embodiment 2, (f) is a Pb 0.5 Sr 0.5 ZrO3 thin film of the embodiment 3, (g) is a Pb 0.4 Sr 0.6 ZrO3 thin film.

[0028] Figure 4 is a diagram showing the evolution of the ratio of the out-of-plane and in-plane lattice constants of the PSZO thin film with composition, calculated from the RSM results of the thin films of the embodiments 1-3 and the comparative examples of the present application.

[0029] Figure 5 is a TEM comparison result of the Pb 0.6 Sr 0.4 ZrO3 thin film of the embodiment 1 and the PbZrO3 thin film; wherein (a) is a TEM diagram of the PbZrO3 thin film sample, (b) is an A-site atom displacement fitting diagram of the boxed area in (a), (c) is a fast Fourier transform result of the boxed area in (a), (d) is a partial enlarged view of (c); (e) is a TEM diagram of the Pb 0.6 Sr 0.4 ZrO3 thin film sample, (f) is an A-site atom displacement fitting diagram of the boxed area in (e), (g) is a fast Fourier transform result of the boxed area in (e), (h) is a partial enlarged view of (g).

[0030] Figure 6 is a electrical property test result of the thin films of the embodiments 1-3 and the comparative examples of the present application, wherein (a) is a leakage current test result, (b) is a dielectric spectrum test result of the thin film, (c) is a Weibull distribution analysis result, (d) is a diagram showing the change of the energy storage density and efficiency with the applied electric field strength under different electric fields. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application are further described in detail below.

[0032] A kind of antiferroelectric material, its chemical formula is Pb 1-x Sr x ZrO3, wherein 0.4≤x≤0.6;The antiferroelectric material has the dipole structure of disordered arrangement, the polarization direction of its dipole is mutually offset in a wide range, as a whole, it does not show polarity. It is prepared using the following steps:

[0033] Step S1, according to the proportion of 11 (1-x) :10x:10 of molar ratio, PbO, SrCO3 and ZrO2 are weighed respectively, mixed with solvent and ball milled for 6-10 h to obtain ball milling slurry;

[0034] Step S2, the ball milling slurry is vacuum dried, ground into powder, and sintered by heating to 800-900 DEG C, and then secondarily ball milled and dried after cooling; the heating rate is 3-8 DEG C / min, and the sintering time is 4-6 h;

[0035] Step S3, polyvinyl alcohol glue is added to the powder obtained in step S2 and mixed uniformly, tabletted, heated to 600-700 DEG C for glue removal, then sintered by heating to 1200-1300 DEG C, cooled to 400 DEG C at a rate of 3-6 DEG C / min, and finally naturally cooled to room temperature to obtain the antiferroelectric material.

[0036] Further, in step S1, the ball milling time is 8 h; in step S2, the heating rate is 5 DEG C / min, and the sintering time is 5 h; in step S3, the heating rate is 2-4 DEG C / min to 650 DEG C for glue removal.

[0037] The antiferroelectric material is used to make an antiferroelectric film, including the following steps:

[0038] Step S10, a (001) oriented SrTiO3 substrate is used as a base and fixed on a heating holder;

[0039] Step S20, the heating holder is placed in the cavity of a pulsed laser deposition device, vacuumed to 10 -3 Pa, heated to 680-720 DEG C, the strontium ruthenate target is switched, and deposited for 2 min in oxygen atmosphere; then cooled to 580-620 DEG C, the oxygen pressure is adjusted to 8-12 Pa, the antiferroelectric material prepared above is switched as a strontium zirconate target, and deposited for 20 min in oxygen atmosphere, finally cooled and annealed in oxygen atmosphere.

[0040] A thin film capacitor comprises the antiferromagnetic thin film prepared above and a top electrode deposited on the antiferromagnetic thin film. The top electrode is a Pt electrode, which is prepared by the following steps: pattern transfer of the top electrode by photolithography, plating of a Pt layer on the antiferromagnetic thin film as the top electrode by magnetron sputtering, and finally removal of the photoresist. The thickness of the top electrode is 40-60 nm.

[0041] The technical solution of the present application obtains disordered antiferromagnetic material by designing the interface between the antiferromagnetic phase and the paraelectric phase. Near the phase interface, the free energy difference of the two phases is small, and the antiferromagnetic phase and the paraelectric phase exist in a mutual competition relationship. On the one hand, the material still maintains the characteristics of mutual compensation of the dipoles of the antiferromagnetic material, and on the other hand, the long-range antiferromagnetic order is broken due to the competition relationship between the two phases, forming a disordered antiferromagnetic body.

[0042] The present application will be described below in conjunction with specific examples.

[0043] Example 1

[0044] An antiferromagnetic material with the chemical formula Pb 0.6 Sr 0.4 ZrO3, which is prepared by the following steps:

[0045] The raw materials required for synthesizing the target material are lead oxide (PbO), strontium carbonate (SrCO3) and zirconium oxide (ZrO2), and the target material is prepared by a hot sintering method. Specifically, PbO, SrCO3 and ZrO2 are weighed according to the molar ratio of 3.3:2:5. Among them, due to the volatility of lead oxide, an excess of 10% is required to overcome the problem of imbalance of stoichiometric ratio. The raw materials are added to a ball mill tank in proportion, and ball milling is performed for 8 hours. After drying the slurry in a vacuum drying oven, the powder is ground, sintered at a rate of 5℃ / min to 850℃ and kept for 5h, cooled and taken out, and then subjected to secondary ball milling and drying. The obtained powder is added to glue and ground uniformly, and finally pressed into a sheet. The obtained target material is sintered again at a rate of 3℃ / min to 650℃, degassed for 5h, and then raised to 1250℃ and kept for 5h. Finally, the temperature is set to decrease at a rate of 5℃ / min to 400℃, and then naturally cooled to room temperature.

[0046] The Pb 0.6 Sr 0.4 ZrO3 antiferromagnetic material obtained above is used as a target material to prepare a Pb 0.6 Sr 0.4 ZrO3 thin film, including the following steps:

[0047] A (001) oriented SrTiO3 (STO) substrate is pasted on a heating holder with silver glue, and then heated to 170℃ to solidify the resin, and the substrate is fixed on the heating holder. The heating holder is put into a Pulsed Laser Deposition (PLD) chamber, and vacuumed to 10 - 3 Pa, and heated to 700℃, and a SrRuO3 target is switched, and a 2min deposition is performed under an oxygen atmosphere. Then, the temperature is lowered to 600℃, the oxygen pressure is adjusted to 10Pa, a Pb 0.6 Sr 0.4 ZrO3 target is switched, and a 20min deposition is performed under an oxygen atmosphere. Finally, the temperature is lowered at a rate of 5℃ / min, and annealing is performed under an oxygen atmosphere. The Pulsed Laser Deposition (PLD) used in the process is a physical vapor deposition technology for high-quality thin film epitaxial growth, which uses laser to bombard the target, and the plasma bombarded from the target is deposited on the substrate to realize epitaxial growth of the thin film. Compared with other antiferromagnetic thin film preparation methods such as sol-gel method, chemical solution deposition method, and atomic layer deposition method, the PLD can uniformly coat the complex composite material, easily ensure the stability of the stoichiometric ratio after coating, and obtain a multi-component thin film with the desired stoichiometric ratio, that is, it has good composition retention characteristics.

[0048] The Pb 0.6 Sr 0.4 ZrO3 thin film prepared by the above method is used to prepare a thin film capacitor, which further includes preparation of a top electrode, specifically including: performing pattern transfer of the top electrode by photolithography, using magnetron sputtering to coat the thin film with a layer of Pt with a thickness of about 50nm as the top electrode, and finally using wet degelling to remove the photoresist.

[0049] The PbZrO3 obtained by the method of the prior art and the Pb 0.6 Sr 0.4 ZrO3 material obtained by Example 1 are tested by using the method of the prior art, and the hysteresis loops of the materials are calculated to obtain the energy storage density, and the results are shown in Figure 1 It can be seen that the maximum energy storage density of the Pb 0.6 Sr 0.4 ZrO3 of the present embodiment reaches 125J / cm 3 , and the energy storage efficiency is 83%.

[0050] Example 2

[0051] An antiferromagnetic material with a chemical formula of Pb 0.5 Sr 0.5 ZrO3, the preparation steps and process conditions of the material are the same as those of Example 1, except that PbO, SrCO3 and ZrO2 are weighed according to a molar ratio of 5.5:5:10.

[0052] Pb 0.5 Sr 0.5 ZrO3thin film and capacitor are prepared according to the procedure of Example 1.

[0053] Example 3

[0054] A material of formula Pb 0.4 Sr 0.6 ZrO3is prepared according to the procedure of Example 1, except that PbO, SrCO3and ZrO2are weighed out in the molar ratio of 4.4:6:10.

[0055] Pb 0.4 Sr 0.6 ZrO3thin film and capacitor are prepared according to the procedure of Example 1.

[0056] Comparative Example 1

[0057] A material of formula Pb 0.7 Sr 0.3 ZrO3is prepared according to the procedure of Example 1, except that PbO, SrCO3and ZrO2are weighed out in the molar ratio of 7.7:3:10.

[0058] Pb 0.7 Sr 0.3 ZrO3thin film and capacitor are prepared according to the procedure of Example 1.

[0059] Comparative Example 2

[0060] A material of formula Pb 0.8 Sr 0.2 ZrO3is prepared according to the procedure of Example 1, except that PbO, SrCO3and ZrO2are weighed out in the molar ratio of 8.8:2:10.

[0061] Pb 0.8 Sr 0.2 ZrO3thin film and capacitor are prepared according to the procedure of Example 1.

[0062] Comparative Example 3

[0063] A material of formula Pb 0.9 Sr 0.1 ZrO3is prepared according to the procedure of Example 1, except that PbO, SrCO3and ZrO2are weighed out in the molar ratio of 9.9:2:10.

[0064] Pb 0.9 Sr 0.1The preparation steps of the ZrO3 thin film and capacitor are the same as in Example 1.

[0065] The films from Examples 1-3 and Comparative Examples 1-3 were subjected to X-ray diffraction analysis along with SrZrCO3 and PbZrO3 films. The results are as follows: Figure 2 As shown, PSZO grown by pulsed laser deposition exhibits good epitaxy and crystallinity. The right figure shows the results of a high-angle line scan, where the growth rate increases with increasing Sr... 2+ With the increase of the content, the (480)o and (004)o diffraction peaks caused by the pseudotetragonal phase in the films of Examples 1 to 3 became degenerate. The (480)o and (004)o diffraction peaks correspond to two domain structures (hereinafter referred to as a domain and c domain, respectively) in the pseudotetragonal unit cell of PZO, pointing outward along the a-axis and c-axis. In pure phase PZO, its pseudotetragonal lattice constant is c t ~4.110. Sr 2+ Its diameter is 144 pm, slightly smaller than Pb. 2+ (149pm), Sr 2+ Doping introduces chemical inhomogeneity, transforming the crystal structure from a pseudotetragonal phase to a pseudocubic phase.

[0066] The thin films of Examples 1-3, Comparative Examples 1-3, and PbZrO3 thin films were subjected to X-ray reciprocal space scanning (RSM) near the crystal plane of a SrTiO3 substrate (103). The results are as follows: Figure 3 As shown, it can be seen that with Sr 2+ As the doping content of Sr increases, the intensity of the superstructure diffraction spots (SS Spot) formed by the ordered arrangement of PbZrO3 dipoles in an "↑↑↓↓" pattern gradually decreases. The superdiffraction spots in Examples 1 to 3 disappear, proving that their long-range antiferroelectric order is completely broken. Meanwhile, with the increase of Sr... 2+ Increased PSZO (103) content pt The diffraction spots of the a-domain and c-domain are degenerate, a result that is consistent with the X-ray diffraction results.

[0067] Figure 4 The figure shows the evolution of the ratio of out-of-plane and in-plane lattice constants (c / a ratio) of PSZO thin films as a function of composition, calculated using RSM results. As Sr... 2+The increase of the c / a ratio of the films gradually approaches 1, which represents the gradual transition of the crystal structure from the pseudo-tetragonal phase to the pseudo-cubic phase. By normalizing the intensity of the superlattice spots, the diffraction intensity of the superlattice spot position at x = 0.4 decreases significantly, and the intensity can be ignored, which represents that the antiferroelectric sequence of the dipole inside the PSZO film is completely broken. This is the result of the competition between the antiferroelectric phase and the paraelectric phase. It has been discussed above that PbZrO3 is a classic antiferroelectric material with long-range antiferroelectric sequence. SrZrO3 is considered to be a paraelectric material, and its pseudo-cubic lattice constant is In the vicinity of the phase interface of the two-phase transition, the free energy difference of the two phases is small, and there is a competition between the two phases. This competition leads to the complete breaking of the antiferroelectric sequence.

[0068] The microstructure of the film was further characterized by transmission electron microscopy (TEM), and the results are shown in Figure 5 It can be seen that for the PbZrO3 antiferroelectric material, the antiferroelectricity is derived from the antiparallel displacement of the A-site Pb atom "↑↑↓↓" and the rotation of the central oxygen octahedron. The PbZrO3 and Pb 0.6 Sr 0.4 ZrO3 film samples were scanned by high-angle annular dark field image (HAADF-STEM) technology with atomic resolution, as shown in Figure 5 (a) and Figure 5 (e). By performing fast Fourier transform (FFT) on the box region of the sample, as shown in Figure 5 (c) and Figure 5 (g) (corresponding to PbZrO3 and Pb 0.6 Sr 0.4 ZrO3, respectively), superlattice spots (SS spots) appear in the antiferroelectric PbZrO3 film, but this feature does not appear in the Pb 0.6 Sr 0.4 ZrO3 film. The appearance of SS spots in the antiferroelectric PbZrO3 is related to the ordered arrangement of the A-site Pb atoms along the direction, and the disappearance of the superlattice spots is related to the breaking of the long-range ordered antiferroelectric sequence. In the antiferroelectric PbZrO3 material, the direction of the dipole is defined by the vector difference between the geometric center position of the A-site atom and the surrounding four B-site atoms. Figure 5 (b) and Figure 5 (f) are the A-site atom displacement fitting diagrams of the box region in the PbZrO3 and Pb 0.6 Sr 0.4 ZrO3 atomic images, respectively. In the PbZrO3 sample, the dipole is arranged in an ordered "↑↑↓↓" antiferroelectric sequence in the direction, as shown in the enlarged view Figure 5 (d). While in the Pb0.6 Sr 0.4 In the ZrO3 sample, the ordered arrangement of the dipoles is completely disrupted, and in a large range, the polarization values of these dipoles are mutually compensated, so that the whole does not show polarity to the outside. As shown in the enlarged view of Figure 6 (h), the uniform structure can effectively reduce the lattice distortion of the antiferroelectric material and reduce the defect density.

[0069] The thin films of Examples 1-3 and Comparative Examples 1-3 were subjected to electrical performance testing with PbZrO3 thin films, and the results are shown in Figure 6 As shown in the leakage current test results of Figure 6 (a), the leakage current of Pb 0.6 Sr 0.4 ZrO3 can be maintained at 10 -7 A / cm 2 In the following, the lowest among all components indicates that the thin film of this component has a lower defect density. Figure 6 (b) is the dielectric spectrum test of the PSZO epitaxial thin film, which has good frequency stability at a frequency of 500-500000 Hz. Reliability and stability are key factors for chargeable and dischargeable capacitors. The E BDS not only improves the Pb max ZrO3 thin film, but also improves the reliability and stability of the energy storage system. Therefore, the Weibull distribution analysis was continued to extract the statistical value of the E BDS of the thin film, as shown in Figure 6 (c). Among them, the analysis value of the Pb 0.6 Sr 0.4 ZrO3 thin film reached 6.0 MV / cm, which is nearly six times higher than the analysis value of the PbZrO3 thin film (1.15 MV / cm). The huge breakdown field strength gives the Pb 0.6 Sr 0.4 ZrO3 thin film excellent energy storage characteristics. ​ (d) is a graph of the energy storage density and efficiency of the PSZO thin film capacitors of Examples and Comparative Examples varying with the applied electric field strength at different electric fields. Among them, the Pb 0.6 Sr 0.4 ZrO3 thin film capacitor has the largest energy storage density, reaching 125 J / cm 3 , and the corresponding energy storage efficiency is 83%.

[0070] In previous studies, breaking the ordered arrangement of the dipole of the anti-ferroelectric material can effectively improve the breakdown field strength and energy storage characteristics. The technical scheme of the present application is different from the previously reported nano-domain structure. The disordered anti-ferroelectric dipole prepared by the method of the present case is in a disordered state, and the dipole polarization values mutually compensate in a wide range, and do not show polarization externally. This uniform structure can effectively reduce the generation of defects, suppress the leakage current and reduce the dielectric loss, greatly improving the intrinsic breakdown field of the film.

[0071] The above is a further detailed description of the present application in combination with specific preferred embodiments, and cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as falling within the protection scope of the present application.

Claims

1. An antiferroelectric material, characterized in that: Its chemical formula For Pb 1-x Sr x ZrO3, wherein 0.4 ≤ x ≤ 0.6; the antiferroelectric material has a disordered dipole structure; The antiferroelectric material was prepared using the following steps: Step S1: Weigh PbO, SrCO3 and ZrO2 according to the molar ratio of 11 (1-x): 10 x: 10, mix them with solvent and ball mill them to obtain ball mill slurry; Step S2: Vacuum dry the ball mill slurry, grind it into powder, heat it to 800-900℃ for heat preservation and sintering, and then cool it down for secondary ball milling and drying. Step S3: Add polyvinyl alcohol adhesive to the powder obtained in step S2, mix evenly, press into sheets, heat to remove adhesive, then heat to 1200-1300℃ for sintering, cool to 400℃ at 3-6℃ / min, and finally cool naturally to room temperature to obtain antiferroelectric material.

2. The method for preparing antiferroelectric materials as described in claim 1, characterized in that: Includes the following steps: Step S1: Weigh PbO, SrCO3 and ZrO2 according to the molar ratio of 11 (1-x): 10 x: 10, mix them with solvent and ball mill them to obtain ball mill slurry; Step S2: Vacuum dry the ball mill slurry, grind it into powder, heat it to 800-900℃ for heat preservation and sintering, and then cool it down for secondary ball milling and drying. Step S3: Add polyvinyl alcohol adhesive to the powder obtained in step S2, mix evenly, press into sheets, heat to remove adhesive, then heat to 1200-1300℃ for sintering, cool to 400℃ at 3-6℃ / min, and finally cool naturally to room temperature to obtain antiferroelectric material.

3. The method for preparing antiferroelectric materials according to claim 2, characterized in that: In step S1, the ball milling time is 6-10 hours; in step S2, the heating rate is 3-8℃ / min, and the holding and sintering time is 4-6 hours; in step S3, the temperature is raised to 600-700℃ for heating and debinding.

4. The method for preparing antiferroelectric materials according to claim 3, characterized in that: In step S1, the ball milling time is 8 hours; in step S2, the heating rate is 5℃ / min, and the holding and sintering time is 5 hours; in step S3, the temperature is increased to 650℃ at a rate of 2-4℃ / min for heating and debinding.

5. An antiferroelectric thin film, characterized in that: It is prepared using the following steps: Step S10: Using a (001) oriented SrTiO3 substrate as a base, fix it on a heating holder; Step S20: Place the heated tray into the cavity of the pulsed laser deposition equipment and evacuate to 10°C. -3 Below Pa, the temperature is raised to 680-720℃, and the strontium ruthenium target is switched to deposited in an oxygen atmosphere for 2 min; then the temperature is lowered to 580-620℃, the oxygen pressure is adjusted to 8-12 Pa, the lead strontium zirconate target is switched to deposited in an oxygen atmosphere for 20 min, and finally the temperature is lowered and annealed in an oxygen atmosphere; wherein the lead strontium zirconate target is the antiferroelectric material as described in claim 1.

6. A thin-film capacitor, characterized in that: It includes the antiferroelectric thin film and top electrode as described in claim 5, wherein the top electrode is deposited on the antiferroelectric thin film.

7. The thin-film capacitor according to claim 6, characterized in that: The top electrode is a Pt electrode, which is prepared by the following steps: transferring the pattern of the top electrode by photolithography, depositing a layer of Pt on the antiferroelectric thin film as the top electrode by magnetron sputtering, and finally removing the photoresist.

8. The thin-film capacitor according to claim 7, characterized in that: The thickness of the top electrode is 40-60 nm.

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