A single-phase white fluorescent powder, a preparation method and application thereof

Abstract

The application relates to the technical field of inorganic luminescence, in particular to a single-phase white fluorescent powder as well as a preparation method and application thereof. 1‑x (VO4)7:xEu 3+ ; the europium ion is an active ion Eu 3+ ; x is a mole percentage coefficient of the active ion Eu 3+ relative to the metal ion La, and x is in a range of 0<=x<=1. The single-phase white fluorescent powder has a high color rendering index and a high color temperature; the fluorescent powder can be used for preparing an LED light-emitting device, can be used for a ratio type fluorescent thermometer, and can also realize non-contact in-situ temperature measurement according to the spectral characteristics of the fluorescent powder.

Description

Technical Field

[0001] This invention relates to the field of inorganic light-emitting technology, specifically to a single-phase white phosphor, its preparation method, and its application. Background Technology

[0002] Photoluminescence refers to the phenomenon of light emission produced by exciting light-emitting materials with ultraviolet, visible, and infrared light. Light-emitting diodes (LEDs), as the most promising next-generation solid-state light source, play a vital role in fields closely related to the national economy and daily life due to their long lifespan, energy efficiency, and environmental friendliness.

[0003] In recent years, compared with traditional lighting sources, white LEDs have attracted widespread attention due to their long lifespan, high luminous efficiency, low energy consumption, and environmental friendliness. Therefore, we believe that as a fourth-generation light source, white LEDs will lead the future of lighting. The most typical assembly method for commercially available white LED lamps uses blue LED chips and yellow phosphor YAG:Ce. 3+ The combination method is problematic. However, due to the lack of red components, this method results in a low color rendering index and high color temperature for the phosphor, severely affecting the quality of the LED. To overcome these shortcomings, near-ultraviolet LED chips or ultraviolet LED chips can be assembled with red, green, and blue phosphors. However, this phosphor assembly method still has certain drawbacks. The light emitted by the red and green phosphors is absorbed a second time by the blue phosphor, leading to low luminous efficiency and difficulty in controlling the emitted color. Furthermore, this method also suffers from unstable white light due to different light decay ratios. These drawbacks limit the widespread adoption of white LEDs. Existing technologies, such as Chinese patent document CN102504814A (application number 201110321220.0), disclose a white phosphor material, which is a composite material composed of yellow phosphor and amorphous glass. This requires the preparation of yellow phosphor first, followed by the preparation of the composite material, which must be carried out under inert gas protection, making the preparation process quite cumbersome.

[0004] Therefore, in order to improve the reproducibility of material luminescence, increase luminous efficiency, and reduce production costs, there is an urgent need for a single-phase white phosphor suitable for excitation by ultraviolet or near-ultraviolet LED chips.

[0005] As a fourth-generation energy source, LEDs are widely used in various lighting fields due to their long lifespan, high efficiency, and energy saving. LED lighting products are gradually replacing traditional lighting products because of their green, energy-saving, and long lifespan advantages. Regarding LED reliability, a key issue lies in solving the thermal problems of the PN junction in LED devices. Therefore, measuring the junction temperature and thermal resistance of LEDs under actual operating conditions is of great significance for reliability assessment and heat dissipation design. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a single-phase white phosphor, its preparation method and application. The phosphor can achieve single-matrix white light emission and has a good color rendering index.

[0007] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0008] A single-phase white phosphor, wherein the chemical composition of the single-phase white phosphor is expressed as: Sr9Yb 1-x (VO4)7:xEu 3+ Europium ions are the activating ions (Eu). 3+ x represents the activated ion Eu. 3+ The molar percentage coefficient of relative metal ions La, x ranges from 0 to x ≤ 1.

[0009] The present invention also provides a method for preparing the above-mentioned single-phase white phosphor, comprising the following steps:

[0010] S1. Sr9Yb according to the chemical composition formula 1-x (VO4)7:xEu 3+ Raw materials were weighed according to stoichiometry: europium source, strontium source, ytterbium source and vanadate source, 0≤x≤1;

[0011] S2. After thoroughly grinding and mixing the raw materials, place them in a muffle furnace for calcination, and cool to room temperature to obtain the first product;

[0012] S3. Grind the first product and calcine it in a muffle furnace. After cooling to room temperature, the second product is obtained.

[0013] S4. Grind the second product and calcine it in a muffle furnace. After cooling to room temperature, grind it again to obtain a single-phase white phosphor.

[0014] Preferably, in steps S2-S4, the calcination temperature in the muffle furnace is 800℃-1000℃, and the calcination time is 40-50h. More preferably, the calcination temperature in the muffle furnace is 1000℃, and the calcination time is 37.5h.

[0015] The present invention also provides the application of the above-described single-phase white phosphor or the single-phase white phosphor prepared by the above-described preparation method in one or more of the following:

[0016] 1) LED light-emitting devices; 2) Ratio-type fluorescent thermometers.

[0017] Specifically, when single-phase white phosphor is used in the fabrication of LEDs, the LEDs can perform non-contact in-situ temperature measurement.

[0018] The preferred method for non-contact in-situ temperature measurement is as follows:

[0019] By reading the emission spectrum of a single-phase white phosphor and finding the corresponding temperature based on the intensity ratio of the peaks in the emission spectrum, the temperature of the LED light-emitting device can be determined.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] (1) This invention provides a representation of Sr9Yb 1-x (VO4)7:xEu 3+ Single-phase white phosphor, see Figure 4 Phosphors have a high color rendering index and a high color temperature.

[0022] (2) The single-phase white phosphor provided by the present invention can not only be used to prepare LED light-emitting devices, but also to ratio fluorescent thermometers. Furthermore, non-contact in-situ temperature measurement can be achieved by reading the spectral characteristics of the phosphor based on its properties.

[0023] (3) Pure substances are not adulterated with Eu 3+ It can also achieve self-illumination.

[0024] (4) Eu can be achieved 3+ High doping does not result in concentration quenching.

[0025] (5) Since Eu replaces the position of Yb, Yb occupies few lattice sites in the crystal of the compound, so high doping can be achieved while the quality of Eu used is low, saving raw materials. Attached Figure Description

[0026] Figure 1 The phosphor Sr9Yb prepared in Example 1 0.9 (VO4)7:0.1Eu 3+ Scanning electron microscope image.

[0027] Figure 2 These are the XRD patterns of the phosphors prepared in Examples 1-6.

[0028] Figure 3 The fluorescence emission spectrum of the phosphors prepared in Examples 1-6 is at 365 nm.

[0029] Figure 4 This is a CIE coordinate diagram of the phosphors prepared in Examples 1-6 at an excitation wavelength of 365 nm.

[0030] Figure 5 This is the temperature-varying spectrum of the phosphor prepared in Example 5 at an excitation wavelength of 365 nm.

[0031] Figure 6 This is a fitting graph of the FIR variation with temperature in the temperature-dependent fluorescence emission spectrum of the phosphor prepared in Example 5 at 365 nm.

[0032] Figure 7 This is a schematic diagram of the phosphor prepared by the method in Example 6 at an excitation wavelength of 350 nm.

[0033] Figure 8 The image shows the XRD pattern of the phosphor prepared in Comparative Example 1.

[0034] Figure 9 The image shows the XRD pattern of the phosphor prepared in Comparative Example 2.

[0035] Figure 10 This is a schematic diagram showing the temperature change with current of the ratio-type fluorescent thermometer prepared in Example 8. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] The raw materials used in each embodiment and comparative example are all existing conventional commercial raw materials, and the experimental equipment are all commonly used experimental equipment in the field. The sources of each raw material and experimental equipment will not be described in detail here.

[0038] To address the problems existing in the prior art, this invention provides a single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 1-x (VO4)7:xEu 3+ Europium ions are the activating ions (Eu). 3+ x represents the activated ion Eu. 3 + The molar percentage coefficient of relative metal ions La, x ranges from 0 to x ≤ 1.

[0039] The present invention also provides a method for preparing the above-mentioned single-phase white phosphor, comprising the following steps:

[0040] S1. Sr9Yb according to the chemical composition formula 1-x (VO4)7:xEu 3+ Raw materials were weighed according to stoichiometry: europium source, strontium source, ytterbium source and vanadate source, 0≤x≤1;

[0041] S2. After thoroughly grinding and mixing the raw materials, place them in a muffle furnace for calcination, and cool to room temperature to obtain the first product;

[0042] S3. Grind the first product and calcine it in a muffle furnace. After cooling to room temperature, the second product is obtained.

[0043] S4. Grind the second product and calcine it in a muffle furnace. After cooling to room temperature, grind it again to obtain a single-phase white phosphor.

[0044] In steps S2-S4, the calcination temperature in the muffle furnace is 800℃-1000℃, and the calcination time is 40-50h. More preferably, the calcination temperature in the muffle furnace is 1000℃, and the calcination time is 37.5h.

[0045] Example 1

[0046] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.9 (VO4)7:0.1Eu 3+ Its preparation method is as follows:

[0047] S1. According to the chemical composition expression of the phosphor Sr9Yb 0.9 Eu 0.1 The stoichiometric proportions of the raw materials for (VO4)7 are as follows: europium source, strontium source, ytterbium source, and vanadate source. The europium source is europium oxide (Eu2O3), the strontium source is strontium carbonate (SrCO3), the ytterbium source is ytterbium oxide (Yb2O3), and the vanadate source is vanadium pentoxide (V2O5). Weigh out 0.0176 g of europium oxide (Eu2O3), 1.3286 g of strontium carbonate (SrCO3), 0.1774 g of ytterbium oxide (Yb2O3), and 0.6365 g of vanadium pentoxide (V2O5).

[0048] S2. The weighed europium oxide, strontium carbonate, indium oxide, and vanadium pentoxide are thoroughly ground and mixed evenly. Specifically, the mixture is placed in a zirconium dioxide ball mill jar and subjected to a solid-phase reaction at 500 rpm in a planetary ball mill for 2 hours to obtain the mixed raw material. The mixed raw material is placed in a crucible and then calcined in a muffle furnace at 1000°C for 50 hours, and then naturally cooled to room temperature to obtain the first product. The first product is removed, ground, and then calcined again in a muffle furnace at 1000°C for 50 hours, and then cooled to room temperature to obtain the second product. The second product is removed, ground, and the phosphor is obtained. The phosphor is then calcined at 1000°C for 50 hours and naturally cooled to room temperature to obtain the third product. The third product is removed, ground, and the phosphor is obtained. The final product is obtained, and the phosphor material composition is: Sr9Yb. 0.9 Eu 0.1 (VO4)7.

[0049] In this embodiment, the grinding method is to place the product in a zirconium dioxide ball mill jar and ball mill it at 500 rpm for 30 minutes in a planetary ball mill.

[0050] Test 1

[0051] Please refer to Figure 1 , Figure 1 The phosphor Sr9Yb prepared in Example 1 0.9 Eu 0.1 Scanning electron microscope image of (VO4)7. Figure 1 Sr9Yb is displayed very clearly. 0.9 Eu 0.1 The micron-sized structure of the (VO4)7 fluorescent material demonstrates that doping with trivalent europium ions does not alter the Sr9Yb composition. 0.9 Eu 0.1 The structure of (VO4)7 material.

[0052] Test 2

[0053] Please refer to Figure 3 and Figure 4 Example 1: Phosphor Sr9Yb 0.9 Eu 0.1 (VO4)7 emits a strong blue-green light emission peak (400-560nm) and an even stronger red light emission peak (600-650nm) when excited by near-ultraviolet light at 365nm; the color coordinates are (0.2925, 0.3229).

[0054] Example 2

[0055] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.7 (VO4)7:0.3Eu 3+ The preparation method differs from that in Example 1 in that the raw materials are weighed differently, specifically: europium oxide (Eu₂O₃) 0.0528g, strontium carbonate (SrCO₃) 1.3286g, ytterbium oxide (Yb₂O₃) 0.1379g, and vanadium pentoxide (V₂O₅) 0.6365g. The preparation method is the same as in Example 1.

[0056] Test 3

[0057] Please refer to Figure 3 and Figure 4 In this embodiment, the phosphor Sr9Yb 0.7 Eu 0.3 (VO4)7 emits a strong blue-green light emission peak (400-560nm) and an even stronger red light emission peak (600-650nm) when excited by near-ultraviolet light at 365nm; the color coordinates are (0.3324, 0.3186).

[0058] Example 3

[0059] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.5(VO4)7:0.5Eu 3+ The preparation method differs from that in Example 1 in that the weight of the raw materials is different. Specifically, 0.0880 g of europium oxide (Eu₂O₃), 1.3286 g of strontium carbonate (SrCO₃), 0.0986 g of ytterbium oxide (Yb₂O₃), and 0.6365 g of vanadium pentoxide (V₂O₅) are weighed. The preparation method is the same as in Example 1.

[0060] Test 4

[0061] Please refer to Figure 3 and Figure 4 In this example, the phosphor Sr9Yb 0.5 Eu 0.5 (VO4)7 emits a strong blue-green light emission peak (400-560nm) and an even stronger red light emission peak (600-650nm) when excited by near-ultraviolet light at 365nm; the color coordinates are (0.3578, 0.335).

[0062] Example 4

[0063] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.3 (VO4)7:0.7Eu 3+ The preparation method differs from that in Example 1 in that the weight of the raw materials is different. Specifically, 0.1232 g of europium oxide (Eu₂O₃), 1.3286 g of strontium carbonate (SrCO₃), 0.0591 g of ytterbium oxide (Yb₂O₃), and 0.6365 g of vanadium pentoxide (V₂O₅) are weighed. The preparation method is the same as in Example 1.

[0064] Test 5

[0065] Please refer to Figure 3 and Figure 4 In this example, the phosphor Sr9Yb 0.3 Eu 0.7 (VO4)7 emits a strong blue-green light emission peak (400-560nm) and an even stronger red light emission peak (600-650nm) when excited by near-ultraviolet light at 365nm; the color coordinates are (0.3553, 0.3337).

[0066] Example 5

[0067] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.1 (VO4)7:0.9Eu 3+The preparation method differs from that in Example 1 in that the weight of the raw materials is different. Specifically, 0.1584 g of europium oxide (Eu₂O₃), 1.3286 g of strontium carbonate (SrCO₃), 0.0197 g of ytterbium oxide (Yb₂O₃), and 0.6365 g of vanadium pentoxide (V₂O₅) are weighed. The preparation method is the same as in Example 1.

[0068] Test 6

[0069] Please refer to Figure 5 Figure 5 shows the Sr9Yb phosphor prepared in Example 3. 0.1 Eu 0.9 The fluorescence temperature curve of (VO4)7 under near-ultraviolet light excitation at 365 nm shows that as the temperature increases, the VO4+ in the phosphor located between 400 and 560 nm decreases. 3- The luminescence intensity decreases with increasing temperature, while the luminescence intensity of Eu located in the 600–650 nm range... 3+ The intensity of the emission peak increases with increasing temperature. Figure 6 The ratio of its spectral intensity to FIR showed a good linear relationship with temperature, indicating high sensitivity.

[0070] Test 7

[0071] Please refer to Figure 3 and Figure 4 In this example, the phosphor Sr9Yb 0.1 Eu 0.9 (VO4)7 emits a strong blue-green light emission peak (400-560nm) and an even stronger red light emission peak (600-650nm) when excited by near-ultraviolet light at 365nm; the color coordinates are (0.3578, 0.335).

[0072] Example 6

[0073] According to the stoichiometric ratio of the phosphor chemical composition formula Sr9Yb(VO4)7, the following raw materials were weighed: strontium source, ytterbium source, and vanadate source. The strontium source is strontium carbonate (SrCO3), the ytterbium source is ytterbium oxide (Yb2O3), and the vanadate source is vanadium pentoxide (V2O5). 1.3286 g of strontium carbonate (SrCO3), 0.1971 g of ytterbium oxide (Yb2O3), and 0.6365 g of vanadium pentoxide (V2O5) were weighed.

[0074] The weighed strontium carbonate, indium oxide, and vanadium pentoxide were thoroughly ground and mixed evenly. Specifically, the mixture was placed in a zirconium dioxide ball mill jar and subjected to a solid-phase reaction at 500 rpm for 2 hours in a planetary ball mill to obtain the mixed raw material. The mixed raw material was placed in a crucible and then calcined in a muffle furnace at 1000°C for 50 hours, and then naturally cooled to room temperature to obtain the first product. The first product was removed, ground, and then calcined again in a muffle furnace, and then cooled to room temperature to obtain the second product. The first product was removed, ground, and then calcined again in a muffle furnace at 1000°C for 50 hours, and then cooled to room temperature to obtain the second product. The second product was removed, ground, and the phosphor was obtained. The phosphor was calcined at 1000°C for 50 hours and then naturally cooled to room temperature to obtain the third product. The third product was removed, ground, and the phosphor was obtained. The final product was obtained, and the phosphor material composition was: Sr9Yb(VO4)7.

[0075] Test 8

[0076] Please refer to Figure 3 and Figure 4 In this embodiment, the phosphor Sr9Yb(VO4)7 emits a strong blue-green light emission peak (400-560nm) under near-ultraviolet light excitation at 365nm; the color coordinates are (0.2453, 0.3175).

[0077] Test 9

[0078] Please refer to Figure 6 The phosphor prepared according to the method of Example 6 can emit light at a specific excitation wavelength. Therefore, the pure Sr9Yb(VO4)7 matrix is ​​not doped with Eu. 3+ It can also achieve self-illumination.

[0079] Test 10

[0080] Please refer to Figure 2 , Figure 2 The XRD patterns are those of the phosphors prepared by the methods of Examples 1 to 6. The diffraction peak positions and lattice of the phosphor materials obtained in Examples 1 to 6 are consistent with those in the database, and no extra peaks appear, indicating that the synthesized samples are pure samples.

[0081] Example 7

[0082] An LED light-emitting device is made from the single-phase white phosphor provided in any one of Examples 1 to 6. In this example, the LED light-emitting device is a diode, a tri-color fluorescent lamp, or a field emission display, etc.

[0083] The LED light-emitting device provided in this embodiment can also perform non-contact in-situ temperature measurement. The specific method is as follows: by reading the emission spectrum of the WLED when it is working, calculating the intensity ratio of the peaks, finding the temperature corresponding to this intensity, the working temperature at this time can be read directly.

[0084] Example 8

[0085] A ratiometric fluorescent thermometer is prepared from the single-phase white phosphor provided in any one of Examples 1 to 6.

[0086] Based on the prepared Sr9Yb 0.1 Eu 0.9 Based on the temperature sensing characteristics of (VO4)7 phosphor, and by establishing the correlation between FIR and current and temperature, a new in-situ temperature detection technology for WLEDs is proposed. Meanwhile, as... Figure 10 As shown, when the current increases from 20mA to 320mA, the corresponding temperature can be determined by monitoring the FIR value. The temperature of the display chip gradually increases from 320.3K to 338.2K, which is basically consistent with the trend of the LED operating temperature. This proves the feasibility of in-situ temperature readings for WLEDs.

[0087] Comparative Example 1

[0088] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.9 (VO4)7:0.1Eu 3+ The preparation method of this comparative example differs from that of Example 1 in that step S2 is as follows:

[0089] S2. The weighed europium oxide, strontium carbonate, indium oxide, and vanadium pentoxide are thoroughly ground and mixed evenly. Specifically, the mixture is placed in a zirconium dioxide ball mill jar and subjected to a solid-phase reaction at 500 rpm in a planetary ball mill for 2 hours to obtain the mixed raw material. The mixed raw material is placed in a crucible and then calcined in the muffle furnace at 1000°C for 50 hours, and then naturally cooled to room temperature to obtain the first product. The first product is removed, ground, and then calcined again in the muffle furnace at 1000°C for 50 hours, and then cooled to room temperature to obtain the second product. The second product is removed and ground to obtain the phosphor, and the final product is obtained. The phosphor material composition is: Sr9Yb. 0.9 Eu 0.1 (VO4)7.

[0090] Insufficient sintering time resulted in incomplete and uniform reaction of the sample, leading to the formation of impurities. Please refer to [reference needed]. Figure 8 , Figure 8The XRD pattern of the phosphor prepared in Comparative Example 1 shows that the diffraction peak positions and lattice of the phosphor material obtained in Comparative Example 1 are inconsistent with those in the database, and there are extra peaks, indicating that the synthesized sample contains impurities.

[0091] Comparative Example 2

[0092] A single-phase white phosphor, the chemical composition of which is expressed as: Sr9Yb 0.9 (VO4)7:0.1Eu 3+ The preparation method of this comparative example differs from that of Example 1 in that step S2 is as follows:

[0093] S2. The weighed europium oxide, strontium carbonate, indium oxide, and vanadium pentoxide are thoroughly ground and mixed evenly. Specifically, the mixture is placed in a zirconium dioxide ball mill jar and subjected to a solid-phase reaction at 500 rpm in a planetary ball mill for 2 hours to obtain the mixed raw material. The mixed raw material is placed in a crucible and then calcined in the muffle furnace at 1000°C for 50 hours, and then naturally cooled to room temperature to obtain the first product. The first product is then removed and ground to obtain the phosphor, and the final product is obtained. The phosphor material composition is: Sr9Yb. 0.9 Eu 0.1 (VO4)7.

[0094] Insufficient sintering time resulted in incomplete and uniform reaction of the sample, leading to the formation of impurities. Please refer to [reference needed]. Figure 9 , Figure 9 The image shows the XRD pattern of the phosphor prepared in Comparative Example 2. The diffraction peak positions and lattice of the phosphor material obtained in Comparative Example 2 are inconsistent with those in the database, and there are extra peaks, indicating that the synthesized sample contains impurities.

Claims

1. A single-phase white phosphor, characterized in that, The chemical composition of the single-phase white phosphor is expressed as: Sr9Yb 1-x (VO4)7:xEu 3+ Europium ions are the activating ions (Eu). 3+ x represents the activated ion Eu. 3+ The molar percentage coefficient of relative metal ions Yb, x ranges from 0.1 to x ≤ 0.

9.

2. The method for preparing the single-phase white phosphor according to claim 1, characterized in that, Includes the following steps: S1. Sr9Yb according to the chemical composition formula 1-x (VO4)7:xEu 3+ Raw materials were weighed according to stoichiometry: europium source, strontium source, ytterbium source, and vanadate source, with 0.1 ≤ x ≤ 0.9; S2. After thoroughly grinding and mixing the raw materials, place them in a muffle furnace for calcination, and cool to room temperature to obtain the first product; S3. Grind the first product and calcine it in a muffle furnace. After cooling to room temperature, the second product is obtained. S4. Grind the second product and calcine it in a muffle furnace. After cooling to room temperature, grind it again to obtain single-phase white phosphor.

3. The preparation method according to claim 2, characterized in that, In steps S2-S4, the calcination temperature in the muffle furnace is 800℃-1000℃, and the calcination time is 40-50h.

4. The use of the single-phase white phosphor as described in claim 1 or the single-phase white phosphor prepared by the preparation method according to any one of claims 2-3 in one or more of the following: 1) LED light-emitting devices; 2) Ratio-type fluorescent thermometers.

5. The application as described in claim 4, characterized in that, When single-phase white phosphor is used in the fabrication of LEDs, the LEDs can perform non-contact in-situ temperature measurement.

6. The application as described in claim 5, characterized in that, The specific method for non-contact in-situ temperature measurement is as follows: By reading the emission spectrum of a single-phase white phosphor and finding the corresponding temperature based on the intensity ratio of the peaks in the emission spectrum, the temperature of the LED light-emitting device can be determined.

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