A layered magnetoelectric composite material and a method for preparing the same

Abstract

The application provides a layered magnetoelectric composite material and a preparation method thereof. 0.5 Na 0.5 TiO3-based piezoelectric material layer, the second layer is a Bi 0.5 Na 0.5 TiO3-based piezoelectric material and a ferrite magnetostrictive material composite layer, and the third layer is a ferrite magnetostrictive material layer. The preparation method comprises the following steps: S1, preparing a ferrite magnetostrictive powder; S2, preparing a piezoelectric phase powder; S3, preparing a magnetoelectric composite powder; and S3, preparing a magnetoelectric composite powder. In the layered magnetoelectric composite material, the phase interface is combined tightly, there are no obvious microstructure defects such as cracks or pores, the interface stress coupling is enhanced, the strong magnetic-electric coupling response is beneficial to be generated, a high magnetoelectric coupling coefficient is obtained, the layered magnetoelectric composite material has good piezoelectric performance, magnetostrictive characteristics and a high magnetoelectric voltage coefficient, and the preparation process is simple, the performance is stable, and the layered magnetoelectric composite material is environmentally friendly and harmless.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically a layered magnetoelectric composite material and its preparation method. Background Technology

[0002] With the rapid development of information technology, single-function materials are insufficient to meet the miniaturization and multifunctionality requirements of new electronic components, making the development of multifunctional materials a research hotspot. Magnetoelectric functional materials not only possess all the properties of single ferroelectric and ferromagnetic materials, but also exhibit the magnetoelectric effect generated by the coupling of electrical and magnetic order, giving them broad application prospects in electronic materials and devices such as magnetic or electric field sensors, magnetoelectric storage units, energy harvesting devices, and microwave devices.

[0003] Magnetoelectric functional materials can be broadly classified into three categories based on their composite structure: particulate, layered, and columnar. Layered magnetoelectric composite materials are formed by co-firing a piezoelectric layer and a magnetostrictive layer to create a composite magnetoelectric material. Compared with particulate and columnar composite structures, layered composite materials, due to their stacked structure, can avoid leakage current problems caused by uneven dispersion and interconnection of low-resistivity phases in the matrix. At the same time, the direct co-firing bonding at the phase interface can improve interfacial stress transfer, which is beneficial for obtaining high magnetoelectric voltage coefficients and high magnetoelectric conversion efficiency. Therefore, they play a unique role as magnetoelectric conversion units or sensitive elements in the application of new intelligent magnetoelectric materials and devices.

[0004] Interfacial coupling is a key factor determining the magnetoelectric effect of layered magnetoelectric composites, making it crucial to enhance the interfacial coupling strength between the piezoelectric and magnetostrictive layers. However, direct high-temperature co-firing of the piezoelectric and magnetostrictive layers can lead to problems such as element diffusion and chemical reactions, microstructural defects, and thermal shrinkage mismatch, weakening interfacial stress transmission and limiting the generation of high magnetoelectric coupling coefficients. Although methods such as lowering the co-firing temperature, doping modification, or introducing sintering aids have improved the interfacial coupling during co-firing to some extent, these methods can also lead to new problems such as low material density and abnormal grain growth at the interface, which are detrimental to improving the magnetoelectric coupling performance of layered magnetoelectric composites. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, the present invention aims to provide a layered magnetoelectric composite material and its preparation method. The layered magnetoelectric composite material exhibits tight interfacial bonding, free from obvious microstructural defects such as cracks or pores, enhanced interfacial stress coupling, which facilitates strong magnetoelectric coupling response, resulting in a high magnetoelectric coupling coefficient. It also possesses excellent piezoelectric properties, magnetostrictive characteristics, and a high magnetoelectric voltage coefficient. Furthermore, the preparation process is simple, the performance is stable, and it is environmentally friendly and harmless, making it suitable for electronic devices such as magnetoelectric sensors, energy harvesters, and filters.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A layered magnetoelectric composite material, comprising three layers arranged sequentially: the first layer is Bi 0.5 Na 0.5 TiO3-based piezoelectric material layer, second layer is Bi 0.5 Na 0.5 The TiO3-based piezoelectric material and ferrite magnetostrictive material composite layer, the third layer is a ferrite magnetostrictive material layer.

[0008] As a further improvement to the above technical solution:

[0009] Second layer Bi 0.5 Na 0.5 The volume fraction ratio of piezoelectric material to magnetostrictive material in the TiO3-based piezoelectric material and ferrite magnetostrictive material composite layer is 1:1.

[0010] The thickness ratio of the first, second, and third layers is 3:1:6 to 3:1:8.

[0011] The ferrite magnetostrictive material in the second and third layers has a spinel structure (Co). 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 Fe2O4, (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 One of Fe2O4.

[0012] The piezoelectric phase is Bi. 0.5 K 0.5 TiO3 modified Bi 0.5 Na 0.5 The ferroelectric solid solution of TiO3 with the molecular formula (1-x)Bi 0.5 Na 0.5 TiO3-xBi 0.5 K 0.5 For TiO3, the value of x is in the range of 0.18 ≤ x ≤ 0.2.

[0013] A method for preparing the above-mentioned layered magnetoelectric composite material includes the following steps:

[0014] Step S1: Preparation of ferrite magnetostrictive powder: Add metal nitrate to water and complexing agent, mix and adjust pH value, heat and stir to obtain ferrite sol; dry the sol and burn it completely, then sinter and ball mill to obtain magnetostrictive material;

[0015] Step S2: Preparation of piezoelectric phase powder: Weigh and mix the oxide or carbon oxide raw materials, ball mill and mix, sinter and crush to obtain piezoelectric phase material;

[0016] Step S3: Preparation of magnetoelectric composite powder: The magnetostrictive material prepared in step S1 and the piezoelectric phase powder prepared in step S2 are thoroughly mixed in a set ratio and dried to obtain composite powder;

[0017] Step S4: Preparation of layered magnetoelectric composite material: Add binder to a set weight of piezoelectric phase powder, mix evenly, and press into a preform to obtain a piezoelectric phase preform layer; add binder to a set weight of the composite powder, stir evenly, pour onto the piezoelectric phase preform layer, and press into a composite layer; add binder to a set weight of ferrite magnetostrictive powder, stir evenly, invert onto the composite layer, and press into a layered preform; heat to remove the binder, perform microwave sintering, and cool to obtain the layered magnetoelectric composite material.

[0018] In step S1, multiple metal nitrates are dissolved in deionized water and a complexing agent is added. The multiple metal nitrates are two or more of the following: nickel nitrate hexahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, copper nitrate trihydrate, magnesium nitrate hexahydrate, manganese nitrate tetrahydrate, and ferric nitrate nonahydrate.

[0019] In step S1, the temperature for drying the sol is 140–160°C, and the drying time is 3–5 h; the sintering temperature is 1210–1250°C, and the sintering time is 4–6 h.

[0020] In step S1, the pH of the mixed solution is adjusted to neutral.

[0021] In step S1, the stirring time is 4 to 5 hours, and the stirring speed is 500 to 950 r / min.

[0022] In step S1, the drying temperature is 140–160°C, and the drying time is 3–5 hours. Preferably, the drying temperature is 150°C.

[0023] In step S1, the combustion temperature is 400–500°C, and the combustion time is 1.5–3 hours. Preferably, the combustion temperature is 450°C.

[0024] In step S1, the sintering temperature is 1210–1250℃ and the sintering time is 4–6 hours.

[0025] In step S2, the sintering temperature is 1100-1150℃ and the sintering time is 1-2 hours.

[0026] In step S3, the magnetostrictive material prepared in step S1 and the piezoelectric phase powder prepared in step S2 are thoroughly mixed in a set ratio and dried to obtain composite powder.

[0027] In step S4, the adhesive is polyvinyl alcohol; the pressure for pressing the preform is 60-80 MPa; the temperature for heating and removing the adhesive is 500-650°C, and the heating and removing time is 20-45 min; the temperature for microwave sintering is 1070-1120°C, and the sintering time is 20-30 min.

[0028] In step S4, the weights of the piezoelectric phase powder, composite powder, and ferrite magnetostrictive powder are weighed according to the weights calculated according to the set ratio.

[0029] The beneficial effects of this invention are:

[0030] 1) The layered magnetoelectric composite material has high density, tight phase interface bonding, and no obvious structural defects, which can solve the shrinkage mismatch problem of co-firing between magnetostrictive and piezoelectric phases; the material has good piezoelectric properties, magnetostrictive characteristics, interlayer coupling effect and excellent magnetoelectric coupling effect, with a high magnetoelectric coupling coefficient.

[0031] 2) By using ferrite magnetostrictive materials with high entropy components and introducing an intermediate composite layer, the mechanical strength of the layered magnetoelectric composite material is superior to that of ordinary layered magnetoelectric composites, making it suitable for the field of large-size and complex magnetoelectric materials.

[0032] 3) Modified lead-free Bi is used 0.5 Na 0.5 TiO3-based piezoelectric materials are environmentally friendly, reducing environmental pollution; they also have high polarization intensity and strong piezoelectric response, and their electrical properties can be adjusted through doping modification and process control to meet various application requirements.

[0033] 4) The microwave sintering process is used to sinter layered magnetoelectric composite materials. It is short, energy-efficient, safe and pollution-free. The process is simple and the resulting materials have stable properties. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of an embodiment of the layered magnetoelectric composite material of the present invention.

[0035] Figure 2 This is a scanning electron micrograph of a cross-section of a layered magnetoelectric composite material according to an embodiment of the present invention.

[0036] Figure 3 This is an X-ray diffraction pattern of a layered magnetoelectric composite material according to an embodiment of the present invention.

[0037] Figure 4 This is a hysteresis loop diagram of a layered magnetoelectric composite material according to an embodiment of the present invention.

[0038] Figure 5This is a hysteresis loop diagram of a layered magnetoelectric composite material according to an embodiment of the present invention.

[0039] Figure 6 This is a graph showing the relationship between the magnetoelectric coupling coefficient and the DC magnetic field of a single-layer magnetoelectric composite material according to an embodiment of the present invention.

[0040] Figure 7 This is a graph showing the relationship between the magnetoelectric coupling coefficient and the DC magnetic field of the layered magnetoelectric composite material in Embodiment 2 of the present invention.

[0041] Figure 8 This is a graph showing the relationship between the magnetoelectric coupling coefficient and the DC magnetic field of the layered magnetoelectric composite material in Embodiment 3 of the present invention. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0043] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0044] A layered magnetoelectric composite material, comprising three layers arranged sequentially: the first layer is Bi 0.5 Na 0.5 TiO3-based piezoelectric material layer 1, the second layer is Bi 0.5 Na 0.5 The first layer is a composite layer of TiO3-based piezoelectric material and ferrite magnetostrictive material, and the third layer is a ferrite magnetostrictive material layer 3. The thickness ratio of the first, second and third layers is 3:1:6 to 3:1:8. The three layers are stacked and co-fired.

[0045] The ferrite magnetostrictive material in the second and third layers has a spinel structure (Co). 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg0.2 Fe2O4, (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 One of Fe2O4.

[0046] Preferably, the piezoelectric phase is Bi. 0.5 K 0.5 TiO3 modified Bi 0.5 Na 0.5 The ferroelectric solid solution of TiO3 with the molecular formula (1-x)Bi 0.5 Na 0.5 TiO3-xBi 0.5 K 0.5 TiO3, with x ranging from 0.18 to 0.2, has a crystal structure characterized by the coexistence of trigonal and tetragonal phases.

[0047] The second layer Bi 0.5 Na 0.5 The volume fraction ratio of piezoelectric material to magnetostrictive material in the TiO3-based piezoelectric material and ferrite magnetostrictive material composite layer 2 is 1:1.

[0048] The following three examples illustrate this.

[0049] Example 1

[0050] In this embodiment, the layered magnetoelectric composite material is made by co-firing three layers of material arranged sequentially, with the first layer being 0.8Bi. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 The first layer is a TiO3 piezoelectric material, and the second layer is 0.8Bi. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 The TiO3 piezoelectric material and ferrite magnetostrictive material composite layer, the third layer is (Co) 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 The second and third layers contain Fe2O4 ferrite magnetostrictive material. The ferrite magnetostrictive materials in the second and third layers have the same chemical formula.

[0051] The thickness ratio of the first, second, and third layers is 3:1:6. The volume of the ferrite magnetostrictive material in the composite material accounts for 0.65% of the total volume of the composite material, meaning that the volume of the ferrite magnetostrictive material in the composite material includes the volume of the ferrite magnetostrictive material in the second and third layers.

[0052] The preparation process of the composite material is as follows:

[0053] Step S1: Preparation of (Co) 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 Fe2O4 magnetostrictive material.

[0054] This process includes the following steps performed sequentially:

[0055] Step S11: Weigh out 2.91g of cobalt nitrate hexahydrate, 2.91g of nickel nitrate hexahydrate, 2.42g of copper nitrate trihydrate, 2.97g of zinc nitrate hexahydrate, 2.56g of magnesium nitrate hexahydrate, and 40.4g of ferric nitrate nonahydrate according to the stoichiometric ratio of Co:Ni:Cu:Zn:Mg:Fe 1:1:1:1:10, dissolve them in deionized water, add 36.17g of ethylenediaminetetraacetic acid and 7.94g of citric acid, stir, and obtain a homogeneous mixture.

[0056] Step S12: Adjust the pH of the above mixture to neutral using ammonia.

[0057] Step S13: Place the prepared solution in a water bath at a constant temperature of 90°C and heat it. Stir at 500 r / min for 4 hours to obtain a stable and uniform sol.

[0058] Step S14: Place the sol in a drying oven at 160℃ and dry for 3 hours. Then, burn the dried gel completely with alcohol to obtain a coral-like ashed material.

[0059] Step S15: Place the ashed powder in a box-type resistance furnace and sinter at 1220℃ for 5 hours. After cooling with the furnace, ball mill the powder and pass it through a 200-mesh sieve to obtain magnetostrictive powder material.

[0060] Step S2: Preparation of 0.8Bi 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 TiO3 piezoelectric material.

[0061] This process includes the following steps performed sequentially:

[0062] Step S21: Weigh 11.65g of bismuth trioxide, 1.06g of sodium carbonate, 0.35g of potassium carbonate and 3.99g of titanium dioxide raw materials according to the stoichiometric ratio of Bi:Na:K:Ti 5:4:1:10, and ball mill for 12h (ball-to-material ratio of 3:1, anhydrous ethanol as medium) to obtain a uniformly mixed slurry.

[0063] Step S22: Dry the slurry thoroughly.

[0064] Step S23: Sinter in a box-type resistance furnace at 1100℃ for 2 hours. After cooling, grind the product thoroughly and pass it through a 200-mesh sieve to obtain piezoelectric powder material.

[0065] Step S3: Preparation of magnetoelectric composite powder. Weigh 2.5g of the magnetostrictive powder prepared in step S1 and 2.5g of the piezoelectric material powder prepared in step S2, respectively, and pour them into a ball mill jar for ball milling for 12 hours (the ball-to-powder ratio is 3:1, and anhydrous ethanol is used as the medium). Take out the slurry and dry it to obtain the magnetoelectric composite powder.

[0066] Step S4: Prepare layered magnetoelectric composite material.

[0067] This process includes the following steps performed sequentially:

[0068] Step S41: Weigh 1.23g of the 0.8Bi obtained in step S2. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 TiO3 powder.

[0069] Step S42: Add 0.018g of polyvinyl alcohol, mix well, fill into a stainless steel mold, and form a piezoelectric preform under a pressure of 60MPa.

[0070] Step S43: Weigh 0.45g of the magnetoelectric composite powder obtained in step S3.

[0071] Step S44: Add 0.009g of polyvinyl alcohol, stir evenly, pour it onto the piezoelectric preform, and press it into a composite preform using a pressure of 60MPa.

[0072] Step S45: Weigh 2.09g of the magnetostrictive material powder obtained in step S1, add 0.02g of polyvinyl alcohol, mix evenly, fill it into the composite preform in the stainless steel mold, and form a preform under a pressure of 80MPa.

[0073] Step S46: Remove the preform and place it in a box-type resistance furnace. Keep it at 550℃ for 30 minutes to remove the glue. Then perform microwave sintering at 1100℃ for 30 minutes. Cool to obtain the layered magnetoelectric composite material.

[0074] In this embodiment, the performance parameters of the layered magnetoelectric composite material are shown in the table below:

[0075]

[0076] As attached Figure 1 As shown, the layered magnetoelectric composite material of this embodiment consists of three layers: piezoelectric layer 1, magnetoelectric composite layer 2, and magnetostrictive layer 3.

[0077] As attached Figure 2 As shown, the microstructure of the layered magnetoelectric composite material in this embodiment is dense, with tight interlayer bonding and no obvious defects such as cracks or gaps.

[0078] As attached Figure 3 As shown, the layered magnetoelectric composite material of this embodiment has a quasi-isomorphic phase boundary piezoelectric material of 0.8Bi. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 It is composed of TiO3 and spinel ferrite, and has no impurities.

[0079] As attached Figure 4 and attached Figure 5 As shown, the layered magnetoelectric composite material in this embodiment exhibits strong polarization and magnetization characteristics, which contributes to the generation of strong magnetoelectric coupling effect.

[0080] As attached Figure 6 As shown, the layered magnetoelectric composite material in this embodiment exhibits a high magnetoelectric voltage coefficient of 42.31 mV / cm·Oe, enabling efficient conversion between magnetic and electrical energy. Calculations show that the interfacial coupling coefficient of the composite material (0.63) is higher than that of bonded double-layer magnetoelectric composite materials (generally between 0.2 and 0.4) or directly sintered layered magnetoelectric composite materials (generally between 0.3 and 0.5), indicating good interfacial coupling.

[0081] Example 2

[0082] Unlike Embodiment 1, in this embodiment, the third layer is (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 The first layer is an Fe2O4 ferrite magnetostrictive material layer, and correspondingly, the second layer is also a Co ferrite magnetostrictive material. 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 The preparation process of Fe2O4 ferrite magnetostrictive material is also different.

[0083] In this embodiment, the layered magnetoelectric composite material is made by co-firing three layers of materials, with the first layer being 0.8Bi. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 The first layer is a TiO3 piezoelectric material, and the second layer is 0.8Bi. 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 The TiO3 piezoelectric material and ferrite magnetostrictive material composite layer, the third layer is (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 The Fe2O4 ferrite magnetostrictive material layer has a layer thickness ratio of 3:1:6 for the first, second, and third layers. The volume fraction of the ferrite magnetostrictive material in the composite material is 0.65% of the total volume. The specific preparation process is as follows:

[0084] Step S1: Preparation of (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 Fe2O4 magnetostrictive material.

[0085] This process includes the following steps performed sequentially:

[0086] Step S11: Weigh 2.91g of cobalt nitrate hexahydrate, 2.91g of nickel nitrate hexahydrate, 2.51g of manganese nitrate tetrahydrate, 2.97g of zinc nitrate hexahydrate, 2.56g of magnesium nitrate hexahydrate, and 40.4g of ferric nitrate nonahydrate according to the stoichiometric ratio of Co:Ni:Mn:Zn:Mg:Fe 1:1:1:1:10, dissolve them in deionized water, add 36.17g of ethylenediaminetetraacetic acid and 7.94g of citric acid, stir, and obtain a homogeneous mixture.

[0087] Step S12: Adjust the pH of the above mixture to neutral using ammonia.

[0088] Step S13: The obtained solution is placed in a water bath at a constant temperature of 85°C and heated, and stirred at 500 r / min for 4 h to obtain a stable and uniform sol.

[0089] Step S14: Place the sol in a drying oven at 160℃ and dry for 3 hours. Then, burn the dried gel completely with alcohol to obtain a coral-like ashed material.

[0090] Step S15: Place the ashed powder in a box-type resistance furnace and sinter at 1170℃ for 5 hours. After cooling with the furnace, ball mill the powder and pass it through a 200-mesh sieve to obtain magnetostrictive powder material.

[0091] Step S2: Preparation of 0.8Bi 0.5 Na 0.5 TiO3-0.2Bi 0.5 K 0.5 TiO3 piezoelectric material.

[0092] Step S3: Prepare magnetoelectric composite powder.

[0093] Steps S2 and S3 are the same as steps S2 and S3 in Embodiment 1, and will not be repeated here.

[0094] Step S4: Prepare layered magnetoelectric composite material.

[0095] Step S4 is basically the same as step S4 in Example 1. The main differences are that in this example, the weight of the magnetostrictive material powder weighed in step S45 is 2.09g; and the sintering temperature in step S46 is 1120℃ and the time is 20min. Other steps and parameters are the same as those in step S4 of Example 1.

[0096] The performance parameters of the layered magnetoelectric composite material in this embodiment are shown in the table below:

[0097]

[0098] As attached Figure 7 As shown, the layered magnetoelectric composite material of this embodiment has a high magnetoelectric voltage coefficient, with a maximum magnetoelectric voltage coefficient of 51.09 mV / cm·Oe at 1 kHz, which can realize efficient conversion of magnetic energy and electrical energy. The interfacial coupling coefficient of the composite material is 0.61, which is higher than that of the double-layer magnetoelectric composite material prepared by bonding (generally between 0.2 and 0.4) or the layered magnetoelectric composite material prepared by direct high-temperature sintering (generally between 0.3 and 0.5), showing good interfacial coupling effect.

[0099] Example 3

[0100] Unlike Embodiment 1, in this embodiment, the first layer is 0.82Bi. 0.5 Na 0.5 TiO3-0.18Bi 0.5 K 0.5 The first layer is a TiO3 piezoelectric material, and the second layer is 0.82Bi. 0.5 Na 0.5 TiO3-0.18Bi 0.5 K 0.5 TiO3 piezoelectric materials and ferrites (Co) 0.2Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 The first layer is a Fe2O4 magnetostrictive material composite layer, and the second layer is (Co) 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 The Fe2O4 ferrite magnetostrictive material layer has a layer thickness ratio of 3:1:8 for the first, second, and third layers. The volume fraction of the ferrite magnetostrictive material in the composite material is 0.708% of the total volume. The specific preparation process is as follows:

[0101] Step S1: Preparation of (Co) 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 Fe2O4 magnetostrictive material.

[0102] Step S1 is the same as step S1 in Embodiment 1, and will not be repeated here.

[0103] Step S2: Preparation of 0.82Bi 0.5 Na 0.5 TiO3-0.18Bi 0.5 K 0.5 TiO3 piezoelectric material.

[0104] Step S21: Weigh 11.65g of bismuth trioxide, 1.08g of sodium carbonate, 0.31g of potassium carbonate and 3.99g of titanium dioxide raw materials according to the stoichiometric ratio of Bi:Na:K:Ti 5:4.1:0.9:10, and ball mill for 12h (ball-to-material ratio of 3:1, anhydrous ethanol as medium) to obtain a uniformly mixed slurry.

[0105] Step S22: Dry the slurry thoroughly.

[0106] Step S23: Sinter in a box-type resistance furnace at 1110℃ for 2 hours. After cooling, grind the product thoroughly and pass it through a 200-mesh sieve to obtain piezoelectric powder material.

[0107] Step S3: Preparation of magnetoelectric composite powder. Weigh 2.5g of magnetostrictive powder and 2.5g of piezoelectric powder respectively, pour them into a ball mill jar and ball mill for 12h (the ball-to-powder ratio is 3:1, and anhydrous ethanol is used as the medium). Take out the slurry and dry it to obtain magnetoelectric composite powder.

[0108] Step S4: Prepare layered magnetoelectric composite material.

[0109] This process includes the following steps performed sequentially:

[0110] Step S41: Weigh 1.23g of the 0.82Bi obtained in step S2. 0.5 Na 0.5 TiO3-0.18Bi 0.5 K 0.5 TiO3 powder.

[0111] Step S42: Add 0.02g of polyvinyl alcohol, mix well, fill into a stainless steel mold, and form a piezoelectric preform under a pressure of 60MPa.

[0112] Step S43: Weigh 0.45g of the magnetoelectric composite powder obtained in step S3.

[0113] Step S44: Add 0.009g of polyvinyl alcohol, stir evenly, and pour it onto the piezoelectric preform layer from step S42. Press it into a composite preform layer using a pressure of 60MPa.

[0114] Step S45: Weigh 2.66g of the magnetostrictive material powder obtained in step S1, add 0.024g of polyvinyl alcohol, mix evenly, fill into a stainless steel mold, and form a preform under a pressure of 80MPa.

[0115] Step S46: Remove the preform and place it in a box-type resistance furnace. Keep it at 550℃ for 30 minutes to remove the glue. Then perform microwave sintering at 1120℃ for 20 minutes. Cool to obtain the layered magnetoelectric composite material.

[0116] In this embodiment, the performance parameters of the layered magnetoelectric composite material are shown in the table below:

[0117]

[0118] As attached Figure 8 As shown, the layered magnetoelectric composite material in this embodiment has a high magnetoelectric voltage coefficient, with a maximum magnetoelectric voltage coefficient as high as 63.12 mV / cm·Oe, which can realize efficient conversion of magnetic and electrical energy. The interfacial coupling coefficient of the composite material is 0.66, which is higher than that of the double-layer magnetoelectric composite material prepared by bonding (generally between 0.2 and 0.4) or the layered magnetoelectric composite material prepared by direct high-temperature sintering (generally between 0.3 and 0.5), showing good interfacial coupling effect.

[0119] In summary, the composite material obtained through this scheme introduces a piezoelectric and magnetostrictive composite transition layer between the piezoelectric layer with a high piezoelectric coefficient and the magnetostrictive layer with a high magnetostrictive coefficient. This effectively connects the two-phase interface, avoids microstructural defects formed at the interface due to direct high-temperature sintering, increases the interlayer bonding force between the piezoelectric layer and the magnetostrictive layer, and strengthens the interfacial stress transmission. The resulting magnetoelectric layered composite material has a tight interfacial bond with no obvious microstructural defects such as cracks or pores. The enhanced interfacial stress coupling is conducive to generating a strong magnetoelectric coupling response and obtaining a high magnetoelectric coupling coefficient.

[0120] Finally, it is necessary to state that the above embodiments are only used to further illustrate the technical solution of the present invention in detail, and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A layered magnetoelectric composite material, characterized in that, It includes three layers arranged sequentially: the first layer is Bi. 0.5 Na 0.5 TiO3-based piezoelectric material layer, second layer is Bi 0.5 Na 0.5 The TiO3-based piezoelectric material and ferrite magnetostrictive material composite layer, the third layer is a ferrite magnetostrictive material layer, and the layer thickness ratio of the first, second and third layers is 3:1:6 to 3:1:

8. The piezoelectric material is Bi. 0.5 K 0.5 TiO3 modified Bi 0.5 Na 0.5 The ferroelectric solid solution of TiO3 with the molecular formula (1-x)Bi 0.5 Na 0.5 TiO3-xBi 0.5 K 0.5 For TiO3, the value of x ranges from 0.18 to 0.

2. Second layer Bi 0.5 Na 0.5 The volume fraction ratio of piezoelectric material to magnetostrictive material in the TiO3-based piezoelectric material and ferrite magnetostrictive material composite layer is 1:

1. The ferrite magnetostrictive material in the second and third layers has a spinel structure (Co). 0.2 Ni 0.2 Cu 0.2 Zn 0.2 Mg 0.2 Fe2O4, (Co) 0.2 Ni 0.2 Mn 0.2 Zn 0.2 Mg 0.2 One of Fe2O4.

2. A method for preparing the layered magnetoelectric composite material according to claim 1, characterized in that: Includes the following steps: Step S1: Preparation of ferrite magnetostrictive powder: Add metal nitrate to water and complexing agent, mix and adjust pH value, heat and stir to obtain ferrite sol; dry the sol and burn it completely, then sinter and ball mill to obtain magnetostrictive material; Step S2: Preparation of piezoelectric phase powder: Weigh and mix the oxide or carbon oxide raw materials, ball mill and mix, sinter and crush to obtain piezoelectric phase material; Step S3: Preparation of magnetoelectric composite powder: The magnetostrictive material prepared in step S1 and the piezoelectric phase powder prepared in step S2 are thoroughly mixed in a set ratio and dried to obtain composite powder; Step S4: Preparation of layered magnetoelectric composite material: Add binder to a set weight of piezoelectric phase powder, mix evenly, and press into a preform to obtain a piezoelectric phase preform layer; add binder to a set weight of the composite powder, stir evenly, pour onto the piezoelectric phase preform layer, and press into a composite layer; add binder to a set weight of ferrite magnetostrictive powder, stir evenly, invert onto the composite layer, and press into a preform; heat to remove the binder, perform microwave sintering, and cool to obtain the layered magnetoelectric composite material.

3. The preparation method according to claim 2, characterized in that: In step S1, multiple metal nitrates are dissolved in deionized water and a complexing agent is added. The multiple metal nitrates are two or more of the following: nickel nitrate hexahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, copper nitrate trihydrate, magnesium nitrate hexahydrate, manganese nitrate tetrahydrate, and ferric nitrate nonahydrate.

4. The preparation method according to claim 2, characterized in that: In step S1, the temperature for drying the sol is 140–160°C, and the drying time is 3–5 h; the sintering temperature is 1210–1250°C, and the sintering time is 4–6 h.

5. The preparation method according to claim 2, characterized in that: In step S2, the sintering temperature is 1100-1150℃ and the sintering time is 1-2 hours.

6. The preparation method according to claim 2, characterized in that: In step S4, the binder is polyvinyl alcohol; the pressure for pressing the preform is 60-80 MPa; the temperature for heating and removing the adhesive is 500-650°C, and the heating and removing time is 20-45 min; the temperature for microwave sintering is 1070-1120°C, and the sintering time is 20-30 min.

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