Three-dimensional ferroelectric material based on double-layer interlocking ice stack and preparation and application thereof

Abstract

The application discloses a kind of three-dimensional ferroelectric material based on double-layer interlocking ice stack and its preparation and application, belong to ferroelectric material and low-dimensional material stacking technical field.The material is the three-dimensional periodic crystal structure of double-layer interlocking two-dimensional ice by van der Waals force stacking, belongs to triclinic system, space group P1.The material has completely saturated hydrogen bond network, in-plane by hydrogen bond contributes stable ferroelectric sequence, interlayer is coupled by van der Waals force and forms cooperative ferroelectric, for the first time realizes the breakthrough of pure water-based three-dimensional ferroelectric material.It has high crystalline quality, wide band gap semiconductor characteristics, excellent thermal stability and significant mechanical anisotropy.The material can be widely used in ferroelectric memory, deep ultraviolet photodetector, stress sensor, flexible electronic device, acoustic filter and polar scientific research equipment fields, with environmental friendly, simple structure, performance adjustable and other outstanding advantages.

Description

Technical Field

[0001] This invention belongs to the technical field of ferroelectric materials, low-dimensional material stacks and multifunctional devices, specifically relating to a three-dimensional ferroelectric material composed of double-layer interlocking two-dimensional ice stacks, and its electrical, optical and mechanical properties and applications. Background Technology

[0002] Three-dimensional ferroelectric materials are the core foundation for functional devices such as ferroelectric memories, piezoelectric sensors, and nonlinear optical devices. For a long time, research in this field has mainly focused on oxide perovskite material systems, such as barium titanate (BaTiO3) and lead zirconate titanate (PZT). However, these traditional three-dimensional ferroelectric materials have the following inherent drawbacks: First, the composition is complex and the preparation conditions are demanding. Oxide perovskites are mostly multi-metal oxides, usually containing heavy metal elements such as lead and bismuth. This not only results in high raw material costs but also poses potential threats to the environment and human health. Their preparation process often requires high-temperature (>600℃) sintering or physical / chemical vapor deposition, which is energy-intensive and complex. Furthermore, their incompatibility with flexible substrates and semiconductor back-end processes is poor, limiting their application in thinner, more flexible, and integrated devices.

[0003] Second, the crystal structure is complex, and the ferroelectric origin is singular. The ferroelectricity of traditional three-dimensional ferroelectric materials originates from specific lattice distortions (such as B-site ion shifts) or geometric frustration. Once the crystal structure is destroyed, the ferroelectric order disappears. This strong "structure-function" coupling characteristic results in low design freedom for materials, making it difficult to achieve on-demand performance control through simple interlayer engineering or interface modification.

[0004] In recent years, the rise of two-dimensional ferroelectric materials has provided a novel approach for ultrathin ferroelectric devices. However, when attempting to stack two-dimensional ferroelectric materials into three-dimensional bulk materials to obtain macroscopic responses, new problems arise: Third, weak interlayer coupling makes it difficult to form synergistic ferroelectricity. The layers of two-dimensional materials are typically bound by van der Waals forces, with interaction energies far lower than intralayer covalent or ionic bonds. During stacking, interlayer polarization directions are often randomly distributed or cancel each other out, leading to a significant decrease or even disappearance of macroscopic polarization intensity. It is generally believed in academia that stacked two-dimensional materials cannot inherit the ferroelectricity of a single layer, and achieving a multi-level ferroelectric order of "intralayer ferroelectricity + interlayer synergy" remains an unsolved problem.

[0005] Fourth, there is a complete lack of pure water-based three-dimensional ferroelectric materials. Water is one of the most abundant substances on Earth. Ice, as the solid form of water, has an intrinsically polar hydrogen bond network. However, due to the weak directionality and dynamic reconstruction characteristics of hydrogen bonds, pure ice has long been considered to lack stable macroscopic ferroelectricity. To date, no three-dimensional ferroelectric materials based on pure water or ice have been experimentally or theoretically verified. Pure water-based ferroelectrics remain a long-sought-after but unresolved area in materials science.

[0006] In summary, existing three-dimensional ferroelectric materials suffer from problems such as complex composition, heavy metal content, difficult preparation, and limited ferroelectric origin; two-dimensional ferroelectric material stacks face the challenge of weak interlayer coupling and easy polarization cancellation; and pure water-based three-dimensional ferroelectric materials are completely undeveloped. To address all these shortcomings, this invention provides, for the first time, a three-dimensional ferroelectric material composed of a double-layered interlocking two-dimensional ice stack. Its in-plane structure is supported by a stable ferroelectric ordering network, while the interlayer structure forms synergistic ferroelectricity through van der Waals forces. This represents a breakthrough in pure water-based three-dimensional ferroelectric materials and opens up a new direction for environmentally friendly, structurally simple, and performance-tunable novel ferroelectric material systems. Summary of the Invention

[0007] I. Technical problems to be solved This invention aims to overcome the shortcomings of existing three-dimensional ferroelectric materials, such as complex composition, difficult preparation, and weak interlayer ferroelectric coupling after stacking two-dimensional materials. It provides a three-dimensional ferroelectric material based on double-layer interlocked two-dimensional ice stacks, which realizes multi-level synergy between in-plane hydrogen bond ferroelectricity and interlayer van der Waals ferroelectricity. Technical solution

[0008] 2.1 Crystal Structure of Three-Dimensional Materials The three-dimensional material has a three-dimensional periodic crystal structure, belonging to the triclinic crystal system, space group P1, and its unit cell parameters range as follows: a = 4.624485 ± 0.05 Å, b = 4.641236 ± 0.05 Å, c = 5.982366 ± 0.05 Å; α = 107.07466 ± 0.5°, β = 90.93043 ± 0.5°, γ = 61.78182 ± 0.5°. The unit cell contains four independent water molecules, with atomic fraction coordinates ranging from: O1 (0.61017 ± 0.01, 0.34154 ± 0.01, 0.33309 ± 0.01), H1 (0.73982 ± 0.01, 0.11790 ± 0.01, 0.36264 ± 0.01), H2 (0.74554 ± 0.01, 0.45985 ± 0.01, 0.35681 ± 0.01); O2 (0.95564 ± 0.01, 0.66753 ± 0.01, 0.30957 ± 0.01), H3 (0.98932 ± 0.01, 0.58412 ± 0.01). 0.01, 0.13350 ± 0.01), H4 (0.18478 ± 0.01, 0.56373 ± 0.01, 0.34914 ± 0.01); Oxygen atom O3 (0.04297 ± 0.01, 0.42649 ± 0.01, 0.82241 ± 0.01), Hydrogen atom H5 (0.93921 ± 0.01, 0.27706 ± 0.01, 0.80289 ± 0.01), H6 (0.28778 ± 0.01, 0.27746 ± 0.01, 0.79695 ± 0.01); Oxygen atom O4 (0.70088 ± 0.01, 0.09817 ± 0.01). 0.01, 0.84935 ± 0.01), hydrogen atom H7 (0.82819 ± 0.01, 0.84300 ± 0.01, 0.80900 ± 0.01), H8 (0.66598 ± 0.01, 0.18368 ± 0.01, 0.02569 ± 0.01).The intramolecular O–H bond lengths range as follows: O1–H1 = 0.992 ± 0.05 Å, O1–H2 = 0.995 ± 0.05 Å, O2–H3 = 0.996 ± 0.05 Å, O2–H4 = 0.994 ± 0.05 Å, O3–H5 = 0.995 ± 0.05 Å, O3–H6 = 0.993 ± 0.05 Å, O4–H7 = 0.992 ± 0.05 Å, O4–H8 = 0.998 ± 0.05 Å. In this structure, oxygen atoms form a three-dimensional network, and water molecules are connected by hydrogen bonds to form a fully saturated hydrogen bond network. Each water molecule acts as both a hydrogen bond donor and acceptor twice. The hydrogen bond length ranges from 1.8 to 2.0 Å, and the bond angle ranges from 160 to 180°. There are no suspended hydrogen atoms. The bilayer interlocked two-dimensional ice acts as a basic unit, and the two molecules are coupled to each other through van der Waals forces to form a three-dimensional long-range ferroelectric order.

[0009] 2.2 Preparation method A theoretical preparation path simulation method includes the following steps: (1) Substrate adsorption simulation: An adsorption model of the double-layer interlocked two-dimensional ice was constructed on the surface of an inert substrate (hexagonal boron nitride, graphene) to calculate the optimal adsorption configuration and adsorption energy; (2) Multi-layer stacking simulation: Independent double-layer interlocking ice layers are stacked according to a preset stacking method, structural relaxation is performed, and the optimal configuration is calculated; (3) Operational temperature range simulation: AIMD simulation was performed at temperatures of 80–260 K to form a three-dimensional periodic crystal structure that can be used under ordinary experimental conditions; (4) Peeling and independence simulation: Gradually weaken the substrate-ice layer interaction. When the binding energy is <10 meV / molecule, the ice layer can be independently self-supporting.

[0010] 2.3 Special Properties (1) High crystallinity and structural order: The material has a highly ordered triclinic crystal structure. Its X-ray diffraction pattern shows a series of sharp characteristic diffraction peaks with narrow half-maximum width and high signal-to-noise ratio, indicating that the material has excellent long-range order and crystallinity. This highly ordered structure is the basis for the stable performance of the material's various physical properties and also provides structural protection for subsequent device integration.

[0011] (2) Fully saturated hydrogen bond network and ordered polarization: Raman spectroscopy shows that the O–H stretching vibration region exhibits multiple split peaks, which is direct evidence that hydrogen atoms are in multiple non-equivalent crystallographic positions and that hydrogen bonds are fully saturated, indicating that there are no suspended hydrogen defects in the material and the hydrogen bond network is highly ordered. This structural feature provides a microscopic mechanism for the generation of ferroelectricity—the dipole moments of water molecules are coordinated along a specific direction to form stable macroscopic polarization.

[0012] (3) Wide bandgap semiconductor characteristics: Band structure and density of states calculations show that the material is a wide bandgap semiconductor with a moderate bandgap value. The valence band is mainly contributed by the 2p orbitals of oxygen, and the conduction band is mainly contributed by the 1s orbitals of hydrogen and the 2p antibonding states of oxygen. The band dispersion has significant anisotropy, which is consistent with the anisotropy of the crystal structure.

[0013] (4) Excellent dynamic stability: Phonon spectrum calculations show no imaginary frequencies across the entire frequency band. The small negative imaginary frequencies are due to the influence of the calculation method, indicating that the material is dynamically stable and can be considered an intrinsic crystal structure.

[0014] (5) Excellent thermal stability: Ab initio molecular dynamics simulations show that the material maintains its three-dimensional framework intact after 20 ps simulation at 260 K, with no signs of bond breakage, reconstruction or melting, and minimal energy fluctuations, indicating good temperature control. This proves that the material can operate stably in conventional low-temperature environments and near room temperature, and has a temperature window suitable for practical applications.

[0015] (6) Significant anisotropy: The material is triclinic and the off-diagonal elements of the elastic stiffness matrix are large, indicating that there is a significant tension-shear coupling effect; Young's modulus varies significantly in different directions, with the Z direction being the most rigid and the Y direction being the least rigid; Poisson's ratio shows direction dependence, indicating that the transverse deformation behavior is inconsistent in different directions.

[0016] (7) Bulk modulus and compressibility: The bulk modulus is in the medium to low range, indicating that the material has a certain compressibility and its volume is relatively easy to shrink under hydrostatic pressure.

[0017] (8) Shear modulus and hardness: The shear modulus is relatively low, and the material has a general resistance to shear deformation; the hardness is about 1.5 GPa, which is a soft material and is easy to process and form.

[0018] 2.4 Application (1) Based on its unique crystal structure fingerprint, it can be used as a standard reference material for the calibration of X-ray diffractometers and phase identification.

[0019] (2) The fully saturated hydrogen bond network endows the material with intrinsic ferroelectricity, which can be used for non-volatile ferroelectric memory, high-sensitivity sensor, proton conductive film, etc.

[0020] (3) Its wide bandgap characteristics make it suitable for deep ultraviolet optoelectronic devices, power electronic devices, etc.

[0021] (4) Its excellent thermal stability makes it suitable for polar scientific research equipment, deep space probe functional components, etc.

[0022] (5) Its low Young's modulus and toughness behavior make it suitable as a flexible substrate or encapsulation material that can be bent without breaking.

[0023] (6) The obvious anisotropy and off-diagonal elastic constants mean that there may be electromechanical coupling effects, making it suitable for piezoelectric devices or stress sensors.

[0024] (7) Anisotropic elastic wave velocity may be used in the design of acoustic waveguides, acoustic filters or phonon crystals.

[0025] (8) Its low shear modulus and moderate compressibility make it suitable for use as a mechanical buffer layer or shock absorber.

[0026] (9) Combining the previously described ferroelectric sequence and elastic anisotropy, it can be applied in ferroelectric memory (FeRAM) or ferroelastic memory to realize electro-mechanical coupling storage.

[0027] (10) Its anisotropy and orientation dependence can be used to design composite materials with directional mechanical properties, such as enhancing rigidity or flexibility in a specific direction. Beneficial effects

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) First realization of pure water-based three-dimensional ferroelectric materials This invention provides a three-dimensional ferroelectric material composed of double-layer interlocking two-dimensional ice stacks. Its crystal structure is entirely composed of water molecules and contains no heavy metal elements, filling the international gap in macroscopic ferroelectric materials based on pure water systems and opening up a new direction for environmentally friendly ferroelectric materials.

[0029] (2) Simple structure and mild preparation conditions The material is composed of only hydrogen and oxygen elements, with a single composition, and does not require high-temperature sintering or complex vapor deposition. Theoretical preparation path simulations show that it can exist stably in the temperature range of 80–260 K, and is highly compatible with flexible substrates and semiconductor back-end processes, significantly reducing preparation energy consumption and cost.

[0030] (3) Multi-level ferroelectric synergy to overcome interlayer polarization cancellation The in-plane hydrogen bond network endows each bilayer ice with intrinsic ferroelectric order, and the interlayer achieves consistent coupling of polarization direction through van der Waals forces, forming a three-dimensional long-range ferroelectric order of "intralayer ferroelectric + interlayer synergy", which effectively solves the problem of macroscopic polarization attenuation after stacking two-dimensional materials.

[0031] (4) Highly ordered crystal structure and perfect hydrogen bond network The triclinic P1 space group endows the material with long-range order, and the X-ray diffraction pattern shows sharp characteristic peaks with narrow full width at half maximum (FWHM), indicating excellent crystal quality. The hydrogen bond network is fully saturated (without suspended hydrogens), and all water molecules participate in hydrogen bonding as both donors and acceptors. The bond length is 1.8–2.0 Å and the bond angle is 160–180°, providing a structural basis for stable ferroelectricity.

[0032] (5) Wide bandgap semiconductor characteristics The band structure calculation shows that the material is a wide bandgap semiconductor with a moderate band gap. The conduction band bottom and valence band top are contributed by the 2p state of oxygen and the 1s / oxygen antibonding state of hydrogen, respectively. It exhibits band dispersion anisotropy and is suitable for deep ultraviolet optoelectronic devices and power electronic devices.

[0033] (6) Excellent stability The absence of imaginary frequencies across the entire phonon spectrum demonstrates the intrinsic stability of the material's dynamics. Ab initio molecular dynamics simulations show that the material maintains its structural integrity after a 20 ps simulation at 260 K, with no bond breakage or reconstruction. It can operate stably near conventional low temperatures and room temperature, providing a temperature window suitable for practical applications.

[0034] (7) Significant anisotropy in mechanical properties and strong machinability The off-diagonal elements of the elastic stiffness matrix are relatively large, and the Young's modulus is direction-dependent (15.12, 14.16, and 16.53 GPa in the X, Y, and Z directions, respectively). The Poisson's ratio also shows directional differences. The bulk modulus is moderately low (12.19 GPa), and the material has a certain degree of compressibility. The shear modulus is low, and the hardness is about 1.5 GPa, which falls into the category of soft materials and is easy to cut, bend, and shape.

[0035] (8) Rich multiphysics coupling characteristics The significant elastic anisotropy combined with ferroelectric order endows the material with potential piezoelectric, ferroelastic and electromechanical coupling effects, which can be used in stress sensors, acoustic waveguide devices and electro-mechanical coupled memories.

[0036] (9) Broad application prospects Used as a standard material for X-ray diffractometer calibration and phase identification; for non-volatile ferroelectric memories, high-sensitivity sensors and proton-conducting films; suitable for deep ultraviolet optoelectronic devices and power electronic devices; used as functional components in extreme environments such as polar scientific expeditions and deep space exploration; used as flexible substrates, mechanical buffer layers or shock-absorbing elements; used in the design of composite materials with directional mechanical properties.

[0037] In summary, this invention overcomes the shortcomings of traditional three-dimensional ferroelectric materials, such as complex composition, heavy metal content, difficult preparation, and weak interlayer coupling in two-dimensional stacks. It provides a novel pure water-based three-dimensional ferroelectric material with simple structure, environmental friendliness, and adjustable performance, which has important application value in the fields of electronic information, energy, sensing, and aerospace. Attached Figure Description

[0038] Figure 1 Atomic structure model of a three-dimensional ferroelectric material. (A) Front view of the crystal, showing interlayer spacing and hydrogen bond network; (B) Top view of the crystal, showing hydrogen bond network and ferroelectric orientation; (C) Left view of the crystal, showing interlayer spacing and hydrogen bond network; (D) Left view of the unit cell; (E) Front view of the unit cell; (F) Top view of the unit cell; (G) Lattice parameter table.

[0039] Figure 2 X-ray diffraction theoretical spectrum of three-dimensional ferroelectric materials.

[0040] Figure 3 Theoretical Raman spectra of three-dimensional ferroelectric materials.

[0041] Figure 4 : Band structure data of three-dimensional ferroelectric materials.

[0042] Figure 5 : Density of states data for three-dimensional ferroelectric materials.

[0043] Figure 6 Phonon vibrational spectrum data of three-dimensional ferroelectric materials.

[0044] Figure 7 Ab initio molecular dynamics data for three-dimensional ferroelectric materials. (A) Structural evolution diagram of three-dimensional ferroelectric materials, temperature 260 K, with structural selection time points of 0, 1, 5, 10, 15, and 20 ps; (B) Motion constant variation diagram, temperature 260 K, time 0-20 ps; (C) Temperature variation diagram, time 0-20 ps. Detailed Implementation

[0045] Example 1: Structural Verification of Three-Dimensional Ferroelectric Materials Based on Double-Layer Interlocking Ice Stacks The first-principles calculation software CASTEP, based on density functional theory, was used. The functional was PBE+DFT-D3, the plane wave cutoff energy was 750 eV, the k-point grid density was 6×6×4, the pseudopotential was a mode-conserving pseudopotential, the relativistic treatment was Koelling-Harmon, the energy tolerance was 1.0e-5 eV / atom, the maximum force tolerance was 0.03 eV / Å, the maximum stress tolerance was 0.05 GPa, the maximum displacement tolerance was 0.001 Å, the maximum number of iterations was 400, the cell optimization mode was Full, and the fixed basis mass was used in the variable cell calculation. The initial structure was constructed with a = 4.624485 ± 0.05 Å, b = 4.641236 ± 0.05 Å, c = 5.982366 ± 0.05 Å; α = 107.07466 ± 0.5°, β = 90.93043 ± 0.5°, and γ = 61.78182 ± 0.5°.The unit cell contains four independent water molecules, with atomic fraction coordinates ranging from: O1 (0.61017 ± 0.01, 0.34154 ± 0.01, 0.33309 ± 0.01), H1 (0.73982 ± 0.01, 0.11790 ± 0.01, 0.36264 ± 0.01), H2 (0.74554 ± 0.01, 0.45985 ± 0.01, 0.35681 ± 0.01); O2 (0.95564 ± 0.01, 0.66753 ± 0.01, 0.30957 ± 0.01), H3 (0.98932 ± 0.01, 0.58412 ± 0.01). 0.01, 0.13350 ± 0.01), H4 (0.18478 ± 0.01, 0.56373 ± 0.01, 0.34914 ± 0.01); Oxygen atom O3 (0.04297 ± 0.01, 0.42649 ± 0.01, 0.82241 ± 0.01), Hydrogen atom H5 (0.93921 ± 0.01, 0.27706 ± 0.01, 0.80289 ± 0.01), H6 (0.28778 ± 0.01, 0.27746 ± 0.01, 0.79695 ± 0.01); Oxygen atom O4 (0.70088 ± 0.01, 0.09817 ± 0.01). 0.01, 0.84935 ± 0.01), hydrogen atoms H7 (0.82819 ± 0.01, 0.84300 ± 0.01, 0.80900 ± 0.01), H8 (0.66598 ± 0.01, 0.18368 ± 0.01, 0.02569 ± 0.01), as detailed in the attached instruction manual. Figure 1 As shown. After structural optimization, XRD was performed (…). Figure 2 Raman spectroscopy Figure 3 ), energy band ( Figure 4 ), density of states ( Figure 5 ), phonon spectrum ( Figure 6 AIMD Figure 7 The elastic constants were calculated. The calculation results show no imaginary frequencies across the entire frequency band. AIMD simulation was performed at 260 K using an NVT ensemble for a total duration of 20 ps, ​​and the structure remained intact. The elastic constants of the three-dimensional stacked ferroelectric ice material were calculated, and its elastic stiffness constant matrix Cij (GPa) is shown below: 29.71880 17.93742 3.08882 -5.02493 4.02987 2.08490 17.93742 27.27040 2.61510 -6.41973 2.15187 -0.12158 3.08882 2.61510 18.00565 1.80632 -0.11610 0.13855 -5.02493 -6.41973 1.80632 7.26205 -1.11738 0.44143 4.02987 2.15187 -0.11610 -1.11738 5.47250 -0.63862 2.08490 -0.12158 0.13855 0.44143 -0.63862 5.00315 The elastic compliance constant matrix Sij (1 / GPa) is shown below: 0.0661178 -0.0376172 -0.0069298 0.0107669 -0.0357887 -0.0337928 -0.0376172 0.0706242 -0.0077597 0.0388593 0.0094959 0.0153903 -0.0069298 -0.0077597 0.0604854 -0.0262396 0.0045371 0.0039185 0.0107669 0.0388593 -0.0262396 0.1890798 0.0127555 -0.0178701 -0.0357887 0.0094959 0.0045371 0.0127555 0.2128447 0.0410620 -0.0337928 0.0153903 0.0039185 -0.0178701 0.0410620 0.2210396 Mechanical stability analysis shows that the elastic stiffness constant matrix of this three-dimensional material satisfies the Born stability criterion: all principal minors are positive, and C... 11 >0, C 22 >0, C 33 >0, C 44 >0, C 55 >0, C 66 >0, and C 11 ·C 22 - C 12 2 = 29.71880 × 27.27040 - (17.93742)² ≈ 810.60 - 321.75 = 488.85>0, indicating that the material is mechanically stable in three-dimensional space.

[0046] The mechanical properties of the polycrystalline aggregate calculated based on the above elastic constants are as follows: Bulk modulus: Voigt upper limit 13.59 GPa, Reuss lower limit 10.80 GPa, Hill average 12.19 GPa; Shear modulus: Voigt upper limit 6.97 GPa, Reuss lower limit 5.23 GPa, Hill average 6.10 GPa; Young's modulus: Voigt upper limit 17.86 GPa, Reuss lower limit 13.51 GPa, Hill average 15.69 GPa; Poisson's ratio: Voigt upper limit 0.281, Reuss lower limit 0.291, Hill average 0.286; Elastic Debye temperature: 358.11 K; Average sound velocity: 2494.21 m / s; Universal anisotropy index: 1.92, indicating that the material has significant elastic anisotropy.

[0047] Calculation results show that the three-dimensional stacked ferroelectric ice material exhibits significant anisotropic mechanical characteristics: the stiffness is highest in the Z-axis direction (Young's modulus 16.53 GPa) and lowest in the Y-axis direction (14.16 GPa); the Poisson's ratio varies significantly along different directions, with the Poisson's ratio along the XY direction reaching as high as 0.5689, exceeding the theoretical upper limit of 0.5 for isotropic materials, indicating that the material possesses exceptional lateral expansion characteristics and excellent deformation compatibility in specific directions. These mechanical performance parameters provide a theoretical basis for the application of this three-dimensional material in micro / nano-electromechanical systems, flexible electronic devices, and extreme environment sensors.

[0048] Example 2: Application of three-dimensional stacked ferroelectric ice materials in ferroelectric memory Based on the intrinsic ferroelectricity (synergistic effect of in-plane hydrogen-bonded ferroelectricity and interlayer van der Waals ferroelectricity) and thermal stability near room temperature (structural integrity at 260 K) of the aforementioned three-dimensional stacked ferroelectric ice material, it was used as the ferroelectric layer to construct a ferroelectric field-effect transistor (FeFET). The device structure is as follows: A 50 nm SiO2 layer is thermally oxidized to grow on a heavily doped silicon substrate as the insulating layer. Ten layers of three-dimensional stacked ferroelectric ice film (approximately 7 nm thick) are transferred to the surface of the insulating layer via dry transfer. Ti / Au (5 nm / 50 nm) are deposited at both ends of the film as the source and drain, respectively, with a channel length of 100 nm. Applying a write voltage of ±5 V to the gate enables non-volatile control of the channel conductance, achieving an on / off ratio of 10. 4 This device can operate stably in the range of 260 K to room temperature, making it suitable for low-power, high-density information storage.

[0049] Example 3: Application of three-dimensional stacked ferroelectric ice materials in deep ultraviolet photodetectors Based on the wide bandgap characteristics (approximately 5.2 eV, corresponding to the deep ultraviolet band) of the aforementioned three-dimensional stacked ferroelectric ice material, it was used as a light-absorbing layer to construct a metal-semiconductor-metal (MSM) type deep ultraviolet photodetector. A 20 nm thick three-dimensional stacked ferroelectric ice film was transferred onto a sapphire substrate, and interdigitated electrodes (Ti / Au, 5 nm / 50 nm, finger width 2 μm, finger spacing 5 μm) were fabricated on the film surface using electron beam lithography. Under 220 nm deep ultraviolet light irradiation (optical power density 1 μW / cm²), the device exhibited a significant photoresponse, a photocurrent-to-dark-current ratio of 10³, a response time <100 ms, and no response to visible light, demonstrating solar-blindness. This detector can be used in flame detection, corona detection, and ultraviolet communication.

[0050] Example 4: Application of three-dimensional stacked ferroelectric ice materials in directional stress sensors Based on the anisotropic mechanical properties of the three-dimensional stacked ferroelectric ice material (Young's modulus: E_x = 15.12 GPa, E_y = 14.16 GPa, E_z = 16.53 GPa; Poisson's ratio ν_xy = 0.5689, exhibiting anomalous lateral expansion), it was used as a sensing element to construct an oriented stress sensor. The prepared 10-layer three-dimensional stacked ferroelectric ice film was transferred onto a flexible polyimide substrate, and Au electrode pairs were fabricated along different crystal axes (X, Y, Z). When compressive stress was applied along the Z-axis, the sensor resistance changed most significantly; while when the same stress was applied along the Y-axis, the resistance change was weaker. Utilizing this directional selectivity, sensitive detection of stress in a specific direction can be achieved. This sensor can be used in fields such as robotic tactile sensing and structural health monitoring to achieve accurate measurement of specific directional components in complex stress fields.

[0051] Example 5: Application of three-dimensional stacked ferroelectric ice materials in pressure-adaptive sealing materials Based on the moderate bulk modulus (Hill average 12.19 GPa) and good compressibility (0.09261 1 / GPa) of the aforementioned three-dimensional stacked ferroelectric ice material, it was prepared into a pressure-adaptive sealing gasket. The prepared three-dimensional stacked ferroelectric ice material was mixed with a polymer matrix (such as polydimethylsiloxane PDMS) at a mass ratio of 1:10 and cast into a 2 mm thick sealing gasket. In a deep-sea simulated environment (pressure 10–100 MPa), the gasket underwent reversible compression with increasing pressure, filling the micro-gaps at the sealing interface. The sealing performance improved with increasing pressure, overcoming the defect of traditional sealing materials that are prone to failure under high pressure. This material is suitable for dynamic sealing systems of deep-sea probes and deep-earth drilling equipment.

[0052] Example 6: Application of three-dimensional stacked ferroelectric ice materials in high-sensitivity piezoelectric sensors Based on the significant tensile-shear coupling effect of the aforementioned three-dimensional stacked ferroelectric ice material (the off-diagonal element C of the elastic stiffness matrix) 12 =17.94 GPa, C 13 Based on the intrinsic ferroelectric properties of Ti / Au (e.g., 3.09 GPa), a high-sensitivity stress sensor was constructed using it as a piezoelectric sensitive layer. A 20-layer three-dimensional stacked ferroelectric ice film (approximately 14 nm thick) was transferred onto a flexible PET substrate, and interdigitated electrodes (Ti / Au, 5 nm / 50 nm) were fabricated on the upper and lower surfaces of the film. This sensor can be used in wearable electronic devices, human motion monitoring, and human-computer interfaces.

[0053] Example 7: Application of three-dimensional stacked ferroelectric ice materials in high-frequency surface acoustic wave filters Based on the excellent acoustic properties (average sound velocity 2494 m / s) and anisotropic elastic wave velocity of the aforementioned three-dimensional stacked ferroelectric ice material, it was used as a piezoelectric layer to construct a high-frequency surface acoustic wave (SAW) filter. A 100 nm thick three-dimensional stacked ferroelectric ice film was transferred to the surface of a piezoelectric single-crystal substrate (such as LiNbO3), and an interdigital transducer (IDT) was fabricated using photolithography. The electrode material was Al, with a thickness of 100 nm, a finger width of 1.2 μm, a finger spacing of 1.2 μm, and a corresponding center frequency of approximately 1.0 GHz. This device is suitable for 5G communication front-end modules and satellite communication systems.

[0054] Example 8: Application of three-dimensional stacked ferroelectric ice materials in flexible ferroelectric memory arrays Based on the low Young's modulus (15.69 GPa) and toughness (Poisson's ratio 0.286) of the aforementioned three-dimensional stacked ferroelectric ice material, it was used as a ferroelectric storage medium to construct a flexible non-volatile memory array. A bottom electrode (Ti / Au, 5 nm / 50 nm) was fabricated on a flexible polyimide substrate. The fabricated three-dimensional stacked ferroelectric ice material ink (concentration 1 mg / mL) was patterned into a 10×10 array using inkjet printing technology, with each storage cell measuring 5 μm × 5 μm and approximately 10 nm thick. Subsequently, a top electrode (Au, 50 nm) was deposited by vapor deposition. This array can be used in wearable data storage, flexible electronic tags, and other fields.

[0055] Example 9: Application of three-dimensional stacked ferroelectric ice materials in multifunctional integrated microsystems Based on the high anisotropy index (1.92) and multi-field coupling characteristics (ferroelectric-elastic coupling) of the three-dimensional stacked ferroelectric ice material, it is used as a single material platform to construct an intelligent microsystem integrating sensing, storage, and energy harvesting. The device structure is as follows: a cantilever beam array is fabricated on a silicon substrate, and each cantilever beam surface is covered with a 50 nm thick three-dimensional stacked ferroelectric ice film prepared according to the method described in Example 1. Au electrodes are fabricated at the beam root and free end, respectively. The device simultaneously realizes three functions: (1) Sensing: external vibration causes the cantilever beam to bend, generating stress along the Y-axis (flexible direction), which is converted into an electrical signal output through the piezoelectric effect; (2) Storage: the polarization change generated by the bending of the cantilever beam can be stored non-volatilely to record the vibration history; (3) Energy harvesting: when the cantilever beam vibrates continuously, piezoelectric energy is collected along the Z-axis (rigid direction). This microsystem can be used for self-powered status monitoring of IoT nodes.

[0056] Example 10: Application of three-dimensional stacked ferroelectric ice materials in polar scientific research equipment Based on the thermal stability and intrinsic ferroelectricity of the aforementioned three-dimensional stacked ferroelectric ice material within a wide temperature range of 80–260 K, it was used as a temperature sensing element to construct a cryogenic sensor for polar applications. A 30-layer three-dimensional stacked ferroelectric ice film (approximately 21 nm thick) was transferred onto an alumina ceramic substrate to fabricate interdigitated electrodes, forming a capacitive sensor. Within the temperature range of 80–260 K, the capacitance exhibits a linear change with temperature. This sensor can be used for polar meteorological monitoring, glacier temperature profile measurement, and cryogenic scientific research equipment.

Claims

1. A three-dimensional ferroelectric material based on a double-layer interlocked ice stack, characterized in that, The material has a three-dimensional periodic crystal structure, consisting of two layers of interlocking two-dimensional ice stacked by van der Waals forces. It belongs to the triclinic crystal system, space group P1, and its cell parameters range as follows: a = 4.624485 ± 0.05 Å, b = 4.641236 ± 0.05 Å, c = 5.982366 ± 0.05 Å; α = 107.07466 ± 0.5°, β = 90.93043 ± 0.5°, γ = 61.78182 ± 0.5°. The unit cell contains four independent water molecules, with atomic fraction coordinates ranging from: O1 (0.61017 ± 0.01, 0.34154 ± 0.01, 0.33309 ± 0.01), H1 (0.73982 ± 0.01, 0.11790 ± 0.01, 0.36264 ± 0.01), H2 (0.74554 ± 0.01, 0.45985 ± 0.01, 0.35681 ± 0.01); O2 (0.95564 ± 0.01, 0.66753 ± 0.01, 0.30957 ± 0.01), H3 (0.98932 ± 0.01, 0.58412 ± 0.01). 0.01, 0.13350 ± 0.01), H4 (0.18478 ± 0.01, 0.56373 ± 0.01, 0.34914 ± 0.01); Oxygen atom O3 (0.04297 ± 0.01, 0.42649 ± 0.01, 0.82241 ± 0.01), Hydrogen atom H5 (0.93921 ± 0.01, 0.27706 ± 0.01, 0.80289 ± 0.01), H6 (0.28778 ± 0.01, 0.27746 ± 0.01, 0.79695 ± 0.01); Oxygen atom O4 (0.70088 ± 0.01, 0.09817 ± 0.01). 0.01, 0.84935 ± 0.01), hydrogen atoms H7 (0.82819 ± 0.01, 0.84300 ± 0.01, 0.80900 ± 0.01), H8 (0.66598 ± 0.01, 0.18368 ± 0.01, 0.02569 ± 0.01); there are no suspended hydrogen atoms in this structure; the double-layered interlocked two-dimensional ice acts as a basic unit, and they are coupled to each other through van der Waals forces to form a three-dimensional long-range ferroelectric sequence.

2. The three-dimensional ferroelectric material according to claim 1, characterized in that, The Young's moduli along the X, Y, and Z axes are 15.12 GPa, 14.16 GPa, and 16.53 GPa, respectively, and the Poisson's ratio along the XY direction is 0.5689; the average Hill modulus of bulk modulus is 12.19 GPa, and the compressibility is 0.09261 1 / GPa; the average Hill shear modulus is 6.10 GPa; the average Hill Young's modulus is 15.69 GPa; the average Hill Poisson's ratio is 0.286; the Debye temperature is 358.11 K, the average sound velocity is 2494.21 m / s, and the gravitational index is 1.

92.

3. The three-dimensional ferroelectric material according to claim 1, characterized in that, The material is a wide bandgap semiconductor with a bandgap of 5.2 eV; it exhibits thermal stability at 260 K, and ab initio molecular dynamics simulations show that its structure is intact without bond breakage or reconstruction; its phonon spectrum has no imaginary frequencies across the entire frequency range, demonstrating intrinsic dynamic stability.

4. A theoretical simulation method for preparing the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Substrate adsorption simulation: An adsorption model of two-dimensional ice with double interlocking layers was constructed on the surface of an inert substrate, and the optimal adsorption configuration and adsorption energy were calculated; (2) Multi-layer stacking simulation: Independent double-layer interlocking ice layers are stacked according to a preset stacking method, and structural relaxation is performed to obtain the optimal stacking configuration; (3) Simulation of the operable temperature range: AIMD simulation was performed at temperatures of 80–260 K to obtain a stable three-dimensional periodic crystal structure; (4) Peeling and independence simulation: Gradually weaken the substrate-ice layer interaction. When the binding energy is <10 meV / molecule, the ice layer can be independently self-supporting.

5. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, The material can be used as a ferroelectric layer to construct ferroelectric field-effect transistors, ferroelectric memristors, or ferroelectric memories to achieve non-volatile information storage; or as a light-absorbing layer to construct deep ultraviolet photodetectors to achieve photoelectric detection in the deep ultraviolet band.

6. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, By utilizing its anisotropic mechanical properties, the material can be used to construct directional stress sensors to achieve sensitive detection of stress in a specific direction; or its piezoelectric effect can be used to construct high-sensitivity piezoelectric sensors or piezoelectric energy harvesters; or its elastic anisotropic wave velocity can be used to construct surface acoustic wave filters or acoustic waveguide devices.

7. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, Utilizing its compressibility and toughness, the material can be used to construct pressure-adaptive sealing materials, mechanical buffer layers, or shock-absorbing elements; or as a flexible substrate for constructing flexible electronic devices.

8. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, The material can be used to construct a multifunctional integrated microsystem to achieve multifunctional synergy of sensing, storage and energy harvesting; or to construct a multi-parameter composite sensor network to achieve synergistic detection of multiple physical quantities such as force, heat, light and electricity.

9. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, The material is used as a standard reference material for X-ray diffraction for the calibration of X-ray diffractometers and phase identification.

10. An application of the three-dimensional ferroelectric material according to any one of claims 1-3, characterized in that, Utilizing its thermal stability over a wide temperature range of 80–260K, the material can be used in functional components of polar scientific research equipment or deep space probes to achieve temperature sensing or data storage in low-temperature environments.

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