Preparation method of high-efficiency red fluorescent powder excited by near-ultraviolet broadband

Abstract

The application discloses a preparation method of a high-efficiency red fluorescent powder excited by a near-ultraviolet broadband, and comprises the following steps: step one, weighing compounds of corresponding ions according to a chemical formula LiKBi 2(1‑x) Eu 2x (MoO4)4; step two, putting the weighed raw materials in the step one into an agate mortar, and grinding for 30 min to obtain a uniform mixed powder; step three, putting the mixed powder obtained in the step two into a corundum crucible, and placing the corundum crucible in a muffle furnace to perform heat treatment, and after cooling, grinding to obtain the high-efficiency red fluorescent powder. The prepared red fluorescent powder has high luminous efficiency, short response time, and an excitation range covering a near-ultraviolet range of 300-400 nm, can be applied to different chips, and has low preparation temperature, simple method, and cheap and easily-obtained raw materials required for preparation, and therefore has good application value.

Description

[0001] This invention is a divisional application of the following parent application, and this divisional application enjoys the filing date of the parent application: Parent application number: 202410676143.8 Application date for the parent case: May 29, 2024 Invention Title: A Highly Efficient Near-Ultraviolet Broadband Excitation Red Phosphor and Its Preparation Method Technical Field

[0002] This invention relates to the field of rare earth luminescent materials technology, and in particular to a method for preparing a high-efficiency red phosphor that is excited by near-ultraviolet broadband. Background Technology

[0003] Phosphors have significant applications in lighting, displays, anti-counterfeiting, and biology, among which red phosphors are one of the most important, playing an irreplaceable role in many crucial industries. Existing commercial red phosphors mainly consist of nitrides and fluorides, but both suffer from insurmountable problems, such as demanding preparation conditions, environmental pollution during preparation, severe reabsorption, and poor luminescence stability. Eu3+ ion-activated red phosphors typically emit light in the 610–620 nm range, which is the red region with the highest sensitivity to the human eye. Their emission color is generally unaffected by the crystal environment, resulting in more stable luminescence. Furthermore, they can be prepared without a reducing atmosphere, and the preparation process is simple and reproducible, making them a hot research topic for researchers.

[0004] However, Eu 3+ Ion-activated red phosphors emit light through 4f-4f electron transitions, resulting in weak absorption. Therefore, researchers commonly employ absorption by other ions, such as Eu. 2+ 、Tb 3+ 、Sm 3+ Bi 3+ Among them, Eu 2+ This requires a certain reducing atmosphere, and its content and concentration are generally difficult to control; while Tb 3+ and Sm 3+ Although it can transfer the absorbed excitation energy to Eu 3+ However, both of these ions have weak absorption, so the effect is not ideal. Bi... 3+ The ions possess a broad absorption band in the near-ultraviolet region and can effectively sensitize Eu. 3+ However, its absorption band is generally located around 320 nm, making it unsuitable for widespread application in various chips. In some Bi... 3+ and Eu 3+In co-doped molybdate phosphor, part of them can shift the absorption band to 400 nm, but the concentration of Eu3+ is usually low, the luminescence is weak, and it still cannot be practically applied. Summary of the Invention

[0005] Aiming at the problem that Eu 3+ ion-activated red phosphors have weak absorption, the present invention provides a high-efficiency red phosphor excited by near-ultraviolet broadband with low cost, simple process, suitable for large-scale production, and a preparation method thereof.

[0006] The present invention provides a preparation method of high-efficiency red phosphor excited by near-ultraviolet broadband, characterized by comprising the following steps: Step 1: According to the chemical formula LiKBi 2(1-x) Eu 2x (MoO4)4 (0.2<x<1.0), weigh the lithium ion-containing compound, potassium ion-containing compound, bismuth ion-containing compound, europium ion-containing compound, and molybdenum ion-containing compound; Step 2: Put the weighed raw materials in Step 1 into an agate mortar and grind for 30 min to obtain a uniform mixed powder; Step 3: Put the mixed powder obtained in Step 2 into a corundum crucible, place it in a muffle furnace for heat treatment, after cooling, grind to obtain the high-efficiency red phosphor; Optionally, in the step 3, the heat treatment temperature is 550~600°C, the heating rate is 4~6°C / min, and the maximum temperature is kept for 6~10 h.

[0007] The present invention has the following beneficial effects: (1) The preparation temperature is as low as 550~600°C, the equipment requirement is not high, and the cost is low; (2) The prepared high-efficiency red phosphor has strong broadband absorption in the near-ultraviolet region, so it can be matched with almost all commercial near-ultraviolet chips; (3) The prepared high-efficiency red phosphor has high luminous efficiency and short response time, and the preparation temperature is low, the method is simple, the raw materials required for preparation are cheap and easy to obtain, and the application range is wide. Description of Drawings

[0008] The above and other objects, features and advantages of the present invention will be apparent from the following description of the preferred embodiments for illustrating the gist and use of the present invention and the accompanying drawings, in which: Figure 1 is the XRD pattern of the novel near-ultraviolet broadband excited high-efficiency red phosphor LiKBi 2(1-x) Eu 2x (MoO4)4 (0.2<x<1) prepared by the present invention, corresponding to Examples 1~3; Figure 2 The optimal composition of the novel near-ultraviolet broadband excited high-efficiency red phosphor prepared in this invention is LiKBi. 0.8 Eu 1.2 Crystal structure diagram of (MoO4)4 (x=0.6), corresponding to Example 2; Figure 3 The optimal composition of the novel near-ultraviolet broadband excited high-efficiency red phosphor prepared in this invention is LiKBi. 0.8 Eu 1.2 The excitation and emission spectra of (MoO4)4 correspond to those of Example 2; Figure 4 The optimal composition of the novel near-ultraviolet broadband excited high-efficiency red phosphor prepared in this invention is LiKBi. 0.8 Eu 1.2 (MoO 4)4 The quantum efficiency detection spectrum corresponds to Example 2. Detailed Implementation

[0009] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] Example 1 According to the chemical formula LiKBi 1.6 Eu 0.4 The stoichiometric proportions of each element in (MoO4)4 were as follows: 0.0665 g of lithium carbonate, 0.1244 g of potassium carbonate, 0.6710 g of bismuth oxide, 0.1267 g of europium oxide, and 1.0364 g of molybdenum oxide. The weighed raw materials were ground in an agate mortar for 0.5 hours to obtain a homogeneous mixture. The mixture was then placed in a dry corundum crucible, which was placed in a muffle furnace and heat-treated in air atmosphere. The heat treatment regime was: heating from room temperature to 550℃ at a rate of 4℃ / min and holding at that temperature for 10 hours. The mixture was then allowed to cool naturally in the furnace to obtain a blocky product. This blocky product was then ground to obtain the final LiKBi. 1.6 Eu 0.4 (MoO4)4 red phosphor, the phase of which is as follows: Figure 2 The sample corresponding to x=0.2.

[0011] Example 2 According to the chemical formula LiKBi 0.8 Eu 1.2The stoichiometric proportions of each element in (MoO4)4 were as follows: 0.0665 g of lithium carbonate, 0.1244 g of potassium carbonate, 0.3355 g of bismuth oxide, 0.3801 g of europium oxide, and 1.0364 g of molybdenum oxide. The weighed raw materials were placed in an agate mortar and ground for 0.5 hours to obtain a homogeneous mixture. The resulting mixture was placed in a dry corundum crucible, which was then placed in a muffle furnace for heat treatment in air atmosphere. The heat treatment regime was: heating from room temperature to 600℃ at a rate of 5℃ / min and holding at that temperature for 6 hours. The mixture was then allowed to cool naturally in the furnace to obtain a blocky product. This blocky product was then ground to obtain the final LiKBi. 0.8 Eu 1.2 (MoO4)4 red fluorescent powder, its phase is as follows Figure 2 The sample corresponding to x=0.6 exhibits bright red light under near-ultraviolet excitation. Its structural diagram, excitation and emission spectra, and luminescence efficiency are shown below. Figure 2 , Figure 3 , Figure 4 .

[0012] Example 3 According to the chemical formula LiKBi 0.4 Eu 1.6 The stoichiometric proportions of each element in (MoO4)4 were as follows: 0.0665 g of lithium carbonate, 0.1244 g of potassium carbonate, 0.1677 g of bismuth oxide, 0.5068 g of europium oxide, and 1.0364 g of molybdenum oxide. The weighed raw materials were ground in an agate mortar for 0.5 hours to obtain a homogeneous mixture. The mixture was then placed in a dry corundum crucible, which was placed in a muffle furnace and heat-treated in air atmosphere. The heat treatment regime was: heating from room temperature to 550℃ at a rate of 6℃ / min and holding at that temperature for 8 hours. The mixture was then allowed to cool naturally in the furnace to obtain a blocky product. The blocky product was then ground to obtain a light pink LiKBi. 0.4 Eu 1.6 (MoO4)4 red phosphor, its crystal phase was analyzed as follows: Figure 2 For the sample corresponding to x=0.8, it can be observed that there is no change in the phase.

[0013] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.

Claims

1. A method for preparing a high-efficiency red phosphor excited by near-ultraviolet broadband, characterized in that, Includes the following steps: Step 1: According to the chemical formula LiKBi 2(1-x) Eu 2x (MoO4)4(0.2<x<1.0), weigh the compound containing lithium ions, the compound containing potassium ions, the compound containing bismuth ions, the compound containing europium ions, and the compound containing molybdenum ions; Step 2: Place the weighed raw materials from Step 1 into an agate mortar and grind for 30 minutes to obtain a uniform mixed powder. Step 3: Place the mixed powder obtained in Step 2 into a corundum crucible and place it in a muffle furnace for heat treatment. After cooling, grind it to obtain a high-efficiency red fluorescent powder. In step three, the heat treatment temperature is 550~600℃, the heating rate is 4~6℃ / min, and the maximum temperature is maintained for 6~10 h.

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