White fluorescent powder, preparation method and application thereof

Abstract

The application provides a white fluorescent powder and a preparation method and application thereof, and belongs to the technical field of fluorescent powder, wherein the chemical formula of the fluorescent powder is Sr 1‑x Ca x Gd 1‑y‑z AlO4:yDy 3+ / zTm 3+ , wherein x, y and z are molar numbers, x is 0.015-0.025, y is 0.01-0.03, and z is 0.005-0.02. The application adopts Ca 2+ and Tm 3+ to dope SrGdAlO4:Dy 3+ fluorescent powder, so as to improve the luminescent performance of SrGdAlO4:Dy 3+ fluorescent powder, and achieve the purpose of high-efficiency white light emission; under the same excitation wavelength, SrCaGdAlO4:Dy 3+ / Tm 3+ fluorescent powder can simultaneously show the characteristic emission peaks of Dy 3+ and Tm 3+ . After Tm 3+ doping, the blue light emission intensity can be improved, and by changing the relative doping concentration ratio of Dy 3+ and Tm 3+ , the SrCaGdAlO4:Dy 3+ / Tm 3+ fluorescent powder can be modulated from warm white light to cold white light.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluorescent powder, in particular to a white fluorescent powder and a preparation method and application thereof. BACKGROUND

[0002] White light emitting diodes (WLEDs) have been widely used in display devices, lighting and plant cultivation due to their high efficiency, good stability and environmental friendliness. However, the traditional wled combines the spectral defects of yellow fluorescent powder and blue light InGaN chip, resulting in weak red and green components, leading to high color temperature (CCT ~ 7750 K) and low color rendering index (CRI < 80), as well as low luminous efficiency and spectral instability. In order to solve these problems, researchers have developed Y2O2S:Eu 3+ Fluorescent powder combined with InGaN chip, which shows high luminous efficiency, plays an important role in the commercial market. However, the synthesis process of Y2O2S:Eu 3+ may release harmful gases such as hydrogen sulfide and carbon disulfide, thereby causing harm to the environment. Therefore, the development of a new type of red fluorescent powder that can be effectively excited by near-ultraviolet and blue light is crucial for improving the luminous efficiency and stability of fluorescent powder, as well as achieving more efficient, energy-saving and environmentally friendly white light emission.

[0003] ABCO4 (A: Sr, Ca, Ba; B: La, Y or other trivalent rare earth ions, C: Al, Ga or other transition trivalent metal cations) belongs to layered perovskite structure with typical K2NiF4 structure. SrGdAlO4 and CaGdAlO4 are typical of this structure, and aluminates are widely used by researchers to prepare and as a matrix of fluorescent powder material due to their good thermal stability, low raw material cost and other advantages.

[0004] Rare earth ions are commonly used fluorescent powder excitation ions, while Dy 3+ is the most commonly used white light excitation ion. Dy 3+ has three main emission peaks in the visible light range, respectively in the yellow region ( 4 F 9 / 2 → 6 H 13 / 2 ), blue region ( 4 F 9 / 2 → 6 H 15 / 2 ) and red region ( 4 F 9 / 2 → 6 H 11 / 2 ), and Dy 3+ doped fluorescent powder is greatly affected by the position of Dy 3+ , when Dy 3+ is in a symmetric site,4 F 9 / 2 → 6 H 13 / 2 transition intensity is stronger than or equivalent to 4 F 9 / 2 → 6 H 15 / 2 , the material emits white light, for example: Qiyun Liu et al. prepared CaLa4(SiO4)3O:Dy 3+ fluorescent powder, and found that the blue light intensity is higher than the yellow light intensity, and the fluorescent powder presents white light effect under ultraviolet excitation. When Dy 3+ is in an asymmetric site, 4 F 9 / 2 → 6 H 13 / 2 transition intensity is much greater than 4 F 9 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 11 / 2 , the material emits yellow light, for example: Yi Che et al. prepared a series of yellow fluorescent powder La7O6(BO3)(PO4)2: Dy 3+ , and found that the transition intensity of Dy 3+ 4 F 9 / 2 → 6 H 13 / 2 (yellow light) is greater than 4 F 9 / 2 → 6 H 15 / 2 (blue light) and 4 F 9 / 2 → 6 H 11 / 2 (red light), and the product emits yellow light under ultraviolet excitation. However, only using Dy 3+ as the excitation ion of the fluorescent powder, the prepared fluorescent powder has insufficient blue light emission and low white light emission efficiency, resulting in poor white light emission performance of the fluorescent powder. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a white fluorescent powder and a preparation method and application thereof, aiming to improve the luminescent performance of SrGdAlO4:Dy 3+ fluorescent powder, so as to achieve the purpose of high-efficiency white light emission.

[0006] In a first aspect, the embodiments of the present application provide a white fluorescent powder, and the chemical formula of the fluorescent powder is Sr 1- x Ca x Gd 1-y-z ​AlO4:yDy 3+ / Tm 3+ , wherein x, y, z are molar numbers, x is 0.015-0.025, y is 0.01-0.03, and z is 0.005-0.02.

[0007] In the technical scheme of the embodiment, Ca 2+ and Tm 3+ are doped into SrGdAlO4:Dy 3+ fluorescent powder, so as to improve the luminescent performance of SrGdAlO4:Dy 3+ fluorescent powder, and achieve the purpose of high-efficiency white light emission.

[0008] In the SrGdAlO4:Dy 3+ fluorescent powder, Ca 2+ is doped, so as to improve the luminescent intensity of the fluorescent powder, and also improve the fluorescent lifetime of the fluorescent powder.

[0009] Under the same excitation wavelength, SrCaGdAlO4:Dy 3+ / Tm 3+ fluorescent powder can simultaneously show the characteristic emission peaks of Dy 3+ and Tm 3+ , after Tm 3+ is doped, the blue light emission intensity can be improved, by changing the relative doping concentration ratio of Dy 3+ and Tm 3+ , the SrCaGdAlO4:Dy 3+ / Tm 3+ fluorescent powder can be modulated from warm white light to cold white light.

[0010] Preferably, the excitation wavelength of the fluorescent powder is 278nm-391nm.

[0011] Preferably, the emission peak wavelength of the fluorescent powder under the excitation wavelength is 460nm-660nm.

[0012] Preferably, the color temperature of the fluorescent powder is 5000K-10000K.

[0013] Preferably, the Y / B value of the fluorescent powder is 0.83-0.98.

[0014] In a second aspect, the embodiment provides a preparation method of white fluorescent powder, comprising the following steps:

[0015] S1, a strontium source, an aluminum source, a gadolinium source, a dysprosium source, a calcium source and an erbium source are mixed according to Sr 1-x Ca x Gd 1-y-z AlO4:yDy 3+ / zTm3+ The stoichiometric ratio of each element in the phosphor powder is dosed and ground to obtain a mixture;

[0016] S2, sintering the mixture in step S1 at a set temperature;

[0017] S3, natural cooling after sintering is completed to obtain a phosphor powder.

[0018] In the technical solution of the embodiment of the application, the raw materials are sintered at a set temperature and then kept at the temperature, and SrCaGdAlO4:Dy 3+ / Tm 3+ phosphor powder can be obtained. 3+ The Ca 2+ and Tm 3+ doped in the SrGdAlO4:Dy 2+ phosphor powder can improve the density of the phosphor powder, and the higher the density, the higher the transmission efficiency of light in the phosphor powder, which indicates that the Ca 3+ and Tm 2+ doped in the SrGdAlO4:Dy 3+ phosphor powder can improve the luminescent performance of the phosphor powder.

[0019] Preferably, the sintering temperature in step S2 is 1300-1500°C, and the holding time at the sintering temperature is 1-6h.

[0020] Preferably, in step S1, the strontium source is one or both of Sr(NO3)2 and SrO, the aluminum source is one or both of Al(NO3)3 and Al2O3, the gadolinium source is one or both of Gd(NO3)3 and Gd2O3, the dysprosium source is one or both of Dy(NO3)3 and Dy2O3, the calcium source is one or more of Ca(NO3)2, CaO and CaCO3, and the thulium source is one or both of Tm(NO3)3 and Tm2O3.

[0021] In a third aspect, the embodiment of the application provides an LED light source comprising the white phosphor powder described above.

[0022] Preferably, the CIE color coordinates of the LED light source range from X=0.282 to 0.353 and Y=0.257 to 0.371.

[0023] Compared with the prior art, the beneficial effects of the application include:

[0024] 1. The Ca 2+ and Tm 3+ doped in the SrGdAlO4:Dy 3+ phosphor powder improves the luminescent performance of the SrGdAlO4:Dy 3+ phosphor powder, so as to achieve the purpose of high-efficiency white light emission.

[0025] The Ca 2+ and Tm 3+ doped in the SrGdAlO4:Dy 3+ phosphor powder improves the luminescent performance of the SrGdAlO4:Dy 3+ phosphor powder, so as to achieve the purpose of high-efficiency white light emission.

[0025] The Ca 2+ and Tm 3+ doped in the SrGdAlO4:Dy 3+ phosphor powder improves the luminescent performance of the SrGdAlO4:Dy 3+ phosphor powder, so as to achieve the purpose of high-efficiency white light emission.3+ Dy 2+ The luminescent intensity of the fluorescent powder can be improved, and the fluorescent life of the fluorescent powder can also be improved.

[0026] SrCaGdAlO4:Dy 3+ / Tm 3+ The fluorescent powder can simultaneously show the characteristic emission peaks of Dy 3+ and Tm 3+ . After being doped with Tm 3+ , the blue light emission intensity can be improved. By changing the relative doping concentration ratio of Dy 3+ and Tm 3+ , the SrCaGdAlO4:Dy 3+ / Tm 3+ fluorescent powder can be modulated from warm white light to cold white light.

[0027] 2. The SrGdAlO4:Dy 3+ fluorescent powder is simultaneously doped with Ca 2+ and Tm 3+ , so that the compactness of the fluorescent powder can be improved. The higher the compactness is, the higher the light transmission efficiency in the fluorescent powder is. Therefore, the simultaneous doping of Ca 2+ and Tm 3+ can improve the luminescent performance of the fluorescent powder.

[0028] 3. The CIE color coordinates of the LED light source of the present application under excitation of different wavelengths of near-ultraviolet light are all located in the white light region, and the standard white light color coordinates are (0.333, 0.333). The color coordinates of the LED light source of the present application are near the standard white light color coordinates, covering the cold white light and warm white light regions. The purpose of adjusting the LED light source from cold white light to warm white light can be achieved by adjusting the excitation wavelength.

[0029] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented in accordance with the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application will be described. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor.

[0031] Figure 1 XRD patterns of the fluorescent powder samples in Examples 1-4;

[0032] Figure 2 SrGd 0.97 AlO4:0.03Dy 3+ Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ Sr 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ SEM images of the phosphor samples, Figure 2 (a) is a 2,000 times magnified SEM image of the phosphor sample in Comparative Example 1, Figure 2 (b) is a 20,000 times magnified SEM image of the phosphor sample in Comparative Example 1, Figure 2 (c) is a 2,000 times magnified SEM image of the phosphor sample in Comparative Example 4, Figure 2 (d) is a 2,000 times magnified SEM image of the phosphor sample in Example 1;

[0033] Figure 3 Emission spectra and chromaticity diagrams of the phosphor samples in Examples 1-4 under an excitation wavelength of 355 nm, Figure 3 (a) is an emission spectrum of the phosphor samples in Examples 1-4, Figure 3 (b) is a chromaticity diagram of the phosphor samples in Examples 1-4;

[0034] Figure 4 Emission spectra of the phosphor samples in Examples 4-6 under an excitation wavelength of 355 nm;

[0035] Figure 5 Emission spectra and chromaticity diagrams of the phosphor samples in Example 1 under different excitation wavelengths, Figure 5 (a) is an emission spectrum of the phosphor samples in Example 1, Figure 5 (b) is a chromaticity diagram of the phosphor samples in Example 1;

[0036] Figure 6 Emission spectra and chromaticity diagrams of the phosphor samples in Comparative Examples 1-5 under an excitation wavelength of 355 nm, Figure 6 (a) is an emission spectrum of the phosphor samples in Comparative Examples 1-5, Figure 6 (b) is a chromaticity diagram of the phosphor samples in Comparative Examples 1-5;

[0037] Figure 7 Fluorescence lifetime curves of the phosphor samples in Comparative Examples 1-5;

[0038] Figure 8The emission spectrum of the phosphor sample in Comparative Examples 6-8 at an excitation wavelength of 355 nm. DETAILED DESCRIPTION

[0039] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "comprising" and "having," and any variations thereof, as used in the specification and claims and the aforementioned drawings, are intended to cover not exclusive inclusions.

[0041] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that the embodiments described herein are merely examples from among a great variety of embodiments that can be claimed as falling within the scope of the application, as explicitly and implicitly reflected by the appended claims.

[0042] Only Dy 3+ As the excitation ions of the phosphor, the prepared phosphor has insufficient blue light emission and low white light emission efficiency, resulting in poor white light emission performance of the phosphor. In order to solve the above technical problems, the present application provides a white phosphor and a preparation method and application thereof, which improves the luminescent performance of SrGdAlO4:Dy 3+ The luminescent performance of the phosphor is improved, and the purpose of high-efficiency white light emission is achieved.

[0043] In a first aspect, the embodiments of the present application provide a white phosphor, and the chemical formula of the phosphor is Sr 1- x Ca x Gd 1-y-z AlO4:yDy 3+ / zTm 3+ , wherein x, y, and z are molar numbers, x is 0.015-0.025, y is 0.01-0.03, and z is 0.005-0.02.

[0044] Preferably, the excitation wavelength of the phosphor is 278-391 nm.

[0045] Preferably, the emission peak wavelength of the phosphor at the excitation wavelength is 460-660 nm.

[0046] Preferably, the phosphor has a color temperature of 5000K-10000K.

[0047] Preferably, the phosphor has a Y / B value of 0.83-0.98.

[0048] In a second aspect, the embodiments of the present application provide a preparation method of a white phosphor, comprising the following steps:

[0049] S1, a strontium source, an aluminum source, a gadolinium source, a dysprosium source, a calcium source and an erbium source are mixed according to Sr 1-x Ca x Gd 1-y-z AlO4:0.03Dy 3+ / zTm 3+ The stoichiometric ratio of each element in the phosphor is dosed and ground to obtain a mixture;

[0050] S2, the mixture in step S1 is sintered at a set temperature;

[0051] S3, after sintering, natural cooling is performed to obtain the phosphor.

[0052] Preferably, the sintering temperature in step S2 is 1300-1500℃, and the holding time at the sintering temperature is 1-6h.

[0053] In a third aspect, the embodiments of the present application provide an LED light source comprising the above white phosphor.

[0054] Preferably, the CIE color coordinate range of the LED light source is X=0.282-0.353, Y=0.257-0.371.

[0055] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. If the specific technology or condition is not specified in the embodiments, it is performed according to the technology or condition described in the literature in the art or according to the product manual. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0056] I. Preparation method

[0057] Example 1

[0058] Example 1 proposes a phosphor with a chemical formula of

[0059] Sr 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ , z=0.005, which is prepared by the following steps:

[0060] Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3, and Tm2O3 were mixed in a molar ratio of 0.98:0.5:0.4825:0.02:0.015:0.0025. The raw materials were precisely weighed using a semi-micro balance and thoroughly ground in an agate mortar to obtain a mixture. The mixture was then transferred to a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500℃. The muffle furnace was programmed with a heating rate of 5℃ / min and a holding time of 3 hours to obtain the phosphor.

[0061] Example 2

[0062] The phosphor preparation method proposed in this embodiment differs from that in Example 1 only in the use of Sr(NO3)2, Al2O3, and Gd2O. 3、 The molar ratios of CaCO3, Dy2O3, and Tm2O3 are different in this embodiment. Sr(NO3)2, Al2O3, and Gd2O3 are also present. 3、 The molar ratio of CaCO3, Dy2O3, and Tm2O3 is 0.98:0.5:0.48:0.02:0.015:0.005, and the chemical formula of the phosphor is Sr. 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ z=0.01.

[0063] Example 3

[0064] The phosphor preparation method proposed in this embodiment differs from that in Example 1 only in the use of Sr(NO3)2, Al2O3, and Gd2O. 3、 The molar ratios of CaCO3, Dy2O3, and Tm2O3 are different in this embodiment. Sr(NO3)2, Al2O3, and Gd2O3 are also present. 3、 The molar ratio of CaCO3, Dy2O3, and Tm2O3 is 0.98:0.5:0.4775:0.02:0.015:0.0075, and the chemical formula of the phosphor is Sr. 0.98 Ca 0.02 Gd 0.97- z AlO4:0.03Dy 3+ / z Tm 3+ z=0.015.

[0065] Example 4

[0066] The difference between the fluorescent powder preparation method of the embodiment and that of embodiment 1 is only that the molar ratio of Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 is different. In the embodiment, the molar ratio of Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 is 0.98:0.5:0.475:0.02:0.015:0.01, and the chemical formula of the fluorescent powder is Sr 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ , z = 0.02.

[0067] Embodiment 5

[0068] Embodiment 1 proposes a fluorescent powder with a chemical formula of

[0069] Sr 1-x Ca x Gd 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ , x = 0.015, which is prepared by the following steps:

[0070] Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 are proportioned according to a molar ratio of 0.985:0.5:0.475:0.015:0.015:0.01, and various raw materials are accurately weighed by using a semi-micro balance and put into an agate mortar for grinding to obtain a mixture. The mixture is transferred into a corundum crucible and put into a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace is as follows: the temperature rising speed is 5°C / min, and the holding time is 3h, to obtain the fluorescent powder.

[0071] Embodiment 6

[0072] The difference between the fluorescent powder preparation method of the embodiment and that of embodiment 1 is only that the molar ratio of Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 is different. In the embodiment, the molar ratio of Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 is 0.975:0.5:0.475:0.025:0.015:0.01, and the chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 0.95AlO4: 0.03Dy 3+ / 0.02Tm 3+ , x = 0.025.

[0073] Comparative Example 1

[0074] The phosphor chemical formula of the present comparative example is SrGd 0.97 AlO4: 0.03Dy 3+ , the preparation method is different from that of Example 1 in that it does not contain CaCO3 and Tm2O3, and is prepared by the following steps:

[0075] Sr (NO3) 2, Al2O3, Gd2O3 and Dy2O3 are proportioned according to the molar ratio of 1:0.5:0.485:0.03, and various raw materials are accurately weighed by using a semi-micro balance and put into an agate mortar for grinding to obtain a mixture. The mixture is transferred into a corundum crucible and put into a high-temperature muffle furnace for sintering at 1500℃. The setting program of the muffle furnace is that the heating rate is 5 ℃ / min, and the holding time is 3h, to obtain the phosphor.

[0076] Comparative Example 2

[0077] The phosphor chemical formula of the present comparative example is Sr 1-x Ca x Gd 0.97 AlO4: 0.03Dy 3+ , x = 0.005, the preparation method is different from that of Example 1 in that it does not contain Tm2O3, and is prepared by the following steps:

[0078] Sr (NO3) 2, Al2O3, Gd2O3, CaCO3 and Dy2O3 are proportioned according to the molar ratio of 0.995:0.5:0.485:0.005:0.015, and various raw materials are accurately weighed by using a semi-micro balance and put into an agate mortar for grinding to obtain a mixture. The mixture is transferred into a corundum crucible and put into a high-temperature muffle furnace for sintering at 1500℃. The setting program of the muffle furnace is that the heating rate is 5 ℃ / min, and the holding time is 3h, to obtain the phosphor.

[0079] Comparative Example 3

[0080] The phosphor preparation method of the present comparative example is different from that of Comparative Example 1 only in that the molar ratio of Sr (NO3) 2, Al2O3, Gd2O3 and Dy2O3 is different. In the present comparative example, the molar ratio of Sr (NO3) 2, Al2O3, Gd2O3 and Dy2O3 is 0.985:0.5:0.485:0.015:0.015, and the chemical formula of the phosphor is Sr 3、 CaCO3 and Dy2O3 is 0.985:0.5:0.485:0.015:0.015, and the chemical formula of the phosphor is Sr 1-x Ca x Gd0.97 AlO4: 0.03Dy 3+ , x = 0.015.

[0081] Comparative Example 4

[0082] The difference between the preparation method of the fluorescent powder of the present comparative example and that of Comparative Example 1 is only in the molar ratio of Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3. In the present comparative example, the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, CaCO3 and Dy2O3 is 0.98:0.5:0.485:0.02:0.015, and the chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 0.97 AlO4: 0.03Dy 3+ , x = 0.02.

[0083] Comparative Example 5

[0084] The difference between the preparation method of the fluorescent powder of the present comparative example and that of Comparative Example 1 is only in the molar ratio of Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3. In the present comparative example, the molar ratio of Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3 and Dy2O3 is 0.975:0.5:0.485:0.015:0.025, and the chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 0.97 AlO4: 0.03Dy 3+ , x = 0.025.

[0085] Comparative Example 6

[0086] The chemical formula of the fluorescent powder of the present comparative example is SrGd 0.97-z AlO4: 0.03Dy 3+ / zTm, z = 0.005, and the difference between the preparation method and that of Example 1 is that it does not contain CaCO3, and is prepared by the following steps:

[0087] Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 are weighed according to the molar ratio of 1:0.5:0.4825:0.015:0.0025, and the raw materials are accurately weighed by using a semi-micro balance and put into an agate mortar for grinding to obtain a mixture. The mixture is transferred into a corundum crucible and put into a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace is as follows: the heating rate is 5°C / min, and the holding time is 3h, to obtain the fluorescent powder.

[0088] Comparative Example 7

[0089] The difference between the preparation method of the fluorescent powder of the present comparative example and comparative example 6 is only in the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3. In the present comparative example, the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 is 1:0.5:0.4775:0.015:0.0075, and the chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ , x = 0.015.

[0090] Comparative example 8

[0091] The difference between the preparation method of the fluorescent powder of the present comparative example and comparative example 6 is only in the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3. In the present comparative example, the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 is 1:0.5:0.475:0.015:0.01, and the chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ , x = 0.02.

[0092] II. Test method

[0093] 1. XRD pattern test of the fluorescent powder sample: a powder X-ray diffractometer (XRD) of Pannalytical Company, Netherlands was used, the radiation source was Cu K α (λ = 1.5418 Å), and the scanning range 2θ was 10º-80º.

[0094] 2. Morphology characterization and energy spectrum analysis of the fluorescent powder sample: a scanning electron microscope (SEM) of FEI Company, USA, with a specification of Quanta 200 was used for morphology characterization and energy spectrum analysis (EDS) of the sample.

[0095] 3. Luminescent performance test of the fluorescent powder: the excitation spectrum and emission spectrum of the fluorescent powder were detected by F-4700 fluorescence spectrophotometer of Hitachi Company, the measurement range was 200-900 nm, the scanning rate was 1200 nm / min, the 150W continuous xenon lamp source, and the voltage was 400V.

[0096] 4. Colorimetric chart detection method: the excitation spectrum was introduced into CIE software, the obtained coordinates were input into CIE1973, and the colorimetric chart was obtained.

[0097] 5: Y / B value detection method: Y / B value is the ratio of yellow light emission intensity to blue light emission intensity in the emission spectrum of the phosphor.

[0098] 6. Fluorescence lifetime detection method: after the phosphor is ground uniformly, it is placed in the solid powder sample cell of F-4700 fluorescence spectrophotometer, and the instrument parameters are set as follows: emission wavelength is 580 nm, and excitation wavelength is 355 nm, so as to detect the fluorescence lifetime of the phosphor under 355 nm excitation.

[0099] III. Analysis of test results of each embodiment and comparative example

[0100] The phosphor samples prepared in Examples 1-4 are subjected to XRD pattern test, and the test results are shown in Figure 1 .

[0101] (1) Figure 1 The XRD patterns of the phosphors doped with Ca 2+ and Tm 3+ in Examples 1-4 are shown in the figure, and it can be seen from the figure that after doping Tm 3+ , the XRD pattern of the sample is consistent with the peak position of the standard PDF card, so it can be known that the material in the standard card can be synthesized by the test method of Examples 1-4, and the phosphor Sr 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ (z=0.005-0.02) is prepared.

[0102] (2) The SrGd 0.97 AlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ phosphor samples prepared in Comparative Example 1, Comparative Example 4 and Example 1 are scanned by SEM, and the SEM images in Figure 2 are obtained. As can be seen from Figure 2 (a) and (b), the SrGd 0.97 AlO4:0.03Dy 3+ is formed by agglomeration of some irregular particles, and the particle size is about 2-40 μm. Figure 2 (b) is the SrGd 0.97AlO4:0.03Dy 3+ The SEM image is shown at a magnification of 20,000x. The image reveals that the sample surface is mostly irregular quadrilaterals, but smooth and exhibits good crystallinity. Figure 2 (c) is Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ SEM image of Ca doping 2+ Afterwards, the shape and particle size of the sample did not change significantly, with particle sizes ranging from 2 μm to 40 μm. Figure 2 (d) is Sr 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ SEM image. Doping Tm 3+ and Ca 2+ Subsequently, under a magnification of 2,000 times, the sample exhibited even higher density, indicating better luminescence performance. This is because higher density translates to higher light transmission efficiency within the sample, indirectly reflecting the simultaneous doping of Tm. 3+ and Ca 2+ It can improve the luminescence properties of the sample.

[0103] (3) Regarding Sr in Examples 1-4 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ (z=0.005~0.02) The phosphor was excited by ultraviolet light at 355nm, and its emission spectrum and chromaticity were measured. The results are as follows: Figure 3 As shown, from Figure 3 As can be seen in (a), Sr 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / zTm 3+ The phosphor exhibits four distinct emission peaks in its emission spectrum under ultraviolet light (355 nm) excitation, located at 460 nm, 484 nm, 580 nm, and 660 nm, respectively. Furthermore, the peak shape and position are almost independent of Tm. 3+ The emission peak intensity changes significantly with changes in doping concentration. The emission peaks at 484 nm and 580 nm originate from the Dy in the phosphor. 3+ of 4 F 9 / 2 → 6 H 15 / 2 and 4 F9 / 2 → 6 H 13 / 2 Energy level transitions, the intensity of these two emission peaks increases with Tm 3+ The emission intensity decreases with increasing doping concentration; the emission peak at 460 nm originates from the Tm content in the phosphor. 3+ of 1 D2→ 3 The F4 level transition and the intensity of these two emission peaks change with Tm 3+ The doping concentration increases, thus enhancing the Dy content. This indicates that the Dy content in the SrCaGdAlO4 lattice increases at this point. 3+ To Tm 3+ Energy transfer exists.

[0104] from Figure 3 As can be seen in (b), SrCaGdAlO4:0.03Dy 3+ / z Tm 3+ Phosphors with Tm 3+ As the doping concentration increases, the color coordinates gradually shift from the white region to the blue region. This is due to Tm 3+ At 460 nm 1 D2→ 3 Caused by the F4 level transition, but because of Tm 3+ The doping concentration is relatively low, so the phosphor is still in the white light region and very close to the center of the white light region.

[0105] To further describe the fluorescence emission characteristics, different Tm values ​​were calculated. 3+ The correlated color temperatures corresponding to different doping concentrations are shown in Table 1:

[0106] Table 1 Sr 0.98 Ca 0.02 Gd 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ Color coordinates and color temperature at different concentrations

[0107]

[0108] The data in Table 1 shows that in Dy 3+ and Tm 3+ In co-doped phosphors, the correlated color temperature of the phosphor will change with Tm 3+ The increase is due to the increase in doping concentration. Therefore, it can be achieved by using SrCaGdAlO4:0.03Dy 3+ A small amount of Tm is doped into the phosphor. 3+ This increases the blue light component of the phosphor, thereby improving its display index and raising its color temperature; by changing Dy3+ Tm 3+ The relative doping concentration ratio can achieve SrCaGdAlO4:Dy 3+ / Tm 3+ The modulation of phosphor from cool white light to warm white light.

[0109] (4) Regarding Sr in Examples 4-6 1-x Ca x Gd 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ The phosphor (x=0.015~0.025) was subjected to emission spectroscopy testing under ultraviolet light excitation at 355nm. The detection results are as follows: Figure 4 As shown, from Figure 4 As can be seen from this, Sr 1-x Ca x Gd 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ The phosphor exhibits four distinct emission peaks under ultraviolet light (355 nm) excitation, and the peak shapes are almost independent of Ca. 2+ The intensity of the emission peak changes with the doping concentration, only the intensity of the emission peak changes with the Ca concentration. 2+ It is enhanced by increasing the doping concentration.

[0110] To further describe the fluorescence luminescence properties, calculations were performed for different Ca... 2+ The correlated color temperatures corresponding to different doping concentrations are shown in Table 2:

[0111] Table 2 Sr 1-x Ca x Gd 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ Color coordinates and color temperature at different concentrations

[0112]

[0113] The data in Table 2 show that the color coordinates of the phosphor do not change with Ca. 2+ The color temperature changes with the doping concentration, but varies with Ca. 2+ It increases with increasing doping concentration.

[0114] (5) Regarding Sr in Example 1 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+The emission spectrum and chromaticity diagram of the phosphor under different excitation wavelengths were detected, and the test results are shown in Figure 5 Sr 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ The color coordinates and color temperature values of the phosphor under different excitation wavelengths are shown in Table 5 below:

[0115] Table 3 Sr 0.98 Ca 0.02 Gd 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ The color coordinates and color temperature under different excitation wavelengths

[0116]

[0117] From Figure 5 (a), it can be seen that the sample can be effectively excited by ultraviolet-near ultraviolet light, and good blue and yellow light emission is produced in the visible light region. In addition, although the emission intensity of the sample under excitation of different excitation wavelengths has obvious difference, the shape of the emission spectrum and the position of the emission peak change little. Under 360 nm excitation, the emission peak of the sample at 480 nm is strong, because 480 nm is the characteristic emission peak of Tm 3+ , which causes the emission spectrum to have a strong emission peak at 480 nm. At the same time, under 360 nm excitation, the characteristic emission peak of Dy 3+ also has intensity, so it can be concluded that there is energy transfer between Dy 3+ and Tm 3+ . The emission spectrum under 355 nm excitation is stronger than that under 277 nm excitation, so 355 nm is the optimal excitation wavelength of the sample. Figure 5 (b) is the chromaticity diagram of the sample under excitation of different wavelengths. From Figure 5 (b), it can be seen that the color coordinates under excitation of different wavelengths are all located in the white light region, which shows that the sample emits white light under ultraviolet wavelength excitation, and from Table 2 it can be seen that the color temperature of the phosphor is about 5000K-10000K, which is suitable for use as a daily lighting lamp source.

[0118] The CIE color coordinates of the phosphor in Example 1 under excitation of different wavelengths are all located in the white light region, the standard white light color coordinates are (0.333, 0.333), and the color coordinates of the phosphor in Example 1 under excitation of different wavelengths are near the standard white light color coordinates, covering the cold white light and warm white light regions, so the purpose of adjusting the LED light source from cold white light to warm white light can be achieved by adjusting the excitation wavelength.

[0119] Sr in Comparative Examples 1 to 5 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ The emission spectrum and chromaticity diagram of the fluorescent powder of Sr Figure 6 (x=0~0.025) were tested, and the test results are shown in Figure 6 (a) and (b) respectively. 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ The emission spectrum of the chromaticity diagram under the excitation of ultraviolet light at 355 nm. As can be seen from the figure, with the increase of the Ca 2+ concentration, the fluorescence intensity of the fluorescent powder also increases, and when the doping concentration of Ca 2+ is 0.02, the luminous intensity of the fluorescent powder SrGdAlO4:Dy 3+ reaches the maximum value, and when the Ca 2 concentration continues to increase, the luminous intensity of the fluorescent powder begins to decrease. +

[0120] Sr in Comparative Examples 1 to 5 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ The color coordinates, color temperature, and Y / B value of the fluorescent powder of Sr (x=0~0.025) under the excitation of 355 nm were detected, and the test results are shown in Table 4.

[0121] Table 4 Color coordinates, color temperature, and Y / B value of Sr 1-x Ca x GdAlO4:0.03Dy 3+

[0122]

[0123] As can be seen from Table 4, the color coordinates of the fluorescent powder doped with different Ca 2+ concentrations are near the standard white light color coordinates (0.350, 0.370), which indicates that the fluorescent powder can present excellent white light under the excitation of ultraviolet light, and the laser method of the fluorescent powder does not change with the change of the Ca 2+ doping concentration.

[0124] The Y / B value of the fluorescent powder increases first and then decreases with the increase of the Ca 2+ concentration, and the Y / B value represents the covalence of Dy-O, and the higher the Y / B value, the higher the covalence of Dy 3+ and O 2-The higher the covalence, and the phosphor can produce excellent white light under ultraviolet excitation. In addition, the color temperature of the phosphor is about 4837K, which belongs to warm white light, suitable for daily lighting use. Therefore, from the perspective of emission intensity and Y / B value, Ca 2+ The optimum doping concentration of the matrix SrGdAlO4 is 0.02.

[0125] (7) The Sr 1-x Ca x Gd 0.97 AlO4:0.03Dy 3+ The fluorescence lifetime of the phosphor (x=0~0.025) under 355nm excitation was detected, and the detection results are shown in Figure 7 From Figure 7 it can be seen that the average lifetime of the phosphor in each Ca 2+ doping concentration in Comparative Examples 1~5 at 580nm (blue light) is 0.370ms, 0.374ms, 0.381ms, 0.383ms, and 0.382ms, respectively. The fluorescence lifetime shows that the fluorescence lifetime of the phosphor increases first and then decreases after the Ca 2+ doping concentration is 0.02, and it is the maximum, and it is also higher than that of the undoped Ca 2+ The long fluorescence lifetime of the phosphor indicates that the doping of Ca 2+ not only improves the luminous intensity of the phosphor, but also improves the fluorescence lifetime of the phosphor, which further indicates that the optimum doping concentration of Ca 2+ is 0.02.

[0126] (8) The SrGd 0.97-z AlO4:0.03Dy 3+ / zTm (z=0.005~0.02) phosphor detection results are shown in Figure 8 From Figure 8 it can be seen that the SrGd 0.97-z AlO4:0.03Dy 3+ / zTm phosphor has four obvious emission peaks in the emission spectrum under ultraviolet light (355nm) excitation, and the peak shape of the emission peak hardly changes with the change of Tm 3+ doping concentration, only the intensity of the emission peak increases with the increase of Tm 3+ doping concentration.

[0127] In order to further describe the fluorescence emission characteristics, the corresponding correlated color temperature under different Tm 3+ doping concentrations was calculated, as shown in Table 5:

[0128] Table 5 SrGd 0.97-z AlO4:0.03Dy 3+Color coordinates and color temperature of the phosphor at different concentrations

[0129]

[0130] From the data in Table 5, it can be found that the color coordinates of the phosphor change with Tm 3+ The color temperature increases with the increase of the doping concentration. 3 + The color temperature increases with the increase of the doping concentration.

[0131] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and exerting the same effects within the scope of the technical solution of the present application are all included in the technical scope of the present application. Furthermore, within the scope of the gist of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A white phosphor, characterized by, The chemical formula of the fluorescent powder is Sr 1-x Ca x Gd 1-y-z AlO4:yDy 3+ / zTm 3 + wherein x, y, z are molar numbers, x is 0.015-0.025, y is 0.01-0.03, and z is 0.005-0.

02.

2. The white phosphor of claim 1, wherein, The excitation wavelength of the fluorescent powder is 278nm-391nm.

3. The white phosphor of claim 2, wherein, The emission peak wavelength of the fluorescent powder under the excitation wavelength is 460nm-660nm.

4. The white phosphor of claim 1, wherein, The fluorescent powder has a color temperature of 5000K-10000K.

5. The white phosphor of claim 1, wherein, The Y / B value of the fluorescent powder is 0.83-0.

98.

6. A method for preparing a white phosphor according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, the strontium source, the aluminum source, the gadolinium source, the dysprosium source, the calcium source and the thulium source are mixed according to Sr 1-x Ca x Gd 1-y-z AlO4: yDy 3+ / zTm 3+ The stoichiometric ratio of each element in the fluorescent powder is dosed and ground to obtain a mixture; S2, sintering the mixture in step S1 at a set temperature; S3, naturally cooling after sintering to obtain the fluorescent powder.

7. The method for preparing white phosphor according to claim 6, characterized in that, In step S1, the strontium source is one or both of Sr(NO3)2 and SrO, the aluminum source is one or both of Al(NO3)3 and Al2O3, the gadolinium source is one or both of Gd(NO3)3 and Gd2O3, the dysprosium source is one or both of Dy(NO3)3 and Dy2O3, the calcium source is one or more of Ca(NO3)2, CaO and CaCO3, and the thulium source is one or both of Tm(NO3)3 and Tm2O3.

8. The method for preparing white phosphor according to claim 6, characterized in that, The sintering temperature in step S2 is 1300-1500℃, and the holding time at the sintering temperature is 1-6h.

9. An LED light source, characterized by The white fluorescent powder according to any one of claims 1-5.

10. The LED light source of claim 9, wherein, The CIE color coordinate range of the LED light source is X=0.282-0.353 and Y=0.257-0.371.

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