Red fluorescent material and preparation method thereof
By dispersing and ball milling treatment of phthalinite with strontium and chromium sources, SrAl12O19:Cr3+ red fluorescent material was prepared, solving the problems of complex and cost in the prior art, and achieving more efficient light absorption and fluorescence intensity.
Patent Information
- Application Number
- CN202410004297.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-03
- Publication Date
- 2025-07-04
AI Technical Summary
The preparation process of existing red fluorescent materials is complex and costly, which limits its wide application in white LEDs and has poor material performance.
The phthalinated aluminite was used as the aluminum source, and dispersed with the strontium and chromium sources in hydrochloric acid solution, mixed with the ball mill and dried and sintered to prepare SrAl12O19:Cr3+ red fluorescent material, which used its unique crystal structure and morphological characteristics to improve light absorption and fluorescence intensity.
It reduces the preparation cost, improves the purity and uniformity of the red fluorescent material, expands the excitation wavelength range, and enhances the fluorescence effect.
Smart Images
Figure CN120248873A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of preparation of fluorescent materials, and particularly relates to a red fluorescent material and a preparation method thereof. Background Art
[0002] With the development of trichromatic lighting and display, the performance of blue and green phosphors is relatively good and basically meets the practical requirements. However, the performance of red phosphors is relatively poor compared to blue and green phosphors. Therefore, searching for and developing red fluorescent materials has become an urgent task for trichromatic lighting and display. Currently, the activators of red phosphors are mainly trivalent rare earth ions such as Eu 3+ , Pr 3+ , Sm 3+ and transition metal ions such as Mn 2+ . Currently, most commercial red phosphors are nitrides or oxynitrides activated by Eu 2+ . The preparation process of such fluorescent materials has relatively high requirements and needs to be carried out under high temperature and high pressure. For example, Eu 2+ doped β-SiAlON needs to be synthesized in a nitrogen atmosphere at 1900 °C and 10 atmospheres. The relatively high preparation cost limits its wide application in white LEDs. Summary of the Invention
[0003] The present invention designs a preparation method of a red fluorescent material, which includes the following steps:
[0004] Weigh pseudoboehmite, strontium source, and chromium source.
[0005] Add the strontium source and chromium source to an aqueous solution for dispersion, add hydrochloric acid until the strontium source and chromium source are dissolved, and then add ammonia water to obtain a dispersion.
[0006] Mix the pseudoboehmite and the dispersion evenly by ball milling, filter out the dispersion to obtain a mixture.
[0007] Dry and sinter the mixture to obtain a red fluorescent material SrAl 12 O 19 :Cr 3+ .
[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: The aluminum source and the strontium source exist in ionic form under the dissolution of hydrochloric acid. Using pseudoboehmite with a high specific surface area as the aluminum source, and utilizing its large pore volume to adsorb the soluble strontium source, the contact area between the aluminum source and the strontium source is increased, which is beneficial to the reaction between the raw materials to be more sufficient, and further makes the composition of the red fluorescent material purer, the impurities less, and the morphology more uniform. When irradiated with light, the red fluorescent material has a higher light absorption rate, and the refraction and reflection paths of light in the red fluorescent material are also more.
[0009] The red fluorescent material of the present invention is doped with a cheaper chromium source, Cr 3+ As the luminescence center, it can absorb the energy of the excitation light provided by the outside world for 4 T2→ 4 A2 transition, SrAl 12 O 19 As the matrix, it provides a suitable spatial doping structure for the doping of Cr 3+ At the same time, since SrAl 12 O 19 itself has a certain fluorescence ability, the addition of Cr 3+ makes it absorb external light to a greater extent, so that the red fluorescent material has a larger excitation wavelength range and stronger fluorescence effect.
[0010] Preferably, strontium source, pseudoboehmite, and chromium source are weighed according to the molar ratio of elements Sr:Al:Cr = 1:12(1 - x):12x, where 0.01% ≤ x ≤ 1%.
[0011] Preferably, the strontium source includes any one or more of strontium carbonate, strontium acetate, strontium oxalate, and strontium chloride,
[0012] The chromium source includes any one or more of chromium oxide, chromium acetate, and chromium trichloride.
[0013] Preferably, by weight, the aqueous solution is 60 - 70 parts, pseudoboehmite is 20 - 40 parts, strontium source is 1 - 6 parts, chromium source is 0.01 - 3 parts, hydrochloric acid is 1 - 5 parts, and ammonia water is 10 - 20 parts.
[0014] Preferably, after adding ammonia water, the pH of the dispersion is adjusted to neutral.
[0015] Preferably, the pseudoboehmite and the dispersion are added into a ball mill tank, the ball milling time is not less than 30 min, the dispersion is filtered out and magnetically stirred for more than 2 h to ensure that Sr 2+ and Cr 3+ are fully adsorbed on the surface of pseudoboehmite.
[0016] Preferably, the drying temperature of the drying treatment is 70 - 90 °C.
[0017] Preferably, the sintering temperature of the sintering treatment is 1400 - 1550 °C.
[0018] The beneficial effect of this preferred scheme is that the present invention is doped with a cheaper chromium source, and the highest sintering temperature is 1550 °C, reducing the preparation cost.
[0019] The present invention also designs a red fluorescent material, and the red fluorescent material is prepared by the above preparation method.
[0020] Preferably, the red fluorescent material is in the shape of a thin plate.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: SrAl 12 O 19 The matrix material belongs to the hexagonal magnetoplumbite structure and the P63 / mmc space group of the monoclinic phase. This multi-element space network structure provides the possibility for ion doping, thereby completing the luminescence composition of different luminescent ions. This unique crystal structure makes the fluorescent material more inclined to grow along the hexagonal structure during the nucleation process. At the same time, the thin plate-like morphology can greatly increase the specific surface area of the material, enabling more light to refract on the particle surface and more doped ions to be excited by light, thereby improving the light utilization rate and fluorescence intensity of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 is the XRD pattern of the red fluorescent material in the embodiment of the present invention;
[0023] Figure 2 is the SEM image of the red fluorescent material in the embodiment of the present invention;
[0024] Figure 3 is the fluorescence excitation and emission spectra of SrAl 12 O 19
[0025] Figure 4 is the fluorescence excitation and emission spectra of the red fluorescent material SrAl 12 O 19 :Cr 3+
[0026] Figure 5 is the comparison chart of the fluorescence intensity at 688 nm under the excitation of the 588 nm wavelength for SrAl 12 O 19 and SrAl 12 O 19 :Cr 3+ in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, 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.
[0028] Example 1
[0029] This embodiment provides a preparation method of a red fluorescent material, including the following steps:
[0030] (1) Weigh strontium source, pseudo-boehmite, and chromium source according to the molar ratio of elements Sr:Al:Cr = 1:12(1 - x):12x, where 0.01% ≤ x ≤ 1%. The strontium source includes strontium carbonate and strontium acetate, and the chromium source includes chromium oxide and chromium acetate. Specifically, by weight, the pseudo-boehmite is 20 parts, the weight of strontium in the strontium source is 4 parts, and the weight of chromium in the chromium source is 0.02 parts.
[0031] (2) Add the strontium source and chromium source to an aqueous solution for dispersion, add hydrochloric acid until the strontium source and chromium source dissolve, and then add ammonia water to obtain a dispersion with a neutral pH. Among them, by weight, the aqueous solution is 60 parts, hydrochloric acid is 1 part, and ammonia water is 10 parts.
[0032] (3) Add the pseudo-boehmite and the dispersion to a ball mill tank, and ball mill for 30 min. Filter out the dispersion and stir magnetically for 2 h to obtain a mixture.
[0033] (4) After drying the mixture at 70 °C, sinter it at a temperature of 1400 °C to obtain a thin plate-shaped red fluorescent material SrAl 12 O 19 :Cr 3+ 。
[0034] Example 2
[0035] This example provides a method for preparing a red fluorescent material, including the following steps:
[0036] (1) Weigh strontium source, pseudo-boehmite, and chromium source according to the molar ratio of elements Sr:Al:Cr = 1:12(1 - x):12x, where 0.01% ≤ x ≤ 1%. The strontium source includes strontium oxalate and strontium chloride, and the chromium source includes chromium acetate and chromium trichloride. Specifically, by weight, the pseudo-boehmite is 30 parts, the weight of strontium in the strontium source is 6 parts, and the weight of chromium in the chromium source is 1 part.
[0037] (2) Add the strontium source and chromium source to an aqueous solution for dispersion, add hydrochloric acid until the strontium source and chromium source dissolve, and then add ammonia water to obtain a dispersion with a neutral pH. Among them, by weight, the aqueous solution is 65 parts, hydrochloric acid is 3 parts, and ammonia water is 15 parts.
[0038] (3) Add the pseudo-boehmite and the dispersion to a ball mill tank, and ball mill for 40 min. Filter out the dispersion and stir magnetically for 2.5 h to obtain a mixture.
[0039] (4) After drying the mixture at 80 °C, sinter it at a temperature of 1500 °C to obtain a thin plate-shaped red fluorescent material SrAl 12 O 19 :Cr 3+ 。
[0040] As Figure 1 shown, the red fluorescent material of this embodiment corresponds to the diffraction peak of SrAl 12 O 19 ; as Figure 2 shown, the red fluorescent material SrAl 12 O 19 :Cr 3+ of this embodiment has a plate-like morphology. As Figures 3-4 shown, compared with SrAl 12 O 19 , the excitation wavelength of the red fluorescent material of this embodiment has an obvious red shift; as Figure 5 shown, under the excitation of the same wavelength, the fluorescence intensity of the red fluorescent material of this embodiment is significantly improved.
[0041] Example 3
[0042] This embodiment provides a preparation method of a red fluorescent material, comprising the following steps:
[0043] (1) Weigh strontium source, pseudo-boehmite, and chromium source according to the molar ratio of elements Sr:Al:Cr = 1:12(1 - x):12x, where 0.01% ≤ x ≤ 1%. The strontium source includes strontium carbonate and strontium chloride, and the chromium source includes chromium oxide and chromium trichloride. Specifically, by weight, pseudo-boehmite is 40 parts, the weight of strontium in the strontium source is 6 parts, and the weight of chromium in the chromium source is 2.5 parts.
[0044] (2) Add the strontium source and chromium source to an aqueous solution for dispersion, add hydrochloric acid until the strontium source and chromium source are dissolved, and then add ammonia water to obtain a dispersion with a neutral pH. Among them, by weight, the aqueous solution is 70 parts, hydrochloric acid is 5 parts, and ammonia water is 20 parts.
[0045] (3) Add the pseudo-boehmite and the dispersion to a ball mill jar, ball mill for 50 min, filter out the dispersion, and stir magnetically for 3 h to obtain a mixture.
[0046] (4) After drying the mixture at 90°C, sinter it at a temperature of 1550°C to obtain a plate-like red fluorescent material SrAl 12 O 19 :Cr 3+ .
[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A preparation method of a red fluorescent material, characterized in that, It includes the following steps: Weigh pseudoboehmite, strontium source, and chromium source. Add the strontium source and chromium source into an aqueous solution for dispersion, add hydrochloric acid until the strontium source and chromium source dissolve, and then add ammonia water to obtain a dispersion. Ball-mill and mix the pseudoboehmite and the dispersion evenly, filter out the dispersion to obtain a mixture. Dry and sinter the mixture to obtain a red fluorescent material.
2. The preparation method of the red fluorescent material according to claim 1, characterized in that, Weigh the strontium source, pseudoboehmite, and chromium source according to the molar ratio of elements Sr:Al:Cr = 1:12(1 - x):12x, where 0.01% ≤ x ≤ 1%.
3. The preparation method of the red fluorescent material according to claim 1, characterized in that, The strontium source includes any one or more of strontium carbonate, strontium acetate, strontium oxalate, and strontium chloride. The chromium source includes any one or more of chromium oxide, chromium acetate, and chromium trichloride.
4. The preparation method of the red fluorescent material according to claim 1, wherein, By weight, the aqueous solution is 60 - 70 parts, pseudoboehmite is 20 - 40 parts, strontium source is 1 - 6 parts, chromium source is 0.01 - 3 parts, hydrochloric acid is 1 - 5 parts, and ammonia water is 10 - 20 parts.
5. The preparation method of the red fluorescent material according to claim 1, characterized in that, After adding ammonia water, adjust the pH of the dispersion to neutral.
6. The preparation method of the red fluorescent material according to claim 1, wherein Add the pseudoboehmite and the dispersion into a ball-mill tank, the ball-milling time is not less than 30 min, filter out the dispersion, and stir magnetically for more than 2 h.
7. The preparation method of the red fluorescent material according to claim 1, wherein, The drying temperature of the drying treatment is 70 - 90°C.
8. The preparation method of the red fluorescent material according to claim 1, wherein, The sintering temperature of the sintering treatment is 1400 - 1550°C.
9. A red fluorescent material, characterized in that, The red fluorescent material is prepared by the preparation method described in any one of claims 1 - 8.
10. The red fluorescent material according to claim 9, wherein, The red fluorescent material is in the shape of a thin plate.