Coating material with high refractive index and preparation method thereof

Abstract

The invention relates to the technical field of coating materials, in particular to a high-refractive-index coating material and a preparation method thereof, and the high-refractive-index coating material comprises T O2 / A < l > 2O3 / S O2 nano laminated core-shell particles, B 2O3 and Nb2O5, the preparation method of the core-shell particles comprises the following steps: preparing a T O2 nano particle dispersion liquid from tetrabutyl titanate, mercaptoacetic acid, deionized water and a solvent, centrifuging, washing and drying to obtain T O2 doped nano particles; preparing a T O2 (at) S O2 core-shell nanoparticle dispersion liquid from the T O2 doped nanoparticles, an ethanol solution of ammonia water, tetraethyl orthosilicate, aluminum nitrate and lanthanum nitrate, and an ethanol solution of ammonia water and deionized water, centrifuging, washing and drying to obtain T O2 / A < l > 2O3 / S O2 laminated core-shell nanoparticles; the core-shell structure cooperates with the Bi 2O3 / Nb2O5 additive, so that the refractive index, the adhesive force and the environmental stability are remarkably improved, and meanwhile, the extinction coefficient is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of coating materials, and in particular to a high-refractive-index coating material and a preparation method thereof. Background Art

[0002] Among optical coating materials, the selection of high-refractive-index materials suitable for electron-beam evaporation is very limited. Most high-refractive-index materials are oxides of titanium, zirconium, hafnium, tantalum, and niobium, as well as mixtures thereof or with other metal oxides. In this technical field, coating with mixtures can alter the refractive index of a single oxide optical film layer, expanding the range of materials available for optical film design and improving properties such as stress in the film.

[0003] In high-end optical devices (such as AR / VR lenses and high numerical aperture microscope objectives), the refractive index (n) of the coating material directly determines the optical efficiency and miniaturization potential of the device. Among the current mainstream materials:

[0004] Although TiO2-based films have a high refractive index (n≈2.0-2.6), there is a sharp increase in the extinction coefficient (>10 -3 @550nm, and easy to desorb in hot and humid environment (Δn>200×10 -4 );

[0005] Although Nb2O5 / Bi2O5 mixed oxides (n≈2.0-2.2) have good stability, the sintering temperature >2000℃ leads to excessive energy consumption, and the high Bi content causes grain boundary brittleness (adhesion Lc<20N).

[0006] Attempts to modify core-shell structures and their limitations

[0007] In order to improve the interface bonding, the existing technology proposes a core-shell particle design: CN112266130A adopts a TiO2@SiO2 core-shell structure, but a single SiO2 shell (CTE≈0.5×10 -6 / ℃) and TiO2 core (CTE≈9×10 -6 / ℃) thermal expansion mismatch leads to film cracking (adhesion Lc≤18N); JP2020159502A introduces an Al2O3 intermediate layer, which improves the bonding strength but does not solve the problem of insufficient shell density. Water and oxygen permeation still makes Δn>150×10 -4 (85℃ / 85%RH, 500h).

[0008] The dilemma of high refractive index and low loss

[0009] Theoretical studies have shown that increasing the refractive index of a material is usually accompanied by the following sacrifices:

[0010] Light scattering enhancement: Nanoparticle interface defects increase the extinction coefficient (such as in Comparative Example 1, k = 8.5 × 10 -4 );

[0011] Environmental stability decreases: Highly active surface accelerates the adsorption of water molecules (such as in comparative example 3, Δn = 280 × 10 -4 );

[0012] The process complexity increases dramatically: To maintain n>2.0, precious metal doping (such as Au@TiO2) needs to be introduced, which increases the cost by 5-10 times. Summary of the Invention

[0013] The purpose of the present invention is to provide a high refractive index coating material and its preparation method, design a TiO2 / Al2O3 / SiO2 stacked core-shell structure, through the Al2O3 transition layer (CTE≈7×10 -6 / ℃) to buffer thermal stress; introduce a lanthanum-doped shell to passivate oxygen vacancies, simultaneously reducing optical loss and diffusion channels; develop a Bi2O3 / Nb2O5 low-temperature eutectic sintering system (eutectic point ≈1850℃) to achieve densification with a porosity of <1%.

[0014] The purpose of the present invention can be achieved through the following technical solutions:

[0015] A high-refractive-index coating material comprising: TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5; wherein the weight ratios of the TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 are 40-80, 1-15, and 1-10, respectively;

[0016] The preparation process of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles comprises the following steps:

[0017] A TiO2 nanoparticle dispersion was prepared with tetrabutyl titanate, thioglycolic acid, deionized water and solvent, and the TiO2 doped nanoparticles were obtained by centrifugation, washing and drying.

[0018] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0019] As a further embodiment of the present invention: the solvent is one or both of ethanol and methanol.

[0020] As a further solution of the present invention: the mass concentration of tetrabutyl titanate is 0.5-2%; the mass concentration of thioglycolic acid is 0.04-0.2%.

[0021] As a further solution of the present invention: the mass concentration of the TiO2-doped nanoparticles is 0.2-1%; the mass concentration of the ammonia water is 2-11%.

[0022] As a further solution of the present invention: the mass concentration of the ethanol solution of tetraethyl orthosilicate is 5-15%.

[0023] As a further solution of the present invention: the mass concentration of the aluminum nitrate ethanol solution is 5-15%.

[0024] As a further solution of the present invention: the mass concentration of the lanthanum nitrate ethanol solution is 0.5-1.5%.

[0025] As a further solution of the present invention: the mass concentration of the ethanol solution of ammonia water and deionized water is 10-20%.

[0026] As a further solution of the present invention: the reaction temperature is 20-30°C, and the reaction time is 24-36h.

[0027] A method for preparing a high-refractive-index coating material comprises the following steps:

[0028] Step 1: preparing a TiO2 nanoparticle dispersion using tetrabutyl titanate, thioglycolic acid, deionized water, and a solvent, centrifuging, washing, and drying to obtain TiO2-doped nanoparticles;

[0029] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0030] Step 2: Mix TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles with Bi2O3 and Nb2O5 in the above proportions and grind them into powders of 0.05-6 μm;

[0031] Step 3: Sinter the powder and cool it after the reaction is completed to obtain the coating material; the sintering process includes: heating to 900°C at a rate of 10°C / min in a vacuum environment, then heating to 1800°C at a rate of 3°C / min and keeping the temperature constant for at least 30 minutes, and then heating to 1900±50°C at a rate of 1°C / min. At this time, the reaction liquid surface of the small particles melts and the reaction is maintained at a constant temperature.

[0032] Beneficial effects of the present invention:

[0033] The coating material prepared by the present invention from TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 has the following effects:

[0034] A synergistic breakthrough in ultra-high refractive index and low optical loss

[0035] Through the synergistic effect of TiO2 / Al2O3 / SiO2 nano-laminated core-shell structure (core layer refractive index>2.5, shell layer hermetically sealed) and Bi2O3 / Nb2O5 high polarizability oxides, the refractive index n≥2.08-2.35 at a wavelength of 550nm in the visible light region is achieved, which is 12%-26% higher than that of conventional optical coating materials;

[0036] Lanthanum doping at the core-shell interface (La 3+ ) effectively passivates oxygen vacancy defects and reduces the extinction coefficient to 0.3-1.2×10 -4 , which is reduced by 76%-94% compared with the undoped system, reaching near-infrared level optical cleanliness.

[0037] Double improvement of membrane-base bonding strength and environmental stability

[0038] The Al2O3 / SiO2 layer on the surface of the core-shell particles provides active hydroxyl groups, forming a strong chemical bond with the matrix, making the critical adhesion of the film reach 38-52N, which is 153%-247% higher than that of the system without core-shell structure;

[0039] The water and oxygen barrier effect of the laminated shell and La 3+ The grain boundary densification effect is synergistic, making the refractive index drift Δn≤35×10 -4 (Examples 1-3), the stability is comparable to that of competing materials (Comparative Example 4, Δn = 120 × 10 -4 ) 3-15 times (Example 3, Δn=8×10 -4 ).

[0040] Controllable material properties brought about by process innovation

[0041] The thickness of the Al2O3 / SiO2 stack in the core-shell particles is controlled by the concentration gradient of aluminum nitrate / tetraethyl orthosilicate (0.5%-15%), achieving an adjustable shell thickness of 10-100nm to adapt to different substrate thermal expansion coefficients;

[0042] The sintering process adopts three-stage temperature control (900℃→1800℃→1850-1950℃), forming liquid phase filling at the Bi2O3-Nb2O5 eutectic point (≈1850℃), eliminating the grain boundary porosity by more than 99% (SEM verification), breaking through the traditional solid-phase sintering densification bottleneck.

[0043] Industrial application advantages of comprehensive performance

[0044] When the refractive index n>2.22, k<1×10 -4, solving the absorption loss problem commonly found in high-refractive materials;

[0045] Under the same refractive index index (n≈1.95), the environmental stability is improved by 5 times compared with the undoped lanthanum system (Comparative Example 2), and the service life of optical devices in a humid and hot environment is extended by more than 3 times (verified by accelerated aging experiments). DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0047] Example 1

[0048] An embodiment of the present invention provides a high-refractive-index coating material comprising: TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5; wherein the weight ratio of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 is 40:1:1;

[0049] More specifically, the preparation process of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles includes the following steps:

[0050] A TiO2 nanoparticle dispersion was prepared with tetrabutyl titanate, thioglycolic acid, deionized water and solvent, and the TiO2 doped nanoparticles were obtained by centrifugation, washing and drying.

[0051] The solvent is one or both of ethanol and methanol; the mass concentration of tetrabutyl titanate is 0.5%; the mass concentration of thioglycolic acid is 0.04%; the mass concentration of deionized water is 2%; and the reaction time is 2 hours.

[0052] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0053] The mass concentration of TiO2-doped nanoparticles is 0.2%; the mass concentration of ammonia water is 2%;

[0054] The mass concentration of the ethanol solution of tetraethyl orthosilicate is 5%, the mass concentration of the ethanol solution of aluminum nitrate is 5%, and the mass concentration of the ethanol solution of lanthanum nitrate is 0.5%; the mass concentration of the ethanol solution of ammonia water and deionized water is 10%; the reaction temperature is 20° C., and the reaction time is 24 hours.

[0055] An embodiment of the present invention also provides a method for preparing a high-refractive-index coating material, comprising the following steps:

[0056] Step 1: preparing a TiO2 nanoparticle dispersion using tetrabutyl titanate, thioglycolic acid, deionized water, and a solvent, centrifuging, washing, and drying to obtain TiO2-doped nanoparticles;

[0057] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0058] Step 2: Mix the TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles with Bi2O3 and Nb2O5 in the above proportions and grind them into 0.05 μm powder;

[0059] Step 3: Sinter the powder and cool it after the reaction is completed to obtain the coating material; the sintering process includes: heating to 900°C at a rate of 10°C / min in a vacuum environment, then heating to 1800°C at a rate of 3°C / min and keeping the temperature constant for at least 30 minutes, and then heating to 1850°C at a rate of 1°C / min. At this time, the reaction liquid surface of the small particles melts and the reaction is maintained at a constant temperature.

[0060] Example 2

[0061] An embodiment of the present invention provides a high-refractive-index coating material comprising: TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5; wherein the weight ratio of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 is 60:8:5;

[0062] More specifically, the preparation process of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles includes the following steps:

[0063] A TiO2 nanoparticle dispersion was prepared with tetrabutyl titanate, thioglycolic acid, deionized water and solvent, and the TiO2 doped nanoparticles were obtained by centrifugation, washing and drying.

[0064] The solvent is one or both of ethanol and methanol; the mass concentration of tetrabutyl titanate is 1.2%; the mass concentration of thioglycolic acid is 0.12%; the mass concentration of deionized water is 6%; and the reaction time is 2.5 hours.

[0065] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0066] The solvent is one or both of ethanol and methanol; the mass concentration of TiO2 nanoparticles is 0.6%; the mass concentration of ammonia water is 6%;

[0067] The mass concentration of the ethanol solution of tetraethyl orthosilicate is 10%, the mass concentration of the ethanol solution of aluminum nitrate is 10%, and the mass concentration of the ethanol solution of lanthanum nitrate is 1.0%; the mass concentration of the ethanol solution of ammonia water and deionized water is 15%; the reaction temperature is 25° C., and the reaction time is 29 hours.

[0068] An embodiment of the present invention also provides a method for preparing a high-refractive-index coating material, comprising the following steps:

[0069] Step 1: preparing a TiO2 nanoparticle dispersion using tetrabutyl titanate, thioglycolic acid, deionized water, and a solvent, centrifuging, washing, and drying to obtain TiO2-doped nanoparticles;

[0070] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0071] Step 2: Mix TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles with Bi2O3 and Nb2O5 in the above proportions and grind into 0.6 μm powder;

[0072] Step 3: Sinter the powder and cool it after the reaction is completed to obtain the coating material; the sintering process includes: heating to 900°C at a rate of 10°C / min in a vacuum environment, then heating to 1800°C at a rate of 3°C / min and keeping the temperature constant for at least 30 minutes, and then heating to 1950°C at a rate of 1°C / min. At this time, the reaction liquid surface of the small particles melts and the reaction is maintained at a constant temperature.

[0073] Example 3

[0074] An embodiment of the present invention provides a high-refractive-index coating material comprising TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5; wherein the weight ratio of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 is 80, 15, and 10;

[0075] More specifically, the preparation process of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles includes the following steps:

[0076] A TiO2 nanoparticle dispersion was prepared with tetrabutyl titanate, thioglycolic acid, deionized water and solvent, and the TiO2 doped nanoparticles were obtained by centrifugation, washing and drying.

[0077] The solvent is one or both of ethanol and methanol; the mass concentration of tetrabutyl titanate is 2%; the mass concentration of thioglycolic acid is 0.2%; the mass concentration of deionized water is 10%; and the reaction time is 3 hours.

[0078] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0079] The solvent is one or both of ethanol and methanol; the mass concentration of TiO2 nanoparticles is 1%; the mass concentration of ammonia water is 11%;

[0080] The mass concentration of the ethanol solution of tetraethyl orthosilicate is 15%, the mass concentration of the ethanol solution of aluminum nitrate is 15%, and the mass concentration of the ethanol solution of lanthanum nitrate is 1.5%; the mass concentration of the ethanol solution of ammonia water and deionized water is 20%; the reaction temperature is 30° C., and the reaction time is 36 hours.

[0081] An embodiment of the present invention also provides a method for preparing a high-refractive-index coating material, comprising the following steps:

[0082] Step 1: preparing a TiO2 nanoparticle dispersion using tetrabutyl titanate, thioglycolic acid, deionized water, and a solvent, centrifuging, washing, and drying to obtain TiO2-doped nanoparticles;

[0083] TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

[0084] Step 2: Mix TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles with Bi2O3 and Nb2O5 in the above proportions and grind into 6 μm powder;

[0085] Step 3: Sinter the powder and cool it after the reaction is completed to obtain the coating material; the sintering process includes: heating to 900°C at a rate of 10°C / min in a vacuum environment, then heating to 1800°C at a rate of 3°C / min and keeping the temperature constant for at least 30 minutes, and then heating to 1950°C at a rate of 1°C / min. At this time, the reaction liquid surface of the small particles melts and the reaction is maintained at a constant temperature.

[0086] Comparative Example

[0087] The design process of Comparative Example 1 is as follows, and Comparative Example 1 is improved based on Example 1;

[0088]

[0089] Performance test methods and conditions

[0090] Refractive index (n) & extinction coefficient (k);

[0091] Equipment: Ellipsometer (JA Woollam M2000);

[0092] Wavelength: 550nm, incident angle 70°;

[0093] hardness

[0094] Standard: ISO 14577 nanoindentation (Berkovich indenter)

[0095] Load: 50mN, hold load 15s;

[0096] Film adhesion

[0097] Standard: ISO 20502 scratch test

[0098] Critical load (Lc) determination: acoustic emission signal mutation + optical microscope verification;

[0099] Environmental stability

[0100] Damp heat aging: 85℃ / 85%RH, 500h;

[0101] Refractive index drift: Δn = n_after aging - n_initial.

[0102] The test results are shown in the following table

[0103]

[0104] As can be seen from the above table, the core-shell structures of Examples 1-3, in conjunction with the Bi2O3 / Nb2O5 additives, significantly improve the refractive index (up to 2.35), adhesion, and environmental stability, while reducing the extinction coefficient. Specifically:

[0105] Optical properties: refractive index and extinction coefficient

[0106] The key role of the core-shell structure (Comparative Example 1):

[0107] The refractive index of ordinary TiO2 powder (Comparative Example 1, n = 1.92) is significantly lower than that of the core-shell structure (Example 1, n = 2.08). The core-shell particles (TiO2@SiO2 / Al2O2) increase the refractive index through enhanced interfacial light scattering and dense stacking.

[0108] Bi2O3 / Nb2O5 synergistic effect (Comparative Example 3):

[0109] The refractive index is the lowest when only core-shell particles are present (n=1.85). The introduction of Bi2O3 (high polarizability) and Nb2O5 (high dielectric constant) fills the grain boundary voids, enhancing the material density and polarization response.

[0110] Lanthanum doping suppresses optical loss (Comparative Example 2):

[0111] The extinction coefficient of the comparative example 2 without lanthanum doping (5.0×10 -4 ) is higher than that in Example 1 (1.2×10 -4 ), indicating that La 3+ Effectively passivate surface defects and reduce light scattering centers.

[0112] Example 3 Performance Peak:

[0113] The high core-shell particle ratio (80 parts) and optimized additive ratio achieve n = 2.35 (26% higher than the competitor) and the lowest extinction coefficient (0.3×10 -4 ), reaching near-infrared optical cleanliness.

[0114] Mechanical properties: film adhesion

[0115] Core-shell structure improves interfacial bonding:

[0116] The Al2O3 / SiO2 layer on the surface of the core-shell particles provides active hydroxyl groups, which enhances the chemical bonding with the matrix (compared with Comparative Example 1: Lc=15N → Example 1: Lc=38N, an increase of 153%).

[0117] Additives optimize cohesion:

[0118] Bi2O3 / Nb2O5 forms a high-strength grain boundary phase during sintering (Comparative Example 3: Lc=12N), and

[0119] As the addition ratio increases (Example 1→3), the adhesion continues to improve.

[0120] Environmental stability: refractive index drift under damp heat aging

[0121] Core-shell structure blocks water and oxygen penetration:

[0122] Comparative Example 1 (without core-shell) has a Δn as high as 210×10-4, while Example 1 has a Δn of only 35×10 -4 , confirming that the SiO2 / Al2O3 shell effectively shields environmental corrosion.

[0123] Lanthanum doping improves density (Comparative Example 2):

[0124] When not doped with lanthanum, Δn=95×10-4, La 3+ Refine the grains, block the grain boundary channels, and reduce the diffusion path of water molecules.

[0125] Example 3 Extreme Stability:

[0126] Δn=8×10-4 (only 1 / 15 of the competitor's product), attributed to the ultra-dense microstructure formed by the high core-shell content (80 parts) and the optimized sintering process (1950℃).

[0127] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A high refractive index coating material, characterized in that: include: TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, Nb2O5; wherein the weight ratios of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles, Bi2O3, and Nb2O5 are 40-80, 1-15, and 1-10; The preparation process of TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles comprises the following steps: A TiO2 nanoparticle dispersion was prepared with tetrabutyl titanate, thioglycolic acid, deionized water and solvent, and the TiO2 doped nanoparticles were obtained by centrifugation, washing and drying. TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying.

2. The high refractive index coating material according to claim 1, characterized in that: The solvent is one or both of ethanol and methanol.

3. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of tetrabutyl titanate is 0.5-2%; the mass concentration of thioglycolic acid is 0.04-0.2%.

4. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of the TiO2-doped nanoparticles is 0.2-1%; the mass concentration of the ammonia water is 2-11%.

5. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of the ethanol solution of tetraethyl orthosilicate is 5-15%.

6. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of the aluminum nitrate ethanol solution is 5-15%.

7. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of the lanthanum nitrate ethanol solution is 0.5-1.5%.

8. The high refractive index coating material according to claim 1, characterized in that: The mass concentration of the ethanol solution of ammonia water and deionized water is 10-20%.

9. The high refractive index coating material according to claim 1, characterized in that: The reaction temperature is 20-30°C and the reaction time is 24-36h.

10. A method for preparing a high refractive index coating material, characterized in that: The following steps are involved: Step 1: preparing a TiO2 nanoparticle dispersion using tetrabutyl titanate, thioglycolic acid, deionized water, and a solvent, centrifuging, washing, and drying to obtain TiO2-doped nanoparticles; TiO2@SiO2 core-shell nanoparticle dispersions were prepared using TiO2-doped nanoparticles, ammonia, tetraethyl orthosilicate, aluminum nitrate, lanthanum nitrate in ethanol, and ammonia and deionized water in ethanol. TiO2 / Al2O3 / SiO2 nanolaminated core-shell particles were obtained by centrifugation, washing, and drying. Step 2: Mix TiO2 / Al2O3 / SiO2 nano-laminated core-shell particles with Bi2O3 and Nb2O5 in the above proportions and grind them into powders of 0.05-6 μm; Step 3: Sinter the powder and cool it after the reaction is completed to obtain the coating material; the sintering process includes: heating to 900°C at a rate of 10°C / min in a vacuum environment, then heating to 1800°C at a rate of 3°C / min and keeping the temperature constant for at least 30 minutes, and then heating to 1900±50°C at a rate of 1°C / min. At this time, the reaction liquid surface of the small particles melts and the reaction is maintained at a constant temperature.

Images