Ultraviolet-excited blue fluorescent material as well as preparation method and application thereof

Abstract

The invention relates to an ultraviolet-excited blue fluorescent material as well as a preparation method and application thereof. The chemical expression of the blue fluorescent material is Ca2Y8-x (BO4) 2 (SiO4) 4F2: xCe < 3 + >, and x is larger than or equal to 0.01 and smaller than or equal to 0.06. The preparation method comprises the following steps: weighing a calcium source compound, a yttrium source compound, a boron source compound, a silicon source compound, a cerium source compound and a fluorine source compound according to a stoichiometric ratio, and grinding to uniformly mix the raw material powder to obtain a mixture; and sintering the mixture at high temperature, and cooling to obtain the blue fluorescent material. Compared with the prior art, the novel ultraviolet-excited blue fluorescent powder provided by the invention has a wide excitation band and can emit blue light of which the central wavelength is 426-438nm under the excitation of ultraviolet light.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent materials, and in particular relates to an ultraviolet excited blue fluorescent material and a preparation method and application thereof. Background Art

[0002] With the advancement of science and the improvement of living standards, people pay more attention to the quality of lighting. Currently commonly used lighting fixtures such as incandescent lamps and fluorescent lamps have obvious defects. White light LEDs have the advantages of small size, fast response, long life, low energy consumption, environmental protection and no pollution, and have become the mainstream lighting method.

[0003] There are currently two main ways to achieve white light LEDs. One is to achieve white light LEDs through multi-color chips. This method has the disadvantages of being very expensive, having a very complex activation circuit, and not being able to produce a uniformly distributed spectrum. It is not the most ideal way to achieve this. The other is to achieve white light LEDs through a single chip plus phosphors. This method has the advantages of low cost, a large adjustable color temperature range, a high color rendering index, and the ability to achieve a continuous spectrum similar to sunlight. It is currently the most widely used method for white light LEDs. Therefore, it is necessary to find phosphors that are suitable for high-quality sunlight-like lighting and that match the chip for excitation and emission.

[0004] Oxide phosphors have the advantages of excellent optical properties, structural rigidity, stable performance, easy preparation and low cost. For example, CN118725862A discloses a phosphor and its preparation method and an LED light-emitting device. 2 B 4 O 8 Ce is doped in 3+ Ions undergo transitions under near-ultraviolet light excitation to emit blue-green light. However, single oxide blue phosphors may have problems such as low quantum efficiency, narrow excitation band spectrum range, and low luminous intensity, making it difficult to meet the demand for full-spectrum white light LEDs.

[0005] Therefore, in order to meet the current urgent needs for white light LEDs, full-spectrum LEDs, etc., new blue phosphors with wide excitation bands are still to be developed. Summary of the invention

[0006] The purpose of the present invention is to provide a blue phosphor with a wide excitation band and to provide an ultraviolet-excited blue fluorescent material and its preparation method and application to meet the current urgent needs of white light LEDs, sunlight-like LEDs, and full-spectrum LEDs.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention first provides a blue fluorescent material excited by ultraviolet light, wherein the chemical expression of the blue fluorescent material is Ca 2 Y 8-x (BO 4 ) 2 (SiO 4 ) 4 F 2 :xCe 3+ , where 0.01≤x≤0.06.

[0009] Furthermore, the x is preferably 0.01-0.05, and can be further selected from 0.01, 0.02, 0.03, 0.04, and 0.05.

[0010] Furthermore, the blue fluorescent material is a powdery material.

[0011] Furthermore, the excitation spectrum range of the blue fluorescent material covers 230-400 nm.

[0012] Furthermore, the optimal excitation wavelength of the blue fluorescent material is at 364 nm.

[0013] Furthermore, the emission spectrum wavelength range of the blue fluorescent material covers 400-550nm.

[0014] Furthermore, the central emission wavelength of the blue fluorescent material is between 426-438 nm.

[0015] Furthermore, the half-peak width of the emission spectrum of the blue fluorescent material is 50 nm.

[0016] Furthermore, the Stokes shift of the blue fluorescent material is 62 nm.

[0017] The ultraviolet excited blue fluorescent material provided by the present invention is a new and unreported ultraviolet excited Ce 3+ Doped fluoride oxide-based blue light emitting fluorescent material. The present invention uses Ce 3+ As the luminescence center, Ce 3+ The 5d electrons of Ce are in the outer layer. 3+ Under near-ultraviolet light excitation, a transition of 4f→5d occurs, emitting blue-green light, and its df transition is easily affected by the crystal field environment, and its spectrum can change significantly with the composition and structure of the matrix material. The blue phosphor of the present invention has a wide excitation band, an effective absorption range covering 230-400nm, and an optimal excitation wavelength of 364nm. In the fluoroapatite of the present invention, due to the extremely large electronegativity of fluorine ions, when forming a covalent bond, the shared electrons tend to be electronegative atoms, making the bond polarized, the greater the electronegativity difference, the stronger the polarity of the bond, and the more stable the structure.

[0018] In the phosphor system, apatite structure compound is an important oxide matrix material for LED phosphors. Its general formula is A 5 (BO 4 ) 3 C, where A and B can be replaced by a variety of cations. Due to its good stability and excellent physical and chemical properties, excellent luminescence properties can be achieved through chemical ion substitution and rare earth ion doping, so the apatite structure system is a very potential phosphor material.

[0019] The present invention also provides a method for preparing an ultraviolet-excited blue fluorescent material, which comprises the following steps: weighing a calcium source compound, a yttrium source compound, a boron source compound, a silicon source compound, a cerium source compound, and a fluorine source compound according to a stoichiometric ratio, grinding the raw material powders to uniformly mix them, and obtaining a mixture; sintering the mixture at a high temperature, and obtaining the blue fluorescent material after cooling.

[0020] Furthermore, the calcium source compound is CaCO 3 , the yttrium source compound is Y 2 O 3 , the boron source compound is H 3 BO 3 , the silicon source compound is SiO 2 The cerium source compound is CeO 2 , the fluorine source compound is NH 4 F.

[0021] Furthermore, according to the chemical formula ratio of the fluorescent material, an additional 10% of the fluorine source compound is added as a fluorine source supplement on the basis of the calculated amount of the fluorine source compound.

[0022] The present invention uses a fluorine source compound in the sintering process, and the synthesis temperature of the reaction does not exceed 1300°C. If the raw materials used in the experiment contain a large amount of fluorine source compounds and are directly sintered at this high temperature, part of the fluorine will be lost in the form of gas, causing the generation of impurities in the production process. Therefore, it is necessary to add a certain amount of fluorine source compounds as a fluorine source supplement, and the type and temperature of the fluorine source supplement for this system will affect the luminescence intensity and physical phase of the sample.

[0023] Furthermore, the grinding time is 5-120 min.

[0024] Furthermore, the high temperature sintering temperature is 900-1300°C, preferably 1200-1300°C.

[0025] Furthermore, the high temperature sintering time is 2-24 hours, preferably 12 hours.

[0026] Furthermore, the high temperature sintering is carried out in a reducing atmosphere, wherein the reducing atmosphere is H 2 With N 2 The mixed gas is preferably 5% H 2 With a volume fraction of 95% N 2 of mixed gases.

[0027] Furthermore, the reducing atmosphere is first evacuated before being introduced, and the system pressure is maintained at 0 MPa, i.e., normal pressure, during high-temperature sintering.

[0028] The blue fluorescent material of the present invention can be prepared by a conventional solid-phase reaction method, has the characteristics of simple preparation process, is conducive to industrial production, can be well matched with existing ultraviolet chips, meets the needs of the commercial market, and can be used as a good candidate material for the wide application of white light LEDs, sunlight-like LEDs, and full-spectrum white light LEDs.

[0029] The present invention also provides an application of an ultraviolet-excited blue fluorescent material, wherein the ultraviolet-excited blue fluorescent material is used to prepare a white light LED, a sunlight-like LED, and a full-spectrum white light LED.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention provides a novel ultraviolet-excited blue phosphor having a wide excitation band and an effective absorption range covering 230-400 nm. The obtained phosphor can emit blue light with a central wavelength of 426-438 nm under the excitation of 364 nm ultraviolet light.

[0032] (2) The blue phosphor of the present invention is Ce 3+ Doped apatite structure blue emitting phosphor, by Ce 3+ Ion doping in the apatite structure produces blue light emission, which has the advantage of stable physical and chemical properties.

[0033] (3) The blue phosphor of the present invention has the advantages of both oxide phosphors and fluoride phosphors, with both activated ions bonding to oxygen and activated ions bonding to fluorine, forming a unique mixed coordination structure. Compared with the structure of a single oxide or fluoride, this structure is distorted, with a certain degree of distortion, reduced symmetry, and a change in the crystal environment, resulting in different amplitudes, reduced phonon energy, increased non-thermal radiation probability, and greatly increased luminescence performance. It not only preserves the advantages of oxide and fluoride phosphors themselves but also has its own unique properties, enriching the phosphor material matrix system while also broadening the application field.

[0034] (4) The blue phosphor of the present invention is prepared by a conventional solid-phase reaction method, has the characteristics of simple preparation process and is conducive to industrial production, and can be used as a good candidate material for the wide application of white light full-spectrum LEDs, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The photoemission spectra of the blue phosphors prepared in Examples 1-5 of the present invention are shown.

[0036] Figure 2 The fluorescence intensity diagram of the blue phosphor of Example 1 of the present invention and Comparative Example 1 at different temperatures. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0039] Embodiment 1:

[0040] This embodiment provides a blue phosphor excited by ultraviolet light, and the preparation method thereof is specifically as follows:

[0041] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F raw material powder 1g, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F=0.1298:0.585:0.0802:0.1559:0.0011:0.0528.

[0042] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2The target product was obtained by calcining at 1300°C for 12 hours in a reducing atmosphere of 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca 2 Y 8-x (BO 4 ) 2 (SiO 4 ) 4 F 2 :xCe 3+ , where x=0.01.

[0043] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1 As shown. The results show that the phosphor of this system has a wide excitation band with a peak value near 364nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 364nm ultraviolet light source, the phosphor emits bright blue light, and the emission spectrum consists of a narrow emission band (FWHM=50nm) with a peak value at 426nm.

[0044] Embodiment 2:

[0045] This embodiment provides a blue phosphor excited by ultraviolet light, and the preparation method thereof is specifically as follows:

[0046] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F raw material powder 1g, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F=0.1298:0.584:0.0802:0.1558:0.0022:0.0528.

[0047] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2 The target product was obtained by calcining at 1300°C for 12 hours in a reducing atmosphere of 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca2 Y 8-x (BO 4 ) 2 (SiO 4 ) 4 F 2 :xCe 3+ , where x = 0.02.

[0048] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1 As shown. The results show that the phosphor of this system has a wide excitation band with a peak value near 364nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 364nm ultraviolet light source, the phosphor emits bright blue light, and the emission spectrum consists of a narrow emission band (FWHM=50nm) with a peak value at 426nm.

[0049] Embodiment 3:

[0050] This embodiment provides a blue phosphor excited by ultraviolet light, and the preparation method thereof is specifically as follows:

[0051] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F raw material powder 1g, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F=0.1298:0.583:0.0801:0.1557:0.0034:0.0528.

[0052] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2 The target product was obtained by calcining at 1300°C for 12 hours in a reducing atmosphere of 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca 2 Y 8-x (BO 4 ) 2 (SiO 4 )4 F 2 :xCe 3+ , where x = 0.03.

[0053] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1 As shown. The results show that the phosphor of this system has a wide excitation band with a peak value near 364nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 364nm ultraviolet light source, the phosphor emits bright blue light, and the emission spectrum consists of a narrow emission band (FWHM=50nm) with a peak value at 426nm.

[0054] Embodiment 4:

[0055] This embodiment provides a blue phosphor excited by ultraviolet light, and the preparation method thereof is specifically as follows:

[0056] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F raw material powder 1g, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F=0.1296:0.5812:0.0801:0.1556:0.0056:0.0528.

[0057] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2 The target product was obtained by calcining at 1300°C for 12 hours in a reducing atmosphere of 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca 2 Y 8-x (BO 4 ) 2 (SiO 4 ) 4 F 2 :xCe 3+ , where x=0.05.

[0058] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1 As shown. The results show that the phosphor of this system has a wide excitation band with a peak value near 364nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 364nm ultraviolet light source, the phosphor emits bright blue light, and the emission spectrum consists of a narrow emission band (FWHM=50nm) with a peak value at 433nm.

[0059] Embodiment 5:

[0060] This embodiment provides a blue phosphor excited by ultraviolet light, and the preparation method thereof is specifically as follows:

[0061] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F raw material powder 1g, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 , H 3 BO 3 、SiO 2 、CeO 2 NH 4 F=0.1297:0.5821:0.0801:0.1567:0.0045:0.0528.

[0062] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2 The target product was obtained by calcining at 1300°C for 12 hours in a reducing atmosphere of 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca 2 Y 8-x (BO 4 ) 2 (SiO 4 ) 4 F 2 :xCe 3+ , where x=0.04.

[0063] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1As shown. The results show that the phosphor of this system has a wide excitation band with a peak value near 364nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 364nm ultraviolet light source, the phosphor emits bright blue light, and the emission spectrum consists of a narrow emission band (FWHM=50nm) with a peak value at 438nm.

[0064] Comparative Example 1:

[0065] This comparative example provides a blue phosphor of a pure oxide system excited by ultraviolet light, and the specific preparation method thereof is as follows:

[0066] (1) Weigh CaCO according to the stoichiometric ratio 3 , Y 2 O 3 、SiO 2 、CeO 2 1g raw material powder, the mass ratio of each raw material is CaCO 3 , Y 2 O 3 、SiO 2 、CeO 2 =0.1381:0.6108:0.2487:0.0024.

[0067] (2) The raw material mixture was placed in an agate mortar and ground for 60 minutes. After the materials were evenly mixed, the mixture was loaded into an alumina crucible and placed in a hydrogen-nitrogen mixture (H 2 Volume fraction 5%, N 2 The target product was obtained by calcining at 1450°C for 8 hours in a reducing atmosphere containing 95% by volume, and then cooling to room temperature. The general formula of the ultraviolet excited blue phosphor obtained in this embodiment is Ca 2 Y 8-x (SiO 4 ) 6 O 2 :xCe 3+ , where x = 0.02.

[0068] The spectral properties of the phosphor in this system were tested using a fluorescence spectrometer, such as Figure 1 As shown. The results show that the phosphor of this system has a wide excitation band, with a peak value near 309nm and a high spectral peak. Under the excitation of a 309nm ultraviolet light source, the phosphor emits bright blue light, with an emission spectrum composition and a peak value at 398nm.

[0069] The preparation parameters and test results of Examples 1-5 and Comparative Example 1 are summarized in Table 1.

[0070] Table 1 Summary of preparation parameters and test results of Examples 1-5 and Comparative Example 1

[0071]

[0072] like Figure 2 As shown, the temperature-dependent photoluminescence intensity of the blue phosphors of Example 1 and Comparative Example 1 was measured to compare the thermal stability, and the temperature rise interval was 30°C. The ratio of the photoluminescence intensity of the blue phosphors of Example 1 and Comparative Example 1 to the room temperature luminescence intensity was measured at 30°C, 60°C, 120°C, 150°C, and 180°C. At 150°C, the luminescence intensity of the fluorescent material of Example 1 of the present invention was 69.25% of that at room temperature. The oxide apatite phosphor Ca of Comparative Example 1 2 Y 8 (SiO 4 ) 6 O 2 :Ce 3+ The luminescence intensity at 150°C is only 48.54% of that at room temperature. Since apatite has a very high electronegativity due to fluoride ions, when forming a covalent bond, the shared electrons tend to be electronegative atoms, making the bond polar. The greater the electronegativity difference, the stronger the polarity of the bond and the more stable the structure. It can be seen that the fluorine-based blue fluorescent material of the present invention has better stability in the oxyfluoride system than the oxide system, and has better luminescence properties.

[0073] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A UV-excited blue fluorescent material, characterized in that: The chemical expression of the blue fluorescent material is Ca2Y 8-x (BO4)2(SiO4)4F2:xCe 3+ , where 0.01≤x≤0.

06.

2. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The excitation spectrum range of the blue fluorescent material covers 230-400 nm.

3. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The optimal excitation wavelength of the blue fluorescent material is at 364 nm.

4. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The emission spectrum wavelength range of the blue fluorescent material covers 400-550nm, and the central emission wavelength of the blue fluorescent material is located at 426-438nm.

5. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The half-peak width of the emission spectrum of the blue fluorescent material is 50 nm.

6. A method for preparing the ultraviolet excited blue fluorescent material according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: weighing a calcium source compound, a yttrium source compound, a boron source compound, a silicon source compound, a cerium source compound and a fluorine source compound according to a stoichiometric ratio, grinding to uniformly mix the raw material powders to obtain a mixture; sintering the mixture at a high temperature, and obtaining the blue fluorescent material after cooling.

7. The method for preparing a blue fluorescent material according to claim 6, characterized in that: The calcium source compound is CaCO3, the yttrium source compound is Y2O3, the boron source compound is H3BO3, the silicon source compound is SiO2, the cerium source compound is CeO2, and the fluorine source compound is NH4F.

8. The method for preparing a blue fluorescent material according to claim 6, characterized in that: According to the chemical formula of the fluorescent material, 10% of the fluorine source compound is additionally added as a fluorine source supplement on the basis of the calculated amount of the fluorine source compound.

9. The method for preparing a blue fluorescent material according to claim 6, characterized in that: The grinding time is 5-120min; The high temperature sintering temperature is 900-1300°C and the time is 2-24h; The high temperature sintering is carried out in a reducing atmosphere, which is a mixed gas of H2 and N2.

10. An application of the ultraviolet excited blue fluorescent material according to any one of claims 1 to 5, characterized in that: The ultraviolet excited blue fluorescent material is used to prepare white light LED, sunlight-like LED and full-spectrum white light LED.

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