A polar vortex structure relaxor ferroelectric ceramic material, a preparation method and application thereof

Abstract

The application relates to the technical field of inorganic nonmetal functional ceramic materials, and discloses a polar vortex structure relaxor ferroelectric ceramic material and a preparation method and application thereof, the material is of a chemical formula (1-x)(0.7NaNbO3-0.3Sr 0.7 Bi 0.2 TiO3)-xCaSnO3, wherein 0<=x<=0.2, and a characteristic value is x=0.1. By adopting a step-by-step solid-phase reaction method, NaNbO3, Sr 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powders are pre-synthesized, then are ball-milled according to a stoichiometric ratio and are sintered into ceramics. The prepared ceramic material has a multi-phase coexistence, core-shell and polar vortex structure, and exhibits high saturation polarization intensity, low hysteresis, large breakdown field strength and excellent service stability, and has potential application in high-power pulse devices. The material is environment-friendly and simple in process, and is expected to provide a new technical path for design and preparation of high-performance and high-stability nonlinear dielectric energy storage materials.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic functional ceramic materials technology, and more specifically to a polar vortex structure relaxor ferroelectric ceramic material, its preparation method, and its application in high-power pulse devices. Background Technology

[0002] Dielectric capacitors, characterized by ultrafast energy conversion rates, high reliability, and environmental friendliness, are widely used in energy and power systems and electronic circuits. They are irreplaceable fundamental components in high-power pulse technology, enabling instantaneous energy release and power amplification, and hold significant strategic importance in ultra-high-power equipment and related cutting-edge scientific research. Relaxors, due to their unique nanodomain structure and diffuse phase transition characteristics, hold promise for supporting the creation and application of wide-temperature-range, high-performance nonlinear dielectric energy storage materials, and are highly favored by researchers. However, the rapid polarization saturation behavior of relaxors results in relatively low saturation polarization, hindering their development towards high performance.

[0003] Currently, improvements in the energy storage characteristics of nonlinear dielectrics largely focus on the manipulation of polar region size, which typically achieves high energy storage efficiency at the expense of saturation polarization. Topological polar vortex structures can enhance dielectric relaxation and reduce remanent polarization, achieving a synergistic improvement in energy density and efficiency. Normally, electric dipoles tend to align in parallel to form trivial domains rather than rotate to form topological structures; moreover, dielectric materials are generally more anisotropic than magnetic materials, thus requiring a greater driving force to rotate electric dipoles to form topological structures. Topological polar structures are unstable; without suitable boundary conditions to maintain them, they will relax back to trivial domain structures. Therefore, the fabrication and stable existence windows of polar topological structures are both narrow. Ferroelectric thin film materials, influenced by substrate and fabrication processes, exhibit significant stress and high-density grain boundaries, making it easy to obtain topological polar structures by modulating elastic and electrostatic properties. In contrast, constructing polar vortex structures in ferroelectric ceramics is extremely challenging. Summary of the Invention

[0004] In view of this, the present invention addresses the problem that the rapid polarization saturation behavior of relaxors leads to relatively low saturation polarization, and proposes a polar vortex structure relaxor ferroelectric ceramic material, its preparation method, and its application.

[0005] It should be noted that researchers, through phase-field simulations of domain structures with different dielectric constants and grain boundary concentrations, discovered that high-concentration low-dielectric-constant grain boundaries induce depolarization fields that promote the formation of polar vortex structures. This theoretical prediction indicates that polar vortex structures can be constructed by controlling the core-shell structure or grain boundary density of ferroelectric ceramics.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first technical objective of this invention is to provide a polar vortex structure relaxor ferroelectric ceramic material with the chemical formula (1-x)(0.7NaNbO3-0.3Sr). 0.7 Bi 0.2 TiO3)-xCaSnO3, where 0≤x≤0.2.

[0008] Furthermore, the characteristic value of the chemical formula of the material is x = 0.1.

[0009] The second technical objective of this invention is to provide a method for preparing a polar vortex structure relaxor ferroelectric ceramic material, which involves pre-synthesizing NaNbO3 and Sr using a stepwise solid-state reaction method. 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powders are then ball-milled and sintered according to stoichiometric ratios to form ceramics.

[0010] Furthermore, the pre-synthesis temperature of the NaNbO3 ceramic powder is 850–900℃, and the time is 3–5 hours.

[0011] Furthermore, the Sr 0.7 Bi 0.2 The pre-synthesis temperature of TiO3 ceramic powder is 900-1000℃, and the time is 3-5h.

[0012] Furthermore, the pre-synthesis temperature of the CaSnO3 ceramic powder is 1000–1050℃, and the time is 3–5 h.

[0013] Furthermore, the (1-x)(0.7NaNbO3-0.3Sr 0.7 Bi 0.2 The sintering heating rate of TiO3-xCaSnO3 ceramic material is 1-10℃ / min, the sintering temperature is 1200-1400℃, and the time is 3-5h.

[0014] The third technical objective of this invention is to provide an application of the polar vortex structure relaxor ferroelectric ceramic material as described above in high-power pulse devices.

[0015] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. This invention defines a material with P21ma, Pnma2, Pbnm, P4 / mbm and P42 / mnm SnO2 multiphase coexistence and core-shell, polar vortex structure, exhibiting high saturation polarization intensity, low hysteresis, large breakdown field strength and excellent service stability, and has potential applications in high-power pulse devices.

[0017] 2. The materials of this invention are environmentally friendly and the process is simple, which is expected to provide a new technical path for the design and preparation of high-performance, high-stability nonlinear dielectric energy storage materials. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 For (1-x)(0.7NaNbO3-0.3Sr) 0.7 Bi 0.2 TiO3-xCaSnO3 ceramic material: (a) PE curves at an electric field of 360 kV / cm and (b) at the maximum breakdown field strength, and (c) energy storage density and efficiency at the maximum breakdown field strength.

[0020] Figure 2 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 (a) Refined X-ray diffraction pattern and (b) Transmission electron microscopy image of TiO3-0.1CaSnO3 ceramic material.

[0021] Figure 3 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 (a) Transmission electron microscopy image of grain boundaries and (b) Energy dispersive spectroscopy (EDS) analysis of elemental composition of TiO3-0.1CaSnO3 ceramic material.

[0022] Figure 4 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 (a) High-angle annular dark-field transmission electron microscope image and polar atom displacement diagram of TiO3-0.1CaSnO3 ceramic material and (b) representative local magnified image and simulation diagram.

[0023] Figure 5 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 The PE curves of TiO3-0.1CaSnO3 ceramic material at (a) different frequencies, (b) different temperatures, and (c) different cycle numbers, and (df) the corresponding energy storage density and efficiency. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Raw material sources: Na2CO3 (98.0%, Afaeza (Tianjin) Chemical Co., Ltd.), CaCO3 (99.0%, Sinopharm Shanghai Chemical Reagent Co., Ltd.), SrCO3 (97.5%, Afaeza (Tianjin) Chemical Co., Ltd.), Bi2O3 (99.0%, Sinopharm Shanghai Chemical Reagent Co., Ltd.), TiO2 (99.5%, Afaeza (Tianjin) Chemical Co., Ltd., Nb2O5 (99.9%, Sinopharm Shanghai Chemical Reagent Co., Ltd.) and SnO2 (99.0%, Sinopharm Shanghai Chemical Reagent Co., Ltd.).

[0026] The present invention relates to (1-x)(0.7NaNbO3-0.3Sr) 0.7 Bi 0.2 The preparation process of TiO3-xCaSnO3 ceramic material is as follows:

[0027] (1) Weigh the required oxides or carbonates according to the stoichiometric ratio, then place the weighed raw materials in a tetrafluoroethylene ball mill jar and wet-mill for 8 hours. After discharge, drying, and pre-calcination at 850-900℃, 900-1000℃, and 1000-1050℃ for 3-5 hours, NaNbO3 and Sr are obtained respectively. 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powder;

[0028] (2) Weigh the above ceramic powder according to the stoichiometric ratio, ball mill, discharge, dry, and then use 8-10% polyvinyl alcohol as a binder to granulate the mixed powder. Under a pressure of 10-100 MPa, press it into ceramic green sheets through a molding die.

[0029] (3) The ceramic green sheets are subjected to a bonding treatment at 550–600℃, and then heated to 1200–1400℃ at a heating rate of 1–10℃ / min, and sintered for 3–5 hours to obtain (1–x)(0.7NaNbO3–0.3Sr) 0.7 Bi 0.2 TiO3)-xCaSnO3 ceramic materials.

[0030] Example 1

[0031] Weigh the required oxides or carbonates according to the stoichiometric ratio, place the weighed raw materials in a tetrafluoroethylene ball mill jar and wet-mill for 8 hours, then discharge, dry, and pre-calcine at 900℃ for 5 hours, 940℃ for 4 hours, and 1000℃ for 3 hours to obtain NaNbO3 and Sr, respectively. 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powders were prepared; the above ceramic powders were weighed according to the stoichiometric ratio, ball-milled, discharged, and dried. Then, granulation was carried out using 8-10% polyvinyl alcohol as a binder. The granules were pressed into ceramic green sheets using a molding die at 20 MPa. After debinding at 550-600℃, the sheets were sintered at 1380℃ for 3 hours at a heating rate of 3℃ / min to obtain (1-x)(0.7NaNbO3-0.3Sr) 0.7 Bi 0.2 TiO3)-xCaSnO3 ceramic material, where x=0,0.05,0.1,0.15,0.2.

[0032] Figure 1 For (1-x)(0.7NaNbO3-0.3Sr) 0.7 Bi 0.2 The PE curves of TiO3-xCaSnO3 ceramic materials under an electric field of 360 kV / cm and at the maximum breakdown field strength, as well as the energy storage density and efficiency at the maximum breakdown field strength, are presented. The results show that the PE curve of the ceramic material gradually evolves into a linear curve with increasing CaSnO3 content, and the maximum breakdown field strength of the optimal composition (x = 0.1) reaches as high as 752 kV / cm. -1 The corresponding energy storage density that can be released is W rec The efficiency η reached 6.83±0.18 J / cm². -3 And 95.7±1.0%.

[0033] Example 2

[0034] The eigenvalue x = 0.1 is selected, which is 0.63NaNbO3 - 0.27Sr. 0.7 Bi 0.2 The microstructure and service stability of TiO3-0.1CaSnO3 ceramic materials were analyzed.

[0035] Figure 2 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 The refined X-ray diffraction pattern and transmission electron microscopy image of TiO3-0.1CaSnO3 ceramic material show that the ceramic material has multiphase coexistence of P21ma, Pnma2, Pbnm, P4 / mbm and P42 / mnm SnO2 and core-shell structure grains.

[0036] Figure 3 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 Transmission electron microscopy images of grain boundaries in TiO3-0.1CaSnO3 ceramic materials and elemental content analysis by energy dispersive spectroscopy line scanning revealed the presence of Ca, Sn, and Bi-rich phases at the ceramic grain boundaries.

[0037] Figure 4 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 High-angle annular dark-field transmission electron microscopy images, polar atom displacement diagrams, and representative local magnified images and simulations of TiO3-0.1CaSnO3 ceramic materials show the presence of local disordered regions and polar vortex structures.

[0038] Figure 5 The concentration is 0.63NaNbO3-0.27Sr. 0.7 Bi 0.2 TiO3-0.1CaSnO3 ceramic material at 500752kV cm -1 PE curves and corresponding energy storage density and efficiency at different frequencies, temperatures, and cycle numbers under an electric field are shown. The results are displayed in the frequency range of 10–200 Hz. rec The efficiency η is 3.41 ± 0.07 J / cm². -3 With 98.1±1.5%, W in the temperature range of room temperature to 150℃ rec The efficiency η is 3.14 ± 0.34 J / cm². -3 Compared with 93.6±7.0%, in the range of 1 to 10 5 W within the loop count range rec The efficiency η is 3.56 ± 0.03 J / cm². -3 With a stability of 97.6 ± 1.4%, it demonstrates excellent service stability.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polar vortex structure relaxor ferroelectric ceramic material, characterized in that, The chemical formula of the material is (1- x (0.7NaNbO3-0.3Sr) 0.7 Bi 0.2 TiO3)- x CaSnO3, in which x =0.

1.

2. A method for preparing a polar vortex structure relaxor ferroelectric ceramic material as described in claim 1, characterized in that, NaNbO3 and Sr were synthesized in advance using a stepwise solid-state reaction method. 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powders are then ball-milled and sintered according to stoichiometric ratios to form ceramics.

3. The method for preparing the polar vortex structure relaxor ferroelectric ceramic material according to claim 2, characterized in that, The pre-synthesis temperature of the NaNbO3 ceramic powder is 850~900℃, and the time is 3~5h.

4. The method for preparing the polar vortex structure relaxor ferroelectric ceramic material according to claim 2, characterized in that, The Sr 0.7 Bi 0.2 The pre-synthesis temperature of TiO3 ceramic powder is 900~1000℃, and the time is 3~5h.

5. The method for preparing the polar vortex structure relaxor ferroelectric ceramic material according to claim 2, characterized in that, The pre-synthesis temperature of the CaSnO3 ceramic powder is 1000~1050℃, and the time is 3~5h.

6. The method for preparing the polar vortex structure relaxor ferroelectric ceramic material according to claim 2, characterized in that, The sintering heating rate of the ceramic material is 1~10℃ / min, the sintering temperature is 1200~1400℃, and the time is 3~5h.

7. The application of a polar vortex structure relaxor ferroelectric ceramic material as described in claim 1 or a polar vortex structure relaxor ferroelectric ceramic material prepared by the method described in claim 2 in high-power pulse devices.

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