A zirconium silicate phosphor that can be excited by violet light to emit red light, its preparation method and application

Abstract

This invention relates to a zirconium silicate phosphor that can be excited by violet light to emit red light, its preparation method, and its applications. The phosphor prepared by this invention exhibits excellent violet light excitation performance, can be excited by violet light at 380-450 nm to achieve excellent red light emission, and has strong thermal stability, high temperature resistance, and high humidity resistance, making it suitable for full-spectrum green lighting applications.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent materials, and specifically relates to a zirconium silicate phosphor that can be excited by violet light to emit red light, its preparation method and application. Background Technology

[0002] White LED (White Light Emitting Diode, WLED) is a new type of green and environmentally friendly solid-state lighting source, hailed as the most valuable new light source of the 21st century, with broad application prospects in many fields. Currently, the mainstream solution for realizing white LEDs is to combine a chip with matching phosphors to produce white light, i.e., phosphor-converted white LEDs. Typically, blue LED chips and YAG:Ce are used. 3+ Yellow phosphors are used to produce white light, but this method produces white light lacking red light components, and the "blue enrichment" of blue LED chips may affect human physiological health. More research is pointing towards using violet LED chips to excite tri-color phosphors to synthesize green, healthy lighting light with high luminous intensity and color rendering index.

[0003] However, existing tri-color phosphors suffer from limitations in achieving good bandgap matching with the violet region, exhibiting issues such as reabsorption and varying degradation rates, which restrict the development of full-spectrum illumination. Meanwhile, many highly efficient red phosphors are fluorides and nitrides, such as SrLiAl3N4:Eu 2+ K2SiF6:Mn 4+ However, its further application is hampered by harsh synthesis conditions and poor chemical stability, especially its incompatibility with violet light chips. Therefore, it is particularly important to select a rare earth ion oxide matrix with a simple and suitable synthesis method to synthesize red phosphors with an excitation band located in the violet region. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a zirconium silicate phosphor that can be excited by violet light to emit red light, its preparation method and application, overcoming the technical defects of most phosphors in the prior art that have the excitation band located in the blue light region, which cannot be matched with violet light chips to achieve efficient white light emission, and the white light has a low color rendering index and lacks red light components, which cannot meet the needs of full-spectrum illumination.

[0005] The fluorescent material of this invention can be excited by violet light at around 400 nm to achieve red emission at around 600 nm, and has excellent luminescence performance and outstanding physicochemical stability, and can be used to prepare white LEDs.

[0006] This invention provides a fluorescent material, wherein the compound of the fluorescent material has the general formula: X₂YSi n O 2n+3: xM, where X is at least one of K, Na, and Rb; Y is at least one of Zr, Ti, and Hf; n≥1; x is 0 to 1; and M is one or more rare earth elements.

[0007] The fluorescent material includes one or more of Na2YSiO5:xM, Na2YSi2O7:xM, X2ZrSiO5:xM, and X2ZrSi2O7:xM, wherein X = one or more of K, Na, and Rb; Y = one or more of Zr, Ti, and Hf; x is 0 to 0.1; and M is one or more of rare earth elements.

[0008] Preferably, the compound has the general formula Na₂ZrSi. n O 2n+3 :xM, where n≥1; x is 0~1; M is one or more rare earth elements.

[0009] More preferably, the general formula is: Na₂ZrSi n O 2n+3 (n=1,2):xM, where x ranges from 0 to 0.4; M is one or more rare earth elements.

[0010] Preferably, n = 1 or 2; x is 0 to 0.4; and the rare earth element is one or more of Sm, Eu, Dy, Cr, and Tb.

[0011] This invention provides a method for preparing the fluorescent material, the method comprising: preparing it by one or more of the following synthesis methods: high-temperature solid-state method, sol-gel method, hydrothermal synthesis method, combustion method and chemical coprecipitation method, using sodium zirconium silicate oxide as the matrix and rare earth ions as activating ions.

[0012] Preferably, the present invention provides a method for preparing a fluorescent material, comprising method 1 or method 2:

[0013] Method 1 includes: using raw materials containing X, Y, Si, or rare earth elements, according to the molecular formula X₂YSi n O 2n+3 Weigh each raw material according to the stoichiometric ratio of the corresponding elements in xM, mix and grind thoroughly to obtain a mixed powder, pre-calcine, compress into tablets, and then react in a solid phase to obtain a fluorescent material;

[0014] Method 2 includes: using raw materials containing X, Y, Si, or rare earth elements, according to the molecular formula X₂YSi n O 2n+3 Weigh each raw material according to the stoichiometric ratio of the corresponding elements in xM, then mix it with nitric acid solution and carry out a hydrothermal reaction to obtain fluorescent material;

[0015] In methods 1 and 2, X is at least one of K, Na, and Rb; Y is Zr, Ti, and Hf; and M is one or more rare earth elements.

[0016] Preferably, in methods 1 and 2, the compound containing X is a carbonate of X; the compound containing Y is an oxide of Y; the compound containing Si is an oxide of Si; and the compound containing rare earth elements is an oxide of rare earth elements.

[0017] Furthermore, the raw materials include Na2CO3, ZrO2, SiO2, Sm2O3 and Eu2O3.

[0018] Preferably, in method 1, the grinding time is 5 min to 10 h, and the mixture is thoroughly ground in the agate slurry;

[0019] Preferably, in method 1, the pre-firing is carried out at 800-900°C for 1-3 hours;

[0020] Preferably, the solid-phase reaction in method 1 is carried out at 1100–1300 °C for 4–8 h.

[0021] Preferably, the heating rate during pre-calcination in method 1 is 1.5–20 °C / min; the heating rate during the solid-phase reaction is 1.5–20 °C / min.

[0022] Preferably, in method 1, the pressure of the tablet is 5-30 MPa, and the diameter of the disc is 5-15 mm.

[0023] Furthermore, in method 1, the tablets are compressed after pre-calcination and re-grinding.

[0024] After the solid-phase reaction in Method 1 is completed, the mixture is cooled to room temperature and then ground.

[0025] In method 1, the powder is thoroughly ground to obtain a mixed powder. The mixed powder is then transferred to a crucible (such as an alumina crucible) and pre-fired in a muffle furnace. The pre-fired powder is pressed into tablets and placed in a high-temperature muffle furnace for a high-temperature solid-phase reaction. After cooling, the tablets are removed and ground again to obtain phosphor powder.

[0026] Preferably, in method 2, the hydrothermal reaction is carried out at 80–120°C for 6–24 hours;

[0027] Preferably, after the hydrothermal reaction in method 2 is completed, the mixture is filtered, washed, and vacuum dried for 12–36 hours.

[0028] In method 2, after mixing with nitric acid solution and magnetically stirring, the mixture is sealed in a stainless steel autoclave for hydrothermal reaction. The autoclave is then naturally cooled to room temperature. The resulting white solid product is filtered, washed with distilled water, and vacuum dried at room temperature for 12–36 hours to obtain phosphor powder.

[0029] The luminescence properties of the red phosphor prepared according to the above procedure were measured under different excitation light bands.

[0030] This invention provides an application of the fluorescent material in the field of lighting, such as its application in LEDs in combination with violet chips to achieve green full-spectrum lighting.

[0031] The fluorescent material of this invention can be effectively excited by ~400nm violet light to achieve 600-617nm red light emission. When combined with commercial phosphors, it can be assembled into white LEDs to achieve green full-spectrum lighting.

[0032] This invention provides a zirconium silicate red phosphor that can be effectively excited by violet light, which can effectively improve the color rendering index and achieve full-spectrum illumination when preparing white LEDs. The phosphor prepared by this invention exhibits strong red luminescence, excellent thermal stability, and resistance to high temperature and humidity. The excitation band is located in the violet region, allowing it to be paired with violet LED chips to achieve full-spectrum illumination and meet the needs of green and healthy lighting. This invention also provides a two-step pre-calcination method for preparing phosphors using a high-temperature solid-state process. This invention introduces rare earth ions into the zirconium silicate matrix to achieve red light emission.

[0033] Beneficial effects

[0034] (1) The red phosphor obtained by the present invention not only meets the basic requirements of "violet light excitation and narrow band red emission", but also has the characteristics of high temperature resistance and high temperature and humidity resistance.

[0035] (2) Compared with traditional red phosphors, the excitation band of the phosphor of the present invention is accurately located in the violet light region, which can be matched with violet light chips to achieve efficient green full-spectrum white light illumination.

[0036] (3) The red phosphor of this invention has excellent high temperature resistance and high temperature and humidity resistance. When combined with commercial powder to prepare and assemble LEDs, it has a high color rendering index of 89, effectively realizing full-spectrum lighting, and has great application prospects in the field of green lighting. Attached Figure Description

[0037] Figure 1 These are the XRD patterns of the phosphors prepared by the high-temperature solid-state method in Examples 1(a) and 2(b);

[0038] Figure 2 This is the excitation and fluorescence spectrum of the phosphor prepared in Example 4;

[0039] Figure 3 The images show the CIE diagram (a) and emission spectrum (b) of the phosphor-assembled LED device prepared in Example 5.

[0040] Figure 4 (a-d) are characterization diagrams of the high-temperature resistance of the phosphor prepared in Example 6.

[0041] Figure 5 (a-b) are characterization diagrams of the high temperature and high humidity resistance of the phosphor prepared in Example 6. Detailed Implementation

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] Table 1 Source of Raw Materials

[0044] raw material Specification Manufacturer <![CDATA[Sodium carbonate (Na2CO3)]]> Analytical Pure Shanghai McLean Biochemical Technology Co., Ltd. <![CDATA[Zirconia (ZrO2)]]> Analytical Pure Bid Pharmaceutical Group Co., Ltd. <![CDATA[Silicon dioxide (SiO2)]]> Analytical Pure Alcon <![CDATA[Samarium Oxide (Sm2O3)]]> Analytical Pure Alcon <![CDATA[Europium Oxide (Eu2O3)]]> Analytical Pure Alcon

[0045] Table 2 Test Methods and Standards

[0046]

[0047] Example 1

[0048] Sodium carbonate (1.0590 g), zirconium dioxide (1.2322 g), silicon dioxide (0.5999 g), tungsten oxide (0.0523 g), and europium oxide (0.0879 g) were weighed according to stoichiometric ratio on a standard analytical balance. The raw materials were mixed in an agate mortar according to the specified ratio and ground thoroughly for 15 minutes until all raw materials were fully mixed. The mixed powder was spread evenly in an alumina crucible and placed in a muffle furnace for pre-calcination at 850℃ for 3 hours. After pre-calcination, the powder was removed, ground again, and then pressed into 10 mm discs using a manual tablet press at 10 MPa pressure. The discs were then placed back in the alumina crucible and reacted in a high-temperature muffle furnace at 1180℃ for 4 hours. After the second reaction, the discs were removed, cooled, and ground again to successfully synthesize Na₂ZrSiO₅:Sm 3+ / Eu 3+ Red fluorescent powder.

[0049] XRD phase characterization was performed on the intrinsic Na2ZrSiO5 phase and the red phosphor doped with Sm and Eu rare earth elements. The results are as follows: Figure 1a: The diffraction peaks in the powder's diffraction pattern are consistent with those of the Na2ZrSiO5 phase (PDF#72-1863J), further proving that rare earth elements have been successfully doped into the Na2ZrSiO5 matrix.

[0050] Example 2

[0051] Sodium carbonate (1.0590 g), zirconium dioxide (1.2322 g), silicon dioxide (1.1999 g), tungsten oxide (0.1221 g), and europium oxide (0.2114 g) were weighed according to stoichiometry on a standard analytical balance. The raw materials were mixed in an agate mortar according to the specified ratio and ground thoroughly for 15 minutes until all materials were fully mixed. The mixed powder was spread evenly in an alumina crucible and placed in a muffle furnace for pre-calcination at 850°C for 3 hours. After pre-calcination, the powder was removed, ground again, and then pressed into 10 mm discs using a manual tablet press at 10 MPa. These discs were then placed back in the alumina crucible and reacted in a high-temperature muffle furnace at 1300°C for 8 hours. After the second reaction, the discs were removed, cooled, and ground again to successfully synthesize Na₂ZrSi₂O₇:Sm 3+ / Eu 3+ Red fluorescent powder.

[0052] XRD phase characterization was performed on the intrinsic Na2ZrSi2O7 phase and the red phosphor doped with Sm and Eu rare earth elements. The results are as follows: Figure 1 b: The diffraction peaks in the powder diffraction pattern are consistent with the peaks of the Na2ZrSi2O7 phase (JCPDS#29-1293), further proving that rare earth elements have been successfully doped into the Na2ZrSi2O7 matrix.

[0053] Example 3

[0054] The reactants, sodium carbonate (1.0590 g), zirconium dioxide (1.2322 g), silicon dioxide (0.5999 g), tungsten oxide (0.0523 g), and europium oxide (0.0879 g), were weighed according to stoichiometric ratios using a standard analytical balance. These reactants were mixed with nitric acid solution and magnetically stirred. The mixture was then sealed in a stainless steel autoclave and maintained at 100°C for 12 hours. After the reaction, the autoclave was allowed to cool naturally to room temperature. The resulting white solid product was filtered, washed with distilled water, and vacuum dried at room temperature for 24 hours to obtain Na₂ZrSiO₅:0.03Sm. 3+ And Na2ZrSiO5: 0.05Eu 3+ Red fluorescent powder.

[0055] Similarly, sodium carbonate (1.0590 g), zirconium dioxide (1.2322 g), silicon dioxide (1.1999 g), tungsten oxide (0.1221 g), and europium oxide (0.2114 g) were weighed in stoichiometric proportions using a standard analytical balance. These reactants were mixed with nitric acid solution and magnetically stirred. The mixture was then sealed in a stainless steel autoclave and maintained at 100°C for 12 hours. After the reaction, the autoclave was allowed to cool naturally to room temperature. The resulting white solid product was filtered, washed with distilled water, and vacuum dried at room temperature for 24 hours to obtain Na₂ZrSi₂O₇:0.07Sm. 3+ And Na2ZrSi2O7: 0.12Eu 3+ Red fluorescent powder.

[0056] Example 4

[0057] Weigh out the following components according to stoichiometry on a standard analytical balance: Group 1: Sodium carbonate (1.0590g), Zirconium dioxide (1.2322g), Silicon dioxide (0.5999g), and Tetraoxide (0.0523g); Group 2: Sodium carbonate (1.0590g), Zirconium dioxide (1.2322g), Silicon dioxide (0.5999g), and Europium oxide (0.0879g); Group 3: Sodium carbonate (1... The following ingredients were used in the first group: sodium carbonate (0.0590g), zirconium dioxide (1.2322g), silicon dioxide (1.1999g), and tungsten oxide (0.1221g); the second group consisted of sodium carbonate (1.0590g), zirconium dioxide (1.2322g), silicon dioxide (1.1999g), and europium oxide (0.2114g). These ingredients were mixed in an agate mortar according to the specified ratio and ground thoroughly for 15 minutes until all ingredients were fully mixed. The mixed powder was spread evenly in an alumina crucible and placed in a muffle furnace for pre-calcination at 850℃ for 3 hours. After pre-calcination, the powder was removed, ground again, and then pressed into 10mm discs using a manual tablet press at 10MPa pressure. These discs were then placed back into the alumina crucible and reacted in a high-temperature muffle furnace at 1180℃ for 4 hours for the first and second groups, and at 1300℃ for 8 hours for the third and fourth groups. After the secondary reaction, the wafers were removed, cooled, and ground again to successfully synthesize Na₂ZrSiO₅: 0.03Sm. 3+ Na2ZrSiO5: 0.05Eu 3+ Na2ZrSi2O7: 0.07Sm 3+ And Na2ZrSi2O7: 0.12Eu 3+ Red fluorescent powder.

[0058] The prepared phosphor was subjected to excitation and emission spectroscopy tests, and the results are as follows: Figure 2It can be seen that the excitation band of this silicate red phosphor is located in the violet light region of 343-405nm, and the narrow-band red emission peak is located at around 600-617nm.

[0059] Example 5

[0060] In this embodiment, Na2ZrSi2O7:0.07Sm is selected. 3+ Red phosphor combined with commercial phosphor BaMgAl 10 O 17 Eu 2+ (BAM),Lu3Al5O 12 White LEDs were fabricated using Ce(LuAG). First, red, green, and blue phosphors were mixed and ground thoroughly for 15 minutes. The resulting phosphor powder was then mixed with AB glue at a 1:10 powder-to-binder ratio and placed in a vacuum oven for 1 hour to remove optical bonding bubbles. The mixture was then uniformly coated onto a 410nm LED chip and cured at 150°C to obtain the LED device. The color temperature (CCT) and luminous efficacy of the fabricated WLED were measured using an LED optoelectronic integrated testing system (HP9000, Hopoo, China).

[0061] The results are as follows Figure 3 As shown, Na2ZrSi2O7:0.07Sm 3+ White LEDs fabricated using phosphors combined with commercial phosphors BAM and LuAG and a 410nm violet light chip exhibit high color saturation (Rg = 104) and excellent color rendering index (Ra = 89.6). This demonstrates that the zirconium silicate phosphor of this invention can be effectively excited by violet light to achieve red emission, thus filling the red band of the full spectrum, improving the color rendering index, and showing great promise in the field of full-spectrum green lighting.

[0062] Example 6

[0063] Weigh out the following components according to stoichiometry on a standard analytical balance: Group 1: Sodium carbonate (1.0590g), Zirconium dioxide (1.2322g), Silicon dioxide (0.5999g), and Tetraoxide (0.0523g); Group 2: Sodium carbonate (1.0590g), Zirconium dioxide (1.2322g), Silicon dioxide (0.5999g), and Europium oxide (0.0879g); Group 3: Sodium carbonate (1... The following ingredients were used in the first group: sodium carbonate (0.0590g), zirconium dioxide (1.2322g), silicon dioxide (1.1999g), and tungsten oxide (0.1221g); the second group consisted of sodium carbonate (1.0590g), zirconium dioxide (1.2322g), silicon dioxide (1.1999g), and europium oxide (0.2114g). These ingredients were mixed in an agate mortar according to the specified ratio and ground thoroughly for 15 minutes until all ingredients were fully mixed. The mixed powder was spread evenly in an alumina crucible and placed in a muffle furnace for pre-calcination at 850℃ for 3 hours. After pre-calcination, the powder was removed, ground again, and then pressed into 10mm discs using a manual tablet press at 10MPa pressure. These discs were then placed back into the alumina crucible and placed in a high-temperature muffle furnace for reaction in the first and second groups at 1180℃ for 4 hours, and in the third and fourth groups at 1300℃ for 8 hours. After the secondary reaction, the wafers were removed, cooled, and ground again to successfully synthesize Na₂ZrSiO₅: 0.03Sm. 3+ Na2ZrSiO5: 0.05Eu 3+ Na2ZrSi2O7: 0.07Sm 3+ And Na2ZrSi2O7: 0.12Eu 3+ Red fluorescent powder.

[0064] The prepared phosphor was subjected to high temperature resistance and high temperature and high humidity resistance tests, and the results are as follows: Figure 4 and Figure 5 The silicate red phosphor exhibits excellent resistance to fluorescent thermal quenching at 175℃. (Na2ZrSiO5:0.03Sm) 3+ The phosphor's luminescence intensity can still be maintained at 76% of that at room temperature. (Na₂ZrSi₂O₇: 0.12Eu) 3+ The phosphor's luminescence intensity can still be maintained at 78% of that at room temperature. (Na₂ZrSiO₅: 0.03Sm) 3+ Na2ZrSiO5: 0.05Eu 3+ Na2ZrSi2O7: 0.07Sm 3+ And Na2ZrSi2O7: 0.12Eu 3+ Four groups of phosphors were subjected to accelerated aging tests under high humidity and heat conditions (85℃, 85% RH). The results showed that after 24 hours in the high humidity and heat environment, all phosphors maintained more than 75% of their initial fluorescence intensity.

Claims

1. A fluorescent material, characterized in that, The fluorescent material compound has the general formula: X₂YSi n O 2n+3 : x M, wherein X is at least one of K, Na, and Rb; Y is at least one of Zr, Ti, and Hf; n=2; 0<x≤0.4; and M is one or more of the rare earth elements Sm and Eu.

2. The fluorescent material according to claim 1, characterized in that, The compound has the general formula Na₂ZrSi. n O 2n+3 : x M.

3. A method for preparing the fluorescent material according to claim 1, comprising method 1 or method 2: Method 1 includes: Using compounds containing X, Y, Si, and M as raw materials, according to the molecular formula X₂YSi n O 2n+3 : x Weigh each raw material according to the stoichiometric ratio of the corresponding elements in M, grind, pre-calcine, compress into tablets, and then react in a solid phase to obtain fluorescent materials; Method 2 includes: using compounds containing X, Y, Si, and M as raw materials, according to the molecular formula X₂YSi n O 2n+3 : x Weigh each raw material according to the stoichiometric ratio of the corresponding elements in M, then mix it with nitric acid solution and carry out a hydrothermal reaction to obtain fluorescent material; In methods 1 and 2, X is at least one of K, Na, and Rb; Y is at least one of Zr, Ti, and Hf; and M is one or more of the rare earth elements Sm and Eu.

4. The preparation method according to claim 3, characterized in that, In methods 1 and 2, the compound containing X is a carbonate of X; the compound containing Y is an oxide of Y; the compound containing Si is an oxide of Si; and the compound containing M is an oxide of M.

5. The preparation method according to claim 3, characterized in that, The grinding time in method 1 is 5 min to 10 h; In method 1, the pre-firing is carried out at 800~900℃ for 1~3 hours; In Method 1, the solid-phase reaction is carried out at 1100~1300℃ for 4-8 hours.

6. The preparation method according to claim 3, characterized in that, The heating rate during pre-calcination in Method 1 is 1.5~20℃ / min; the heating rate for the solid-phase reaction is 1.5~20℃ / min. In Method 1, the pressure of the tablet is 5~30MPa, and the diameter of the disc is 5~15mm; after the solid-phase reaction is completed, grinding is performed.

7. The preparation method according to claim 3, characterized in that, In method 2, the hydrothermal reaction is carried out at 80-120℃ for 6-24 hours. After the hydrothermal reaction in Method 2 is completed, the mixture is filtered, washed, and vacuum dried for 12-36 hours.

8. The application of the fluorescent material according to any one of claims 1-2 in the field of lighting.

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