A silicon-oxygen-aluminum ternary composite optical coating material and its preparation method

Abstract

This invention belongs to the field of optical functional thin film materials, specifically relating to a silicon-oxygen-aluminum ternary composite optical coating material and its preparation method. Addressing the problem in existing technologies of achieving high transmittance, high hardness, and corrosion resistance synergistically within a single ternary material system, this invention utilizes a single-crystal thin film with a completely ordered single-phase structure epitaxially grown on a MgAl2O4 spinel single-crystal substrate, co-doped with transition metal ions and protons. Employing a combined laser molecular beam epitaxy and low-temperature proton implantation technique, alternatingly ablates the silicon target, aluminum target, and doped target, and simultaneously irradiating with a low-energy hydrogen ion beam under ultra-high vacuum, atomic-level epitaxial growth and in-situ proton embedding are achieved, resulting in a unified high transmittance, high hardness, and corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of optical functional thin film materials, specifically relating to a silicon-oxygen-aluminum ternary composite optical coating material and its preparation method. Background Technology

[0002] Optical coating materials play a crucial role in many high-tech fields (CN120208661A). For example, transparent protective windows, wear-resistant optical components, and adaptive optics devices all require coatings to possess both excellent optical transmittance and mechanical stability. However, traditional single-material systems struggle to achieve multiple properties simultaneously. Taking commonly used transparent oxide ceramics as an example, silicon oxide films offer good light transmittance but have limited hardness, while alumina or spinel ceramics possess high hardness and weather resistance but lack dynamic response capabilities.

[0003] Magnesium aluminum spinel is a transparent ceramic material widely used in the manufacture of transparent armor, protective windows, and optical components due to its excellent properties such as wide-band high transmittance, high hardness, and high mechanical strength. High-purity sintered or single-crystal spinel materials exhibit superior impact and corrosion resistance in harsh environments while maintaining optical clarity. This makes it an ideal candidate for high-performance optical coatings, significantly superior to ordinary glass in applications requiring wear resistance and high transparency.

[0004] However, the aforementioned traditional optical ceramic materials are typically inert and fixed in properties, meaning their optical characteristics cannot be adjusted once fabricated. For example, while spinel or sapphire films are robust and transparent, their transmittance or spectral characteristics cannot be altered in response to external signals. Similarly, electrochromic WO3 films change color under an electric field and are used in tunable transparent glass. However, such dynamically responsive materials often suffer from deficiencies in mechanical and chemical stability.

[0005] Existing technologies have attempted to combine high-hardness materials with dynamic materials, such as adding a hard protective layer to a soft color-changing layer, or creating a multilayered structure. However, such multilayer films have complex interfaces, refractive index mismatch leading to increased optical loss, and thermal expansion and contraction and cyclic stress at the interface may cause delamination or cracking. Furthermore, due to the significant differences in material systems corresponding to different properties, achieving high light transmittance, high hardness, and corrosion resistance in a single material is extremely difficult.

[0006] In summary, developing a novel optical coating material that possesses high transmittance, high hardness, and corrosion inertness similar to spinel ceramics, while also being able to operate reliably for a long period of time, is a major technical challenge facing this field. Summary of the Invention

[0007] This invention provides a silicon-oxygen-aluminum ternary composite optical coating material and its preparation method, aiming to overcome the limitations of existing technologies that make it difficult to simultaneously achieve high light transmittance, high hardness, and corrosion resistance. Through composition design and preparation process, the thin film material of this invention simultaneously achieves high optical transparency, high mechanical strength, and corrosion resistance in a single continuous solid solution crystalline phase.

[0008] The specific technical solution is as follows:

[0009] A silicon-oxygen-aluminum ternary composite optical coating material and its preparation method are as follows:

[0010] S1: Material preparation.

[0011] S11: Magnesium aluminum spinel is used as a substrate and is ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence. After cleaning, it is immersed in a mixed solution A at a temperature of 70-80℃ for 10-15 minutes, and then immersed in a mixed solution B at a temperature of 70-80℃ for 10-15 minutes. After cleaning and drying, the primary substrate is obtained.

[0012] S12: The primary substrate prepared in S11 is placed in the sample inlet chamber of the epitaxial growth equipment, baked at a constant temperature, then placed in the growth chamber, and oxygen with a purity of 99.999% is introduced, with the oxygen partial pressure controlled at 1×10⁻⁶. -4 Pa, isothermal annealing, after which the temperature is lowered to 650℃ to obtain an atomic-level substrate.

[0013] S2: Target and cavity preparation. The silicon target, aluminum target, aluminum-chromium alloy target and waste wafer target for cleaning are installed on the multi-target rotating frame in the laser molecular beam epitaxial growth cavity. The target is baked to remove vapors and cooled to room temperature. The atomic-level substrate prepared in S12 is placed on the sample stage.

[0014] S3: Epitaxial growth and simultaneous proton injection. The epitaxial growth temperature is 650℃, and oxygen with a purity of 99.999% is introduced, with the oxygen partial pressure controlled at 5 × 10⁻⁶. -4 Pa uses an excimer laser as the light source for thin film epitaxial growth, while simultaneously turning on a low-energy hydrogen ion source to vertically irradiate the sample growth surface until the growth is complete.

[0015] S4: Subsequent processing: anneal in situ at 650℃ and oxygen partial pressure for 10-15 min, then anneal at 400℃ for 30 min in a pure oxygen atmosphere to obtain the composite optical film.

[0016] Furthermore, the magnesium aluminum spinel described in S11 is a single-crystal magnesium aluminum spinel with a (100) crystal plane orientation.

[0017] The ultrasonic cleaning described in S11 has the following parameters: power 100-150W, temperature 25-40℃, and duration 15-20min.

[0018] The mixed solution A described in S11 is a mixture of ammonia, hydrogen peroxide, and deionized water, with a volume ratio of 1:1:5.

[0019] The mixed solution B described in S11 is a mixture of hydrochloric acid, hydrogen peroxide, and deionized water, with a volume ratio of 1:1:6.

[0020] The drying process described in S11 involves blowing air with nitrogen gas of 99.999% purity.

[0021] The constant temperature baking described in S12 has the following parameter settings: vacuum degree 1×10 -5 Pa, temperature 250~350℃, duration 1~2h.

[0022] The isothermal annealing described in S12 has the following parameters: temperature 750~850℃, duration 30~60min.

[0023] Furthermore, the aluminum-chromium alloy target described in S2 contains 5% chromium in terms of atomic percentage.

[0024] Furthermore, the excimer laser described in S3 has the following parameter settings: wavelength 248 nm, energy density 1–5 J / cm². 2 The pulse repetition frequency is 1 to 10 Hz.

[0025] The irradiation described in S3 has the following parameter settings: ion beam energy 50–100 eV; beam current density 1–10 μA / cm. 2 .

[0026] Furthermore, the composite optical film described in S4 has a thickness of 10 to 100 nm, wherein the atomic ratio of Al to Si is (2-x):x, and 0.1 ≤ x ≤ 0.4.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention ensures atomically flat epitaxial growth through laser molecular beam epitaxy, and achieves in-situ embedding and positioning of protons during the growth process through synchronous low-temperature proton injection, avoiding lattice damage caused by subsequent injection, and ensuring effective coupling between protons and transition metal ions.

[0029] 2. This invention achieves in-situ embedding and positioning of protons during the growth process through synchronous low-temperature proton injection, avoiding lattice damage caused by subsequent injection and ensuring effective coupling between protons and transition metal ions. Attached Figure Description

[0030] Figure 1This is a process flow diagram for the preparation of a silicon-oxygen-aluminum ternary composite optical coating material.

[0031] Figure 2 This is the XRD pattern of the composite optical coating material finally prepared in Example 1.

[0032] Figure 3 This is the SIMS diagram of the final composite optical coating material prepared in Example 1.

[0033] Figure 4 Figure 1 shows the STEM imaging and EELS elemental line scan analysis of the composite optical coating material finally prepared in Example 1. Figure (a) is the HAADF-STEM atomic resolution image of the coating material, Figure (b) is the cross-interface EELS elemental line scan result, and Figure (c) is the OK edge ELNES comparison spectrum in the frozen environment.

[0034] Figure 5 Figure 1 shows the in-situ optical test diagram of the composite optical coating material finally prepared in Example 1. Figure (a) is the dynamic response diagram of the in-situ ultraviolet-visible-near infrared absorption spectrum, and Figure (b) is the dynamic switching diagram of the transmittance at 550 nm over time.

[0035] Figure 6 This is a comparison chart of the transmittance and nanohardness data of the composite optical films finally prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0036] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0037] This invention proposes a silicon-oxygen-aluminum ternary composite optical coating material and its preparation method. It employs epitaxial growth of a single-crystal γ-silicon-aluminum spinel structure, using a magnesium-aluminum spinel single crystal as a substrate to form a completely ordered single-phase structure. During the growth process, a specific ratio of transition metal ions and protons are precisely co-doped, forming reversible photoinduced electron-proton coupling transfer centers in adjacent coordination within the crystal lattice, thereby endowing the thin film with dynamically switchable optical properties. (See attached diagram) Figure 1 The diagram shows a method for preparing a silicon-aluminum ternary composite optical coating material, the detailed technical solution of which is as follows:

[0038] 1. Raw material preparation

[0039] Magnesium aluminum spinel was used as a substrate and ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water. After cleaning, it was immersed in mixed solution A, and then immersed in mixed solution B. After cleaning and drying, a primary substrate was obtained. The primary substrate was placed in the sample inlet chamber of the epitaxial growth equipment, baked at a constant temperature, and then placed in the growth chamber. The base vacuum of the growth chamber was evacuated to 5 × 10⁻⁶. -7 Pa, then high-purity oxygen is introduced, controlling the oxygen partial pressure at 1×10. -4 Pa, isothermal annealing, after which the temperature is lowered to the epitaxial growth temperature to obtain an atomic-level substrate.

[0040] High-purity magnesium aluminum spinel effectively prevents substrate impurities from diffusing into the thin film during high-temperature processing and epitaxy, thus avoiding the introduction of non-acceptor defects. Acetone, anhydrous ethanol, and deionized water are used sequentially, utilizing the gradient change in solvent polarity to gradually dissolve and remove different types of contaminants. Alkali treatment is first used to remove fine particles and some organic residues, followed by acid treatment to remove alkali metal ions and transition metal ion contaminants. High-purity nitrogen is used to dry the substrate surface to avoid introducing new particles or water stains. Isothermal baking promotes the desorption of volatile contaminants such as water molecules and hydrocarbons physically adsorbed on the substrate surface, which are then removed by a vacuum system to prevent release during the high vacuum environment of the early stages of epitaxial growth, thus preventing contamination of the growth interface. Isothermal annealing utilizes the high temperature to provide sufficient surface atomic migration energy. Under thermal drive, surface atoms escape metastable positions and migrate to lower-energy lattice sites, thereby eliminating micro-roughness and cleaning residual microscopic damage layers, achieving surface smoothing. Simultaneously, under specific temperature and oxygen pressure conditions, a thermodynamically stable, periodic atomic arrangement structure forms on the surface.

[0041] 2. Target and cavity preparation

[0042] The silicon target, aluminum target, aluminum-chromium alloy target, and waste wafer target for cleaning are mounted on a multi-target rotating frame in the laser molecular beam epitaxy growth cavity, baked to remove vapor, cooled to room temperature, and the atomic-level substrate is placed on the sample stage.

[0043] Using an aluminum-chromium alloy target ensures that chromium atoms and aluminum atoms are fully mixed in the plasma plume, achieving a more uniform doping distribution and avoiding interface fluctuations caused by excessively fast ablation rate of pure chromium targets or excessive differences in plume characteristics.

[0044] 3. Epitaxial growth and synchronous proton injection

[0045] The epitaxial growth temperature was 650℃, and oxygen with a purity of 99.999% was introduced, with the oxygen partial pressure controlled at 5×10⁻⁶. -4 Pa uses an excimer laser as the light source for thin film epitaxial growth, while simultaneously turning on a low-energy hydrogen ion source to vertically irradiate the sample growth surface until the growth is complete.

[0046] The temperature must be high enough to ensure sufficient migration of deposited atoms on the substrate surface to form an ordered crystal, but it cannot be too high to prevent excessive interdiffusion between the substrate and the thin film or premature proton desorption. Appropriate amounts of oxygen react with the Al, Si, and Cr plasma generated by laser ablation to ensure sufficient oxidation of the thin film and to compensate for potential lattice oxygen loss due to high temperature or proton injection, while also controlling the film's crystallinity and point defect type.

[0047] When a laser pulse bombards the target surface, the high energy density causes a tiny area on the target surface to vaporize and ionize instantaneously, forming a forward-spraying plasma plume containing high-energy atoms, ions, and electrons. These high-energy particles travel in a straight line in ultra-high vacuum, reaching the heated substrate surface. Driven by heat, they migrate on the substrate surface, finding the lowest energy position (lattice point) extending from the MgAl2O4 substrate lattice and chemically adsorbing it. They then react with introduced oxygen to form oxide bonds, growing epitaxially layer by layer. The alternating deposition of Al and Si facilitates the ordered occupancy of cations in the spinel structure (Al mainly occupies octahedrons, while Si occupies tetrahedrons), promoting the formation of a fully ordered single-phase γ-structure.

[0048] Proton implantation is not performed after all film growth is complete, nor at the intervals between each growth cycle, but rather overlaps temporally with the laser ablation deposition process. Its purpose is to establish coupling centers, not to alter conductivity. From the first laser pulse trigger until the end of the growth cycle, a low-energy hydrogen ion beam is continuously activated and aligned with the sample growth surface. This is due to the high-energy laser ablation of the target material, whose main components are high-kinetic-energy metal atoms, ions, and electrons, while the low-energy hydrogen ion beam has lower energy and beam current density (50–100 eV, 1–10 μA / cm). 2 Therefore, the former has little scattering or deflection effect on the latter. The surface of the growing film is dynamic and not completely sealed, with low-energy H... + When an ion beam irradiates this surface, the protons tend to occupy the relatively empty tetrahedral or octahedral interstitial sites in the spinel structure. Since chromium ions (Al-Cr target) replace aluminum ion lattice sites in the crystal lattice, when a proton is embedded in a neighboring interstitial site, the chromium ion traps the proton, naturally forming spatially adjacent Cr-OH coupling units. This in-situ, synchronous doping-implantation method ensures that protons and transition metal ions form proximity coordination with the highest probability in three-dimensional space.

[0049] 4. Follow-up processing

[0050] The composite optical film was annealed in situ at 650℃ and oxygen partial pressure, and then cooled to 400℃ in a pure oxygen atmosphere for 30 min to obtain the composite optical film.

[0051] In-situ annealing allows the final deposited atomic layer sufficient time to migrate to the lowest energy position, repairs possible micro-defects at the growth front, and enables the injected protons to achieve a more stable distribution within their interstitial sites.

[0052] Example 1

[0053] A method for preparing a silicon-oxygen-aluminum ternary composite optical coating material is as follows:

[0054] Table 1 Main Raw Materials

[0055]

[0056] S1: Material preparation.

[0057] S11: Magnesium aluminum spinel was used as a substrate and ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water. After cleaning, it was immersed in a mixed solution A at 75°C for 13 minutes, and then immersed in a mixed solution B at 75°C for 13 minutes. After cleaning, it was dried using nitrogen gas with a purity of 99.999% to obtain the primary substrate. The ultrasonic cleaning parameters were set as follows: power 125W, temperature 33°C, duration 18 minutes; mixed solution A was a mixture of ammonia, hydrogen peroxide, and deionized water with a volume ratio of 1:1:5; mixed solution B was a mixture of hydrochloric acid, hydrogen peroxide, and deionized water with a volume ratio of 1:1:6.

[0058] S12: The primary substrate prepared in S11 is placed in the sample inlet chamber of the epitaxial growth equipment, baked at a constant temperature, then placed in the growth chamber, and oxygen with a purity of 99.999% is introduced, with the oxygen partial pressure controlled at 1×10⁻⁶. -4 Pa, isothermal annealing, followed by cooling to 650℃ to obtain an atomic-level substrate. The isothermal baking parameters were set as follows: vacuum degree 1×10⁻⁶. -5 Pa, temperature 300℃, duration 1.5h; isothermal annealing parameter settings: temperature 800℃, duration 45min.

[0059] S2: Target and cavity preparation. The silicon target, aluminum target, aluminum-chromium alloy target (chromium atomic percentage is 5%) and waste wafer target for cleaning are installed on the multi-target rotating frame in the laser molecular beam epitaxial growth cavity. The target is baked to remove vapors and cooled to room temperature. The atomic-level substrate prepared in S12 is placed on the sample stage.

[0060] S3: Epitaxial growth and simultaneous proton injection. The epitaxial growth temperature is 650℃, and oxygen with a purity of 99.999% is introduced, with the oxygen partial pressure controlled at 5 × 10⁻⁶. -4Pa was used as the light source for thin film epitaxial growth, with a low-energy hydrogen ion source simultaneously irradiating the sample growth surface vertically until growth was complete. The excimer laser parameters were set as follows: wavelength 248 nm, energy density 3 J / cm². 2 The pulse repetition frequency was 5 Hz. Epitaxial growth cycle parameters were set as follows: for aluminum targets, the single-pulse deposition depth was 0.04 atomic monolayers, with 20 laser pulses continuously emitted at 5 Hz and a migration time of 8 s; for silicon targets, the single-pulse deposition depth was 0.05 atomic monolayers, with 8 laser pulses continuously emitted at 5 Hz and a migration time of 8 s; for aluminum-chromium alloy targets, the single-pulse deposition depth was 0.038 atomic monolayers, with 1 laser pulse emitted at 5 Hz and a migration time of 8 s. Low-energy hydrogen ion source vertical irradiation parameters were set as follows: ion beam energy 75 eV; beam current density 5 μA / cm². 2 .

[0061] S4: Subsequent processing: In-situ annealing at 650℃ and oxygen partial pressure for 12.5 min, followed by annealing at 400℃ in a pure oxygen atmosphere for 30 min, yielding a film thickness of 50 nm and a chromium atom doping concentration of 0.5% (Al). 1.7 Si 0.3 Composite optical film of O4.

[0062] Example 2

[0063] The composition and preparation process are the same as in Example 1, except that:

[0064] In the preparation process S11, the temperature of mixed solution A is 70℃ and the soaking time is 10min, the temperature of mixed solution B is 70℃ and the soaking time is 10min, and other steps are the same.

[0065] The isothermal baking parameters in step S12 of the preparation process are set as follows: vacuum degree 1×10⁻⁶. -5 Pa, temperature 250℃, duration 1h; constant temperature annealing parameter settings: temperature 750℃, duration 30min, other steps are the same.

[0066] The excimer laser in the S3 fabrication process has the following parameters: wavelength 248 nm, energy density 1 J / cm². 2 Pulse repetition frequency 1 Hz; Irradiation parameters: Ion beam energy 50 eV; Beam current density 1 μA / cm² 2 The other steps are the same.

[0067] In the S3 stage of the fabrication process, epitaxial growth is performed. The single-pulse deposition amount for the aluminum target is 0.04 atomic monolayers, for the aluminum-chromium alloy target it is 0.038 atomic monolayers, and for the silicon target it is 0.05 atomic monolayers. The cycle parameters are set as follows: First, five laser pulses from the aluminum target are continuously emitted at 1 Hz with a migration time of 8 s. Then, one laser pulse from the aluminum-chromium alloy target is emitted at 1 Hz with a migration time of 8 s. Second, four laser pulses from the aluminum target are continuously emitted at 1 Hz with a migration time of 8 s. Then, one laser pulse from the silicon target is emitted at 1 Hz with a migration time of 8 s. Finally, one laser pulse from the aluminum-chromium alloy target is emitted at 1 Hz with a migration time of 8 s. The first and second steps are repeated alternately three times. Then, four laser pulses from the aluminum target and one laser pulse from the aluminum-chromium alloy target are deposited at 1 Hz, each with a migration time of 8 s. The other steps are the same.

[0068] In step S4 of the preparation process, in-situ annealing is performed for 10 minutes, and the other steps are the same.

[0069] In the S4 process of the composite optical film, the atomic doping percentage of chromium atoms is 0.8%, the atomic ratio of Al to Si is 1.9:0.1, the film thickness is 10 nm, and other components are the same.

[0070] Example 3

[0071] The composition and preparation process are the same as in Example 1, except that:

[0072] In the preparation process S11, the temperature of mixed solution A is 80℃ and the soaking time is 15min, the temperature of mixed solution B is 80℃ and the soaking time is 15min, and other steps are the same.

[0073] The isothermal baking parameters in step S12 of the preparation process are set as follows: vacuum degree 1×10⁻⁶. -5 Pa, temperature 350℃, duration 2h; constant temperature annealing parameter settings: temperature 850℃, duration 60min, other steps are the same.

[0074] The excimer laser in the S3 fabrication process has the following parameters: wavelength 248 nm, energy density 5 J / cm². 2 Pulse repetition frequency 10Hz; Irradiation parameters: Ion beam energy 100eV; Beam current density 10μA / cm² 2 The other steps are the same.

[0075] In the S3 stage of the fabrication process, epitaxial growth is performed. The single-pulse deposition amount for the aluminum target is 0.04 atomic monolayer, for the aluminum-chromium alloy target it is 0.038 atomic monolayer, and for the silicon target it is 0.05 atomic monolayer. The cycle parameters are set as follows: Step 1: Five laser pulses to the aluminum target are continuously emitted at 10 Hz with a migration time of 8 s. This step is repeated three times. Step 2: Four laser pulses to the aluminum target, one laser pulse to the silicon target, and one laser pulse to the aluminum-chromium alloy target are continuously emitted at 10 Hz, each with a migration time of 8 s. Step 3: Five laser pulses to the aluminum target are continuously emitted at 10 Hz with a migration time of 8 s. Then, one laser pulse to the silicon target is emitted at 10 Hz with a migration time of 8 s. Step 4: Step 3 is repeated. Step 5: Steps 2 to 4 are repeated once. The other steps are the same.

[0076] In step S4 of the preparation process, in-situ annealing is performed for 15 minutes, and the other steps are the same.

[0077] In the S4 process of the composite optical film, the atomic doping percentage of chromium atoms is 0.5%, the ratio of Al to Si atoms is 1.6:0.4, the film thickness is 100 nm, and other components are the same.

[0078] Comparative Example 1

[0079] The composition and preparation process are the same as in Example 1, except that:

[0080] In step S1 of the fabrication process, amorphous SiO2 glass is used as the substrate, and the other steps are the same.

[0081] Comparative Example 2

[0082] The composition and preparation process are the same as in Example 1, except that:

[0083] In step S3 of the fabrication process, simultaneous proton implantation is not performed. Instead, a high-energy (30keV) ion implanter is used to implant protons into the already grown single-crystal thin film. The other steps are the same.

[0084] The composite optical coating material of Example 1 was sampled (10mm × 10mm) for XRD testing. A non-contaminating marker was used to mark the back of the sample. The scanning speed was 2° / min, and the scanning angle was 10°–80°. The results are as follows: Figure 2As can be seen from the figure, there is an extremely strong and sharp peak at 44.8°, which corresponds to the (400) crystal plane diffraction of the MgAl2O4 substrate; at 45.2°, a diffraction peak with lower intensity but equally sharp appears, which corresponds to the (400) crystal plane of the 50nm thick optical composite film grown epitaxially. The film peak and the substrate peak have the same crystal plane orientation, and no other impurity peaks or polycrystalline rings appear in the scanning range, which proves that the film is epitaxially grown along the substrate lattice direction and has a highly ordered single crystal structure.

[0085] Samples (10mm × 10mm) of the composite optical coating material from Example 1 were taken for secondary ion mass spectrometry (SIMS) analysis. The samples were gold-plated. For protons, the primary ion energy was set to 200 eV; for elements such as chromium, aluminum, silicon, oxygen, and magnesium, the primary ion energy was set to 2000 eV. Figure 3 As shown, by Figure 3 It can be seen that within the thin film region, the signal intensity of Si is high and stable, while the signal intensity of Mg is low. After entering the substrate, the Si signal drops sharply and the Mg signal rises sharply. Cr and proton H both show uniform and stable signal plateaus within the thin film region and drop sharply at the interface, proving that Cr and H were successfully introduced and uniformly distributed throughout the thin film layer, achieving the expected co-doping.

[0086] The composite optical coating material of Example 1 was sampled and analyzed using scanning transmission electron microscopy (STEM), combined with cross-interface EELS elemental line scanning. The sample was thinned by cutting along a direction perpendicular to the film surface using a focused ion beam, preparing an extremely thin cross-section sample that could be penetrated by the electron beam. To avoid the breaking of fragile OH bonds, proton desorption, and formation of local oxygen vacancies caused by high-energy electron beam bombardment in subsequent tests, cryogenic transport was used. The cross-sectional sample was transferred to a transmission electron microscope equipped with a cryogenic stage, ensuring that the sample remained at liquid nitrogen temperature throughout the entire testing process. The accelerating voltage was set to 300 kV, the energy resolution to <0.3 eV, and the detection mode to be atomic-resolution point-by-point line scanning. Figure 4 Figure (a) shows the morphology of the thin film, which is a completely ordered single-phase structure formed by epitaxial growth on a magnesium aluminum spinel single crystal substrate; Figure 4 As shown in Figure (b), the signal intensity of O, Al, Si and Cr elements with spatial position was extracted by line scanning. The results show that chromium enrichment was successfully detected at specific spatial pixel points, which is consistent with the process design of doping with 0.5% chromium atoms and simultaneous proton injection in Example 1. Figure 4 As shown in Figure (c), the matrix region (black line) exhibits a normal oxygen K-side near-edge fine structure unaffected by proton coupling, while the coupling region (red line) is rich in Cr and H. +In this region, due to the strong electronegativity difference between hydrogen and oxygen atoms and their electron-withdrawing inductive effect, the density of unoccupied states of the hybrid O 2p-Cr 3d undergoes a redistribution. This is visually manifested in a significant chemical shift of the OK-edge absorption threshold towards lower energies in the high-resolution EELS spectrum, along with changes in the relative intensity and splitting width of the doublets. The spatial sites of the characteristic protonation chemical shift exhibit a high degree of geometric overlap with the spatial pixels enriched in chromium, providing intuitive and visual confirmation of the effective spatial coupling between protons and transition metal Cr ions at the nanoscale physical limit.

[0087] The composite optical coating material of Example 1 was sampled and subjected to in-situ optical testing. The samples were tested using an in-situ ultraviolet-visible-near-infrared absorption spectrometer with a spectral detection range set to 300-1800 nm. The external excitation light source was a laser with a center wavelength of 532 nm and a power density of 10 mW / cm². 2 The dynamic monitoring wavelength was selected from the 550nm band, which is most sensitive to the human eye. Figure 5 As shown in Figure (a), without an external excitation source, the film maintains low absorbance over a very wide spectral range, indicating that it exhibits excellent static transmittance similar to ordinary spinel without excitation. When the excitation source is turned on to irradiate the film, the reversible photoinduced electron-proton coupling transfer centers inside are activated. This leads to a transient reorganization of the film's electronic band structure, which is visually represented in the spectrum as a significant enhancement and reorganization of the absorption bands in the visible to near-infrared region. Figure 5 As shown in Figure (b), during the period from 0 to 70 seconds, without external excitation, the system is in a high-transmittance ground state with a transmittance of about 90%. When light excitation is introduced at the 70th second, the transmittance drops rapidly and stabilizes at an excited state of about 60%, resulting in a significant steady-state transmittance modulation difference. After the external excitation light field is removed at the 180th second, the transmittance curve rises rapidly, and the system can quickly and spontaneously recover to the initial high-transmittance ground state. This process not only proves the extremely fast response speed of dynamic modulation, but also verifies the high reversibility of the photoinduced electron-proton coupling transfer center.

[0088] Based on Examples 1-3 and Comparative Examples 1-2, samples were taken from the composite optical film and the transmittance was tested: using a UV-Vis spectrophotometer, with the bare substrate as 100% baseline, the scanning wavelength was 380-780nm, and the average value at 550nm was calculated, referring to the standard GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics".

[0089] Based on Examples 1-3 and Comparative Examples 1-2, samples of the finally prepared composite optical film were taken for nanohardness testing: a nanoindenter was used with a 5×5 matrix, and the average value was taken, referring to the standard GB / T 21838.1-2019 "Instrumented Indentation Tests of Hardness and Material Parameters of Metallic Materials - Part 1: Test Methods".

[0090] Based on Examples 1-3 and Comparative Examples 1-2, samples of the finally prepared composite optical film were taken and roughness change rate tests were performed: the sample was partially immersed in the etching solution (5% NaCl solution, pH 6.8), and after 240 hours, the surface roughness of the same area before and after etching was measured using an atomic force microscope or profilometer, and the roughness change was calculated, referring to the standard GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test".

[0091] The specific test results are shown in Table 2. Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown:

[0092] Table 2 Comparison of core performance of Examples 1-3 and Comparative Examples 1-2

[0093]

[0094] Note: Corrosion resistance is specifically manifested in the rate of change of roughness.

[0095] The comparison results above show that Example 1 exhibits the best overall performance. The lattice matching of the magnesium-aluminum spinel substrate, the atomically smooth surface obtained through annealing, and the dynamic defect repair during growth via simultaneous low-energy proton implantation all contribute to achieving both high transmittance and ultra-high hardness. The dense single-crystal structure and uniform doping make it difficult for corrosive media to penetrate. Simultaneous proton implantation provides optimized ion migration channels without damaging the crystal structure. This demonstrates that Example 1 successfully solves the problem of balancing high transmittance and high hardness in thin films. Example 2, on the other hand, reduces the processing intensity, resulting in a thinner film with slightly decreased hardness and corrosion resistance. Furthermore, the lower pulse frequency leads to slight interface defects. By adjusting the atomic ratio of Al to Si and the cycling strategy, a higher chromium doping concentration was achieved, resulting in stronger absorption modulation capabilities at specific wavelengths. Example 3 improved the process strength, yielding a thicker film and higher hardness, but the slightly higher ion beam energy may introduce minor point defects, leading to a slightly lower transmittance than Example 1. Comparative Example 1 used an amorphous SiO2 glass substrate, which could not epitaxially grow a single-crystal film, only yielding amorphous or polycrystalline films with extremely low hardness, poor corrosion resistance, and completely lacking the ordered ion migration channels required for electrochromism. Comparative Example 2's proton injection severely damaged the already grown crystal structure, resulting in a decrease in hardness.

[0096] In summary, it is clear from the above embodiments and comparative examples that the silicon-aluminum ternary composite optical film provided by the present invention is significantly superior to traditional solutions in terms of light transmittance, nano-hardness, and corrosion resistance. This is attributed to the construction of a three-in-one system of single-crystal substrate selection, precise laser molecular beam epitaxy growth, and low-energy proton injection synchronized with growth, thereby solving the integration challenges of high light transmittance, high hardness, and corrosion resistance.

Claims

1. A silicon-oxygen-aluminum ternary composite optical coating material, prepared by epitaxial growth from a single-crystal substrate, characterized in that: The single crystal substrate is a magnesium-aluminum spinel substrate, the optical coating material, wherein transition metal ions of chromium are co-doped, the transition metal ions of chromium occupy Al 3+ sites of the optical coating material lattice, and the transition metal ions of chromium and the protons form spatial adjacent coordination in the lattice; the optical coating material, wherein the atomic ratio of Al to Si is (2-x):x, 0.1≤x≤0.

4.

2. The silicon-oxygen-aluminum ternary composite optical coating material according to claim 1, characterized in that: The magnesium aluminum spinel substrate is a single-crystal magnesium aluminum spinel with (100) crystal plane orientation.

3. The silicon-oxygen-aluminum ternary composite optical coating material according to claim 1, characterized in that: The transition metal ion chromium has an atomic doping percentage of 0.5% to 0.8%.

4. The silicon-oxygen-aluminum ternary composite optical coating material according to claim 1, characterized in that, The silicon-oxygen-aluminum ternary composite optical coating has a thickness of 10-100 nm, a transmittance of ≥97% at 550 nm, a Vickers hardness of ≥24 GPa, and a corrosion resistance of ≤3%.

5. The preparation method of the silicon-aluminum ternary composite optical coating material according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Material preparation; S11: Magnesium aluminum spinel is used as a substrate and is ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence. After cleaning, it is immersed in a mixed solution A at a temperature of 70-80℃ for 10-15 minutes, and then immersed in a mixed solution B at a temperature of 70-80℃ for 10-15 minutes. After cleaning and drying, the primary substrate is obtained. S12: Place the primary substrate prepared in S11 into the sample inlet chamber of the epitaxial growth equipment, bake it at a constant temperature, then place it in the growth chamber, and then introduce oxygen with a purity of 99.999%, controlling the oxygen partial pressure at 1×10⁻⁶. -4 Pa, isothermal annealing, after which the temperature is lowered to 650℃ to obtain an atomic-level substrate; S2: Target and cavity preparation. The silicon target, aluminum target, aluminum-chromium alloy target and waste wafer target for cleaning are installed on the multi-target rotating frame in the laser molecular beam epitaxial growth cavity. The target is baked to remove vapors and cooled to room temperature. The atomic-level substrate prepared in S12 is placed on the sample stage. S3: Epitaxial growth and simultaneous proton injection. The epitaxial growth temperature is 650℃, and oxygen with a purity of 99.999% is introduced, with the oxygen partial pressure controlled at 5 × 10⁻⁶. -4 Pa uses an excimer laser as a light source for thin film epitaxial growth, while simultaneously turning on a low-energy hydrogen ion source to vertically irradiate the sample growth surface until the growth is complete. S4: Subsequent processing: anneal in situ at 650℃ and oxygen partial pressure for 10-15 minutes, then anneal at 400℃ for 30 minutes in a pure oxygen atmosphere to obtain the composite optical film.

6. The method for preparing a silicon-oxygen-aluminum ternary composite optical coating material according to claim 5, characterized in that: The ultrasonic cleaning described in S11 has the following parameter settings: power 100-150W, temperature 25-40℃, duration 15-20min. The mixed solution A described in S11 is a mixed solution of ammonia water, hydrogen peroxide and deionized water, with a volume ratio of 1:1:

5. The mixed solution B described in S11 is a mixed solution of hydrochloric acid, hydrogen peroxide and deionized water, with a volume ratio of 1:1:

6. The drying process described in S11 involves blowing air with nitrogen gas of 99.999% purity.

7. The method for preparing a silicon-oxygen-aluminum ternary composite optical coating material according to claim 5, characterized in that: The constant temperature baking described in S12 has the following parameter settings: vacuum degree 1×10 -5 Pa, temperature 250~350℃, duration 1~2h; The isothermal annealing described in S12 has the following parameters: temperature 750~850℃, duration 30~60min.

8. The method for preparing a silicon-oxygen-aluminum ternary composite optical coating material according to claim 5, characterized in that: The aluminum-chromium alloy target described in S2 has an atomic percentage of 5% chromium.

9. The method for preparing a silicon-oxygen-aluminum ternary composite optical coating material according to claim 5, characterized in that: The excimer laser described in S3 has the following parameters: wavelength 248 nm, energy density 1–5 J / cm². 2 The pulse repetition frequency is 1–10 Hz; The irradiation described in S3 has the following parameter settings: ion beam energy 50–100 eV; beam current density 1–10 μA / cm. 2 .

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