Organic-inorganic layered magnetoelectric composite material and preparation method thereof

Abstract

The invention relates to the technical field of preparation of magnetoelectric materials, and provides an organic-inorganic layered magnetoelectric composite material and a preparation method thereof, and the preparation method of the composite material comprises the following steps: S1, uniformly mixing dimethylformamide, barium titanate and P (VDF-HFP) to obtain a mixed slurry; s2, carrying out tape casting on the mixed slurry on the surface of a frosted plate by adopting a tape casting method, and drying to obtain a P (VDF-HFP) / BaTiO3 composite film; and S3, the dried composite film is quenched and then dried, nickel is sputtered on one face of the composite film, nickel or copper is sputtered on the opposite face of the composite film, and then annealing is conducted to obtain the organic-inorganic layered magnetoelectric composite material. The composite film provided by the invention has excellent electrical performance, magnetic performance and magnetoelectric coupling performance; when a magnetic field perpendicular to the electric signal output direction is applied, the magnetoelectric coupling performance can be enhanced through interface normal stress transfer, and a new thought is provided for preparation of high-performance functional devices.

Description

Technical Field

[0001] This invention relates to the technical field of magnetoelectric material preparation, and more particularly to an organic-inorganic layered magnetoelectric composite material and its preparation method. Background Technology

[0002] Magnetoelectric composites, possessing both ferroelectric and ferromagnetic properties, can achieve the interconversion of magnetic and electrical energy, demonstrating great application potential in sensors, memory devices, and energy harvesting devices. Among them, the 2-2 type layered organic-inorganic composite system, combining the flexibility and easy processing of organic polymers with the high dielectric and high magnetostrictive properties of inorganic ceramics / metals, has become a research hotspot in this field.

[0003] Currently, organic-inorganic layered magnetoelectric composite materials suffer from low stress transfer efficiency in vertical configurations (where the external magnetic field direction is perpendicular to the electrical signal output direction), which limits the application of this type of magnetoelectric composite material in the field of flexible electronic devices. Summary of the Invention

[0004] In view of this, the present invention proposes an organic-inorganic layered magnetoelectric composite material and its preparation method, which effectively solves the problems of poor interfacial compatibility and low stress transfer efficiency under vertical configuration.

[0005] The technical solution of this invention is achieved as follows: On one hand, this invention provides a method for preparing an organic-inorganic layered magnetoelectric composite material, comprising the following steps: S1, mix dimethylformamide, barium titanate and P(VDF-HFP) evenly to obtain a mixed slurry; S2, using the casting method, a mixed slurry is cast onto the surface of a frosted plate and then dried to obtain a P(VDF-HFP) / BaTiO3 composite film; S3, after the dried composite film is quenched and dried, nickel is sputtered on one side of the composite film and nickel or copper is sputtered on the opposite side, and then annealed to obtain an organic-inorganic layered magnetoelectric composite material.

[0006] Specifically, this invention uses a frosted plate as a casting template, and optimizes the phase structure transformation (α→β phase) of the organic phase by adjusting the surface roughness of the substrate, thereby improving the dielectric and piezoelectric properties and strengthening the interfacial stress coupling effect between the magnetostrictive phase and the piezoelectric phase. It also clarifies the contribution mechanism of the local normal stress component to the electric displacement output under a rough interface, breaking through the technical bottleneck of improving the magnetoelectric coupling coefficient.

[0007] Specifically, this invention improves the ferromagnetic response characteristics and magnetostrictive deformation transfer efficiency of the composite film by optimizing the sputtering process (single-sided / double-sided Ni layer deposition), thereby further enhancing the magnetoelectric coupling performance.

[0008] Based on the above technical solutions, preferably, in step S1, the mass ratio of dimethylformamide, barium titanate and P(VDF-HFP) is 30-40:1-2:10.

[0009] Based on the above technical solutions, preferably, in step S2, the interface roughness of the frosted plate is 10μm-18.75μm.

[0010] Specifically, when the interface of the frosted plate is too rough, i.e. less than 800 mesh, the leakage current is too large, and the sample is very easy to break down, which cannot meet the actual production requirements.

[0011] Based on the above technical solutions, preferably, in step S2, the thickness of the P(VDF-HFP) / BaTiO3 composite film is 10-20 μm.

[0012] Based on the above technical solutions, preferably, in step S3, the annealing temperature is 200-250℃ and the time is 2-3h.

[0013] Specifically, when the annealing temperature exceeds 250℃, it exceeds the decomposition temperature of P(VDF-HFP), and the sample decomposes and cannot form a complete film.

[0014] Based on the above technical solutions, preferably, in step S3, the sputtering temperature is 100-200℃, the time is 1-2h, and the atmosphere is argon.

[0015] Based on the above technical solutions, preferably, in step S3, the sputtering thickness of copper is 20-30 nm and the sputtering thickness of nickel is 500-600 nm.

[0016] Based on the above technical solutions, preferably, in step S3, the quenching temperature is 180-200℃ and the time is 5-13min.

[0017] On the other hand, the present invention also provides an organic-inorganic layered magnetoelectric composite material, which is prepared by the above-described preparation method.

[0018] The organic-inorganic layered magnetoelectric composite material and its preparation method of the present invention have the following advantages over the prior art: This invention improves dielectric and piezoelectric properties and strengthens the interfacial stress coupling effect between the magnetostrictive and piezoelectric phases by controlling the surface roughness of the matrix and optimizing the phase structure transformation (α→β phase) of the organic phase. It effectively solves the problems of poor interfacial compatibility and low stress transfer efficiency of traditional magnetoelectric composite materials under vertical configuration, as well as the problem of neglecting the role of interface morphology in regulating the magnetoelectric coupling mechanism in existing preparation processes. It clarifies the contribution mechanism of local normal stress components to electric displacement output under rough interfaces and breaks through the technical bottleneck of improving the magnetoelectric coupling coefficient.

[0019] This invention improves the ferromagnetic response characteristics and magnetostrictive deformation transfer efficiency of the composite film by optimizing the sputtering process (single-sided / double-sided Ni layer deposition), further enhancing the magnetoelectric coupling performance; it effectively solves the problem of insufficient matching between ferromagnetic properties and stress transfer caused by a single magnetostrictive layer deposition method. This invention provides a simple and highly repeatable method for preparing vertically configured organic-inorganic magnetoelectric composite materials, achieving synergistic optimization of the material's dielectric, piezoelectric, ferromagnetic, and magnetoelectric coupling properties, and providing a new path for the development of high-performance magnetoelectric functional devices. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The figures show the optical profilometer test results of the composite film in Comparative Example 1 and Examples 1-2; Figure 2 The image shows the field emission scanning electron microscope test results of the composite film in Comparative Example 1. Figure 3 The Fourier transform infrared spectra of the composite films in Comparative Example 1 and Examples 1-2 are shown in the figure. Figure 4 The graph shows the dielectric test results of the composite film in Comparative Example 1 and Examples 1-3; Figure 5 The graph shows the ferroelectric test results of the composite film in Comparative Example 1 and Examples 1-3; Figure 6 The graph shows the ferromagnetic test results of the composite film in Comparative Example 1 and Examples 1-3; Figure 7 The graph shows the change of magnetoelectric coupling coefficient with frequency under DC magnetic field 0 in Comparative Example 1 and Examples 1-3. Figure 8 The graph shows the variation of the magnetoelectric coupling coefficient of the composite film in Comparative Example 1 and Examples 1-3 as a function of the magnitude of the DC magnetic field.

[0022] In the above figure, Figure A corresponds to the test figure of Comparative Example 1, and Figures B, C, and D correspond to the test figures of Examples 1, 2, and 3, respectively. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] The P(VDF-HFP) required for this invention was purchased from the Solvay Group, model Solef® 21216, with a molecular weight of 570-600 kDa.

[0025] Example 1

[0026] This embodiment provides a method for preparing an organic-inorganic magnetoelectric composite material, including the following steps: (1) Weigh 40g of dimethylformamide, 1g of barium titanate (BaTiO3) and 10g of P (VDF-HFP) into a bottle, shake for 24h and sonicate for 1h; (2) Use roughness R a The mixed solution was cast onto a 10μm frosted plate and dried at 90℃ to obtain a 15μm thick P(VDF-HFP) / BaTiO3 composite film. (3) Quench the dried composite film at 200℃ for 10 min, and then dry it at 90℃; (4) Sputtering nickel (Ni) on one side of the composite film (the side that is in contact with the frosted plate) and magnetron sputtering copper (Cu) electrode on the other side to obtain Cu-P(VDF-HFP) / BaTiO3-Ni composite film. The sputtering temperature is 200℃, the time is 1h, the atmosphere is argon atmosphere, the pressure is 1Pa, the power is 100W, the sputtering thickness of nickel (Ni) is 561nm, and the sputtering thickness of copper electrode is 25nm. (5) After sputtering, anneal at 250°C for 2 hours.

[0027] The microscopic surface morphology of the P(VDF-HFP) / BaTiO3 composite film bonded to the frosted plate was characterized using an optical profilometer. The test results are as follows: Figure 1 Figure B shows the average surface roughness of the composite membrane. R a =2.12 μm, root mean square R q =2.59 μm, maximum value R p =7.76 μm.

[0028] The phase composition and calculations of the P(VDF-HFP) / BaTiO3 composite film were performed using Fourier transform infrared spectroscopy. The test results are as follows: Figure 3 As shown in Figure B, the β phase content is 65.7%, which is higher than that of the composite film in Comparative Example 1. This is because the rough interface generates tensile stress, which promotes the transformation from α phase to β phase.

[0029] The dielectric properties, including dielectric constant and dielectric loss, of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using an impedance analyzer. The test results are as follows: Figure 4 As shown in Figure B. In 10 3 At Hz, the dielectric constant of the composite film is 19.0, and the dielectric loss is 0.029. The increase in dielectric constant compared to the composite film of Comparative Example 1 is due to the increase in the β phase content.

[0030] The piezoelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a quasi-static d / g ​​piezoelectric constant meter. The piezoelectric coefficient was... d 33 =19.4 pC / N. The increase in piezoelectric coefficient compared to the composite film of Comparative Example 1 is due to the increased β-phase content.

[0031] The ferroelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a comprehensive ferroelectric testing system. The test results are as follows: Figure 5 As shown in Figure B, the composite film exhibits a typical ferroelectric hysteresis loop at an electric field strength of 2500 kV / cm. The maximum polarization of the composite film at an electric field strength of 2500 kV / cm is... P m =6.47 μC / cm 2 Residual polarization P r =3.02 μC / cm 2 coercive field strength E c =963.0 kV / cm, with a maximum withstand field strength of 3000 kV / cm. The increase in maximum polarization and remanent polarization compared to the composite film of Comparative Example 1 is due to the increased β-phase content, which brings more effective dipoles.

[0032] The ferromagnetic properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a vibrating sample magnetometer. The test results are as follows: Figure 6 As shown in Figure B, the hysteresis loop of the composite film still exhibits the typical soft magnetic characteristics of easy magnetization at low fields, indicating the formation of a continuous and well-crystallized Ni film on the surface of the P(VDF-HFP) / BTO substrate. The maximum magnetization of the composite film... M s=346.7 emu / cm 3 Residual magnetization M r =65.2 emu / cm 3 coercive field strength H c =85.2 Oe. All composite films reached magnetization saturation at around 1 kOe. This indicates that domain wall displacement is more significant at low fields, thus the composite films possess excellent low-field magnetization response.

[0033] The magnetoelectric coupling performance of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film was measured using a magnetoelectric material testing system. The measurement results are as follows: Figure 7 and Figure 8 As shown. Figure 7 Figure B in the diagram shows the variation of the magnetoelectric coupling coefficient of the composite film with the frequency of the AC magnetic field when the DC magnetic field is zero. Figure 8 Figure B shows the variation of the magnetoelectric coupling coefficient of the composite film with the magnitude of the DC magnetic field when the AC magnetic field strength is 0.24 Oe and the frequency is 30 kHz. A significant magnetoelectric coupling response was observed in the composite film under a DC magnetic field of 0.24 Oe. The composite film exhibits a response around 600 Oe. α 13 The maximum value indicates that the magnetic domain orientation of the Ni layer in the composite film is most regular and the magnetostrictive effect is strongest under this magnetic field. At the resonant frequency, the maximum magnetoelectric coupling coefficient of the composite film is 3.0 mV / (cm·Oe). The reason for the increase in the magnetoelectric coupling coefficient compared to the composite film in Comparative Example 1 is that the rough interface increases the contact area between the two phases, while the local interface increases the normal stress of the interface. T n It produced a larger component in three directions, enhancing... d 33 The contribution can be expressed by the following formula:

[0034] in, D 13 wave and D 13 flat These are the electric displacements output in three directions when an external magnetic field in one direction is applied to a rough interface (the surface in contact with the frosted plate) and a smooth interface (the opposite surface). T 1 P and respectively T 1 P＇ It represents the stress field transmitted from the interface in direction 1 to the piezoelectric layer under both rough and smooth interfaces. T 3 P＇This describes the stress field transmitted from the three-directional interface to the piezoelectric layer under a rough interface. d 31 and d 33 These are the transverse and longitudinal piezoelectric coefficients, respectively.

[0035] Example 2

[0036] The difference between Example 2 and Example 1 is: the template roughness is selected. R a The material is a frosted plate with a thickness of 18.75 μm; the rest of the contents are the same as in Example 1.

[0037] The microscopic surface morphology of the side of the P(VDF-HFP) / BaTiO3 composite film bonded to the frosted plate was characterized using an optical profilometer. The test results are as follows: Figure 1 Figure C shows the average surface roughness of the composite membrane. R a =3.33 μm, root mean square R q =3.8μm, maximum value R p =10.85 μm.

[0038] The phase composition and calculations of the P(VDF-HFP) / BaTiO3 composite film were performed using Fourier transform infrared spectroscopy. The test results are as follows: Figure 3 As shown in Figure C, the β phase content is 73.7%, which is a further increase compared to the composite membrane in Example 1. This is because the rougher interface provides more tensile stress to the composite membrane, thus promoting the increase in β phase content.

[0039] The dielectric properties, including dielectric constant and dielectric loss, of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using an impedance analyzer. The test results are as follows: Figure 4 As shown in Figure C. In 10 3 At Hz, the dielectric constant of the composite film is 22.8, and the dielectric loss is 0.022. The increase in dielectric constant compared to the composite film of Example 1 is due to the increase in β phase content.

[0040] The piezoelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a quasi-static d / g ​​piezoelectric constant meter. The piezoelectric coefficient was... d 33 =23.5 pC / N. The increase in piezoelectric coefficient compared to the composite film of Example 1 is due to the increased β-phase content.

[0041] The ferroelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a comprehensive ferroelectric testing system. The test results are as follows: Figure 5As shown in Figure C, the composite film exhibits a typical ferroelectric hysteresis loop at an electric field strength of 2500 kV / cm. The composite film reaches maximum polarization at an electric field strength of 2500 kV / cm. P m =6.63 μC / cm 2 Residual polarization P r =3.13 μC / cm 2 coercive field strength E c =863.5 kV / cm, with a maximum withstand field strength of 2600 kV / cm. The increase in maximum polarization and remanent polarization compared to the composite film of Example 1 is due to the increased β-phase content, which brings more effective dipoles.

[0042] The ferromagnetic properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a vibrating sample magnetometer. The test results are as follows: Figure 6 As shown in Figure C, the hysteresis loop of the composite film still exhibits the typical soft magnetic rectangle characteristic of easy magnetization under low fields, indicating the formation of a continuous and well-crystallized Ni film on the surface of the P(VDF-HFP) / BTO substrate. The maximum magnetization of the composite film... M s =291.9 emu / cm 3 Residual magnetization M r =49.7 emu / cm 3 coercive field strength H c =85.2 Oe. All composite films reached magnetization saturation at around 1 kOe. This indicates that domain wall displacement is more significant at low fields, thus the composite films possess excellent low-field magnetization response.

[0043] The magnetoelectric coupling performance of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film was measured using a magnetoelectric material testing system. The measurement results are as follows: Figure 7 and Figure 8 As shown. Figure 7 Figure C in the diagram shows the change in the magnetoelectric coupling coefficient of the composite film with the frequency of the AC magnetic field at a DC magnetic field of 0. Figure 8 Figure C shows the variation of the magnetoelectric coupling coefficient of the composite film with the magnitude of the DC magnetic field when the AC magnetic field strength is 0.24 Oe and the frequency is 30 kHz. A significant magnetoelectric coupling response was observed in the composite film under a DC magnetic field of 0.24 Oe. The composite film exhibits a response around 600 Oe. α 13The maximum value indicates that the magnetic domain orientation of the Ni layer in the composite film is most regular and the magnetostrictive effect is strongest under this magnetic field. At the resonant frequency, the maximum magnetoelectric coupling coefficient of the composite film is 3.6 mV / (cm·Oe). The reason for the increase in the magnetoelectric coupling coefficient compared to the composite film of Example 1 is that the rougher interface increases the contact area between the two phases, while the local interface increases the normal stress of the interface. T n It produces a larger component in the 3 directions.

[0044] Example 3

[0045] The difference between Example 3 and Example 1 is that Ni was sputtered on both sides (one side replaced with Ni instead of Cu), and the sputtering thickness of nickel on both sides was 561 nm. The rest of the contents are the same as in Example 1.

[0046] The dielectric properties of the Ni-P(VDF-HFP) / BaTiO3-Ni composite film, including dielectric constant and dielectric loss, were measured using an impedance analyzer. The test results are as follows: Figure 4 As shown in Figure D in 10. 3 At Hz, the dielectric constant of the composite film is 26.1, and the dielectric loss is 0.024. The increase in dielectric constant compared to the composite film of Example 1 is due to the improved density of the film crystallization and the reduction of lattice defects.

[0047] The ferroelectric properties of the Ni-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a comprehensive ferroelectric testing system. The test results are as follows: Figure 5 As shown in Figure D, the composite film exhibits a typical ferroelectric hysteresis loop at an electric field strength of 2500 kV / cm. The composite film reaches maximum polarization at an electric field strength of 2500 kV / cm. P m =6.56 μC / cm 2 Residual polarization P r =3.10 μC / cm 2 coercive field strength E c =854.9 kV / cm, with a maximum withstand field strength of 2600 kV / cm. This is not significantly different from the composite membrane in Example 2.

[0048] The ferromagnetic properties of the Ni-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a vibrating sample magnetometer. The test results are as follows: Figure 6 As shown in Figure D, the hysteresis loop of the composite film still exhibits the typical soft magnetic rectangle characteristic of easy magnetization under low fields, indicating the formation of a continuous and well-crystallized Ni film on the surface of the P(VDF-HFP) / BTO substrate. The maximum magnetization of the composite film... M s =289.9 emu / cm3 Residual magnetization M r =66.6 emu / cm 3 coercive field strength H c =85.2 Oe. All composite films reached magnetization saturation at around 1 kOe. This indicates that domain wall displacement is more significant at low fields, thus the composite films possess excellent low-field magnetization response. The increase in remanent magnetization compared to the composite film of Example 1 is mainly due to the improved crystallinity of Ni particles.

[0049] The magnetoelectric coupling performance of the Ni-P(VDF-HFP) / BaTiO3-Ni composite film was measured using a magnetoelectric material testing system. The measurement results are as follows: Figure 7 and Figure 8 As shown. Figure 7 Figure D shows the variation of the magnetoelectric coupling coefficient of the composite film with the frequency of the AC magnetic field at a DC magnetic field of 0. Figure 8 Figure D shows the variation of the magnetoelectric coupling coefficient of the composite film with the magnitude of the DC magnetic field when the AC magnetic field strength is 0.24 Oe and the frequency is 30 kHz. A significant magnetoelectric coupling response was observed in the composite film under a DC magnetic field of 0.24 Oe. The composite film exhibits a response around 600 Oe. α 13 The peak value indicates that the magnetic domain orientation of the Ni layer in the composite film is most regular and the magnetostriction effect is strongest under this magnetic field. At the resonant frequency, the maximum value of the magnetoelectric coupling coefficient of the composite film is 7.6 mV / (cm·Oe). The improvement in the magnetoelectric coupling coefficient compared to the composite film in Example 1 is mainly due to the fact that the Ni layer sputtered on the flat surface provides the composite film with an effective ferromagnetic layer volume ratio compared to the rough surface, and the improved crystal quality of the Ni layer makes the deformation of the composite film under the external magnetic field more significant.

[0050] Example 4

[0051] This embodiment provides a method for preparing an organic-inorganic magnetoelectric composite material, including the following steps: (1) Weigh 30g of dimethylformamide, 2g of barium titanate (BaTiO3) and 10g of P (VDF-HFP) into a bottle, shake for 36h and sonicate for 1h; (2) A well-mixed solution was cast using a frosted plate with a roughness Ra of 15 μm, and dried at 100℃ to obtain a P(VDF-HFP) / BaTiO3 composite film with a thickness of 10 μm; (3) Quench the dried composite film at 180℃ for 13 min, and then dry it at 100℃; (4) Sputtering nickel (Ni) on one side of the composite film (the side that is in contact with the frosted plate) and magnetron sputtering copper (Cu) electrode on the other side to obtain Cu-P(VDF-HFP) / BaTiO3-Ni composite film. The sputtering process is 100℃ for 2h; the sputtering thickness of nickel (Ni) is 500nm and the sputtering thickness of copper electrode is 20nm. (5) After sputtering, anneal at 200℃ for 3 hours.

[0052] The final measured magnetoelectric coupling coefficient was 3.2 mV / (cm·Oe), which is lower than that of Example 2. This result is due to the low interfacial roughness of the prepared composite film and the low interfacial normal stress. T n piezoelectric coefficient in three directions d 33 Their contribution was insufficient.

[0053] Example 5

[0054] This embodiment provides a method for preparing an organic-inorganic magnetoelectric composite material, including the following steps: (1) Weigh 35g of dimethylformamide, 1.5g of barium titanate (BaTiO3) and 10g of P (VDF-HFP) respectively, put them into a bottle, shake for 48h, and sonicate for 2h; (2) A well-mixed solution was cast using a frosted plate with a roughness Ra of 15 μm, and dried at 120 °C to obtain a P(VDF-HFP) / BaTiO3 composite film with a thickness of 20 μm. (3) Quench the dried composite film at 190℃ for 5 minutes, and then dry it at 120℃; (4) Sputtering nickel (Ni) on one side of the composite film (the side that is in contact with the frosted plate) and magnetron sputtering copper (Cu) electrode on the other side to obtain Cu-P(VDF-HFP) / BaTiO3-Ni composite film. The sputtering process is 150℃ for 1.5h. The sputtering thickness of nickel (Ni) is 600nm and the sputtering thickness of copper electrode is 30nm. (5) After sputtering, anneal at 220℃ for 2.5h.

[0055] The final measured magnetoelectric coupling coefficient was 3.23 mV / (cm·Oe), which was not significantly different from that in Example 4. This indicates that changing the amount of solvent within a certain range does not have a significant impact on the final performance of the composite membrane (in fact, the role of the solvent is only to dissolve P(VDF-HFP) and barium titanate).

[0056] Comparative Example 1 Compared with Example 1, in Comparative Example 1, the smooth glass plate was replaced with a 1500-mesh frosted plate in step (2), and the rest of the contents were the same as in Example 1.

[0057] The microscopic surface morphology of the side of the P(VDF-HFP) / BaTiO3 composite film bonded to the frosted plate was characterized using an optical profilometer. The test results are as follows: Figure 1 As shown in Figure A, the average surface roughness of the composite membrane. R a =3.4 nm, root mean square R q =4.5nm, maximum value R p =46.4 nm.

[0058] The microstructure of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film was characterized using field emission scanning electron microscopy. The test results are as follows: Figure 2 As shown, the Ni layer thickness is 561 nm, and the BaTiO3 particles are uniformly distributed in the P(VDF-HFP) matrix.

[0059] The phase composition and calculations of the P(VDF-HFP) / BaTiO3 composite film were performed using Fourier transform infrared spectroscopy. The test results are as follows: Figure 3 As shown in Figure A, the β phase content is 37.3%.

[0060] The dielectric properties, including dielectric constant and dielectric loss, of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using an impedance analyzer. The test results are as follows: Figure 4 As shown in Figure A. In 10 3 At Hz, the dielectric constant of the composite film is 16.4, and the dielectric loss is 0.026. With increasing frequency, the dielectric constant of the composite film continuously decreases, and its trend depends on the relaxation characteristics of P(VDF-HFP). The dielectric loss changes with frequency in the opposite direction to the dielectric constant.

[0061] The piezoelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a quasi-static d / g ​​piezoelectric constant meter. The piezoelectric coefficient was... d 33 =17.1 pC / N. Due to the incorporation of inorganic BaTiO3, the piezoelectric coefficient is improved compared to pure P (VDF-HFP).

[0062] The ferroelectric properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a comprehensive ferroelectric testing system. The test results are as follows: Figure 5 As shown in Figure A, the composite film exhibits a typical ferroelectric hysteresis loop at an electric field strength of 2500 kV / cm. The maximum polarization of the composite film at an electric field strength of 2500 kV / cm is... P m =6.27 μC / cm2 Residual polarization P r =2.93 μC / cm 2 coercive field strength E c =963.5 kV / cm, with a maximum withstand field strength of 3400 kV / cm.

[0063] The ferromagnetic properties of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film were measured using a vibrating sample magnetometer. The test results are as follows: Figure 6 As shown in Figure A, the hysteresis loop of the composite film exhibits typical soft magnetic rectangular characteristics, indicating easy magnetization under low fields. This suggests the formation of a continuous and well-crystallized Ni film on the P(VDF-HFP) / BTO substrate surface, without severe domain destruction due to substrate surface roughness. The maximum magnetization of the composite film... M s =377.2 emu / cm 3 Residual magnetization M r =74.73 emu / cm 3 coercive field strength H c =65.2 Oe. All composite films reached magnetization saturation at around 1 kOe. This indicates that domain wall displacement is more significant at low fields, thus the composite films possess excellent low-field magnetization response.

[0064] The magnetoelectric coupling performance of the Cu-P(VDF-HFP) / BaTiO3-Ni composite film was measured using a magnetoelectric material testing system. The measurement results are as follows: Figure 7 and Figure 8 As shown. Figure 7 Figure A shows the variation of the magnetoelectric coupling coefficient of the composite film with the frequency of the AC magnetic field at a DC magnetic field of 0. Figure 8 Figure A in the text is H ac =0.24 Oe, f At 30 kHz, the magnetoelectric coupling coefficient of the composite film depends on the magnitude of the DC magnetic field. Significant magnetoelectric coupling response was observed in the composite film under zero DC magnetic field, which is attributed to the intrinsic coupling characteristics between the magnetostrictive Ni phase and the piezoelectric P (VDF-HFP) / BTO substrate. The composite film exhibits [further details needed] near 600 Oe. α 13 The maximum value indicates that the magnetic domain orientation of the Ni layer in the composite film is most regular and the magnetostriction effect is strongest under this magnetic field. At the resonant frequency, the maximum value of the magnetoelectric coupling coefficient of the composite film is 2.6 mV / (cm·Oe).

[0065] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the annealing temperature in step (5) is 300°C, and the rest is the same as in Example 1.

[0066] Comparative Example 2 was damaged because its sintering temperature was higher than the decomposition temperature of the P(VDF-HFP) matrix, and therefore the performance test could not be completed.

[0067] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the template was replaced with a 50μm frosted plate, and the rest is the same as Example 1.

[0068] Comparative Example 3 had an excessively rough interface and excessive leakage current, making the sample extremely prone to breakdown and thus unable to complete the performance test.

[0069] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the amount of P(VDF-HFP) used exceeds the limit, specifically 20g. The rest of the content is the same as in Example 1.

[0070] During the preparation of the composite film, the amount of P(VDF-HFP) exceeded the limit, which prevented it from being completely dissolved in the solvent, and the mixed slurry could not be cast on the template.

[0071] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the thickness of the P(VDF-HFP) / BaTiO3 composite film exceeds the specified range, specifically 50 μm. The rest of the contents are the same as in Example 1.

[0072] The final measured magnetoelectric coupling coefficient was 2.1 mV / (cm·Oe), which is significantly lower than that of Example 1. This result is closely related to the thickness ratio of the magnetostrictive layer to the piezoelectric layer: when the piezoelectric layer is too thick, it will significantly weaken the stress transfer efficiency of the magnetostrictive phase, which will lead to a significant decrease in the magnetoelectric coupling response of the composite film.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an organic-inorganic layered magnetoelectric composite material, characterized in that, Includes the following steps: S1, mix dimethylformamide, barium titanate and P(VDF-HFP) evenly to obtain a mixed slurry; S2, using the casting method, a mixed slurry is cast onto the surface of a frosted plate and dried to obtain a P(VDF-HFP) / BaTiO3 composite film; S3, after the dried composite film is quenched and dried, nickel is sputtered on one side of the composite film and nickel or copper is sputtered on the opposite side, and then annealed to obtain an organic-inorganic layered magnetoelectric composite material.

2. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S2, the surface roughness of the frosted plate is 10μm-18.75μm.

3. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S1, the mass ratio of dimethylformamide, barium titanate, and P(VDF-HFP) is 30-40:1-2:

10.

4. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S2, the thickness of the P(VDF-HFP) / BaTiO3 composite film is 10-20 μm.

5. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S3, the annealing temperature is 200-250℃ and the time is 2-3 hours.

6. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S3, the sputtering temperature is 100-200℃, the time is 1-2 hours, and the atmosphere is argon.

7. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S3, the sputtering thickness of copper is 20-30 nm, and the sputtering thickness of nickel is 500-600 nm.

8. The method for preparing an organic-inorganic layered magnetoelectric composite material as described in claim 1, characterized in that: In step S3, the quenching temperature is 180-200℃ and the time is 5-13 minutes.

9. An organic-inorganic layered magnetoelectric composite material, characterized in that: It is prepared by the preparation method described in any one of claims 1-8.

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