High-stability piezoelectric nano material for lithium tantalate wafer and preparation method of high-stability piezoelectric nano material

Abstract

The invention discloses a high-stability piezoelectric nano material for a lithium tantalate wafer and a preparation method of the high-stability piezoelectric nano material, and belongs to the technical field of modified nano materials. The nano material is prepared by taking a lithium tantalate nano matrix as a core and combining a rare earth doping agent, silicon carbide nano fibers, graphene quantum dots, a SiO2-Al2O3 ceramic layer and an organic silicon modifier through a multi-layer structure design and a fine process. The preparation method comprises the steps of core layer synthesis, middle layer preparation, outer layer coating and stepped sintering, and the uniformity and stability of the material structure are ensured. The innovation points are that rare earth doping optimizes the lattice structure and improves the piezoelectric property; the mechanical strength and the electrical conductivity are enhanced through nanometer compounding; and the ceramic layer provides high-temperature-resistant and corrosion-resistant protection. The obtained material shows excellent piezoelectric property and structural stability in extreme environments such as high temperature, moisture and corrosion, and is suitable for high-performance application of lithium tantalate wafers in the fields of aerospace, deep sea exploration and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of modified nanomaterials, and in particular relates to a high-stability piezoelectric nanomaterial for lithium tantalate wafers and a preparation method thereof. Background Art

[0002] As one of the core materials in modern science and technology, piezoelectric materials play an irreplaceable role in the fields of sensors, actuators, energy converters and ultrasonic equipment. Its core characteristic is the ability to convert mechanical energy into electrical energy. This unique physical property gives it broad application prospects in the fields of industry, medical care and consumer electronics. With the rapid development of nanotechnology, piezoelectric nanomaterials have gradually become a research hotspot due to their special size effect and high performance. Compared with traditional bulk materials, nanoscale piezoelectric materials can significantly improve the response speed, sensitivity and energy conversion efficiency. However, the preparation and performance optimization of nanomaterials still face many challenges, especially in terms of high stability, durability and environmental adaptability.

[0003] Lithium tantalate is an important piezoelectric material that has attracted much attention due to its high Curie temperature (above about 600°C), excellent piezoelectric properties and chemical stability. Compared with other common piezoelectric materials such as quartz or lead zirconate titanate, lithium tantalate shows significant advantages in high-temperature and high-frequency applications, such as its widespread use in surface acoustic wave devices and optical components. However, with the complexity of application scenarios, such as extreme environments such as aerospace and deep-sea exploration, higher requirements are placed on the performance of piezoelectric materials. Traditional lithium tantalate wafers may experience performance degradation under high temperature, humidity or strong corrosive conditions, such as reduced piezoelectric coefficient or decreased structural stability, which limits their application in harsh environments. Therefore, the development of a high-stability piezoelectric nanomaterial for lithium tantalate wafers and its preparation method is not only of great scientific significance, but also of practical value in promoting the advancement of related technologies.

[0004] In the prior art, the preparation of lithium tantalate wafers mainly relies on traditional crystal growth methods, such as the Chai method and the Bridgman method. These methods can grow high-quality lithium tantalate single crystals by precisely controlling the melt temperature and the crystal pulling rate, meeting the needs of most conventional applications. For example, the Chai method prepares crystals with low defect density and high purity by slowly pulling out single crystals after melting the raw materials. However, these traditional methods have some inherent defects: the Chai method and the Bridgman method require complex equipment and high-purity raw materials, the growth process takes a long time (usually several days to several weeks), and the energy consumption is high, resulting in high production costs. The wafers prepared by traditional methods are mostly micron- or millimeter-level thicknesses, and nanoscale structures cannot be directly formed, which limits their application in the field of nanotechnology. Traditional lithium tantalate wafers are prone to oxidation, corrosion, or increased lattice defects under high temperatures or harsh environments, resulting in a decrease in piezoelectric properties and mechanical strength.

[0005] In order to overcome these problems, researchers have begun to explore the introduction of nanotechnology into the preparation and optimization of piezoelectric materials in recent years. Nanomaterials can significantly improve the physical and chemical properties of materials due to their high specific surface area and quantum size effect. For example, the introduction of nanoparticles, nanowires or nanofilm structures can improve the sensitivity and response speed of piezoelectric materials while reducing the amount of materials used. However, the preparation and stability control of nanomaterials is still a technical difficulty. Especially for lithium tantalate, how to achieve the stability of the nanostructure while maintaining its excellent piezoelectric properties is the focus and difficulty of current research. In the prior art, there are some methods that have attempted to improve the performance of piezoelectric nanomaterials. For example, lithium tantalate nanoparticles or films are prepared by chemical vapor deposition or sol-gel method, which can achieve the control of nanostructure to a certain extent. Studies have shown that after reducing the particle size to the nanoscale, the piezoelectric response and thermal conductivity of lithium tantalate are improved. However, the nanomaterials prepared by these methods are prone to agglomeration or oxidation in high temperature or humid environments, resulting in unstable performance. In addition, the morphology and size control of the nanostructure have a significant impact on the final performance. For example, nanoparticles with too small a particle size are prone to agglomeration due to their high surface energy, while uneven size may lead to local stress concentration and reduce the durability of the material.

[0006] In response to these problems, it is particularly urgent to develop a high-stability piezoelectric nanomaterial and its preparation method specifically for lithium tantalate wafers. The key is to achieve precise control of the nanostructure through innovative preparation processes, while improving the stability and durability of the material in extreme environments. For example, the size and morphology of nanoparticles can be regulated by optimizing synthesis conditions (such as reaction temperature, pressure, and precursor ratio); the uniformity and stability of nanomaterials in the matrix can be improved by introducing new dispersion technologies or composite structures. These improvements can not only improve the piezoelectric properties of lithium tantalate wafers, but also provide new possibilities for their application in aerospace, deep-sea exploration and other fields. Summary of the invention

[0007] Problem to be solved

[0008] To solve the above problems, the present invention adopts the following technical solution. This technical solution aims to develop a high-stability piezoelectric nanomaterial for lithium tantalate wafers and a preparation method thereof, and overcome the shortcomings of traditional lithium tantalate materials in performance degradation under extreme environments through innovative material design and process optimization, improve their piezoelectric performance and durability, and provide a reliable solution for high-performance applications.

[0009] Technical Solution

[0010] To solve the above problems, the present invention adopts the following technical solutions.

[0011] A high-stability piezoelectric nanomaterial for lithium tantalate wafers, comprising the following components by weight: lithium tantalate nanomatrix: 85-92wt%; rare earth dopant: rare earth element Nd 3+ With Er 3+ The total doping amount of the nitrate complex is 0.5-1.2wt%; silicon carbide nanofibers: diameter 10-30nm, length 1-5μm, accounting for 5-8wt%, uniformly dispersed in the lithium tantalate nanomatrix; graphene quantum dots: accounting for 0.3-0.8wt%; SiO 2 -Al 2 O 3 The ceramic layer has a thickness of 3-8nm and is coated on the surface of lithium tantalate nanoparticles; the organic silicon modifier is γ-aminopropyltriethoxysilane (CAS No. 919-30-2), accounting for 1.5-2.5wt%; the piezoelectric nanomaterial includes the following structure: core layer: lithium tantalate nanomatrix, the lattice constant c-axis direction is 13.85-13.92Å; middle layer: rare earth doped lithium tantalate nanomatrix, the lattice distortion rate is ≤1.2%; outer layer: SiO 2 -Al 2 O 3 Ceramic layer, the dielectric constant ε_r is 4.5-5.8 under 1kHz conditions.

[0012] Preferably, the rare earth dopant Nd 3+ With Er 3+ The molar ratio is 1:1-3.

[0013] Preferably, the lithium tantalate nanomatrix is ​​lithium tantalate nanoparticles with a particle size of 20-50 nm.

[0014] Preferably, the doping position of the rare earth dopant is Ta in the lithium tantalate lattice. 5+ Location.

[0015] Preferably, the flake size of the graphene quantum dots is 2-8 nm, and the surface oxygen-containing functional group density is 3-8%.

[0016] Preferably, the SiO 2 -Al 2 O 3 SiO in ceramic layer 2 With Al 2 O 3 The molar ratio is 1:(0.2-0.5).

[0017] The method for preparing a high-stability piezoelectric nanomaterial for lithium tantalate wafers as described above comprises the following steps: (1) synthesis of a core layer: 2 CO 3 (CAS No. 554-13-2) and Ta2 O 5 (CAS No. 1314-61-0) as raw materials, mixed at a Li / Ta molar ratio of 1.05-1.1, using ethanol-glycerol binary solvent, wherein the volume ratio of ethanol to glycerol is 3:1, and treated at 180-220°C for 12-18h to prepare lithium tantalate nanomatrix. (2) Preparation of the intermediate layer: The lithium tantalate nanomatrix is ​​immersed in a volume ratio of 1: (2-4) Nd(NO 3 ) 3 (CAS No. 10045-95-1) and Er(NO 3 ) 3 (CAS No. 10031-51-3) rare earth dopant, ultrasonically disperse for 30-60min, calcine at 800-850℃ for 30min, heating rate 15-20℃ / min, then, disperse silicon carbide nanofibers and graphene quantum dots uniformly on the outer surface of lithium tantalate nanomatrix by ball milling; the ball-to-material ratio of ball milling is zirconium oxide ball: material = 10:1 (weight ratio). (3) Preparation of outer layer: After adding organic silicon modifier, stir and react at 60-80℃ for 3-5h, adopt atomic layer deposition method, use trimethylaluminum (CAS No. 75-24-1) and silane (CAS No. 7803-62-5) as precursors, the ratio between the two in the precursor is 1:0.8, and deposit Al on the outer surface of lithium tantalate nanomatrix in sequence. 2 O 3 Layer with SiO 2 (4) Step sintering: heat up to 600°C at a rate of 300°C / h and keep warm for 1h; then heat up to 1250-1300°C at a rate of 5°C / min and keep warm for 2-4h to obtain a densified wafer.

[0018] For the atomic layer deposition method mentioned above, the precursors and reaction systems are shown in Table 1 below.

[0019] Table 1

[0020]

[0021] Preferably, the rotation speed of the ball milling method is 300-500 rpm, and the time of the ball milling method is 2-4 hours.

[0022] Preferably, Al is deposited 2 O 3 When depositing SiO 2 When the layer is formed, the reaction temperature is 250-300°C and the reaction chamber pressure is 0.2-1.5 Torr.

[0023] Beneficial Effects

[0024] Significantly improved piezoelectric performance: Rare earth doping optimization: Through the precise doping of Nd³⁺ and Er³⁺, the lattice structure of lithium tantalate is optimized, the lattice distortion is reduced (distortion rate ≤ 1.2%), and the piezoelectric coefficient of the material (d 33 ). Compared with traditional lithium tantalate materials, the piezoelectric response of the present invention is stronger, and it can produce a larger charge output under the same stress, which is suitable for high-sensitivity sensors and actuators. Nanocomposite reinforcement: The introduction of silicon carbide nanofibers (diameter 10-30nm, length 1-5μm) enhances the mechanical strength of the material and effectively prevents the nanoparticles from breaking or deforming under stress. At the same time, the addition of graphene quantum dots (sheet size 2-8nm) improves conductivity and promotes rapid transmission and response of charges, thereby improving the overall piezoelectric conversion efficiency.

[0025] Excellent high temperature resistance: Ceramic layer protection: SiO 2 -Al 2 O 3 The ceramic layer (3-8nm thick) has excellent thermal stability and can effectively protect the internal lithium tantalate nanomatrix from oxidation and thermal decomposition in high temperature environments. Compared with traditional lithium tantalate wafers, the material of the present invention can still maintain stable piezoelectric properties and structural integrity at high temperatures, and is particularly suitable for high-temperature sensors and actuators in the aerospace field.

[0026] Excellent corrosion and moisture resistance: Corrosion resistance: SiO 2 -Al 2 O 3 The chemical inertness of the ceramic layer enables it to remain stable in corrosive environments such as strong acids and alkalis, significantly extending the service life of the material, making it particularly suitable for acoustic devices and sensors in deep-sea exploration. Moisture resistance: The use of an organic silicon modifier (γ-aminopropyltriethoxysilane) improves the hydrophobicity of the material, reduces the effect of moisture on piezoelectric properties, and ensures the stable operation of the material in a high humidity environment.

[0027] Excellent structural stability: Multi-level structural design: The present invention adopts a core layer (lithium tantalate nano-matrix), an intermediate layer (rare earth doped lithium tantalate nano-matrix and nano-composite material) and an outer layer (SiO 2 -Al 2 O 3 The collaborative design of the ceramic layer ensures the structural integrity and functional stability of the material under extreme conditions. Fine process control: Through advanced processes such as hydrothermal reaction, ultrasonic dispersion, ball milling, atomic layer deposition and step sintering, the uniformity and density of the material structure are achieved, effectively avoiding the common problems of agglomeration, defects and inhomogeneity in traditional preparation methods.

[0028] Wide application prospects: Aerospace: In extreme environments such as high temperature and high pressure, the material can maintain stable piezoelectric properties, and is suitable for key components such as high-temperature sensors, actuators and energy converters. Deep-sea exploration: Excellent corrosion resistance and moisture resistance enable it to work stably for a long time in deep-sea environments, and is suitable for acoustic devices, sensors and communication equipment. Other high-performance applications: such as ultrasonic equipment, precision measuring instruments, etc., can all benefit from the high sensitivity and high stability of the material of the present invention.

[0029] Economic benefits: Extended service life: The excellent stability and durability of the material in extreme environments significantly reduce the frequency of maintenance and replacement, and reduce long-term operating costs. Improved performance: The improved piezoelectric performance and response speed can achieve more precise control and higher energy conversion efficiency, providing a solid foundation for the performance improvement of related equipment and systems.

[0030] In summary, the present invention has successfully developed a high-stability piezoelectric nanomaterial through innovative material design and preparation technology, which significantly improved the performance and reliability of lithium tantalate wafers in extreme environments, and provided a reliable solution for high-performance applications in aerospace, deep-sea exploration and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a surface morphology image of the material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments.

[0033] Unless otherwise defined, the technical and scientific terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. In practical application, the weight parts referred to in the present invention can be set as the unit kilogram.

[0034] Example 1

[0035] This embodiment provides a specific preparation process of a lithium tantalate wafer high-stability piezoelectric nanomaterial, in which all component amounts are absolute values ​​and process parameters are clearly quantified. The raw material ratio is shown in Table 2.

[0036] Table 2

[0037]

[0038] The preparation steps are as follows: core layer synthesis, raw materials: Li 2 CO 3 423g、Ta 2 O 5577g (Li / Ta molar ratio 1.075); Solvent: 300mL ethanol + 100mL glycerol (volume ratio 3:1). Hydrothermal reaction: 200℃ constant temperature reaction for 15h to obtain LiTaO with a particle size of 30nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: Lithium tantalate nanomatrix is ​​impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3 Mixed solution (volume ratio 1:2), ultrasonic dispersion for 45min. Calcination: calcination at 825℃ for 30min, heating rate 18℃ / min. Composite dispersion: add silicon carbide nanofibers and graphene quantum dots, ball milling for 3h (speed 400rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 60℃ for 4h. ALD deposition: Al 2 O 3 Layer: 180℃, 0.5Torr, deposition 3nm; SiO 2 Layer: 275℃, 0.8Torr, deposition 2nm (total thickness 5nm). Step sintering: First stage: 300℃ / h heating to 600℃, keep warm for 1h; second stage: 5℃ / min heating to 1275℃, keep warm for 3h, obtain densified wafer.

[0039] The key parameter verification is shown in Table 3 below.

[0040] Table 3

[0041]

[0042] Example 2

[0043] This embodiment provides another precise preparation scheme for lithium tantalate wafer high stability piezoelectric nanomaterials, and all component amounts and process parameters are limited by absolute values. The raw material ratio is shown in Table 4.

[0044] Table 4

[0045]

[0046] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 398g、Ta 2 O 5 552g (Li / Ta molar ratio 1.08). Solvent: ethanol 270mL + propylene glycol 90mL (volume ratio 3:1). Hydrothermal reaction: constant temperature reaction at 210℃ for 14h to obtain LiTaO with a particle size of 45nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: Lithium tantalate nanomatrix is ​​impregnated with Nd(NO 3 )3 With Er(NO 3 ) 3 Mixed solution (volume ratio 1:3), ultrasonic dispersion for 60min. Calcination: calcination at 850℃ for 30min, heating rate 20℃ / min. Composite dispersion: add silicon carbide nanofibers and graphene quantum dots, ball milling for 4h (speed 500rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 70℃ for 5h. ALD deposition: Al 2 O 3 Layer: 220℃, 0.3Torr, deposition 2nm. SiO 2 Layer: 300℃, 1.2Torr, deposited 4nm (total thickness 6nm). Step sintering: First stage: 300℃ / h to 600℃, keep warm for 1h, second stage: 5℃ / min to 1300℃, keep warm for 2h, complete densification.

[0047] The key parameter verification is shown in Table 5 below.

[0048] Table 5

[0049]

[0050] Example 3

[0051] This embodiment provides a third precise preparation scheme for lithium tantalate wafer high-stability piezoelectric nanomaterials, all parameters are defined in absolute values, and are used to verify the boundary conditions of the patented technology. The raw material ratio is shown in Table 6.

[0052] Table 6

[0053]

[0054] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 435g, Ta 2 O 5 585g (Li / Ta molar ratio 1.09). Solvent: ethanol 315mL + propylene glycol 105mL (volume ratio 3:1). Hydrothermal reaction: 190℃ constant temperature reaction for 16h to obtain LiTaO with a particle size of 25nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: Lithium tantalate nanomatrix is ​​impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3Mixed solution (volume ratio 1:1.5), ultrasonic dispersion for 50min. Calcination: calcination at 800℃ for 30min, heating rate 15℃ / min. Composite dispersion: add silicon carbide nanofibers and graphene quantum dots, ball milling for 2h (speed 300rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 80℃ for 3h. ALD deposition: Al 2 O 3 Layer: 200℃, 0.8Torr, deposition 4nm. SiO 2 Layer: 260℃, 1.0Torr, deposition 3nm (total thickness 7nm). Step sintering: First stage: 300℃ / h to 600℃, keep warm for 1h. Second stage: 5℃ / min to 1250℃, keep warm for 4h to complete lattice densification.

[0055] The key parameter verification is shown in Table 7.

[0056] Table 7

[0057]

[0058] Example 4

[0059] This embodiment verifies the high performance boundary of the patented technology through extreme parameter combinations. All dosages and process parameters are clearly defined in absolute values, which is suitable for extreme corrosion and high temperature scenarios. The raw material ratio is shown in Table 8.

[0060] Table 8

[0061]

[0062] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 412g、Ta 2 O 3 568g (Li / Ta molar ratio 1.1). Solvent: 360mL ethanol + 120mL glycerol (volume ratio 3:1). Hydrothermal reaction: 220℃ constant temperature reaction for 18h (time limit), obtain LiTaO with a particle size of 40nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: The substrate is impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3Mixed solution (volume ratio 1:2.5), ultrasonic dispersion for 60min (time limit). Calcination: calcination at 850℃ for 30min (temperature limit), heating rate 20℃ / min. Composite dispersion: add silicon carbide fiber and graphene quantum dots, ball milling for 4h (speed 500rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stir reaction at 75℃ for 5h to form a dense hydrophobic layer. ALD deposition: Al 2 O 3 Layer: 210℃, 0.2Torr, deposition 5nm (Al 2 O 3 SiO 2 Layer: 300℃, 1.5Torr, deposition 3nm (total thickness 8nm, patent upper limit). Step sintering: First stage: 300℃ / h heating to 600℃, keep warm for 1h. Second stage: 5℃ / min heating to 1300℃ (temperature upper limit), keep warm for 4h (time upper limit).

[0063] The key parameter verification is shown in Table 9 below.

[0064] Table 9

[0065]

[0066] Example 5

[0067] This embodiment verifies the universality of the patented technology through a combination of differentiated parameters. All dosages and process parameters are limited to absolute values, focusing on optimizing conductivity and moisture and heat resistance, and is suitable for precision microelectronic devices. The raw material ratio is shown in Table 10.

[0068] Table 10

[0069]

[0070] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 417g、Ta 2 O 5 573g (Li / Ta molar ratio 1.06). Solvent: 330mL ethanol + 110mL glycerol (volume ratio 3:1). Hydrothermal reaction: 195℃ constant temperature reaction for 17h to obtain LiTaO with a particle size of 35nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: The substrate is impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3Mixed solution (volume ratio 1:2.2), ultrasonic dispersion for 55min. Calcination: calcination at 830℃ for 30min, heating rate 17℃ / min. Composite dispersion: add silicon carbide fiber and graphene quantum dots, ball milling for 3.5h (speed 450rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 65℃ for 4.5h to form a uniform hydrophobic interface. ALD deposition: Al 2 O 3 Layer: 195℃, 0.6Torr, deposition 3.5nm. SiO 2 Layer: 280℃, 1.0Torr, deposition 3.5nm (total thickness 7nm). Step sintering: First stage: 300℃ / h to 600℃, keep warm for 1h. Second stage: 5℃ / min to 1280℃, keep warm for 3h.

[0071] The key parameter verification is shown in Table 11 below.

[0072] Table 11

[0073]

[0074] Example 6

[0075] This embodiment is specially optimized for the needs of high-frequency piezoelectric devices. By precisely controlling the dielectric properties and nanostructure of the ceramic layer, all dosages and process parameters are limited by absolute values, and is suitable for the fields of 5G communications and terahertz sensors. The raw material ratio is shown in Table 12.

[0076] Table 12

[0077]

[0078] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 428g, Ta 2 O 5 582g (Li / Ta molar ratio 1.095). Solvent: 345mL ethanol + 115mL glycerol (volume ratio 3:1). Hydrothermal reaction: 205℃ constant temperature reaction for 13h to obtain LiTaO with a particle size of 22nm 3 Nanoparticles (ultrafine size optimizes high frequency response). Intermediate layer preparation, rare earth doping: the substrate is impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3Mixed solution (volume ratio 1:3.5), ultrasonic dispersion for 35min. Calcination: calcination at 805℃ for 30min, heating rate 16℃ / min. Composite dispersion: add silicon carbide fiber and graphene quantum dots, ball milling for 2.5h (speed 350rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 55℃ for 4.2h to form an ultra-thin hydrophobic interface. ALD deposition: Al 2 O 3 Layer: 190℃, 0.4Torr, deposition 2.5nm (low Al 2 O 3 proportion to reduce dielectric loss). SiO 2 Layer: 290℃, 1.3Torr, deposition 4.5nm (total thickness 7nm, dielectric constant gradient design). Step sintering: First stage: 300℃ / h heating to 600℃, keep warm for 1h. Second stage: 5℃ / min heating to 1260℃, keep warm for 3.5h.

[0079] The key parameter verification is shown in Table 13 below.

[0080] Table 13

[0081]

[0082] Example 7

[0083] This embodiment optimizes the material durability for dynamic fatigue environment, improves the cycle life by adjusting the reinforcement phase and sintering process, and all parameters are limited to absolute values, which is suitable for the field of vibration energy collection and Internet of Things sensors. The raw material ratio is shown in Table 14.

[0084] Table 14

[0085]

[0086] Preparation steps: core layer synthesis, raw materials: Li 2 CO 3 420g, Ta 2 O 5 580g (Li / Ta molar ratio 1.07). Solvent: 342mL ethanol + 114mL glycerol (volume ratio 3:1). Hydrothermal reaction: 215℃ constant temperature reaction for 12h to obtain high crystallinity LiTaO with a particle size of 38nm 3 Nanoparticles. Intermediate layer preparation, rare earth doping: The substrate is impregnated with Nd(NO 3 ) 3 With Er(NO 3 ) 3Mixed solution (volume ratio 1:2.8), ultrasonic dispersion for 40 minutes. Calcination: calcination at 840℃ for 30 minutes, heating rate 19℃ / min. Composite dispersion: add silicon carbide fiber and graphene quantum dots, ball milling for 3.2 hours (speed 420rpm, zirconium oxide ball: material = 10:1). Outer layer coating, silicone modification: stirring reaction at 68℃ for 4.8 hours to form a high-toughness interface layer. ALD deposition: Al 2 O 3 Layer: 205℃, 0.7Torr, deposition 3.8nm. SiO 2 Layer: 285℃, 0.9Torr, deposition 4.2nm (total thickness 8nm, patent upper limit). Step sintering: First stage: 300℃ / h heating to 600℃, keep warm for 1h. Second stage: 5℃ / min heating to 1290℃, keep warm for 3.8h (optimize grain boundary fatigue resistance).

[0087] The key parameter verification is shown in Table 15 below.

[0088] Table 15

[0089]

[0090] Through the systematic verification of 7 examples, the technology has achieved a 40-53% increase in piezoelectric coefficient, and has shown excellent stability under extreme conditions such as high temperature (650°C), strong corrosion (pH=1) and high frequency (18.5GHz), providing a material basis for high-end applications such as aerospace sensors and 5G communication devices. In addition, taking Example 1 as an example, its surface morphology is as follows Figure 1 As shown, the surface appears relatively smooth.

[0091] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the field of modified nanomaterial technology to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted by the present invention.

Claims

1. A high-stability piezoelectric nanomaterial for lithium tantalate wafers, characterized in that: The following components are included by weight: lithium tantalate nanomatrix: 85-92wt%; rare earth dopant: rare earth element Nd 3+ With Er 3+ The nitrate complex has a total doping amount of 0.5-1.2wt%; silicon carbide nanofibers: diameter 10-30nm, length 1-5μm, accounting for 5-8wt%, uniformly dispersed in the lithium tantalate nanomatrix; graphene quantum dots: accounting for 0.3-0.8wt%; SiO2-Al2O3 ceramic layer, thickness 3-8nm, coated on the surface of lithium tantalate nanoparticles; organic silicon modifier: γ-aminopropyltriethoxysilane, accounting for 1.5-2.5wt%; the piezoelectric nanomaterial includes the following structure: core layer: lithium tantalate nanomatrix, lattice constant c-axis direction is 13.85-13.92Å; Middle layer: rare earth doped lithium tantalate nano-matrix, lattice distortion rate ≤1.2%; outer layer: SiO2-Al2O3 ceramic layer, dielectric constant ε_r is 4.5-5.8 under 1kHz conditions.

2. The high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 1, characterized in that: The rare earth dopant Nd 3+ With Er 3+ The molar ratio is 1:1-3.

3. The high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 2, characterized in that: The lithium tantalate nano matrix is ​​lithium tantalate nano particles with a particle size of 20-50nm.

4. The high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 1, characterized in that: The doping position of the rare earth dopant is Ta in the lithium tantalate lattice. 5+ Location.

5. The high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 1, characterized in that: The flake size of the graphene quantum dots is 2-8nm, and the surface oxygen-containing functional group density is 3-8%.

6. The high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 1, characterized in that: The molar ratio of SiO2 to Al2O3 in the SiO2-Al2O3 ceramic layer is 1:(0.2-0.5).

7. The method for preparing a high-stability piezoelectric nanomaterial for lithium tantalate wafers according to claim 1, characterized in that: The following steps are involved: (1) Synthesis of the core layer: Li2CO3 and Ta2O5 are used as raw materials, mixed at a Li / Ta molar ratio of 1.05-1.1, and ethanol-glycerol binary solvent is used, wherein the volume ratio of ethanol to glycerol is 3:

1. The lithium tantalate nanomatrix is ​​prepared by hydrothermal reaction at 180-220°C for 12-18h; (2) Preparation of the intermediate layer: The lithium tantalate nanomatrix is ​​impregnated with a rare earth dopant of Nd(NO3)3 and Er(NO3)3 in a volume ratio of 1:(2-4), ultrasonically dispersed for 30-60min, and calcined at 800-850°C for 30min, with a heating rate of 15 -20℃ / min, then, the silicon carbide nanofibers and graphene quantum dots are evenly dispersed on the outer surface of the lithium tantalate nanomatrix by ball milling; (3) Preparation of the outer layer: Add an organic silicon modifier, stir and react at 60-80℃ for 3-5h, and use the atomic layer deposition method to use trimethylaluminum and silane as precursors to deposit Al2O3 layer and SiO2 layer on the outer surface of the lithium tantalate nanomatrix in sequence; (4) Step sintering: heat up to 600℃ at a rate of 300℃ / h and keep warm for 1h; then heat up to 1250-1300℃ at 5℃ / min and keep warm for 2-4h to obtain a densified wafer.

8. The method for preparing a high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 7, characterized in that: The rotation speed of the ball milling method is 300-500 rpm, and the time of the ball milling method is 2-4 hours.

9. The method for preparing a high-stability piezoelectric nanomaterial for lithium tantalate wafer according to claim 8, characterized in that: When depositing the Al2O3 layer, the reaction temperature is 180-220°C and the reaction chamber pressure is 0.1-1.0 Torr; when depositing the SiO2 layer, the reaction temperature is 250-300°C and the reaction chamber pressure is 0.2-1.5 Torr.

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