Double perovskite tungstate red phosphor and its preparation method and application

Abstract

The present invention discloses a double perovskite tungstate red phosphor and its preparation method and application, and relates to the field of red phosphor. The chemical formula of the red phosphor of the present invention is NaGd(Mg y Zn z ) 1‑2x Zr x WO6:Eu 3+ , where 0<x<0.5. The present invention uses NaGd(MgZn)WO6 as the matrix material and introduces Zr 4+ Doping to obtain NaGd(Mg y Zn z ) 1‑ 2x Zr x WO6:Eu 3+ Double perovskite red fluorescent material.

Description

Technical Field

[0001] The present invention relates to the field of red phosphor materials for WLEDs, and in particular to a double perovskite tungstate red phosphor and a preparation method and application thereof. Background Art

[0002] Human lighting sources have evolved from the earliest incandescent lamps to fluorescent lamps, high-pressure gas discharge lamps and LEDs, and are gradually developing into high-quality lighting sources. WLEDs are known as the "green light source" of the 21st century. They have the advantages of high energy conversion efficiency, long service life, high safety and low energy consumption, and have attracted widespread attention from researchers in recent years.

[0003] The combination of blue light chips and yellow phosphors is currently the mainstream implementation method of commercial WLEDs. However, due to the lack of red light-emitting components, the resulting device has a low color rendering index and a high correlated color temperature. Therefore, another WLED packaging method has emerged, that is, the combination of near-ultraviolet chips and red, green, and blue primary color phosphors. The introduction of the red component significantly improves the optoelectronic performance of the device.

[0004] Red phosphor plays a key role in WLED devices. However, the luminous intensity of current commercial red phosphor materials is prone to thermal quenching when the device operating temperature rises, resulting in a significant deterioration in luminous efficiency. This cannot meet the needs of high-power devices. Therefore, it is crucial to develop efficient red phosphors with excellent thermal stability. Summary of the Invention

[0005] The purpose of the present invention is to provide a double perovskite tungstate red phosphor and its preparation method and application, using NaGd (MgZn) WO6 as the matrix material, introducing Zr 4+ Doping to obtain NaGd(Mg y Zn z ) 1- 2x Zr x WO6:Eu 3+ Double perovskite red fluorescent material.

[0006] Specifically, the chemical formula of the double perovskite tungstate red phosphor of the present invention is NaGd(Mg y Zn z ) 1-2x Zr x WO6:Eu 3+ , where 0<x<0.5.

[0007] Zr-doped 4+ After that, the traps on the phosphor surface can be made more numerous and deeper, thereby capturing more photons. 4+The red phosphor induced by the cation vacancies has high light absorption utilization rate in the near-ultraviolet region-blue light region (365-500nm), high color purity, excellent optical properties, and good thermal stability. The red phosphor of the present invention can be used as a red component to encapsulate WLEDs suitable for working in high-temperature environments.

[0008] Among them, y:z=9:1, preferably, y=0.9, z=0.1, that is, Mg 2+ and Zn 4+ These two ions with the same charge are co-doped, Mg 2+ and Zn 2+ The molar ratio of Zr is 9:1. 4+ To increase the depth and density of electron traps, as well as the probability of electron capture during energy transfer, thereby improving thermal stability.

[0009] Furthermore, 0<x≤0.12. Preferably, x=0.03 or x=0.07.

[0010] On the other hand, a method for preparing a double perovskite tungstate red phosphor comprises the following steps:

[0011] Place NaNO3, Gd(NO3)3, Mg(NO3)2, Eu(NO3), C6H4O4Zn, and ZrO(NO3)2 in a beaker, and add deionized water to obtain solution A;

[0012] Dissolve citric acid monohydrate in deionized water to obtain solution B;

[0013] Dissolve ammonium metatungstate in distilled water to obtain solution C;

[0014] After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol;

[0015] The pH of the sol was adjusted to weak alkalinity with aqueous ammonia and stirred in a water bath to form a wet gel;

[0016] After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed;

[0017] After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained;

[0018] The fluffy precursor was ground and then kept in a muffle furnace at 1100° C. for 6 hours to obtain a red phosphor.

[0019] Furthermore, the present invention also proposes a second invention object, which is to use the above-mentioned red phosphor in a high-power device, wherein the high-power device includes a WLED device.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] The present invention discloses a double perovskite tungstate red phosphor and its preparation method and application. The present invention uses NaGd(MgZn)WO6 as the matrix material and introduces Zr 4+ Doping to obtain NaGd(Mg y Zn z ) 1-2x Zr x WO6:Eu 3 + Double perovskite red fluorescent material. Doped with Zr 4+ This creates more and deeper traps on the phosphor surface, thereby capturing more photons. At higher temperatures, the phosphor of the present invention releases more trapped photons, compensating for the missing luminescence performance. Consequently, the phosphor of the present invention has significantly improved thermal stability, making it suitable for operation in high-temperature environments and effectively avoiding the problem of thermal quenching when the device operating temperature rises.

[0022] Under excitation of ultraviolet light at 393nm, the color purity is as high as 94% at x=0.03. When the phosphor of the present invention is packaged in WLED devices, the color rendering index is higher than 85, which is better than similar commercial devices. The chromaticity coordinates are close to standard white light (0.333, 0.333), and it emits bright warm white light. Therefore, the phosphor of the present invention can be used as an excellent red component in high-power devices such as WLED. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0024] Figure 1 These are the X-ray diffraction patterns of the red phosphors of Examples 1-3 and Comparative Example 1.

[0025] Figure 2 The scanning electron microscope images of the red phosphors of Examples 1-3 and Comparative Example 1 are shown; Figure 2 (a) is a scanning electron microscope image of the red phosphor of Comparative Example 1; Figure 2 (b) is a scanning electron microscope image of the red phosphor of Example 1; Figure 2 (c) is a scanning electron microscope image of the red phosphor of Example 2; Figure 2 (d) is a scanning electron microscope image of the red phosphor of Example 3;.

[0026] Figure 3 These are the excitation spectra of the red phosphors of Examples 1-3 and Comparative Example 1 at an emission wavelength of 615 nm.

[0027] Figure 4 The emission spectra and chromaticity coordinates of the red phosphors of Examples 1-3 and Comparative Example 1 are shown. Figure 4 (a) is the emission spectrum with an excitation wavelength of 393 nm; Figure 4 (b) is the emission spectrum with an excitation wavelength of 464 nm; Figure 4 (c) is the chromaticity coordinate diagram with an excitation wavelength of 393 nm; Figure 4 (d) is the chromaticity coordinate diagram with an excitation wavelength of 464 nm;

[0028] Figure 5 (a) is the temperature-dependent emission spectrum of the phosphor of Example 1 under 393 nm excitation; Figure 5 (b) is the temperature-dependent emission spectrum of the phosphor of Example 2 under 393 nm excitation; Figure 5 (c) is the temperature-dependent emission spectrum of the phosphor of Example 3 under 393 nm excitation; Figure 5 (d) is a graph of the normalized relative luminous intensity of the phosphors of Examples 1-3 and Comparative Example 1;

[0029] Figure 6 (a) is the temperature-dependent emission spectrum of the phosphor of Example 1 under 464 nm excitation; Figure 6 (b) is the temperature-dependent emission spectrum of the phosphor of Example 2 under 464 nm excitation; Figure 6 (c) is the temperature-dependent emission spectrum of the phosphor of Example 3 under 464 nm excitation; Figure 6 (d) is a graph of the normalized relative luminous intensity of the phosphors of Examples 1-3 and Comparative Example 1;

[0030] Figure 7 The electroluminescence spectra of the red phosphors of Example 1 and Example 2 are shown in FIG.

[0031] Figure 8 This is a configuration coordinate diagram of the phosphor of the present invention. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following examples and accompanying drawings. However, the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions or selected according to the product specifications.

[0033] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] Example 1

[0035] A double perovskite tungstate red phosphor with the chemical formula of NaGd(Mg 0.9 Zn 0.1 ) 1-2x Zr x WO6:Eu 3+ , where x = 0.03.

[0036] A method for preparing a double perovskite tungstate red phosphor comprises the following steps:

[0037] 0.1717 g NaNO3, 0.3502 g Gd(NO3)3, 0.4382 g Mg(NO3)2, 0.5358 g Eu(NO3), 0.0416 g C6H4O4Zn, and 0.0139 g ZrO(NO3)2 were placed in a beaker, and deionized water was added to obtain solution A;

[0038] Dissolve 5.0687 g of citric acid monohydrate in deionized water to obtain solution B;

[0039] Dissolve 0.4952 g of ammonium metatungstate in distilled water to obtain solution C;

[0040] After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol;

[0041] The pH of the sol was adjusted to weak alkalinity with aqueous ammonia and stirred in a water bath to form a wet gel;

[0042] After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed;

[0043] After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained;

[0044] The fluffy precursor was ground and then kept in a muffle furnace at 1100° C. for 6 hours to obtain the red phosphor of this embodiment.

[0045] Example 2

[0046] A double perovskite tungstate red phosphor with the chemical formula of NaGd(Mg 0.9 Zn 0.1 )1-2x Zr x WO6:Eu 3+ , where x = 0.07.

[0047] A method for preparing a double perovskite tungstate red phosphor comprises the following steps:

[0048] 0.1717 g NaNO3, 0.3502 g Gd(NO3)3, 0.4009 g Mg(NO3)2, 0.5358 g Eu(NO3), 0.0381 g C6H4O4Zn, and 0.0325 g ZrO(NO3)2 were placed in a beaker, and deionized water was added to obtain solution A;

[0049] Dissolve 5.0687 g of citric acid monohydrate in deionized water to obtain solution B;

[0050] Dissolve 0.4952 g of ammonium metatungstate in distilled water to obtain solution C;

[0051] After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol;

[0052] The pH of the sol was adjusted to weak alkalinity with aqueous ammonia and stirred in a water bath to form a wet gel;

[0053] After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed;

[0054] After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained;

[0055] The fluffy precursor was ground and then kept in a muffle furnace at 1100° C. for 6 hours to obtain the red phosphor of this embodiment.

[0056] Example 3

[0057] A double perovskite tungstate red phosphor with the chemical formula of NaGd(Mg 0.9 Zn 0.1 ) 1-2x Zr x WO6:Eu 3+ , where x = 0.12.

[0058] A method for preparing a double perovskite tungstate red phosphor comprises the following steps:

[0059] 0.1717 g NaNO3, 0.3502 g Gd(NO3)3, 0.3543 g Mg(NO3)2, 0.5358 g Eu(NO3), 0.0337 g C6H4O4Zn, and 0.0558 g ZrO(NO3)2 were placed in a beaker, and deionized water was added to obtain solution A;

[0060] Dissolve 5.0687 g of citric acid monohydrate in deionized water to obtain solution B;

[0061] Dissolve 0.4952 g of ammonium metatungstate in distilled water to obtain solution C;

[0062] After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol;

[0063] The pH of the sol was adjusted to weak alkalinity with aqueous ammonia and stirred in a water bath to form a wet gel;

[0064] After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed;

[0065] After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained;

[0066] The fluffy precursor was ground and then kept in a muffle furnace at 1100° C. for 6 hours to obtain the red phosphor of this embodiment.

[0067] Comparative Example 1

[0068] A double perovskite tungstate red phosphor with the chemical formula of NaGd(Mg 0.9 Zn 0.1 ) 1-2x Zr x WO6:Eu 3+ , where x=0.

[0069] A method for preparing a double perovskite tungstate red phosphor comprises the following steps:

[0070] 0.1717 g NaNO3, 0.3502 g Gd(NO3)3, 0.4662 g Mg(NO3)2, 0.5358 g Eu(NO3), and 0.0443 g C6H4O4Zn were placed in a beaker, and deionized water was added to obtain solution A;

[0071] Dissolve 5.0687 g of citric acid monohydrate in deionized water to obtain solution B;

[0072] Dissolve 0.4952 g of ammonium metatungstate in distilled water to obtain solution C;

[0073] After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol;

[0074] The pH of the sol was adjusted to weak alkalinity with aqueous ammonia and stirred in a water bath to form a wet gel;

[0075] After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed;

[0076] After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained;

[0077] The fluffy precursor was ground and then kept in a muffle furnace at 1100° C. for 6 hours to obtain the red phosphor of Comparative Example 1.

[0078] Experimental Example 1

[0079] (1) X-ray diffraction analysis was performed on the red phosphors in Examples 1-3 and Comparative Example 1.

[0080] The X-ray diffraction patterns of the red phosphors in Examples 1-3 and Comparative Example 1 are as follows: Figure 1 As shown. Figure 1 In the figure, the horizontal axis is the diffraction angle 2θ, and the vertical axis is the diffraction intensity.

[0081] The red phosphors in Examples 1-3 and Comparative Example 1 all have good crystallinity and sharp diffraction peaks, which are consistent with the standard card (NaLaMgWO6 PDF-370243). Figure 1 It can be seen that the red phosphors of Examples 1-3 and Comparative Example 1 are pure-phase monoclinic structures.

[0082] (2) The red phosphors in Examples 1-3 and Comparative Example 1 were tested using a scanning electron microscope.

[0083] Figure 2 (a) is a scanning electron microscope image of the red phosphor of Comparative Example 1; Figure 2 (b) is a scanning electron microscope image of the red phosphor of Example 1; Figure 2 (c) is a scanning electron microscope image of the red phosphor of Example 2; Figure 2 (d) is a scanning electron microscope image of the red phosphor of Example 3. Figure 2 It can be seen that when the doping concentration x = 0 and x = 0.03, the sample exhibits a polyhedral shape, especially when x = 0.03, the crystallinity is the best, and the particle size is about 200nm-1μm. When the doping concentration x = 0.07 and x = 0.12, the morphology and size of the sample change significantly.

[0084] Therefore, from Figure 2 It can be seen that when x=0.03, the crystallinity is the best and the thermal stability is better.

[0085] (3) The red phosphors in Examples 1-3 and Comparative Example 1 were subjected to room temperature fluorescence testing.

[0086] Figure 3 The excitation spectra of the red phosphors of Examples 1-3 and Comparative Example 1 are shown below. Figure 3 The horizontal axis is the excitation wavelength and the vertical axis is the emission intensity. emis the emission wavelength.

[0087] like Figure 3 As shown, the excitation band in the range of 200-350nm is O 2 -→W 6+ The sharp peak in the wavelength range of 350-500 nm is attributed to Eu 3+ , Eu 3+ As the central luminescent ion, Eu 3+ The ff transitions in the matrix lattice correspond to 7 F0→ 5 D4 (363nm), 7 F0→ 5 L7 (383nm), 7 F0→ 5 L6 (393nm), 7 F0→ 5 D3 (418nm) and 7 F0→ 5 D2 (464nm) transition, where 7 F0→ 5 The L6 (393 nm) transition is the strongest absorption peak, which matches well with the output wavelength of the near-ultraviolet light-emitting diode chip, indicating that the phosphors of Examples 1-3 and Comparative Example 1 can be used for WLEDs packaged with near-ultraviolet chips.

[0088] Figure 4 (a) is the emission spectrum with an excitation wavelength of 393 nm. The horizontal axis of the emission spectrum is the wavelength, and the vertical axis is the fluorescence intensity. ex is the excitation wavelength; Figure 4 As shown in (a), under the excitation of 393nm, the fluorescence intensity of x=0.03 remains basically unchanged compared with x=0. 4+ As the doping amount increases, the fluorescence intensity gradually decreases.

[0089] Figure 4 (c) is a chromaticity coordinate diagram with an excitation wavelength of 393 nm. In the chromaticity coordinate diagram, the horizontal axis x represents the relative value related to red, the vertical axis y represents the relative value related to green, and z represents the relative value related to blue, and z = 1-(x+y). Figure 4 It can be found from the chromaticity coordinate diagram (c) that the CIE chromaticity coordinates of the red phosphors in Examples 1-3 and Comparative Example 1 are all located in the red region, and have excellent red emission.

[0090] Figure 4 (b) is the emission spectrum with an excitation wavelength of 464 nm, as shown in Figure 4 As shown in (b), under the excitation of 464nm, as Zr 4+As the doping amount increases, the fluorescence intensity gradually decreases.

[0091] Figure 4 (d) is the chromaticity coordinate diagram of the excitation wavelength of 464nm. Figure 4 It can be found from the chromaticity coordinate diagram (d) that the CIE chromaticity coordinates of the red phosphors in Examples 1-3 and Comparative Example 1 are all located in the orange-red region.

[0092] The chromaticity coordinates (CIE), correlated color temperature (CCT) and color purity of the red emission of the red phosphors in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0093] Table 1

[0094]

[0095] It can be seen from Table 1 that under the excitation of ultraviolet light and blue light, the red phosphors of Examples 1-3 and Comparative Example 1 can emit warm white light with a color temperature of 1800-2500K.

[0096] Zr-doped 4+ The phosphor has good color purity under both ultraviolet light (393nm) and blue light (464nm) excitation, close to the purity required for field emission displays, indicating that the red phosphor of Examples 1-3 and Comparative Example 1 is a warm red light phosphor with potential application value.

[0097] Experimental Example 2

[0098] The fluorescence spectra of the phosphors of Examples 1-3 and Comparative Example 1 at different temperatures were plotted. The fluorescence spectra at an excitation wavelength of 393 nm are shown in FIG. Figure 5 As shown, the fluorescence spectrum with an excitation wavelength of 464 nm is Figure 6 shown.

[0099] in, Figure 5 (a) is the temperature-dependent emission spectrum of the phosphor of Example 1 under 393 nm excitation; Figure 5 (b) is the temperature-dependent emission spectrum of the phosphor of Example 2 under 393 nm excitation; Figure 5 (c) is the temperature-dependent emission spectrum of the phosphor of Example 3 under 393 nm excitation; Figure 5 (d) is the normalized relative luminous intensity diagram of the phosphors of Examples 1-3 and Comparative Example 1; under ultraviolet light (393 nm) excitation, Eu 3+ The position of the characteristic peak of Zr did not change significantly at different temperatures. As the temperature increased, the luminescence intensity gradually increased and then decreased. At 125°C, the fluorescence intensities of x = 0.03, 0.07 and 0.12 remained at 100%, 100% and 91% of those at 25°C, respectively.4+ The phosphor with doping concentration x=0.03 can maintain 94% of the relative luminous intensity in a harsh working environment of up to 150°C, and can maintain 94% of the relative luminous intensity when x=0.07, both of which are better than the luminous performance of x=0.

[0100] Combined with the CIE coordinates (x, y) obtained at different temperatures, when x = 0.03, the CIE coordinate change value Δx = 0.01203 and Δy = 0.01195; when x = 0.07, the CIE coordinate change value Δx = 0.01171 and Δy = 0.01163; when x = 0.12, the CIE coordinate change value Δx = 0.01171 and Δy = 0.01163, the above data can prove that NaGd (Mg 0.9 Zn 0.1 ) 1-2x Zr x WO6:Eu 3+ , (0<x≤0.12) phosphor has excellent thermal stability under near-ultraviolet excitation.

[0101] Figure 6 (a) is the temperature-dependent emission spectrum of the phosphor of Example 1 under 464 nm excitation; Figure 6 (b) is the temperature-dependent emission spectrum of the phosphor of Example 2 under 464 nm excitation; Figure 6 (c) is the temperature-dependent emission spectrum of the phosphor of Example 3 under 464 nm excitation; Figure 6 (d) is the normalized relative luminous intensity diagram of the phosphors of Examples 1-3 and Comparative Example 1; under the excitation of blue light (464 nm), Eu 3+ The position of the characteristic peak of Zr did not change significantly at different temperatures. As the temperature increased, the luminescence intensity gradually increased and then decreased. At 125°C, the fluorescence intensities of x = 0.03, 0.07 and 0.12 remained at 103%, 101% and 95% of that at 25°C, respectively. 4+ Phosphors with a doping concentration of x=0.03 can maintain 98% of the relative luminous intensity in a harsh working environment of up to 150°C, and can maintain 96% of the relative luminous intensity when x=0.07, both of which are better than the luminous performance of x=0.

[0102] Combined with the CIE coordinates (x, y) obtained at different temperatures, when x = 0.03, the CIE coordinate change value Δx = 0.00917 and Δy = 0.0091; when x = 0.07, the CIE coordinate change value Δx = 0.00934 and Δy = 0.00928; when x = 0.12, the CIE coordinate change value Δx = 0.00939 and Δy = 0.00932, the above data can prove that NaGd (Mg0.9 Zn 0.1 ) 1-2x Zr x WO6:Eu 3+ , (0<x≤0.12) phosphor has excellent thermal stability under blue light excitation and is expected to be used in high-power LED devices.

[0103] Experimental Example 3

[0104] The red phosphors obtained in Example 1 and Example 2 (x = 0.03, 0.07) were packaged into WLED devices and their photoelectric performance was tested. 2+ ) / Blue phosphor (BaMgAl 10 O 17 :Eu 2+ ) was compounded with a near-ultraviolet chip (390-395nm), and the WLED device was packaged to evaluate the applicability of the obtained product in normal lighting tools.

[0105] The luminescence performance of the prepared WLED device was measured using a high-precision rapid spectral analysis integrated test system.

[0106] Figure 7 The corresponding electroluminescence spectrum under stable current driving is shown. The emission band around 393nm corresponds to the NUV chip. Obviously, there are two broad emissions in the blue and green regions, corresponding to the commercial green powder ((Sr,Ba)2SiO4:Eu 2+ ) and commercial blue powder (BaMgAl 10 O 17 :Eu 2+ ). Meanwhile, the sharp peak in the range of 580-730 nm is attributed to Eu 3+ The corresponding transitions of ions. Several emission peaks in the red region correspond to the Eu 3+ of 5 D0→ 7 F1, 5 D0→ 7 F2, 5 D0→ 7 F3 and 5 D0→ 7 F4 jump. From Figure 7 It can be concluded that Example 1 and Example 2 can achieve strong warm white light, and are expected to be operational and generally applicable to WLED devices.

[0107] The correlated color temperature (CCT) values ​​of the devices obtained in Example 1 and Example 2 are all below 5000K (warm white light), the chromaticity coordinates are all in the white light region, and the color rendering index (Ra) values ​​are all above 85. Therefore, the NaGd (Mg 0.9 Zn 0.1 ) 1- 2x Zr x WO6:Eu 3+ Can be used in high-power devices such as WLED.

[0108] Since room temperature fluorescence is not the only criterion for measuring the quality of phosphors, the present inventors further conducted temperature-dependent fluorescence tests on the phosphors of Examples 1-3 and Comparative Example 1.

[0109] The thermal stability of phosphors is one of the key factors in determining their commercialization. When WLEDs are working, their operating temperature can reach approximately 150°C.

[0110] It can be seen from Experimental Example 1 and Experimental Example 2 that Examples 1-3 and Comparative Example 1 are all expected to be used in the WLED field. However, based on Comparative Example 1, the present invention doped with Zr 4+ , Zr 4+ Doping into Mg 2+ When the site is filled with cation vacancies, the doping of ions with different charge amounts will produce defect energy levels. The defect energy levels capture electrons that transition from the excited state to the conduction band and store some energy. After heating, due to thermal disturbances, the electrons captured by the defect energy levels will be released back to the 5d excited state, generating additional red light in the 4f band of the transition, thereby increasing thermal stability. In addition, doping Zr 4+ The traps on the phosphor surface are more numerous and deeper, thus capturing more photons. When the temperature is higher, more captured photons are released, thereby compensating for the missing part of the luminescence performance, resulting in the "reverse thermal quenching" effect. Figure 6 At 125 degrees, there are even relative intensities of 103% and 101%, which is caused by the release of captured photons.

[0111] Figure 8 is the configuration coordinate diagram of the phosphor of the present invention, through Figure 8 Further reveal the thermal quenching mechanism of phosphors. Under near-ultraviolet or blue light excitation, Eu 3+ The electrons from 7 F0 energy level transition to 5 L6 energy level, returns to lower energy through non-radiative transition 5 D0 energy level, then the electron 5 D0 energy level transitions back to the ground state 7 F2 energy level, and finally Eu can be obtained at 615nm 3+Typical red emission. As the temperature increases, 5 The electrons on the D0 energy level will gain additional energy and reach 5 D0 energy level and 7 The intersection point B of the F2 energy level returns directly to the ground state 7 F2 energy level, energy will gradually not be released in the form of light energy, Eu 3+ The greater the activation energy ΔE, the greater the energy required for electrons to reach the intersection, and the better the thermal stability of the phosphor.

[0112] Therefore, as Zr 4+ The red phosphors of the present invention do not experience thermal quenching when the device operating temperature rises, thereby improving luminous efficiency and effectively meeting the requirements of high-power devices.

[0113] The above descriptions are only some specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double perovskite tungstate red phosphor, characterized in that: The chemical formula is NaGd(Mg y Zn z ) 1-2x Zr x WO6:Eu 3 + , where 0<x<0.5, y:z=9:

1.

2. The double perovskite tungstate red phosphor according to claim 1, characterized in that: 0＜x≤0.12。 3. The double perovskite tungstate red phosphor according to claim 1, characterized in that: x＝0.03。 4. The double perovskite tungstate red phosphor according to claim 1, characterized in that: x＝0.07。 5. The double perovskite tungstate red phosphor according to claim 1, characterized in that: y=0.9,z=0.

1.

6. A method for preparing a double perovskite tungstate red phosphor according to any one of claims 1 to 5, characterized in that: The following steps are involved: Place NaNO3, Gd(NO3)3, Mg(NO3)2, Eu(NO3), C6H4O4Zn, and ZrO(NO3)2 in a beaker, and add deionized water to obtain solution A; Dissolve citric acid monohydrate in deionized water to obtain solution B; Dissolve ammonium metatungstate in distilled water to obtain solution C; After solution C is clarified, solution A and solution B are added to solution C and mixed to obtain a sol; The pH of the sol was adjusted to a weak alkaline state and stirred in a water bath to form a wet gel; After the wet gel is dried in a constant temperature oven, a transparent xerogel is formed; After the transparent xerogel is heated and kept warm, a fluffy precursor is obtained; The fluffy precursor is ground and then calcined in a muffle furnace to obtain red phosphor.

7. The method for preparing a double perovskite tungstate red phosphor according to claim 6, characterized in that: The red phosphor was obtained by keeping the temperature in a muffle furnace at 1100°C for 6 hours.

8. The method for preparing a double perovskite tungstate red phosphor according to claim 6, characterized in that: The pH of the sol was adjusted to weak alkaline with aqueous ammonia.

9. Use of the red phosphor according to any one of claims 1 to 5 in high-power devices.

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