Adjustable cold white light fluorescent powder with abnormal thermal quenching effect as well as preparation method and application of adjustable cold white light fluorescent powder

Abstract

The invention discloses adjustable cold white light fluorescent powder with an abnormal thermal quenching effect and a preparation method and application thereof, and belongs to the field of energy-saving and environment-friendly industries. The preparation method comprises the following steps: S1, weighing the raw materials; s2, grinding all the raw materials to obtain powder; s3, pre-sintering the ground powder; s4, grinding into powder, and firing; and S5, after the firing is completed, cooling to room temperature to obtain the NaGd < 1-x-y > Tm < x > Dyy GeO4 fluorescent powder. And S6, carrying out test analysis on the prepared NaGd < 1-x-y > Tm < x > Dyy GeO < 4 > fluorescent powder. The fluorescent powder prepared by the invention shows an abnormal thermal quenching effect, so that the fluorescent powder has better luminous efficiency and thermal stability under high-power density excitation, and the problem that color temperature, color coordinates and color rendering index are remarkably changed due to color light proportion change caused by power increase is relieved. Meanwhile, the spectral performance, the luminous intensity, the fluorescence lifetime, the excitation light source and the like of the fluorescent powder can be kept stable, the situations of attenuation and the like are not prone to occurring, the service life of an LED can be prolonged, and the energy consumption of the LED can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of energy-saving and environmental protection industries, and in particular to an adjustable cold white light phosphor with abnormal thermal quenching effect, and a preparation method and application thereof. Background Art

[0002] In recent years, white light emitting diodes (WLEDs) have attracted much attention and have been widely used in many fields due to their outstanding performance characteristics, such as excellent luminous efficiency, significant energy-saving effects, environmental protection characteristics and relatively low manufacturing costs. At present, there are two main ways to realize WLED on the market. The first is to combine blue LED chips with yellow phosphors, and produce white light by coating a layer of yellow phosphor (usually YAG yellow phosphor) on the GaN-based blue LED chip. Another method is to use ultraviolet or near-ultraviolet LEDs to excite the three-primary color phosphors to achieve a white light effect. However, these methods still have some shortcomings in practical applications. For example, problems such as high cost, poor stability and poor light output performance cannot meet some practical needs.

[0003] At present, as the ambient temperature increases, the fluorescence conversion materials change due to the cross-relaxation and thermal ionization between the excited state and the ground state energy level of the activated ions under high-temperature working conditions, which leads to a significant weakening of the luminescence intensity of the fluorescent materials, that is, thermal quenching occurs. This phenomenon limits the application of materials at high temperatures in various fields. Therefore, the ability of fluorescent materials to maintain or even enhance energy at high temperatures will greatly promote their application in high-tech fields. According to existing research, based on adding sensitizer ions to the matrix lattice of fluorescent materials to achieve energy transfer between ions, the present invention proposes an adjustable cold white light phosphor with an anomalous thermal quenching effect, providing new materials for the fields of solid-state lighting, temperature sensing, etc. Summary of the invention

[0004] In view of the above problems, the present invention aims to provide an adjustable cold white light phosphor with abnormal thermal quenching effect, a preparation method and application thereof, which has an abnormal thermal quenching effect, so that the phosphor can have better luminous efficiency and thermal stability under high power density excitation, and alleviate the change in color light ratio caused by power increase. At the same time, its spectral performance, luminous intensity, fluorescence life and excitation light source are all kept stable, thereby improving the service life of the LED.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an adjustable cold white light phosphor with abnormal thermal quenching effect comprises the following steps:

[0007] S1: weigh the raw materials;

[0008] S2: Grind all raw materials to obtain powder;

[0009] S3: pre-calcining the ground powder;

[0010] S4: grinding into powder and then firing;

[0011] S5: After firing, cool to room temperature to obtain NaGd1-x-yTmxDyyGeO4 phosphor;

[0012] S6: Prepared NaGd 1-x-y Tm x Dy y GeO4 phosphor was tested and analyzed.

[0013] Furthermore, the specific operation of step S1 includes the following steps:

[0014] Sodium carbonate, gadolinium oxide, thulium oxide, dysprosium oxide, and germanium oxide are weighed as raw materials in a molar ratio of Na, Gd, Tm, Dy, and Ge of 1:(1-xy):x:y:1;

[0015] Where 0≤x≤0.05, y=0.15, 0.20, 0.25, 0.30 and 0.35.

[0016] Further, x=0.02, y=0.20.

[0017] Furthermore, the pre-firing temperature in step S3 is 800° C. and the pre-firing time is 2 hours.

[0018] Furthermore, the firing temperature in step S4 is 1100° C. and the firing time is 3 hours.

[0019] Furthermore, the present invention also provides an adjustable cold white light phosphor prepared by the above-mentioned preparation method.

[0020] Furthermore, the present invention also provides the use of the above-mentioned adjustable cool white light phosphor in an LED lighting device.

[0021] The beneficial effects of the present invention are:

[0022] The adjustable cold white light phosphor prepared by the present invention has an abnormal thermal quenching effect, so that the phosphor can have better luminous efficiency and thermal stability under high power density excitation, and alleviate the problem of significant changes in color temperature, color coordinates, and color rendering index caused by the change in color light ratio due to power increase. At the same time, its spectral performance, luminous intensity, fluorescence life, and excitation light source are all stable, and it is not easy to attenuate, etc., which can increase the service life of LEDs and reduce the energy consumption of LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 In the present invention, NaGd 0.98-y Tm 0.02 Dy y XRD diffraction patterns of GeO4 (y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors.

[0024] Figure 2 In the present invention, NaGd 1-x-y Tm x Dy y Emission spectrum of GeO4 (0.01≤x≤0.05, y=0) series phosphors under 354nm excitation.

[0025] Figure 3 In the present invention, NaGd 1-x-y Tm x Dy y The emission spectrum of GeO4 (x = 0.02, y = 0) at 354 nm and NaGd 1-x-y Tm x Dy y Excitation spectrum of GeO4 (x=0, y=0.20) at 577nm.

[0026] Figure 4 In the present invention, NaGd 1-x-y Tm x Dy y Emission spectra of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors under 354nm excitation.

[0027] Figure 5 In the present invention, NaGd 1-x-y Tm x Dy y Energy level diagram of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors.

[0028] Figure 6 In the present invention, NaGd 1-x-y Tm x Dy y Fluorescence lifetime spectra of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors under 354nm excitation.

[0029] Figure 7 In the present invention, NaGd 1-x-y Tm x Dy yFluorescence lifetime spectrum of GeO4 (x=0.02, y=0) under 354nm excitation.

[0030] Figure 8 The NaGd 1-x-y Tm x Dy y The temperature-dependent fluorescence spectrum of GeO4 (x=0.02, y=0.20) from 293K to 573K under 354nm excitation.

[0031] Fig. 9 The NaGd 1-x-y Tm x Dy y Color coordinate diagram of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors under 354nm excitation. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0033] Embodiment 1

[0034] A method for preparing an adjustable cold white light phosphor with abnormal thermal quenching effect comprises the following steps:

[0035] S1: weigh the raw materials;

[0036] Specifically, the specific operation of step S1 includes the following steps:

[0037] Weigh 0.7796 g of sodium carbonate, 2.2129 g of gadolinium oxide, 0.0568 g of thulium oxide, 0.4115 g of dysprosium oxide, and 1.5392 g of germanium oxide as raw materials, respectively, and pour them into the same mortar; the molar ratio of Na, Gd, Tm, Dy, and Ge is 1:0.83:0.02:0.15:1.

[0038] S2: Grind all raw materials to obtain powder;

[0039] Specifically, the specific operation of step S2 includes the following steps:

[0040] 4 ml of anhydrous ethanol was added to the mortar, and then ground with a grinding rod for 40 minutes, followed by a second addition of 2 ml of anhydrous ethanol and grinding for another 20 minutes to fully mix the raw materials.

[0041] S3: pre-calcining the ground powder;

[0042] Specifically, the specific operation of step S3 includes the following steps:

[0043] The ground powder sample was poured into a crucible, placed in a high-temperature muffle furnace, and pre-fired at 800 °C for 2 h.

[0044] S4: grinding into powder and then firing;

[0045] Specifically, the specific operation of step S4 includes the following steps:

[0046] Pour the sample into a crucible, add anhydrous ethanol and grind for 20 minutes until the sample is in powder form; pour the sample powder into a crucible and keep it in a high-temperature muffle furnace at 1100°C for 3 hours.

[0047] S5: After firing, cool to room temperature to obtain NaGd 0.83 Tm 0.02 Dy 0.15 GeO4 phosphor;

[0048] S6: Prepared NaGd 0.83 Tm 0.02 Dy 0.15 GeO4 phosphor was tested and analyzed.

[0049] In order to fully evaluate the luminescence performance of the prepared tunable cold white phosphor with anomalous thermal quenching effect, the NaGd 0.83 Tm 0.02 Dy 0.15 The fluorescence spectrum and lifespan of GeO4 phosphor were tested.

[0050] Embodiment 2:

[0051] In Example 2, 0.7790 g of sodium carbonate, 2.0780 g of gadolinium oxide, 0.0567 g of thulium oxide, 0.5483 g of dysprosium oxide, and 1.5381 g of germanium oxide were weighed as raw materials and poured into the same mortar; the molar ratio of Na, Gd, Tm, Dy, and Ge was 1:0.78:0.02:0.20:1. Finally, NaGd 0.78 Tm 0.02 Dy 0.20 GeO4 phosphor. Other steps are the same as those in Example 1.

[0052] Embodiment three:

[0053] In Example 3, 0.7784 g of sodium carbonate, 1.9433 g of gadolinium oxide, 0.0567 g of thulium oxide, 0.6848 g of dysprosium oxide, and 1.5368 g of germanium oxide were weighed as raw materials and poured into the same mortar; the molar ratio of Na, Gd, Tm, Dy, and Ge was 1:0.73:0.02:0.25:1. Finally, NaGd 0.73 Tm 0.02 Dy0.25 GeO4 phosphor. Other steps are the same as those in Example 1.

[0054] Embodiment 4:

[0055] In Example 4, 0.7778 g of sodium carbonate, 1.8088 g of gadolinium oxide, 0.0566 g of thulium oxide, 0.8211 g of dysprosium oxide, and 1.5357 g of germanium oxide were weighed as raw materials and poured into the same mortar; the molar ratio of Na, Gd, Tm, Dy, and Ge was 1:0.68:0.02:0.30:1. Finally, NaGd 0.68 Tm 0.02 Dy 0.30 GeO4 phosphor. Other steps are the same as those in Example 1.

[0056] Embodiment five:

[0057] In Example 5, 0.7772 g of sodium carbonate, 1.6745 g of gadolinium oxide, 0.0566 g of thulium oxide, 0.9572 g of dysprosium oxide, and 1.5345 g of germanium oxide were weighed as raw materials and poured into the same mortar; the molar ratio of Na, Gd, Tm, Dy, and Ge was 1:0.63:0.02:0.35:1. Finally, NaGd 0.63 Tm 0.02 Dy 0.35 GeO4 phosphor. Other steps are the same as those in Example 1.

[0058] In order to fully evaluate the luminescence performance of the prepared tunable cold white phosphor with anomalous thermal quenching effect, the NaGd 1-x-y Tm x Dy y The fluorescence spectrum and lifetime of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) phosphors were tested. 0.98-y Tm 0.02 Dy y The material usage of each component of GeO4 (y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors at different concentrations.

[0059] The materials used for the components of the phosphors of Examples 1 to 5 are shown in Table 1 below.

[0060] Table 1 NaGd 0.98-y Tm 0.02 Dy y Materials used for different components of GeO4 (y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors at different concentrations

[0061]

[0062] The performance test and analysis of the phosphors prepared in Examples 1 to 5 were performed, and the results are as follows:

[0063] Attached Figure 1 NaGd 1-x-y Tm x Dy y The XRD diffraction patterns of the GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors are consistent with the standard card PDF#88-1176 of NaGdGeO4, so the prepared phosphors are pure phase.

[0064] Attached Figure 2 NaGd 1-x-y Tm x Dy y Emission spectrum of GeO4 (0.01≤x≤0.05, y=0) series phosphors under 354nm excitation; with the continuous increase of Tm concentration, the emission intensity first increases and then weakens. When the doping concentration is 2mol%, the intensity reaches the highest, and when it is 5mol%, the intensity reaches the lowest. Therefore, 0.02Tm 3+ Tm 3+ concentration.

[0065] Attached Figure 3 The NaGd 1-x-y Tm x Dy y The emission spectrum of GeO4 (x = 0.02, y = 0) at 354 nm and NaGd 1-x-y Tm x Dy y The excitation spectrum of GeO4 (x=0, y=0.20) at 577nm has an obvious overlap near 450nm, which means that Tm 3+ and Dy 3+ There is an energy transfer relationship between them.

[0066] Attached Figure 4 The NaGd 1-x-y Tm x Dy y The emission spectra of GeO4 (x = 0.02, y = 0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors under 354nm excitation, along with Dy 3+ As the concentration increases, Tm 3+ The blue light emission intensity of Dy 3+The intensity of the yellow light emission of the ion first increases and then decreases, reaching the highest level at a concentration of 0.15 mol%.

[0067] Attached Figure 5 The NaGd 1-x-y Tm x Dy y Energy level diagram of GeO4 (x = 0.02, y = 0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors. Under 354nm light excitation, Tm 3 + ions first act as energy absorbers, capturing the energy of incident photons and stimulating their electrons to 1 D2 energy level, thus forming a stable electron population at this energy level. Subsequently, this excited state Tm 3 + ions do not return to the ground state completely through their own radiation transition, but part of their energy is received by neighboring Dy3+ ions through an efficient non-radiative process, energy transfer (ET). This energy transfer mechanism promotes the 4 I 15 / 2 The energy level is filled, preparing the conditions for its subsequent radiation transition. At 459nm, 486nm, 577nm, 667nm, Tm 3+ Happened 1 D2 to 3 F4 transition, Dy3+ ion receives the 3 + ion energy, 4 F 9 / 2 The electrons on the energy level become unstable, and then undergo multiple radiative transitions to lower 6H series energy levels (including 6 H 15 / 2 , 6 H 13 / 2 and 6 H 11 / 2 ).

[0068] To further verify the Tm 3+ and Dy 3+ The energy transfer between NaGd 1-x-y Tm x Dy y GeO4 (x = 0.02, y = 0, 0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors and NaGd 1-x-y Tm x Dy y The GeO4 (x=0.02, y=0) phosphor was tested for lifespan. The lifespan spectrum is shown in the attached figure. Figure 6 and attached Figure 7As shown; the average life span and energy transfer efficiency are calculated by the life calculation formula and the energy transfer efficiency formula, as shown in Table 2, the energy transfer efficiency is not 0, and as Dy 3+ As the concentration increases, Tm 3+ The lifetime of the phosphor is decreasing, which further proves that Tm 3+ and Dy 3+ The energy transfer between them.

[0069] Table 2NaGd 1-x-y Tm x Dy y Transfer efficiency of GeO4 (x=0.02, y=0, 0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors under 354nm excitation

[0070]

[0071] Attached Figure 8 For example NaGd 0.78 Tm 0.02 Dy 0.20 Fluorescence spectrum of GeO4 under 354nm excitation from 293K to 573K. Tm at 454nm 3+ The characteristic peak intensity decreases with increasing temperature. 3+ The intensity first increases and then remains basically unchanged, which is an abnormal thermal quenching effect.

[0072] Attached Fig. 9 NaGd 1-x-y Tm x Dy y Color coordinate diagram of GeO4 (x=0.02, y=0, 0.15, 0.20, 0.25, 0.30, 0.35) series phosphors; 3+ As the concentration increases, the color coordinates of the fluorescent pink gradually approach the white light region; Table 3 records the color coordinate data values ​​and color temperature values ​​of different concentrations. In particular, when y=0.20, the color coordinates of the fluorescent pink are (0.2964, 0.2592), which are very close to the ideal white light color coordinates (0.33, 0.33); in addition, the color temperature of the fluorescent powder is 9742K, showing that it has good cold white light characteristics.

[0073] Table 3 NaGd 1-x-y Tm x Dy y Color coordinate values ​​and color temperature values ​​of GeO4 (x=0.02, y=0.15, 0.20, 0.25, 0.30 and 0.35) series phosphors at various concentrations under 354nm excitation

[0074]

[0075] Application examples:

[0076] The fluorescent powder prepared in the present invention can be assembled with a chip into an LED lighting device. By adjusting the amount of the fluorescent powder, the color temperature of the LED lighting device can be precisely controlled to meet the lighting needs in different scenes.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing an adjustable cold white light phosphor with abnormal thermal quenching effect, characterized in that: The following steps are included: S1: weigh the raw materials; S2: Grind all raw materials to obtain powder; S3: pre-calcining the ground powder; S4: grinding into powder and then firing; S5: After firing, cool to room temperature to obtain NaGd 1-x-y Tm x Dy y GeO4 phosphor; S6: Prepared NaGd 1-x-y Tm x Dy y GeO4 phosphor was tested and analyzed.

2. The method for preparing a tunable cold white light phosphor with abnormal thermal quenching effect according to claim 1, characterized in that: The specific operation of step S1 includes the following steps: Sodium carbonate, gadolinium oxide, thulium oxide, dysprosium oxide, and germanium oxide are weighed as raw materials in a molar ratio of Na, Gd, Tm, Dy, and Ge of 1:(1-xy):x:y:1; Where 0≤x≤0.05, y=0.15, 0.20, 0.25, 0.30 and 0.

35.

3. The method for preparing a tunable cold white light phosphor with abnormal thermal quenching effect according to claim 2, characterized in that: x=0.02, y=0.

20.

4. The method for preparing a tunable cold white light phosphor with abnormal thermal quenching effect according to claim 1, characterized in that: The pre-firing temperature in step S3 is 800° C. and the pre-firing time is 2 hours.

5. The method for preparing a tunable cold white light phosphor with abnormal thermal quenching effect according to claim 1, characterized in that: The firing temperature in step S4 is 1100° C. and the firing time is 3 hours.

6. The tunable cold white light phosphor prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the adjustable cool white light phosphor as claimed in claim 6 in LED lighting devices.

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