Green emission fluorescent powder and preparation method and application thereof

Abstract

The invention discloses green emission fluorescent powder as well as a preparation method and application thereof. The chemical composition of the green emission fluorescent powder is Sr2Mg (1-x) ZnxSi2O7: 0.05 Tb < 3 + >, wherein x is the molar coefficient of Zn, and x is larger than or equal to 0.1 and smaller than or equal to 0.9. The green emission fluorescent powder emits green light under the excitation of ultraviolet light, and high-quality white light can be generated when the green emission fluorescent powder is used together with red fluorescent powder and blue fluorescent powder.

Description

Technical Field

[0001] The invention relates to green emitting fluorescent powder and a preparation method and application thereof. Background Art

[0002] The development of efficient and energy-saving white light sources plays an important role in significantly reducing lighting electricity consumption. White light emitting diodes (white light LEDs) are a new type of light source after incandescent lamps and fluorescent lamps. Compared with traditional light sources, they have the advantages of small size, long life, high luminous efficiency, energy saving and environmental protection. They can be widely used in mobile communications, urban landscape lighting, car lights, traffic lights, liquid crystal displays, indoor and outdoor lighting and other fields. White light LEDs are mainly composed of LED chips and phosphors. LED chips emit blue light or ultraviolet light, which then excites different phosphors to emit light of other colors, and white light is produced by mixing light. The luminous performance of white light LEDs can be improved by improving the luminous performance of phosphors.

[0003] CN1544575A discloses a green fluorescent powder for white light LED, the chemical composition of which is Y 0.4 G 0.5 Mg 0.95 B 4.5 P 0.5 O 10 :Ce 0.05 , Tb 0.05 , Mn 0.05 , Ce 0.05 , Tb 0.05 , Mn 0.05 The green phosphor uses too many elements, which increases the preparation cost.

[0004] CN102337122A discloses a silicate green phosphor, the chemical composition of which is: Sr x Ba (2-x-y-z) Eu y M z Si p O (2+2p) , where 0.8≤x≤1.2, 0.04≤y≤0.1, 0≤z≤0.1, 0.8≤p≤1, and M is at least one of Pr, Ce, Tb, and Sm. The green phosphor is doped with Eu, which is relatively expensive.

[0005] The literature (Zhai Yongqing et al., Journal of Hebei University (Natural Science Edition), 2014, 34(1): 28-33) discloses a green rare earth polysilicate phosphor Sr 2-x ZnSi2O7:Tb x 3+, when x=0.08, the luminous intensity is the maximum. However, the green phosphor emits strong green light under 254nm excitation and is not suitable for ultraviolet light excitation. At the same time, the green phosphor is prepared by microwave-assisted gel-combustion method using nitrate and organic matter as raw materials. This preparation method requires the raw materials to be made into gel first and then sintered, which is complicated and easy to introduce impurity elements. Summary of the invention

[0006] In view of this, one object of the present invention is to provide a green emitting phosphor, which can be used together with a blue emitting phosphor and a red emitting phosphor to produce white light with a high color rendering index and a moderate color temperature. Another object of the present invention is to provide a method for preparing the above green emitting phosphor. Another object of the present invention is to provide a use of the above green emitting phosphor. Another object of the present invention is to provide a white light LED light source assembly. Another object of the present invention is to provide a white light LED device.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0008] In one aspect, the present invention provides a green emitting phosphor, the chemical composition of which is Sr2Mg 1-x Zn x Si2O7:0.05Tb 3 + ; Wherein, x is the molar coefficient of Zn, 0.1≤x≤0.9.

[0009] According to the green emitting phosphor of the present invention, preferably, 0.2≤x≤0.8.

[0010] On the other hand, the present invention also provides a method for preparing the green emitting phosphor, comprising the following steps:

[0011] 1) providing raw materials according to the chemical composition of green emitting phosphor and preparing raw material powder, mixing the raw material powder with a boron-containing flux to obtain a mixed powder; wherein the weight of the boron-containing flux is 1 to 5 wt% of the weight of the raw material powder;

[0012] 2) The mixed powder is sintered in a reducing atmosphere at 1000-1300° C. for 3-6 hours, and then ground after cooling to obtain a green emitting phosphor.

[0013] According to the preparation method of the present invention, preferably, the raw materials include strontium oxide or inorganic salt, magnesium oxide or inorganic salt, zinc oxide or inorganic salt, silicon oxide or inorganic salt and terbium oxide or inorganic salt.

[0014] According to the preparation method of the present invention, preferably, the inorganic salt is a carbonate.

[0015] According to the preparation method of the present invention, preferably, the boron-containing flux is selected from at least one of boric acid, borates and boron oxides.

[0016] In another aspect, the present invention further provides use of the green emitting phosphor in a white light LED, wherein the green emitting phosphor exhibits broadband green light emission under the excitation of ultraviolet light, and the emission wavelength range is 510 to 570 nm.

[0017] On the other hand, the present invention also provides a white light LED light source assembly, comprising the above green emitting phosphor, and also comprising a blue emitting phosphor, a red emitting phosphor and an ultraviolet LED chip.

[0018] According to the white light LED light source assembly of the present invention, preferably, the blue emitting phosphor is aluminate blue phosphor; and the red emitting phosphor is nitride red phosphor.

[0019] In yet another aspect, the present invention further provides a white light LED device, comprising the above-mentioned white light LED light source assembly.

[0020] The green emitting phosphor of the present invention emits green light under the excitation of ultraviolet light, and can generate high-quality white light together with red phosphor and blue phosphor. The color rendering index Ra of the white light is at least 85, and the color temperature is 5000-5200K. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The X-ray diffraction data result diagram of the green emitting phosphors of Examples 1 to 3;

[0022] Figure 2 This is a scanning electron microscope result of the green emitting phosphor of Example 1;

[0023] Figure 3 This is an X-ray spectrum element result diagram of the green emitting phosphor of Example 1;

[0024] Figure 4 The excitation spectrum results of the green emitting phosphors of Examples 1 to 3 are shown;

[0025] Figure 5 The steady-state emission spectrum results of the green-emitting phosphors of Examples 1 to 3;

[0026] Figure 6 This is the electroluminescence spectrum result of the white light LED prepared in Experimental Example 1;

[0027] Figure 7 This is the CIE color coordinate diagram of the white light LED prepared in Experimental Example 1. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0029] The "color rendering index" mentioned in the present invention refers to an indicator used to measure the ability of a light source to restore the true color of an object, usually denoted as Ra; the value range of the color rendering index is from 0 to 100, and the higher the color rendering index, the stronger the ability of the light source to restore the color of the object.

[0030] The "color temperature" mentioned in the present invention refers to the temperature at which a black body is heated to emit light of the same color as the light emitted by a certain light source. The temperature at which the black body is heated is called the color temperature of the light source, or color temperature for short, and its unit is Kelvin (K).

[0031] The "color coordinates" described in the present invention are a method of representing color coordinates, which are used to determine a point on a chromaticity diagram, which accurately represents the color of the light. The color coordinates are usually composed of two numbers, the horizontal axis is x and the vertical axis is y, and these two numbers represent the position of the color on the chromaticity diagram.

[0032] <Green Emitting Phosphor>

[0033] The green light emitting phosphor of the present invention can be applied to ultraviolet excited white light LEDs, and the green light band spectrum can be effectively obtained by utilizing the principle of ultraviolet chip exciting three-primary color phosphors. The green light emitting phosphor of the present invention is used together with the blue light emitting phosphor and the red light emitting phosphor to obtain white light with moderate color temperature and high color rendering index in the process of realizing white light.

[0034] The green emitting phosphor of the present invention has a chemical composition of Sr2Mg 1-x Zn x Si2O7:0.05Tb 3+ Among them, x is the molar coefficient of Zn, 1-x is the molar coefficient of Mg, Tb 3+ The molar coefficient is 0.05, and the molar ratio of Sr, Si and O is 2:2:7.

[0035] According to one embodiment of the present invention, x may be 0.1≤x≤0.9; preferably 0.2≤x≤0.8; more preferably 0.3≤x≤0.7.

[0036] According to one embodiment of the present invention, the green emitting phosphor is a solid solution phosphor.

[0037] The present invention controls the element ratio within the above range, which can ensure that the green emitting phosphor exhibits broadband cyan emission under the excitation of ultraviolet light, and is conducive to the generation of high-quality white light when the green emitting phosphor is used together with the blue emitting phosphor and the red emitting phosphor.

[0038] <Preparation method>

[0039] The preparation method of the green emitting phosphor includes a mixing step and a sintering step, which are described in detail below.

[0040] Mixing steps

[0041] According to the chemical composition of the green emitting phosphor, raw materials are provided and prepared into raw material powder, and the raw material powder is mixed with a boron-containing flux to obtain a mixed powder.

[0042] According to one embodiment of the present invention, the raw materials may include oxides or inorganic salts of strontium (Sr), oxides or inorganic salts of magnesium (Mg), oxides or inorganic salts of zinc (Zn), oxides or inorganic salts of silicon (Si), and oxides or inorganic salts of terbium (Tb).

[0043] Preferably, the inorganic salt is a carbonate.

[0044] More preferably, the raw material includes SrCO3, MgO, ZnO, SiO2 and Tb4O7.

[0045] According to one embodiment of the present invention, the boron-containing flux can be selected from at least one of boric acid, borates, and boron oxides; preferably, it is selected from at least one of boric acid and boron oxides; more preferably, it is boric acid (H3BO3).

[0046] According to one embodiment of the present invention, the weight of the boron-containing flux may be 1 to 5 wt% of the weight of the raw material powder; preferably 2 to 5 wt%; more preferably 2 to 4 wt%.

[0047] The raw materials used in the present invention can be commercially available products or prepared by existing preparation methods, and are not particularly limited here. The purity of the raw materials of the present invention is at least industrial purity (99.9wt%).

[0048] Sintering steps

[0049] The mixed powder is sintered, cooled and ground to obtain green emitting phosphor.

[0050] According to one embodiment of the present invention, the heating of the present invention is carried out under a reducing atmosphere. The reducing atmosphere refers to an atmosphere formed by passing a mixed gas of hydrogen and a protective gas. The protective gas can be selected from at least one of nitrogen and an inert gas; preferably selected from at least one of nitrogen, helium, neon, and argon; more preferably selected from at least one of nitrogen, helium, and argon. The volume ratio of hydrogen to protective gas can be 2 to 10:90 to 98; preferably 3 to 9:91 to 97; more preferably 5 to 8:92 to 95.

[0051] According to one embodiment of the present invention, the sintering temperature may be 1000-1300°C; preferably 1050-1250°C; more preferably 1080-1200°C.

[0052] According to another embodiment of the present invention, the sintering time may be 3 to 6 hours; preferably 3.5 to 5.5 hours; more preferably 4 to 5 hours.

[0053] In the present invention, sintering can be performed in any high temperature resistant equipment known in the art, and is not particularly limited herein. For example, it can be performed in a high temperature sintering furnace.

[0054] In the present invention, cooling can be achieved by any cooling method known in the art, and is not particularly limited here. For example, it can be natural cooling or air cooling.

[0055] According to one embodiment of the present invention, the average particle size D of the green emitting phosphor particles after grinding is 50 It may be 20 to 100 μm, preferably 30 to 80 μm, and more preferably 40 to 60 μm.

[0056] In the present invention, grinding can be achieved by any grinding method known in the art, and is not particularly limited herein. For example, a dry grinder can be used.

[0057] Reasonable heating conditions combined with the composition of the phosphor raw materials are conducive to promoting the growth of phosphor crystals and making their structure more complete, thereby improving the luminous efficiency and thermal stability of the phosphor, and ensuring that the phosphor can emit bright green light under ultraviolet light excitation.

[0058] The preparation method of the present invention can adjust the crystallinity and luminous intensity of the green emitting phosphor by changing the content of Zn. The preparation process of the present invention is simple and suitable for application in the field of white light LED lighting.

[0059] <Purpose>

[0060] The present invention also provides the use of the green emitting phosphor in a white light LED.

[0061] According to one embodiment of the present invention, the green emitting phosphor exhibits broadband green light emission under the excitation of ultraviolet light, and the emission wavelength range may be 510 to 570 nm; preferably 520 to 560 nm; more preferably 530 to 550 nm.

[0062] The green light emitting phosphor of the present invention is used together with the blue light emitting phosphor and the red light emitting phosphor in a white light LED to obtain white light with a moderate color temperature and a high color rendering index.

[0063] <White LED light source components>

[0064] The present invention also provides a white light LED light source assembly, comprising the green emitting phosphor mentioned above, and further comprising a blue emitting phosphor, a red emitting phosphor and an ultraviolet LED chip.

[0065] According to one embodiment of the present invention, the blue emitting phosphor can be a commercial blue emitting phosphor; preferably a commercial aluminate blue phosphor; more preferably a blue phosphor with a chemical composition of BaMgAl 10 O 17 :Eu 2+ Commercial aluminate blue phosphor.

[0066] According to another embodiment of the present invention, the red emitting phosphor can be a commercial red phosphor; preferably a commercial nitride red phosphor; more preferably a red phosphor having a chemical composition of (Ca, Sr)SiAlN3:Eu or CaAlSiN3:Eu. 2+ Commercial nitride red phosphor.

[0067] According to one embodiment of the present invention, the mass ratio of the green emitting phosphor, the blue emitting phosphor and the red emitting phosphor can be 1:(0.01-0.05):(0.01-0.05); preferably 1:(0.02-0.05):(0.01-0.03); more preferably 1:(0.02-0.04):(0.02-0.03).

[0068] The green emitting phosphor of the present invention can be used together with the red phosphor and the blue phosphor to produce high-quality white light. The color rendering index Ra of the white light can be at least 85, preferably at least 86, and more preferably at least 86.5. The color temperature of the white light can be 5000-5200K, preferably 5100-5180K, and more preferably 5150-5175K.

[0069] <White light LED devices>

[0070] The present invention also provides a white light LED device, comprising the above white light LED light source assembly.

[0071] <Test method>

[0072] XRD determination: The X'Pert PRO XRD powder diffractometer produced by Panalytical was used for the test.

[0073] Scanning electron microscopy measurement: The test was conducted using a Sigma500 field emission scanning electron microscope produced by ZEISS.

[0074] Steady-state emission spectrum and excitation spectrum were measured using the FSL1000 steady-state / transient fluorescence spectrometer produced by Edinburgh Instruments.

[0075] Electroluminescence spectrum measurement: The test was conducted using the OHSP-350M photoelectric color comprehensive testing system produced by Hangzhou Hongpu Optoelectronics Technology Co., Ltd.

[0076] Color rendering index determination: tested using the OHSP-350M photoelectric color comprehensive testing system produced by Hangzhou Hongpu Optoelectronics Technology Co., Ltd.

[0077] <Ingredients>

[0078] The raw materials in the following examples are all commercially available products unless otherwise specified.

[0079] Example 1

[0080] Preparation of green emitting phosphor:

[0081] According to Sr2Mg 0.7 Zn 0.3 Si2O7:0.05Tb 3+ The chemical composition provides raw materials SrCO3, MgO, ZnO, SiO2 and Tb4O7 and grinds the above raw materials into raw material powders, mixes 10g of the raw material powders with 0.2g of H3BO3 powder to obtain mixed powders.

[0082] The mixed powder was placed in a high-temperature sintering furnace, and a mixed gas of hydrogen and nitrogen with a volume ratio of 5:95 was introduced, and sintered at 1100°C for 4 hours. Then, the mixed powder was naturally cooled to room temperature (25°C), and the sintered product was taken out and ground to obtain a green emitting phosphor.

[0083] The green emitting phosphor prepared in this embodiment was subjected to corresponding tests:

[0084] X-ray diffraction data results are shown in Figure 1 , the results show that it is a pure phase;

[0085] The scanning electron microscopy results are shown in Figure 2 . X-ray spectroscopy element results are shown in Figure 3 .from Figure 2 and Figure 3 It can be seen that the average particle size D of the green emitting phosphor prepared in this embodiment is 50 The size of the nanostructured particles is about 50 μm, and the corresponding EDS (energy dispersive spectrometer) element scan confirmed its chemical composition.

[0086] The results of the excitation spectrum and steady-state emission spectrum are shown in Figure 4 and Figure 5 .Depend on Figure 4 and Figure 5 It can be seen that the green emitting phosphor prepared in this embodiment has a fluorescence emission wavelength (λ em ) is 542nm, the maximum excitation wavelength is 378nm;ex ) is 378nm and the maximum emission wavelength is 542nm.

[0087] Example 2

[0088] The only difference from Example 1 is that the chemical composition is different. The chemical composition of the green emitting phosphor in this example is Sr2Mg 0.5 Zn 0.5 Si2O7:0.05Tb 3+ .

[0089] The XRD results of the green emitting phosphor obtained are shown in Figure 1 , the excitation spectrum and steady-state emission spectrum results are shown in Figure 4 and Figure 5 . X-ray diffraction data showed that it was phase pure.

[0090] Example 3

[0091] The only difference from Example 1 is that the chemical composition is different. The chemical composition of the green emitting phosphor in this example is Sr2Mg 0.3 Zn 0.7 Si2O7:0.05Tb 3+ .

[0092] The XRD results of the green emitting phosphor obtained are shown in Figure 1 , the excitation spectrum and steady-state emission spectrum results are shown in Figure 4 and Figure 5 . X-ray diffraction data showed that it was phase pure.

[0093] Application Experiment Example 1

[0094] 136 mg of the green emitting phosphor prepared in Example 1 and 4 mg of the commercial aluminate blue phosphor BaMgAl 10 O 17 :Eu 2+ 、3mg commercial nitride red phosphor CaAlSiN3:Eu 2+ The white light LED light source assembly is obtained by encapsulating it on a 370nm ultraviolet LED chip. The white light LED light source assembly is used to prepare a white light LED device.

[0095] The electroluminescence spectrum and color rendering index of the white light LED device were measured, and the results were as follows: Figure 6 and Figure 7 shown.

[0096] Depend on Figure 6 and Figure 7It can be seen that under the condition of 378nm ultraviolet excitation, the electroluminescence spectrum of the green emitting phosphor prepared in Example 1 shows emission with a central wavelength in the green band. The green emitting phosphor is coupled with a purple LED chip (wavelength of 370nm) and a commercial aluminate blue phosphor BaMgAl is introduced. 10 O 17 :Eu 2+ Compared with commercial nitride red phosphor CaAlSiN3:Eu 2+ , and high-quality warm white light was obtained. The color rendering index Ra of the white light was 86.8, the color temperature was 5172K, and the color coordinates were (0.3396, 0.3330). It can be seen that the green-emitting phosphor of the present invention can be combined with the blue phosphor and the red phosphor to obtain white light with a high color rendering index and a moderate color temperature.

[0097] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A green emitting phosphor, characterized in that: Its chemical composition is Sr2Mg 1-x Zn x Si2O7:0.05Tb 3+ ; Wherein, x is the molar coefficient of Zn, 0.1≤x≤0.

9.

2. The green emitting phosphor according to claim 1, characterized in that: 0.2≤x≤0.8。 3. A method for preparing the green emitting phosphor according to claim 1 or 2, comprising the following steps: 1) providing raw materials according to the chemical composition of green emitting phosphor and preparing raw material powder, mixing the raw material powder with a boron-containing flux to obtain a mixed powder; wherein the weight of the boron-containing flux is 1 to 5 wt% of the weight of the raw material powder; 2) The mixed powder is sintered in a reducing atmosphere at 1000-1300° C. for 3-6 hours, and then ground after cooling to obtain a green emitting phosphor.

4. The preparation method according to claim 3, characterized in that: The raw materials include oxides or inorganic salts of strontium, oxides or inorganic salts of magnesium, oxides or inorganic salts of zinc, oxides or inorganic salts of silicon and oxides or inorganic salts of terbium.

5. The preparation method according to claim 4, characterized in that: The inorganic salt is carbonate.

6. The preparation method according to claim 3, characterized in that: The boron-containing flux is selected from at least one of boric acid, borates and boron oxides.

7. Use of the green emitting phosphor according to claim 1 or 2 in a white light LED, characterized in that: The green emitting phosphor exhibits broadband green light emission under the excitation of ultraviolet light, and the emission wavelength range is 510-570nm.

8. A white light LED light source assembly, characterized in that: The white light LED light source assembly comprises the green emitting phosphor, the blue emitting phosphor, the red emitting phosphor and an ultraviolet LED chip as described in claim 1 or 2.

9. The white light LED light source assembly according to claim 8, characterized in that: The blue emitting phosphor is aluminate blue phosphor; and the red emitting phosphor is nitride red phosphor.

10. A white light LED device, characterized in that: The white light LED device comprises the white light LED light source assembly according to claim 8 or 9.

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