White fluorescent powder as well as preparation method and application thereof

Abstract

The invention provides white fluorescent powder and a preparation method and application thereof, and belongs to the technical field of fluorescent powder, the chemical formula of the fluorescent powder is Sr < 1-x > CaxGd < 1-y-z > AlO4: yDy < 3 + > / zTm < 3 + >, x, y and z are mole numbers, x is 0.015-0.025, y is 0.01-0.03, and z is 0.005-0.02. The SrGdAlO4: Dy < 3 + > fluorescent powder is doped with Ca < 2 + > and Tm < 3 + >, so that the luminescence property of the SrGdAlO4: Dy < 3 + > fluorescent powder is improved, and the purpose of efficient white light emission is achieved; under the same excitation wavelength, the SrCaGdAlO4: Dy < 3 + > / Tm < 3 + > fluorescent powder can simultaneously display characteristic emission peaks of Dy < 3 + > and Tm < 3 + >. After Tm < 3 + > is doped, the blue light emission intensity can be improved, and the modulation of the SrCaGdAlO4: Dy < 3 + > / Tm < 3 + > fluorescent powder from warm white light to cold white light can be realized by changing the relative doping concentration ratio of Dy < 3 + > to Tm < 3 + >.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent powders, and in particular to a white fluorescent powder and a preparation method and application thereof. Background Art

[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, traditional WLEDs combine yellow phosphors with blue light InGaN chip spectral defects, resulting in weak red and green components, high color temperature (CCT ~7750 K) and low color rendering index (CRI <80), as well as low luminous efficiency and spectral instability. To solve these problems, researchers used Y2O2S:Eu 3+ The phosphor is combined with InGaN chips to make WLEDs, which show high luminous efficiency and play an important role in the commercial market. 3+ The synthesis process may release harmful gases such as hydrogen sulfide and carbon disulfide, which may harm the environment. Therefore, the development of a new red phosphor that can be effectively excited by near-ultraviolet light and blue light is crucial to improve the luminous efficiency and stability of the phosphor and achieve 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 the layered perovskite structure, with a typical K2NiF4 structure. SrGdAlO4 and CaGdAlO4 belong to this structure. Aluminates are used by a large number of researchers to prepare and use as the matrix of phosphor materials due to their good thermal stability and low raw material cost.

[0004] Rare earth ions are commonly used as phosphor excitation ions, and Dy 3+ It is the most commonly used white light excited ion. 3+ There are three main emission peaks in the visible light range, in the yellow region ( 4 F 9 / 2 → 6 H 13 / 2 )、Blue Zone( 4 F 9 / 2 → 6 H 15 / 2 ) and the red zone ( 4 F 9 / 2 → 6 H 11 / 2 ), Dy 3+ The phosphor doped with Dy 3+ The position has a great influence. 3+ At a symmetrical position,4 F 9 / 2 → 6 H 13 / 2 The transition strength is stronger than or equal 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+ Phosphor, it is found that the intensity of blue light is higher than that of yellow light, and the phosphor shows the effect of white light under ultraviolet excitation. 3+ At an asymmetric site, 4 F 9 / 2 → 6 H 13 / 2 The 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 phosphors La7O6(BO3)(PO4)2: Dy 3+ , found that Dy 3+ of 4 F 9 / 2 → 6 H 13 / 2 (yellow light) has a transition intensity greater than 4 F 9 / 2 → 6 H 15 / 2 (Blu-ray) and 4 F 9 / 2 → 6 H 11 / 2 (red light), the product emits yellow light under ultraviolet excitation. 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. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a white phosphor and its preparation method and application, aiming to improve SrGdAlO4:Dy 3+ The luminescent properties of phosphors are improved to achieve efficient white light emission.

[0006] In a first aspect, the present invention provides a white phosphor, the chemical formula of which is Sr 1- x Ca x G 1-y-zAlO4:yDy 3+ / zTm 3+ , where 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.

[0007] In the technical solution of the embodiment of the present application, Ca is used 2+ and Tm 3+ Doped SrGdAlO4:Dy 3+ Phosphors to improve SrGdAlO4:Dy 3+ The luminescent properties of phosphors are improved to achieve efficient white light emission.

[0008] This application is in SrGdAlO4:Dy 3+ Ca doping in phosphors 2+ It can improve the luminous intensity of the phosphor and also prolong the fluorescence life of the phosphor.

[0009] At the same excitation wavelength, SrCaGdAlO4:Dy 3+ / Tm 3+ Phosphor can show Dy 3+ and Tm 3+ The characteristic emission peak of Tm 3+ After that, the blue light emission intensity can be increased by changing Dy 3+ and Tm 3+ The relative doping concentration ratio of SrCaGdAlO4:Dy 3+ / Tm 3+ Modulation of phosphor from warm white light to cool white light.

[0010] Preferably, the excitation wavelength of the phosphor is 278 nm to 391 nm.

[0011] Preferably, the emission peak wavelength of the phosphor under the excitation wavelength is 460nm~660nm.

[0012] Preferably, the phosphor has a color temperature of 5000K~10000K.

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

[0014] In a second aspect, the present invention provides a method for preparing a white phosphor, comprising the following steps: S1. Mix strontium source, aluminum source, gadolinium source, dysprosium source, calcium source and thulium source according to Sr 1-x Ca x G 1-y-z AlO4:yDy 3+ / zTm 3+The stoichiometric ratio of each element in the phosphor is mixed and ground to obtain a mixture; S2, sintering the mixture in step S1 at a set temperature; S3. After sintering, the mixture is naturally cooled to obtain phosphor powder.

[0015] In the technical solution of the embodiment of the present application, after the raw materials are sintered at a set temperature and kept warm, SrCaGdAlO4:Dy 3+ / Tm 3+ Phosphor, in SrGdAlO4:Dy 3+ Ca doping in phosphors 2+ and Tm 3+ , can improve the density of phosphors. The higher the density, the higher the efficiency of light transmission in phosphors. 2+ and Tm 3+ Can improve the luminescence performance of phosphor.

[0016] Preferably, the sintering temperature in step S2 is 1300-1500° C., and the holding time at the sintering temperature is 1-6 hours.

[0017] 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.

[0018] In a third aspect, an embodiment of the present application provides an LED light source, comprising the above-mentioned white phosphor.

[0019] Preferably, the CIE color coordinate range of the LED light source is X=0.282~0.353, Y=0.257~0.371.

[0020] Different from the existing technical solutions, the beneficial effects of this application include: 1. This application adopts Ca 2+ and Tm 3+ Doped SrGdAlO4:Dy 3+ Phosphors to improve SrGdAlO4:Dy 3+ The luminescent properties of phosphors are improved to achieve efficient white light emission.

[0021] This application is in SrGdAlO4:Dy 3+ Ca doping in phosphors 2+It can improve the luminous intensity of the phosphor and also prolong the fluorescence life of the phosphor.

[0022] At the same excitation wavelength, SrCaGdAlO4:Dy 3+ / Tm 3+ Phosphor can show Dy 3+ and Tm 3+ Characteristic emission peak of Tm 3+ After that, the blue light emission intensity can be increased by changing Dy 3+ and Tm 3+ The relative doping concentration ratio of SrCaGdAlO4:Dy 3+ / Tm 3+ Modulation of phosphor from warm white light to cool white light.

[0023] 2. In SrGdAlO4:Dy 3+ Ca doped phosphor 2+ and Tm 3+ , can improve the density of phosphors. The higher the density, the higher the efficiency of light transmission in phosphors. Therefore, doping with Ca 2+ and Tm 3+ Can improve the luminescence performance of phosphor.

[0024] 3. The CIE color coordinates of the LED light source of the present application under the excitation of near-ultraviolet light of different wavelengths are all 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.

[0025] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 XRD diagram of the phosphor samples in Examples 1 to 4; Figure 2The SrGd ​​prepared in Comparative Example 1, Comparative Example 4 and Example 1 of this application 0.97 AlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ SEM image of phosphor sample, Figure 2 (a) is a 2,000-fold magnified SEM image of the phosphor sample in Comparative Example 1. Figure 2 (b) is a SEM image of the phosphor sample in Comparative Example 1 magnified 20,000 times. Figure 2 (c) is a 2,000-fold magnified SEM image of the phosphor sample in Comparative Example 4. Figure 2 (d) is a SEM image of the phosphor sample in Example 1 magnified 2,000 times; Figure 3 The emission spectra and chromaticity diagrams of the phosphor samples in Examples 1 to 4 at an excitation wavelength of 355 nm are shown in FIG. Figure 3 (a) is the emission spectrum of the phosphor samples in Examples 1 to 4, Figure 3 (b) is a chromaticity diagram of the phosphor samples in Examples 1 to 4; Figure 4 is the emission spectrum of the phosphor samples in Examples 4 to 6 at an excitation wavelength of 355 nm; Figure 5 The emission spectra and chromaticity diagram of the phosphor sample in Example 1 at different excitation wavelengths are shown in FIG. Figure 5 (a) is the emission spectrum of the phosphor sample in Example 1, Figure 5 (b) is a chromaticity diagram of the phosphor sample in Example 1; Figure 6 The emission spectra and chromaticity diagrams of the phosphor samples in Comparative Examples 1 to 5 at an excitation wavelength of 355 nm are shown in FIG. Figure 6 (a) is the emission spectrum of the phosphor samples in Comparative Examples 1 to 5, Figure 6 (b) is the chromaticity diagram of the phosphor samples in Comparative Examples 1 to 5; Figure 7 is the fluorescence lifetime curve of the phosphor samples in Comparative Examples 1 to 5; Figure 8 This is the emission spectrum of the phosphor samples in Comparative Examples 6 to 8 at an excitation wavelength of 355 nm. DETAILED DESCRIPTION

[0028] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0030] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] 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 its preparation method and application. 3+ The luminescent properties of the phosphor achieve the purpose of efficient white light emission.

[0032] In a first aspect, the present invention provides a white phosphor, the chemical formula of which is Sr 1- x Ca x G 1-y-z AlO4:yDy 3+ / zTm 3+ , where 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.

[0033] Preferably, the excitation wavelength of the phosphor is 278 nm to 391 nm.

[0034] Preferably, the emission peak wavelength of the phosphor under the excitation wavelength is 460nm~660nm.

[0035] Preferably, the phosphor has a color temperature of 5000K~10000K.

[0036] Preferably, the Y / B value of the phosphor is 0.83-0.98.

[0037] In a second aspect, the present invention provides a method for preparing a white phosphor, comprising the following steps: S1. Mix strontium source, aluminum source, gadolinium source, dysprosium source, calcium source and thulium source according to Sr 1-x Ca x G 1-y-z AlO4:yDy 3+ / zTm 3+ The stoichiometric ratio of each element in the phosphor is mixed and ground to obtain a mixture; S2, sintering the mixture in step S1 at a set temperature; S3. After sintering, the mixture is naturally cooled to obtain phosphor powder.

[0038] Preferably, the sintering temperature in step S2 is 1300-1500° C., and the holding time at the sintering temperature is 1-6 hours.

[0039] In a third aspect, an embodiment of the present application provides an LED light source, comprising the above-mentioned white phosphor.

[0040] Preferably, the CIE color coordinate range of the LED light source is X=0.282~0.353, Y=0.257~0.371.

[0041] 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 should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0042] 1. Preparation method Example 1 Example 1 provides a phosphor having a chemical formula of Sr 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ , z = 0.005, is obtained by the following steps: Sr(NO3)2, Al2O3, Gd2O 3、CaCO3, Dy2O3 and Tm2O3 were prepared in a molar ratio of 0.98:0.5:0.4825:0.02:0.015:0.0025. Various raw materials were accurately weighed using a semi-micro balance and put into an agate mortar for full grinding to obtain a mixture. The mixture was transferred into a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace was: the heating rate was 5°C / min, the holding time was 3h, and the phosphor was obtained.

[0043] Example 2 The phosphor preparation method proposed in this embodiment is different from that in embodiment 1 only in that Sr(NO3)2, Al2O3, Gd2O 3、 The molar ratios of CaCO3, Dy2O3 and Tm2O3 are different. In this embodiment, Sr(NO3)2, Al2O3, Gd2O 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 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ , z=0.01.

[0044] Example 3 The phosphor preparation method proposed in this embodiment is different from that in embodiment 1 only in that Sr(NO3)2, Al2O3, Gd2O 3、 The molar ratios of CaCO3, Dy2O3 and Tm2O3 are different. In this embodiment, Sr(NO3)2, Al2O3, Gd2O 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 G 0.97- z AlO4:0.03Dy 3+ / z Tm 3+ , z=0.015.

[0045] Example 4 The phosphor preparation method proposed in this embodiment is different from that in embodiment 1 only in that Sr(NO3)2, Al2O3, Gd2O 3、 The molar ratios of CaCO3, Dy2O3 and Tm2O3 are different. In this embodiment, Sr(NO3)2, Al2O3, Gd2O 3、The molar ratio of CaCO3, Dy2O3 and Tm2O3 is 0.98:0.5:0.475:0.02:0.015:0.01, and the chemical formula of the phosphor is Sr 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ , z=0.02.

[0046] Example 5 Example 1 provides a phosphor having a chemical formula of Sr 1-x Ca x G 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ , x=0.015, is obtained by the following steps: Sr(NO3)2, Al2O3, Gd2O 3、 CaCO3, Dy2O3 and Tm2O3 were prepared in a molar ratio of 0.985:0.5:0.475:0.015:0.015:0.01. Various raw materials were accurately weighed using a semi-micro balance and put into an agate mortar for full grinding to obtain a mixture. The mixture was transferred into a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace was: the heating rate was 5°C / min, the holding time was 3h, and the phosphor was obtained.

[0047] Example 6 The phosphor preparation method proposed in this embodiment is different from that in embodiment 1 only in that Sr(NO3)2, Al2O3, Gd2O 3、 The molar ratios of CaCO3, Dy2O3 and Tm2O3 are different. In this embodiment, Sr(NO3)2, Al2O3, Gd2O 3、 The molar ratio of CaCO3, Dy2O3 and Tm2O3 is 0.975:0.5:0.475:0.025:0.015:0.01, and the chemical formula of the phosphor is Sr 1-x Ca x G 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ , x=0.025.

[0048] Comparative Example 1 The chemical formula of the phosphor in this comparative example is SrGd 0.97 AlO4:0.03Dy 3+The difference between the preparation method and Example 1 is that it does not contain CaCO3 and Tm2O3, and is prepared by the following steps: Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3 were prepared in a molar ratio of 1:0.5:0.485:0.03, and various raw materials were accurately weighed using a semi-micro balance and put into an agate mortar for full grinding to obtain a mixture, which was then transferred into a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace was: the heating rate was 5°C / min, and the holding time was 3h to obtain the phosphor.

[0049] Comparative Example 2 The chemical formula of the phosphor in this comparative example is Sr 1-x Ca x G 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: Sr(NO3)2, Al2O3, Gd2O3, CaCO3 and Dy2O3 were prepared in a molar ratio of 0.995:0.5:0.485:0.005:0.015, and various raw materials were accurately weighed using a semi-micro balance and put into an agate mortar for full grinding to obtain a mixture, which was then transferred into a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace was: the heating rate was 5°C / min, and the holding time was 3h to obtain the phosphor.

[0050] Comparative Example 3 The difference between the phosphor preparation method proposed in this comparative example and that in comparative example 1 is that the molar ratio of Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3 is different. 3、 The molar ratio of 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 G 0.97 AlO4:0.03Dy 3+ , x=0.015.

[0051] Comparative Example 4 The difference between the phosphor preparation method proposed in this comparative example and that in comparative example 1 is that the molar ratio of Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3 is different. The molar ratio of Sr(NO3)2, Al2O3, Gd2O3, CaCO3 and Dy2O3 in this comparative example is 0.98:0.5:0.485:0.02:0.015. The chemical formula of the phosphor is Sr 1-x Ca x G 0.97 AlO4:0.03Dy 3+ , x=0.02.

[0052] Comparative Example 5 The difference between the phosphor preparation method proposed in this comparative example and that in comparative example 1 is that the molar ratio of Sr(NO3)2, Al2O3, Gd2O3 and Dy2O3 is different. 3、 The molar ratio of CaCO3 and Dy2O3 is 0.975:0.5:0.485:0.015:0.025, and the chemical formula of the phosphor is Sr 1-x Ca x G 0.97 AlO4:0.03Dy 3+ , x=0.025.

[0053] Comparative Example 6 The chemical formula of the phosphor in this comparative example is SrGd 0.97-z AlO4:0.03Dy 3+ / zTm, z=0.005, the preparation method is different from that of Example 1 in that it does not contain CaCO3, and is prepared by the following steps: Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 were prepared in a molar ratio of 1:0.5:0.4825:0.015:0.0025, and various raw materials were accurately weighed using a semi-micro balance and put into an agate mortar for full grinding to obtain a mixture, which was then transferred into a corundum crucible and placed in a high-temperature muffle furnace for sintering at 1500°C. The setting program of the muffle furnace was: the heating rate was 5°C / min, and the holding time was 3h to obtain the phosphor.

[0054] Comparative Example 7 The difference between the phosphor preparation method proposed in this comparative example and that in comparative example 6 is that the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 is different. The molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 in this comparative example is 1:0.5:0.4775:0.015:0.0075, and the chemical formula of the phosphor is Sr 1-xCa x G 0.97 AlO4:0.03Dy 3+ , x=0.015.

[0055] Comparative Example 8 The difference between the phosphor preparation method proposed in this comparative example and that in comparative example 6 is that the molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 is different. The molar ratio of Sr(NO3)2, Al2O3, Gd2O3, Dy2O3 and Tm2O3 in this comparative example is 1:0.5:0.475:0.015:0.01, and the chemical formula of the phosphor is Sr 1-x Ca x G 0.97 AlO4:0.03Dy 3+ , x=0.02.

[0056] 2. Test Method 1. XRD spectrum test of phosphor samples: The powder X-ray diffractometer (XRD) of PANalytical of the Netherlands was used, and the radiation source was Cu K α (λ=1.5418 Å), and the scanning range 2θ was 10º~80º.

[0057] 2. Phosphor sample morphology characterization and energy spectrum analysis: The samples were subjected to morphological characterization and energy spectrum analysis (EDS) using a scanning electron microscope (SEM) of Quanta 200 manufactured by FEI Company of the United States.

[0058] 3. Test of the luminescence performance of phosphor: The excitation spectrum and emission spectrum of phosphor were tested by F-4700 fluorescence spectrophotometer of Hitachi, with a measuring range of 200-900 nm, a scanning rate of 1200 nm / min, a 150W continuous xenon lamp source, and a voltage of 400V.

[0059] 4. Chromaticity diagram detection method: import the excitation spectrum into CIE software, calculate the coordinates, input the color coordinates into CIE1973, and obtain the chromaticity diagram.

[0060] 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.

[0061] 6. Fluorescence lifetime detection method: Grind the phosphor evenly and put it into the solid powder sample cell of the F-4700 fluorescence spectrophotometer. Then set the instrument parameters to an emission wavelength of 580 nm and an excitation wavelength of 355 nm to detect the fluorescence lifetime of the phosphor under 355 nm excitation.

[0062] III. Analysis of test results of various embodiments and comparative examples The phosphor samples prepared in Examples 1 to 4 were subjected to XRD pattern testing, and the test results were as follows: Figure 1 shown.

[0063] (1) Figure 1 In Examples 1 to 4, Ca is doped 2+ and Tm 3+ The XRD pattern of the phosphor after doping shows that 3+ Afterwards, the XRD spectrum of the sample matched the peak position of the standard PDF card, which showed that the material in the standard card could be synthesized by the experimental methods of Examples 1 to 4, and the phosphor Sr 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ (z=0.005~0.02).

[0064] (2) SrGd ​​prepared in Comparative Example 1, Comparative Example 4, and Example 1 0.97 AlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ , Sr 0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ The phosphor samples were scanned by SEM to obtain Figure 2 SEM images of Figure 2 It can be seen from (a) and (b) that SrGd 0.97 AlO4:0.03Dy 3+ When magnified 2,000 times and 20,000 times, the sample is composed of agglomerates of irregular particles with a particle size ranging from 2μm to 40μm. Figure 2 (b) SrGd 0.97 AlO4:0.03Dy 3+ SEM image at a magnification of 20,000 times. From the image, it can be seen that the surface of the sample is mostly irregular trapezoids, but the surface is smooth and has good crystallinity. Figure 2 (c) Sr 0.98 Ca 0.02 GdAlO4:0.03Dy 3+ SEM image of Ca-doped 2+ After precipitating, the shape and particle size of the samples did not change much, and the particle size was about 2μm to 40μm. Figure 2 (d) Sr0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ SEM image of Tm-doped 3+ and Ca 2+ Afterwards, the sample was magnified 2,000 times and the density was higher, which means that the luminescence performance of the sample is better, because the higher the density, the higher the efficiency of light transmission in the sample, which also reflects the doping of Tm 3+ and Ca 2+ It can improve the luminescence performance of the sample.

[0065] (3) For Sr in Examples 1 to 4 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ (z=0.005~0.02) The phosphor was excited by 355nm ultraviolet light to conduct emission spectrum and chromaticity diagram test. The test results are as follows Figure 3 As shown, from Figure 3 As can be seen from (a), Sr 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / zTm 3+ The emission spectrum of the phosphor under ultraviolet light (355nm) excitation has four obvious emission peaks, located at 460nm, 484nm, 580nm, and 660nm, and the peak shape and peak position of the emission peak are almost independent of Tm 3+ The emission peaks at 484nm and 580nm are from Dy 3+ of 4 F 9 / 2 → 6 H 15 / 2 and 4 F 9 / 2 → 6 H 13 / 2 Energy level transition, the intensity of these two emission peaks increases with Tm 3+ The emission peak at 460nm comes from Tm in the phosphor. 3+ of 1 D2→ 3 F4 energy level transition, the intensity of these two emission peaks increases with Tm 3+ The increase of doping concentration increases. This shows that at this time, Dy in the SrCaGdAlO4 lattice 3+ To Tm3+ There is energy transfer.

[0066] from Figure 3 As can be seen from (b), SrCaGdAlO4:0.03Dy 3+ / z Tm 3+ Phosphor powder with Tm 3+ As the doping concentration increases, the color coordinates gradually shift from the white area to the blue area. This is due to the fact that Tm 3+ At 460 nm 1 D2→ 3 F4 energy level transition, but because Tm 3+ The doping concentration is relatively small, so the phosphor as a whole is still in the white light area and very close to the center of the white light area.

[0067] In order to further describe the fluorescence characteristics, different Tm 3+ The corresponding correlated color temperature under the doping concentration is shown in Table 1: Table 1 Sr 0.98 Ca 0.02 G 0.97-z AlO4:0.03Dy 3+ / z Tm 3+ Color coordinates and color temperature at different concentrations

[0068] From the data in Table 1, it can be found that in Dy 3+ and Tm 3+ In co-doped phosphors, the correlated color temperature of the phosphors changes with Tm 3+ The doping concentration increases. Therefore, it can be achieved by adding SrCaGdAlO4:0.03Dy 3+ A small amount of Tm is doped into the phosphor 3+ To increase the blue light component of the phosphor, thereby improving the display index of the phosphor and raising the color temperature; by changing Dy 3+ 、Tm 3+ The relative doping concentration ratio of SrCaGdAlO4:Dy 3+ / Tm 3+ The regulation of phosphor from cold white light to warm white light.

[0069] (4) For Sr in Examples 4 to 6 1-x Ca x G 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+, (x=0.015~0.025) The phosphor is excited by 355nm ultraviolet light to conduct emission spectrum test. The test results are as follows Figure 4 As shown, from Figure 4 It can be seen that Sr 1-x Ca x G 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ The emission spectrum of the phosphor under ultraviolet light (355nm) excitation has four obvious emission peaks, and the peak shape of the emission peak is almost independent of Ca 2+ The doping concentration changes with the change of Ca 2+ The increase of doping concentration increases.

[0070] In order to further describe the fluorescence characteristics, the different Ca 2+ The corresponding correlated color temperature under the doping concentration is shown in Table 2: Table 2 Sr 1-x Ca x G 0.95 AlO4:0.03Dy 3+ / 0.02Tm 3+ Color coordinates and color temperature at different concentrations

[0071] From the data in Table 2, it can be found that the color coordinates of the phosphor do not vary with Ca 2+ The color temperature varies with the doping concentration, but the color temperature varies with Ca 2+ increases with the increase of doping concentration.

[0072] (5) For Sr in Example 1 0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ The emission spectrum and chromaticity diagram of the phosphor were tested at different excitation wavelengths. The test results are shown in Figure 5 , Sr. 0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ The color coordinates and color temperature values ​​of the phosphor at different excitation wavelengths are shown in Table 5 below: Table 3 Sr 0.98 Ca 0.02 G 0.965 AlO4:0.03Dy 3+ / 0.005Tm 3+ Color coordinates and color temperature at different excitation wavelengths

[0073] from Figure 5 As can be seen in (a), the sample can be effectively excited by ultraviolet-near ultraviolet light, producing good blue and yellow light emission in the visible light region. In addition, although the emission intensity of the sample is significantly different under the excitation of different excitation wavelengths, the shape of the emission spectrum and the position of the emission peak do not change much. Under 360 nm excitation, the sample has a stronger emission peak at 480 nm, which is because 480 nm is the Tm 3+ The characteristic emission peak of Dy leads to a strong emission peak at 480 nm. 3+ The characteristic emission peak of Dy also has intensity, so it can be concluded that 3+ and Tm 3+ There is energy transfer between them. The intensity of the emission spectrum under 355 nm excitation is higher than that under 277 nm excitation. Therefore, 355 nm is the best excitation wavelength for the sample. Figure 5 (b) is the chromaticity diagram of the sample under different wavelength excitation. Figure 5 As can be seen in (b), the color coordinates under different wavelength excitation are all in the white light region, which means that under ultraviolet wavelength excitation, the samples all emit white light. And from Table 2, it can be seen that the color temperature of the phosphor is around 5000K-10000K, which is suitable as a daily lighting source.

[0074] Moreover, the CIE color coordinates of the phosphor in Example 1 under excitation at different wavelengths are all in the white light region, and the standard white light color coordinates are (0.333, 0.333). The color coordinates of the phosphor in Example 1 under excitation at different wavelengths 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.

[0075] (6) Sr in Comparative Examples 1 to 5 1-x Ca x G 0.97 AlO4:0.03Dy 3+ (x=0~0.025) The phosphor is tested for emission spectrum and chromaticity diagram. The test results are as follows Figure 6 As shown, Figure 6 (a) Sr 1-x Ca x G 0.97 AlO4:0.03Dy 3+ The emission spectrum of the chromaticity diagram under 355nm ultraviolet light excitation. 2+ As the concentration increases, the fluorescence intensity of the phosphor increases.2+ When the doping concentration is 0.02, the phosphor SrGdAlO4:Dy 3+ The luminescence intensity reaches the maximum value, and the Ca 2 + When the concentration reaches 0.04, the luminous intensity of the phosphor begins to decrease.

[0076] Sr in Comparative Examples 1 to 5 1-x Ca x G 0.97 AlO4:0.03Dy 3+ (x=0~0.025) The color coordinates, color temperature, and Y / B value of the phosphor under 355nm excitation are tested. The test results are shown in Table 4 below: Table 4 Sr 1-x Ca x GdAlO4:0.03Dy 3+ Color coordinates, color temperature, Y / B value

[0077] It can be seen from Table 4 that different Ca 2+ The color coordinates of the concentration-doped phosphor are near the standard white light color coordinates (0.350, 0.370), which shows that the phosphor can present excellent white light under the excitation of ultraviolet wavelength, and the laser method of the phosphor does not change with Ca 2+ The doping concentration varies.

[0078] The Y / B value of the phosphor increases with the Ca 2+ The concentration of doping increases first and then decreases. The value of Y / B represents the covalency of Dy-O. The higher the Y / B, the higher the covalency of Dy 3+ and O 2- The higher the covalency, the better the white light. In addition, the color temperature of the phosphor is around 4837K, which is warm white light and suitable for daily lighting. Therefore, from the perspective of comprehensive emission intensity and Y / B value, Ca 2+ The optimum doping concentration in the matrix SrGdAlO4 is 0.02.

[0079] (7) Sr in Comparative Examples 1 to 5 1-x Ca x G 0.97 AlO4:0.03Dy 3+ (x=0~0.025) The fluorescence lifetime of the phosphor under 355nm excitation is tested. The test results are as follows Figure 7 As shown. Figure 7 It can be seen that in Comparative Examples 1 to 5, each Ca 2+The average lifetimes of the Ca-doped phosphors at 580nm (blue light) are 0.370ms, 0.374ms, 0.381ms, 0.383ms, and 0.382ms, respectively. 2+ After that, the fluorescence lifetime of the phosphor increases first and then decreases, reaching the maximum when the doping concentration is 0.02, and is higher than that of the undoped Ca 2+ The fluorescent lifetime of the phosphor is long, which indicates that Ca 2+ The doping of Ca not only improves the luminescence intensity of the phosphor, but also increases the fluorescence lifetime of the phosphor, which further illustrates that 2+ The optimum doping concentration is 0.02.

[0080] (8) SrGd ​​in Comparative Examples 6 to 8 0.97-z AlO4:0.03Dy 3+ / zTm (z=0.005~0.02) phosphor test results are as follows Figure 8 As shown, from Figure 8 It can be seen that SrGd 0.97-z AlO4:0.03Dy 3+ / zTm phosphor has four obvious emission peaks in the emission spectrum under ultraviolet light (355nm), and the peak shape of the emission peak is almost independent of Tm 3+ The doping concentration changes, but the intensity of the emission peak changes with Tm 3+ The increase of doping concentration increases.

[0081] In order to further describe the fluorescence characteristics, different Tm 3+ The corresponding correlated color temperature under the doping concentration is shown in Table 5: Table 5SrGd 0.97-z AlO4:0.03Dy 3+ / zTm color coordinates and color temperature at different concentrations

[0082] From the data in Table 5, it can be found that the color coordinates of the phosphor decrease with Tm 3+ The color temperature changes with the change of doping concentration. 3 + increases with the increase of doping concentration.

[0083] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A white phosphor, characterized in that: The chemical formula of the phosphor is Sr 1-x Ca x G 1-y-z AlO4:yDy 3+ / zTm 3 + , where 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.

2. The white phosphor according to claim 1, characterized in that: The excitation wavelength of the phosphor is 278nm~391nm.

3. The white phosphor according to claim 2, characterized in that: The emission peak wavelength of the phosphor under the excitation wavelength is 460nm~660nm.

4. The white phosphor according to claim 1, characterized in that: The phosphor has a color temperature of 5000K-10000K.

5. The white phosphor according to claim 1, characterized in that: The Y / B value of the phosphor 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 steps include: S1. Mix strontium source, aluminum source, gadolinium source, dysprosium source, calcium source and thulium source according to Sr 1-x Ca x G 1-y-z AlO4:yDy 3+ / zTm 3+ The stoichiometric ratio of each element in the phosphor is mixed and ground to obtain a mixture; S2, sintering the mixture in step S1 at a set temperature; S3. After sintering, the mixture is naturally cooled to obtain phosphor 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° C., and the holding time at the sintering temperature is 1-6 hours.

9. An LED light source, characterized in that: The invention comprises the white phosphor according to any one of claims 1 to 5.

10. The LED light source according to claim 9, characterized in that: The CIE color coordinate range of the LED light source is X=0.282~0.353, Y=0.257~0.371.

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