A holmium-activated garnet-based green down-conversion fluorescent powder and a preparation method thereof

Abstract

The present application relates to the field of luminescent material, and disclose a kind of holmium activated garnet-based green down-conversion fluorescent powder, including Na, Y, Ho, Ga, In and Ge, wherein, the amount-of-substance ratio of metal elements is Na:Y:Ho:Ga:In:Ge=1:2-2x:2x:2:1:2, and 0.01≤x<0.10, x is the doping amount of holmium in inert rare earth lattice, the holmium activated garnet-based green down-conversion fluorescent powder and its preparation method, reduce the solid-phase synthesis reaction temperature to 1200-1250 DEG C, energy saving and consumption reduction and short preparation time, perfect crystallinity, reduce preparation cost;Preparation process does not need cosolvent, environment-friendly, reduce the influence on environment;Preparation process is simplified to one-step sintering and does not need reducing atmosphere, improve preparation efficiency and the feasibility of production process.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials, specifically to a holmium-activated garnet-based green downconversion phosphor and its preparation method. Background Technology

[0002] In dynamic or interactive display applications, the luminescent performance of phosphors is crucial, and fluorescence lifetime is one of the key indicators for measuring their response speed. Phosphors with shorter fluorescence lifetimes can respond to input signals faster, achieving higher display refresh rates and thus significantly improving display performance. However, many phosphors currently on the market have long fluorescence lifetimes, which limits their application in high-speed display applications. Therefore, developing high-performance phosphors with shorter fluorescence lifetimes has become a top priority.

[0003] In fluorescent materials research, Ho 3+ Ho ions, as green light-emitting ions, exhibit unique properties that give them potential advantages in dynamic or interactive display applications. Unlike other green light-emitting ions (such as Mn, Eu, and Tb), Ho ions do not require reduction, making them more convenient in the preparation and application of fluorescent materials. Of particular note is the extremely short fluorescence lifetime of Ho ions, typically only tens of microseconds, at least two orders of magnitude shorter than that of Tb ions, and the emission position of Ho, like that of Tb, is located at 545-550 nm. By utilizing Ho… 3+ Due to the short fluorescence lifetime of ions, phosphors can respond to input signals more quickly, achieving higher display refresh rates and thus significantly improving the effect of dynamic or interactive displays.

[0004] Against this backdrop, this paper proposes an innovative phosphor material—Ho doped in a sodium yttrium gallium indium germanium garnet matrix. 3+ Holmium-activated garnet-based green downconversion phosphors were developed using ion conversion. This resulted in a significant reduction in the phosphor's luminescence lifetime, and the phosphor material exhibits the advantage of rapid input signal response, making it suitable for dynamic or high-speed display applications. Furthermore, this paper provides a method for preparing this phosphor material. Through reasonable synthesis processes and parameters, a high-performance sodium yttrium gallium indium germanium garnet matrix doped with Ho was successfully obtained. 3+ The conversion of holmium-activated garnet-based green downconversion phosphors is a simple and efficient method that can be scaled up in industrial production, laying a solid foundation for its widespread application in practice. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a holmium-activated garnet-based green downconversion phosphor and its preparation method. This phosphor can be effectively excited by blue light (420–480 nm), near-ultraviolet light (350–390 nm), or ultraviolet light (280–300 nm), and under excitation by excitation light in the near-ultraviolet to blue light region, it produces green downconversion luminescence. It emits a narrow band of green light with a strongest peak at 548 nm, accompanied by deep red light in the 745–775 nm range. 3+ The activated downconversion phosphor has a lifetime of less than 20 microseconds, which meets the requirements for applications in the field of ultrafast response fluorescence.

[0007] Furthermore, this phosphor can be sintered in one step at temperatures as low as 1200℃ without the need for a reducing atmosphere or co-solvent, and only requires 3 hours to form the phase. The synthesis time is short and the energy consumption is low, which solves the problem of high synthesis temperature and high production energy consumption of garnet-type matrix phosphors.

[0008] (II) Technical Solution

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a holmium-activated garnet-based green downconversion phosphor, comprising Na, Y, Ho, Ga, In, and Ge, wherein the molar ratio of the metal elements is Na:Y:Ho:Ga:In:Ge=1:2-2x:2x:2:1:2, where: 0.01≤x<0.10, and x is the amount of holmium doping at the inert rare earth sites.

[0010] A method for preparing a holmium-activated garnet-based green downconversion phosphor includes the following steps:

[0011] S1: Weigh the raw materials containing Na, Y, Ho, Ga, In and Ge according to their chemical composition;

[0012] S2: Add an additional 10% Ga2O3 to compensate for Ga loss during the high-temperature reaction, grind it thoroughly to make it uniform, and put it into the reaction vessel;

[0013] S3: Sintering is carried out in an atmospheric pressure air atmosphere, followed by cooling to room temperature, and then grinding to obtain the target phosphor.

[0014] Preferably, the sintering procedure in S3 is as follows: the temperature is increased from room temperature to 1200–1250°C at a rate of 5°C / min, and then held at a constant temperature for 3–4 hours after the temperature increase is completed.

[0015] Preferably, the raw material containing Na is selected from sodium bicarbonate.

[0016] Preferably, the raw material containing Ho is selected from holmium oxide.

[0017] Preferably, the Ga-containing raw material is selected from gallium oxide.

[0018] Preferably, the raw material containing In is selected from indium oxide.

[0019] Preferably, the raw material containing Ge is selected from germanium oxide.

[0020] Preferably, the raw material containing Y is selected from yttrium oxide.

[0021] Preferably, the target phosphor is suitable for light-emitting devices, of which LED devices are an application area, and is suitable for dynamic or interactive display applications.

[0022] (III) Beneficial Effects

[0023] Compared with the prior art, the present invention provides a holmium-activated garnet-based green downconversion phosphor and its preparation method, which has the following beneficial effects:

[0024] 1. The holmium-activated garnet-based green downconversion phosphor and its preparation method reduce the solid-phase synthesis reaction temperature to 1200-1250℃, saving energy and reducing consumption, with short preparation time, good crystallinity, and reduced preparation cost; the preparation process does not require a co-solvent, is environmentally friendly, and reduces the impact on the environment; the preparation process is simplified to one-step sintering and does not require a reducing atmosphere, improving preparation efficiency and the feasibility of the production process.

[0025] 2. The holmium-activated garnet-based green downconversion phosphor and its preparation method. The phosphor of the present invention can be effectively excited by blue light, near-ultraviolet light and ultraviolet light. Compared with some existing phosphors that can only be excited within a specific wavelength range, it has a wider excitation adaptability and flexibility.

[0026] 3. This holmium-activated garnet-based green downconversion phosphor and its preparation method, under the excitation light in the near-ultraviolet to blue light region, the phosphor of this invention produces green downconversion luminescence. Its strongest main peak is located at 548 nm, which can provide a high-brightness and high-contrast green light source.

[0027] 4. The holmium-activated garnet-based green downconversion phosphor and its preparation method, and the Ho content of the phosphor. 3+ Phosphors have a short fluorescence lifetime, typically only tens of microseconds. Compared to the longer fluorescence lifetimes of other ions, this ultrafast signal response characteristic gives phosphors a significant advantage in dynamic or interactive display applications. Phosphors can respond to input signals more quickly, achieving higher display refresh rates, thus significantly improving the performance of dynamic or interactive displays. Attached Figure Description

[0028] Figure 1 The Ho prepared in Example 3 3+ X-ray powder diffraction pattern of doped sodium yttrium gallium indium germanium garnet-based holmium activated garnet-based green downconversion phosphor;

[0029] Figure 2 The Ho prepared in Example 3 3+ Fluorescence emission spectrum of doped sodium yttrium gallium indium germanium garnet-based holmium activated garnet-based green downconversion phosphor;

[0030] Figure 3 The Ho prepared in Example 3 3+ Fluorescence excitation spectrum of doped sodium yttrium gallium indium germanium garnet-based holmium activated garnet-based green downconversion phosphor;

[0031] Figure 4 The Ho prepared in Example 3 3+ Fluorescence lifetime diagram of doped sodium yttrium gallium indium germanium garnet-based holmium activated garnet-based green downconversion phosphor;

[0032] Figure 5 The Ho prepared in Example 3 3+ Color coordinate diagram of doped sodium yttrium gallium indium germanium garnet-based holmium activated garnet-based green downconversion phosphor. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Please see Figure 1-5 A holmium-activated garnet-based green downconversion phosphor and its preparation method are described in the following examples:

[0035] Example 1:

[0036] Weigh out 0.0840 g of sodium bicarbonate (NaHCO3), 0.2236 g of yttrium oxide (Y2O3), 0.0038 g of holmium oxide (Ho2O3), 0.2093 g of germanium oxide (GeO2), 0.2062 g of gallium oxide (Ga2O3), and 0.1388 g of indium oxide (In2O3). Grind the above raw materials in an agate mortar until uniform. Then, carry out a solid-state reaction. Under normal pressure and air atmosphere, heat to 1200℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. After cooling, grind until uniform to obtain holmium-activated garnet-based green downconversion phosphor.

[0037] Example 2:

[0038] Weigh out 0.0840 g of sodium bicarbonate (NaHCO3), 0.2190 g of yttrium oxide (Y2O3), 0.0113 g of holmium oxide (Ho2O3), 0.2093 g of germanium oxide (GeO2), 0.2062 g of gallium oxide (Ga2O3), and 0.1388 g of indium oxide (In2O3). Grind the above raw materials in an agate mortar until uniform. Then, carry out a solid-state reaction. Under normal pressure and air atmosphere, heat to 1200℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. After cooling, grind until uniform to obtain holmium-activated garnet-based green downconversion phosphor.

[0039] Example 3:

[0040] Weigh out 0.0840 g of sodium bicarbonate (NaHCO3), 0.2145 g of yttrium oxide (Y2O3), 0.0189 g of holmium oxide (Ho2O3), 0.2093 g of germanium oxide (GeO2), 0.2062 g of gallium oxide (Ga2O3), and 0.1388 g of indium oxide (In2O3). Grind the above raw materials in an agate mortar until uniform. Then, carry out a solid-state reaction. Under normal pressure and air atmosphere, heat to 1200℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. After cooling, grind until uniform to obtain holmium-activated garnet-based green downconversion phosphor.

[0041] Example 4:

[0042] Weigh out 0.0840 g of sodium bicarbonate (NaHCO3), 0.2100 g of yttrium oxide (Y2O3), 0.0265 g of holmium oxide (Ho2O3), 0.2093 g of germanium oxide (GeO2), 0.2062 g of gallium oxide (Ga2O3), and 0.1388 g of indium oxide (In2O3). Grind the above raw materials in an agate mortar until uniform. Then, carry out a solid-state reaction. Under normal pressure and air atmosphere, heat to 1200℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. After cooling, grind until uniform to obtain holmium-activated garnet-based green downconversion phosphor.

[0043] Example 5:

[0044] Weigh out 0.0840 g of sodium bicarbonate (NaHCO3), 0.2055 g of yttrium oxide (Y2O3), 0.0340 g of holmium oxide (Ho2O3), 0.2093 g of germanium oxide (GeO2), 0.2062 g of gallium oxide (Ga2O3), and 0.1388 g of indium oxide (In2O3). Grind the above raw materials in an agate mortar until uniform. Then, carry out a solid-state reaction. Under normal pressure and air atmosphere, heat to 1200℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. After cooling, grind until uniform to obtain holmium-activated garnet-based green downconversion phosphor.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A holmium-activated garnet-based green downconversion phosphor, characterized in that, It includes Na, Y, Ho, Ga, In and Ge, where the molar ratio of the metal elements is Na:Y:Ho:Ga:In:Ge=1:2-2x:2x:2:1:2, where 0.01≤x<0.10, and x is the amount of holmium doped in the inert rare earth sites.

2. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 1, characterized in that, Includes the following steps: S1: Weigh out the raw materials containing Na, Y, Ho, Ga, In and Ge according to their chemical composition; S2: Add an additional 10% Ga2O3 to compensate for Ga loss during the high-temperature reaction, grind thoroughly to make it uniform, and put it into the reaction vessel; S3: Sintering is carried out in an atmospheric pressure air atmosphere, followed by cooling to room temperature, and then grinding to obtain the target phosphor.

3. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The sintering procedure in S3 is as follows: the temperature is increased from room temperature to 1200–1250℃ at a rate of 5℃ / min, and then held at a constant temperature for 3–4 hours after the temperature increase is completed.

4. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The raw material containing Na is selected from sodium bicarbonate.

5. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The raw materials containing Ho are selected from holmium oxide.

6. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The raw materials containing Ga are selected from gallium oxide.

7. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: Raw materials containing In are selected from indium oxide.

8. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The raw material containing Ge is selected from germanium oxide.

9. The method for preparing a holmium-activated garnet-based green downconversion phosphor according to claim 2, characterized in that: The raw material containing Y is selected from yttrium oxide.

10. The holmium-activated garnet-based green downconversion phosphor according to claim 1, characterized in that: Phosphors are used in light-emitting devices, with LED devices being one application area, and are suitable for dynamic or interactive display applications.

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