A Cr 3+ Ion-doped transparent gamma-Al2O3 luminescent ceramic and method of making same

Abstract

The application provides a kind of Cr 3+ Preparation method of ion-doped transparent gamma-Al2O3 luminescent nanoceramics, and a kind of Cr 3+ Ion-doped transparent gamma-Al2O3 luminescent nanoceramics, when the incident wavelength is more than 700nm, the light transmittance is greater than 66%. First, 1g AlCl3 and 0-0.01g CrCl3·6H2O are added to 40mL anhydrous ethanol and mixed uniformly; then the mixed solution is poured into a reaction kettle, sealed and kept at 180℃ for 36 hours; after the reaction is completed, the product is collected and dispersed in anhydrous ethanol for centrifugation; the colloidal product obtained by centrifugation is laid on a culture dish, dried at 60℃ for 12 hours; the small pieces obtained by drying are put into a crucible and calcined at 800℃ for 1 hour to obtain Cr 3+ Ion-doped transparent gamma-Al2O3 luminescent nanoceramics. The Cr 3+ Ion-doped transparent gamma-Al2O3 ceramic is a block formed by interweaving nanobands, and the ceramic emits red fluorescence under green light irradiation at 530nm.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of inorganic oxide transparent ceramics, and specifically relates to a Cr 3+ Ion-doped transparent γ-Al2O3 luminescent nanoceramics. Background Art

[0002] Transparent ceramics combine the advantages of glass and single crystals for light transmission with the high-temperature and corrosion-resistant properties of ceramics, offering a broad range of applications. Since the development of the first transparent Al2O3 ceramic, "Lucalox," in the late 1950s, transparent ceramics have made significant progress over the past few decades, finding applications in laser gain media, transparent armor, aerospace windows, solid-state lighting, and magneto-optical materials. Generally speaking, materials with highly symmetrical crystal structures are more readily suited for preparing transparent ceramics. Low-symmetry grains exhibit optical anisotropy, which can cause birefringence and affect the material's transparency. Consequently, most transparent ceramics have a cubic structure. γ-Al2O3 is the most common intermediate form of aluminum oxide, with a face-centered cubic lattice that is stable at low temperatures. Theoretically, it should be able to transmit light over a wide wavelength range (from the deep ultraviolet to the mid-infrared). However, research on bulk transparent γ-Al2O3 ceramics is limited. In 2021, Beauvoir et al. prepared translucent γ-AlOOH bulk materials under uniaxial pressure of 500 MPa and temperatures below 400°C. Annealing in ambient air at 500°C produced translucent γ-Al2O3 glass-ceramics. However, the resulting γ-Al2O3 glass-ceramics contained an amorphous phase, and the actual online transmittance of the material was not reported. In 2023, Chen et al. used a combination of homogeneous precipitation and high pressure to prepare bulk γ-Al2O3 transparent ceramics under the optimal conditions of 5 GPa and 300°C. The resulting ceramics had Vickers hardness and compressive strength comparable to sapphire, and a maximum transmittance of 86%, demonstrating the feasibility of preparing highly transparent γ-Al2O3 bulk transparent ceramics with excellent mechanical properties. In 2024, Gao et al. used γ-Al2O3 powder as the raw material and prepared a translucent ceramic with a transmittance of 16% at around 800 nm by cold sintering.

[0003] Near-infrared light has strong penetrating power and can be absorbed by some molecular features, and can be widely used in plant growth, food analysis, medical imaging and other fields. Due to its unique atomic structure, the transition metal ion Cr 3+ Ion-doped materials have good luminescence effects and adjustable broadband luminescence in the near-infrared region, and have shown great application potential in the production of pc-LEDs, lighting and spectral analysis. Ruby (Cr 3+Chromium-doped aluminum oxide is one of the earliest laser materials. Existing chromium-doped near-infrared luminescent materials still have defects, such as low thermal quenching temperature. There is an urgent need to develop more efficient, thermally stable near-infrared luminescent materials with longer emission wavelengths. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] 1. Provide a method for preparing Cr 3+ Method for ion-doped transparent γ-Al2O3 luminescent nanoceramics;

[0006] 2. Provide a Cr prepared by the above method 1. 3+ The ion-doped transparent γ-Al2O3 luminescent nanoceramics have good optical transparency and the doped ceramics have good photoluminescence effect in the range of 650-800nm.

[0007] The specific technical solutions of the present invention are as follows:

[0008] Anhydrous aluminum chloride, chromium chloride hexahydrate and anhydrous ethanol are used as raw materials. First, anhydrous aluminum chloride and anhydrous ethanol are mixed evenly in a ratio of 40 mL of anhydrous ethanol per gram of anhydrous aluminum chloride. Then, 0-0.01 g of CrCl3·6H2O are weighed and added to the mixed solution of anhydrous aluminum chloride and anhydrous ethanol and mixed evenly. Then, the mixed solution is poured into a reactor and sealed and kept warm at 180°C for 36 hours. After the reaction is completed, the reactor is cooled naturally to room temperature, the product is collected and dispersed in anhydrous ethanol and centrifuged. The colloidal product obtained by centrifugation is spread flat on a petri dish and dried at 60°C for 12 hours. The dried small pieces are placed in a crucible and calcined at 800°C for 1 hour to obtain Cr 3+ Ion-doped transparent γ-Al2O3 luminescent nanoceramics. The molar ratios of CrCl3·6H2O and anhydrous AlCl3 are 0.2:99.8, 0.4:99.6, and 0.5:99.5, respectively.

[0009] The Cr prepared by the present invention 3+ The ion-doped transparent γ-Al2O3 luminescent nanoceramics are formed by interweaving and stacking nanobelts. The nanobelts are 50-100nm long, 5-30nm wide, and about 3nm thick. There are pores between the nanobelts, and the porosity is 60%-75%.

[0010] The Cr prepared by the present invention 3+ The ion-doped transparent γ-Al2O3 luminescent nanoceramics have good optical transparency and emit red fluorescence under 530nm green light. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1The bulk transparent γ-Al2O3 nano-ceramics and Cr prepared in Example 1, Example 2, Example 3 and Example 4 are 3+ Photo of ion-doped transparent γ-Al2O3 luminescent nanoceramics.

[0012] Figure 2 The bulk transparent γ-Al2O3 nano-ceramics and Cr prepared in Example 1, Example 2, Example 3 and Example 4 are 3+ Transmittance curve of ion-doped transparent γ-Al2O3 luminescent nanoceramics.

[0013] Figure 3 The bulk transparent γ-Al2O3 nano-ceramics and Cr prepared in Example 1, Example 2, Example 3 and Example 4 are 3+ XRD pattern of ion-doped transparent γ-Al2O3 luminescent nanoceramics.

[0014] Figure 4 The bulk transparent γ-Al2O3 nano-ceramics and Cr prepared in Example 1, Example 2 and Example 4 are 3+ Emission spectrum of ion-doped transparent γ-Al2O3 luminescent nanoceramics under excitation at a wavelength of 530nm.

[0015] Figure 5 The Cr-2O3 prepared in Example 2 has a molar ratio of 0.2:99.8. 3+ SEM image of ion-doped γ-Al2O3 luminescent ceramics. DETAILED DESCRIPTION

[0016] Example 1

[0017] Using anhydrous aluminum chloride and anhydrous ethanol as raw materials, first weigh 1g of anhydrous aluminum chloride and add it to a beaker containing 40mL of anhydrous ethanol, and mix it evenly with a magnetic stirrer; then pour the mixed solution into a reactor, seal it and keep it warm at 180°C for 36 hours; after the reaction is completed, wait for it to cool naturally to room temperature, collect the product and disperse it in anhydrous ethanol by centrifugation; the colloidal product obtained by centrifugation is spread flat on a petri dish and dried at 60°C for 12 hours; the dried small pieces are placed in a crucible and calcined at 800°C for 1 hour to obtain γ-Al2O3 transparent nanoceramics.

[0018] Figure 1 A photo of the γ-Al2O3 transparent nanoceramic prepared in Example 1 is given. The ceramic is a translucent block.

[0019] Figure 2The transmittance curve of the 0.5mm thick γ-Al2O3 transparent nanoceramic prepared in Example 1 is shown. The ceramic has high transparency in the long-wavelength direction. When the incident wavelength exceeds 550nm, the light transmittance is greater than 60%; when the incident wavelength exceeds 700nm, the light transmittance is greater than 76%.

[0020] Figure 3 The XRD pattern of the transparent γ-Al2O3 ceramic prepared in Example 1 is given, and the diffraction peak can be indexed to the cubic structure of γ-Al2O3.

[0021] Figure 4 The emission spectrum of the γ-Al2O3 nanoceramic prepared in Example 1 under excitation at a wavelength of 530 nm is given. The γ-Al2O3 nanoceramic has no emission peak in the range of 600-800 nm.

[0022] Example 2

[0023] Anhydrous aluminum chloride, chromium chloride hexahydrate and anhydrous ethanol are used as raw materials. First, 1g of anhydrous aluminum chloride is weighed and added to a beaker containing 40mL of anhydrous ethanol and mixed evenly with a magnetic stirrer. Then, 0.004g of CrCl3·6H2O is weighed and added to the mixed solution of anhydrous aluminum chloride and anhydrous ethanol and mixed evenly. Then, the mixed solution is poured into a reactor and sealed and kept warm at 180°C for 36 hours. After the reaction is completed, it is allowed to cool naturally to room temperature, the product is collected and dispersed in anhydrous ethanol and centrifuged. The colloidal product obtained by centrifugation is spread flat on a petri dish and dried at 60°C for 12 hours. The dried small pieces are placed in a crucible and calcined at 800°C for 1 hour to obtain Al 1.996 Cr 0.004 O3 transparent luminescent ceramics.

[0024] Figure 1 The Al prepared in Example 2 is given. 1.996 Cr 0.004 Photo of O3 transparent luminescent ceramic, which is a yellow translucent block.

[0025] Figure 2 The Cr film with a molar ratio of 0.2:99.8 and a thickness of 0.5 mm prepared in Example 2 is given. 3+ The transmittance curve of ion-doped transparent γ-Al2O3 luminescent ceramics shows that the ceramic has high transparency in the long-wave direction. When the incident wavelength exceeds 550nm, the light transmittance is greater than 56%; when the incident wavelength exceeds 700nm, the light transmittance is greater than 72%.

[0026] Figure 3 The Cr with a molar ratio of 0.2:99.8 prepared in Example 2 is given. 3+The XRD pattern of ion-doped transparent γ-Al2O3 luminescent ceramic, no extra diffraction peak appeared after doping, indicating that the doping did not change the crystal structure of the material.

[0027] Figure 4 The photo of Al2O3 transparent nanoceramic prepared in Example 3 is given, and the ceramic is a yellow translucent block. 3+ The emission spectrum of ion-doped transparent γ-Al2O3 luminescent ceramic under 530 nm wavelength excitation, the ceramic has a broadband emission peak in the range of 650-800 nm, with a peak at 691 nm.

[0028] Figure 5 The photo of Al2O3 transparent nanoceramic prepared in Example 3 is given, and the ceramic is a yellow translucent block. 3+ The SEM image of ion-doped transparent γ-Al2O3 luminescent ceramic, it can be seen that the ceramic is composed of nanobands interwoven and stacked, and there are nanopores between the nanobands.

[0029] This embodiment is the best embodiment.

[0030] Example 3

[0031] Anhydrous aluminum chloride, chromium chloride hexahydrate and anhydrous ethanol were used as raw materials. First, 1 g of anhydrous aluminum chloride was weighed into a beaker containing 40 mL of anhydrous ethanol and mixed uniformly with a magnetic stirrer. Then, 0.008 g of CrCl3·6H2O was added to the mixed solution of anhydrous aluminum chloride and anhydrous ethanol, and mixed uniformly. The mixed solution was then poured into a reaction kettle and sealed for 36 hours at 180°C. After the reaction was completed, it was naturally cooled to room temperature, and the product was collected and dispersed in anhydrous ethanol for centrifugation. The gel product obtained by centrifugation was spread on a petri dish and dried at 60°C for 12 hours. The small pieces obtained by drying were placed in a crucible and calcined at 800°C for 1 hour to obtain Al2O3 transparent luminescent ceramic. 1.992 Cr 0.008 O3 transparent luminescent ceramic.

[0032] Figure 1 The photo of Al2O3 transparent nanoceramic prepared in Example 3 is given, and the ceramic is a yellow translucent block. 1.992 Cr 0.008 O3 transparent luminescent ceramic.

[0033] Figure 2 The photo of Al2O3 transparent nanoceramic prepared in Example 3 is given, and the ceramic is a yellow translucent block. 3+ The transmittance curve of ion-doped transparent γ-Al2O3 luminescent ceramic, the ceramic has high transparency in the long-wave direction, but is lower than the undoped γ-Al2O3 transparent nanoceramic and the Cr 3+The doped γ-Al2O3 transparent nanoceramics has a light transmittance of more than 46% when the incident wavelength is more than 550 nm, and a light transmittance of more than 66% when the incident wavelength is more than 700 nm.

[0034] Figure 3 The Cr 3+ The XRD pattern of the ion-doped transparent γ-Al2O3 luminescent ceramics shows no extra diffraction peaks after doping, indicating that the doping does not change the crystal structure of the material.

[0035] Example 4

[0036] Anhydrous aluminum chloride, chromium chloride hexahydrate and anhydrous ethanol were used as raw materials. First, 1 g of anhydrous aluminum chloride was weighed into a beaker containing 40 mL of anhydrous ethanol and mixed uniformly with a magnetic stirrer. Then, 0.01 g of CrCl3·6H2O was weighed into the mixed solution of anhydrous aluminum chloride and anhydrous ethanol and mixed uniformly. The mixed solution was then poured into a reaction kettle and sealed for 36 hours at 180°C. After the reaction was completed, the product was collected and dispersed in anhydrous ethanol after natural cooling to room temperature. The gelatinous product obtained by centrifugation was spread on a petri dish and dried at 60°C for 12 hours. The small pieces obtained by drying were placed in a crucible and calcined at 800°C for 1 hour to obtain Al 1.990 Cr 0.010 O3 transparent nanoceramics.

[0037] Figure 1 The photo of the Al 1.990 Cr 0.010 O3 transparent nanoceramics prepared in Example 4 is shown. The ceramic is a yellow translucent block.

[0038] Figure 2 The Cr 3+ The transmittance curve of the ion-doped transparent γ-Al2O3 luminescent ceramics is shown. The ceramic has a higher transparency in the long-wave direction, but is lower than the transmittance obtained in the previous three examples. The light transmittance is more than 40% when the incident wavelength is more than 550 nm, and more than 66% when the incident wavelength is more than 700 nm.

[0039] Figure 3 The Cr 3+ The XRD pattern of the ion-doped transparent γ-Al2O3 luminescent ceramics shows no extra diffraction peaks after doping, indicating that the doping does not change the crystal structure of the material.

[0040] Figure 4The Cr-doped transparent γ-AI2O3 nanoceramics obtained in Example 4 with a molar ratio of 0.5:99.5 3+ The emission spectrum of the ion-doped transparent γ-AI2O3 nanoceramics under excitation at a wavelength of 530 nm shows a broad emission peak in the range from 650 to 800 nm with a maximum at 691 nm, the luminescence intensity being lower than that of the Cr-doped transparent γ-AI2O3 nanoceramics with a molar ratio of 0.2:99.8 3+ Ion-doped transparent γ-AI2O3 nanoceramics.

Claims

1. A Cr 3+ ion-doped transparent γ-Al2O3 luminescent ceramic, and the chemical formula of the product is γ-Al 2-x Cr x O3 (0 < x ≤ 0.01), which is characterized in that: The ceramic is a block formed by interweaving nanobelts. The nanobelts are 50-100 nm long, 5-30 nm wide, and about 3 nm thick. There are pores between the nanobelts with a porosity of 60%-75%. 3+ After ion doping, the ceramic can still maintain a high degree of transparency. When the incident wavelength exceeds 550 nm, the light transmittance is greater than 40%; when the incident wavelength exceeds 700 nm, the light transmittance is greater than 66%. In addition, Cr 3+ The ion-doped transparent γ-Al2O3 luminescent ceramics have good photoluminescence properties in the range of 650-800 nm, with the emission peak located at 691 nm.

2. A Cr 3+ The preparation method of ion-doped transparent γ-Al2O3 luminescent ceramics is characterized by: First, 1 g of anhydrous aluminum chloride was weighed and added to a beaker containing 40 mL of anhydrous ethanol and mixed evenly with a magnetic stirrer. Then, 0.004-0.01 g of CrCl3·6H2O was weighed and added to the mixed solution of anhydrous aluminum chloride and anhydrous ethanol and mixed evenly. The mixed solution was then poured into a reactor and sealed and kept warm at 180°C for 36 hours. After the reaction was completed, it was allowed to cool naturally to room temperature, the product was collected and dispersed in anhydrous ethanol and centrifuged. The colloidal product obtained by centrifugation was spread flat on a petri dish and dried at 60°C for 12 hours. The dried small pieces were placed in a crucible and calcined at 800°C for 1 hour to obtain CrCl3. 3+ Ion-doped transparent γ-Al2O3 luminescent ceramics.

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