Inorganic bulk luminescent material and method for producing the same

Abstract

The application discloses an inorganic bulk luminescent material and a preparation method thereof, and relates to the technical field of light sources for illumination and display. The material comprises an inorganic matrix, fluorescent powder dispersed in the interior and a substrate at the bottom. The preparation method comprises the following steps: firstly, mixing an inorganic silica gel solution and a curing agent solution; adding the fluorescent powder into the mixed solution and stirring; then, dropping the mixed solution at the center of the substrate and rotating on a rotating table; heating by using a hot air blower to realize preliminary shaping of the bulk luminescent material; and finally, heating and heat-insulating in a muffle furnace to obtain the inorganic bulk luminescent material. The application adopts a preforming and firing secondary process to prepare the inorganic silica gel packaged bulk luminescent material, has higher luminescent efficiency, better luminescent stability, a simple preparation process and is suitable for industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light source for lighting and display, in particular to an inorganic bulk luminescent material and a preparation method thereof. BACKGROUND

[0002] The fluorescent conversion material is the core luminescent element of semiconductor lighting (including LED lighting and laser lighting). Among them, the fluorescent powder packaged by organic silicon glue is difficult to realize high-power application due to its low thermal conductivity. Therefore, some new packaging forms are needed, such as glass, ceramic, single crystal and other bulk materials. However, the preparation process of the above bulk luminescent material is relatively complex, which is difficult to realize industrialization, and a new packaging form of fluorescent powder body needs to be found.

[0003] The main component of inorganic silicon glue is silicon dioxide, which has obvious advantages in water resistance and heat resistance over organic paint. The inorganic silicon glue coating is dense and hard, does not produce static electricity, and various dust in the air is difficult to adhere. Compared with the thermal conductivity of 0.5 W / m·K of organic silicon glue, the thermal conductivity of inorganic silicon glue is about 1.4 W / m·K, which is more than 3 times higher in heat dissipation performance, which can better conduct heat and ensure the stable operation of the fluorescent powder body. In addition, the refractive index of inorganic silicon glue is 1.43-1.45, which is more matched with the refractive index 1.7 of the fluorescent powder, and can realize higher quantum efficiency compared with glass and other bulk materials. In addition, the firing temperature of inorganic silicon glue is relatively low, and the preparation process is simpler and more efficient than other inorganic bulk luminescent materials.

[0004] Therefore, how to prepare an inorganic silicon glue packaged bulk material luminescent material with stable luminescent performance and uniform distribution of fluorescent powder is crucial. SUMMARY

[0005] In view of this, the present application discloses an inorganic bulk luminescent material and a preparation method thereof to meet the demand of semiconductor lighting for high light color quality and low cost fluorescent conversion material.

[0006] An inorganic bulk luminescent material, comprising an inorganic matrix, fluorescent powder dispersed inside, and a substrate at the bottom. The preparation method comprises the following steps:

[0007] Step 1: mixing inorganic silicon glue solution and curing agent solution;

[0008] Step 2: adding fluorescent powder into the mixed solution obtained in step 1 and stirring;

[0009] Step 3: dropping the mixed solution obtained in step 2 at the center of the substrate, and then rotating on a rotating table;

[0010] Step 4: heating by using a hot air machine to realize preliminary shaping of the bulk luminescent material;

[0011] Step 5: Put the bulk luminescent material obtained in step 4 into a muffle furnace for heating and heat preservation, and finally obtain the inorganic bulk luminescent material.

[0012] Preferably, in step 1, the inorganic silica gel solution is an aqueous solution of anhydrous silicon dioxide, and the content of silicon dioxide is 20-30wt%; the curing agent solvent is an aqueous solution of lithium silicate, and the content of lithium silicate is 1.5-3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1-1:1.2.

[0013] Preferably, in step 2, the fluorescent powder is Ce-doped YAG yellow powder or LuAG green powder, and the addition amount of the fluorescent powder is 3.0-6.0wt% of the addition amount of the inorganic silica gel solution and the curing agent solution.

[0014] Preferably, in step 2, the stirring rate is 60-70r / min, and the stirring time is 30min.

[0015] Preferably, in step 3, the addition amount of the mixed solution is 1-4mL; and the substrate is an aluminum substrate with a size of φ30-60mm.

[0016] Preferably, in step 3, the rotation speed of the rotating table is 60-70r / min, and the rotation time is 30min.

[0017] Preferably, in step 4, the heating temperature of the air heater is 120-150℃, and the heating time is 2min.

[0018] Preferably, in step 5, the heating temperature of the muffle furnace is 180-200℃, and the heat preservation time is 10min.

[0019] Preferably, the quantum efficiency of the inorganic bulk luminescent material is 95-98% of that of the fluorescent powder, and the light decay at 150℃ is 0.9-8.1%.

[0020] Compared with the prior art, the inorganic bulk luminescent material and the preparation method thereof have the following advantages:

[0021] (1) The preparation method is simple and controllable, and the preforming and firing two-step process is innovatively adopted to prepare the inorganic silica gel packaged bulk luminescent material, which significantly improves the quantum efficiency of the luminescent material.

[0022] (2) Compared with the existing silica gel packaged fluorescent powder, the thermal conductivity is increased by nearly 3 times, and therefore the luminescent performance is better. Generally, the light decay at 150℃ is about 15%, and the temperature-induced luminescent decay of the present application is lower, reaching 8% (YAG) and 0.9% (LuAG).

[0023] (3) The preparation process provided by the present application is simple and suitable for industrialization. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a method for preparing an inorganic bulk luminescent material disclosed in this invention.

[0025] Figure 2 The variable-temperature fluorescence spectra of Examples 1, 2 and Comparative Example 1 of the present invention are shown. Detailed Implementation

[0026] All raw materials and reagents used in the following examples are commercially available products. The phosphor is commercially available Ce:YAG or Ce:LuAG, wherein the Ce doping concentration is 0.5-1.0 mol%.

[0027] Example 1

[0028] An inorganic bulk luminescent material includes an inorganic matrix, phosphors dispersed within it, and a substrate at the bottom.

[0029] like Figure 1 As shown, its preparation method includes the following steps.

[0030] Step 1: Solution mixing, i.e., mixing the inorganic silica gel solution and the curing agent solution. The inorganic silica gel solution is an anhydrous silica aqueous solution with a silica content of 20 wt%; the curing agent solvent is a lithium silicate aqueous solution with a lithium silicate content of 1.5 wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1.

[0031] Step 2: Powder mixing and stirring, i.e., adding the phosphor to the mixed solution obtained in Step 1 and stirring. The phosphor is Ce-doped LuAG green powder, and the amount of phosphor added is 6.0 wt% of the total amount of inorganic silica gel solution and curing agent solution added; the stirring rate is 60 r / min, and the stirring time is 30 min;

[0032] Step 3: Coating, which involves dropping the mixed solution obtained in Step 2 onto the center of the substrate, and then rotating it on a rotating stage. The amount of mixed solution added is 4 mL; the substrate is an aluminum substrate with a size of φ60 mm; the rotation speed of the rotating stage is 60 r / min, and the rotation time is 30 min.

[0033] Step 4: Heating pre-forming, that is, using a hot air blower to heat and achieve the initial shaping of the bulk luminescent material. The heating temperature of the hot air blower is 150℃ and the heating time is 2 minutes.

[0034] Step 5: Firing. The bulk luminescent material obtained in Step 5 is placed in a muffle furnace and heated and held at 200℃ for 10 minutes. The inorganic bulk luminescent material is then obtained.

[0035] As shown in Figure 2 The above inorganic bulk luminescent material is placed into a quantum efficiency test system for testing, and the quantum efficiency retains 98% of the original powder; the above inorganic bulk luminescent material is placed into a fluorescence spectrometer for testing, and compared with the luminescent intensity at 25℃, the material can still maintain 99.1% at 150℃, the luminescent decay is 0.9%, the luminescent efficiency is high, and the luminescent performance is stable.

[0036] Example 2

[0037] An inorganic bulk luminescent material, comprising an inorganic matrix, fluorescent powder dispersed inside, and a substrate at the bottom.

[0038] As shown in Figure 1 The preparation method comprises the following steps.

[0039] Step 1: solution mixing, i.e. mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an anhydrous silica aqueous solution, and the content of silica is 30wt%; the curing agent solution is a lithium silicate aqueous solution, and the content of lithium silicate is 3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1.2;

[0040] Step 2: powder mixing and stirring, i.e. adding fluorescent powder into the mixed solution obtained in step 1 and stirring. The fluorescent powder is Ce-doped YAG yellow powder, and the addition amount of the fluorescent powder is 3.0wt% of the addition amount of the inorganic silica gel solution and the curing agent solution; the stirring rate is 70r / min, and the stirring time is 30min;

[0041] Step 3: coating, i.e. dropping the mixed solution obtained in step 2 at the center of a substrate, and then rotating on a rotating table. The addition amount of the mixed solution is 1mL; the substrate is an aluminum substrate, and the size is φ30mm; the rotating table speed is 70r / min, and the rotating time is 30min;

[0042] Step 4: heating preforming, i.e. heating by using a hot air gun to realize the preliminary shaping of the bulk luminescent material. The heating temperature of the hot air gun is 120℃, and the heating time is 2min;

[0043] Step 5: sintering, i.e. placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, and the heating temperature is 180℃, and the heat preservation time is 10min. Finally, the inorganic bulk luminescent material is obtained.

[0044] As shown in Figure 2As shown, the above inorganic bulk luminescent material is placed into a quantum efficiency test system for testing, which retains 95% of the original powder quantum efficiency; the above inorganic bulk luminescent material is placed into a fluorescence spectrometer for testing, which can still maintain 91.9% at 150℃ compared with the luminescent intensity at 25℃, and the luminescent decay is 8.1%, the luminescent efficiency is high, and the luminescent performance is stable.

[0045] Comparative Example 1

[0046] An inorganic bulk luminescent material, comprising an inorganic matrix, a fluorescent powder dispersed inside, and a bottom substrate.

[0047] As shown, the preparation method comprises the following steps. Figure 1

[0048] Step 1: solution mixing, i.e. mixing inorganic silica gel solution and curing agent solution. The inorganic silica gel solution is anhydrous silica aqueous solution, and the content of silica is 30wt.%; the curing agent solution is lithium silicate aqueous solution, and the content of lithium silicate is 3.0wt%; the mass ratio of inorganic silica gel solution to curing agent solution is 1:1.2;

[0049] Step 2: powder mixing and stirring, i.e. adding fluorescent powder into the mixed solution obtained in step 1 and stirring. The fluorescent powder is Ce-doped YAG yellow powder, and the addition amount of fluorescent powder is 3.0wt% of the addition amount of inorganic silica gel solution and curing agent solution; the stirring rate is 70r / min, and the stirring time is 30min;

[0050] Step 3: coating, i.e. dropping the mixed solution obtained in step 2 at the center of the substrate, and then rotating on a rotating table. The addition amount of mixed solution is 1mL; the substrate is an aluminum substrate with a size of φ30mm; the rotating table speed is 70r / min, and the rotating time is 30min;

[0051] Step 4: heating preforming, i.e. heating with a hair dryer to realize the preliminary shaping of the bulk luminescent material. The heating temperature of the hair dryer is 120℃, and the heating time is 2min;

[0052] Step 5: sintering, i.e. placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, and the heating temperature is 200℃, and the heat preservation time is 10min. Finally, the inorganic bulk luminescent material is obtained.

[0053] As shown, Figure 2 ​As shown, the above inorganic bulk luminescent material is placed into a quantum efficiency test system for testing, which retains 81.3% of the original powder quantum efficiency; the above inorganic bulk luminescent material is placed into a fluorescence spectrometer for testing, which has only 85.5% of the luminescent intensity at 25°C, and the luminescent decay is 14.5%. This is mainly due to the high secondary sintering temperature, which destroys the bonding properties between the inorganic encapsulating material and the luminescent particles, and the poor heat dissipation performance. This results in low luminescent material efficiency and unstable luminescent performance.

[0054] Comparative Example 2

[0055] An inorganic bulk luminescent material, comprising an inorganic matrix, a fluorescent powder dispersed inside, and a bottom substrate.

[0056] As shown, the preparation method comprises the following steps. Figure 1

[0057] Step 1: solution mixing, i.e. mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an aqueous silica solution, and the content of silica is 20wt%; the curing agent solution is a lithium silicate aqueous solution, and the content of lithium silicate is 1.5wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1;

[0058] Step 2: powder mixing and stirring, i.e. adding fluorescent powder to the mixed solution obtained in step 1 and stirring. The fluorescent powder is Ce-doped LuAG green powder, and the addition amount of the fluorescent powder is 6.0wt% of the addition amount of the inorganic silica gel solution and the curing agent solution; the stirring rate is 60r / min, and the stirring time is 30min;

[0059] Step 3: coating, i.e. dropping the mixed solution obtained in step 2 at the center of the substrate, and then rotating on a rotating table. The addition amount of the mixed solution is 4mL; the substrate is an aluminum substrate, and the size is φ60mm; the rotating table speed is 80r / min, and the rotating time is 30min;

[0060] Step 4: heating preforming, i.e. heating with a hot air gun to realize the preliminary shaping of the bulk luminescent material. The heating temperature of the hot air gun is 110°C, and the heating time is 2min;

[0061] Step 5: sintering, i.e. placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, and the heating temperature is 200°C, and the heat preservation time is 10min. Finally, the inorganic bulk luminescent material is obtained.

[0062] ​The surface of the inorganic bulk luminescent material appears cracking phenomenon. On the one hand, due to the rotation table rotation speed is too fast in the preforming stage, the fluorescent powder is unevenly distributed, which can cause defects in the later sintering. In addition, the temperature of the hot air heater is not enough, the preforming of the bulk material is not realized, which causes the final sintered product to be broken.

[0063] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application and in the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing an inorganic bulk luminescent material, characterized in that, It includes the following steps: Step 1: Mix the inorganic silicone solution and the curing agent solution; Step 2: Add the phosphor to the mixed solution obtained in Step 1 and stir; Step 3: Drop the mixed solution obtained in Step 2 onto the center of the substrate, and then place it on a rotating stage for rotation; Step 4: Use a hot air blower to heat the material and achieve initial shaping of the bulk luminescent material; Step 5: Place the bulk luminescent material obtained in Step 4 into a muffle furnace for heating and heat preservation to finally obtain the inorganic bulk luminescent material; In step 1, the inorganic silica gel solution is an anhydrous silica aqueous solution with a silica content of 20-30 wt%; the curing agent solution is a lithium silicate aqueous solution with a lithium silicate content of 1.5-3.0 wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1 to 1:1.

2. In step 2, the phosphor is Ce-doped YAG yellow phosphor or Ce-doped LuAG green phosphor, and the amount of phosphor added is 3.0~6.0 wt% of the total amount of inorganic silica gel solution and curing agent solution added. In step 3, the amount of mixed solution added is 1~4 mL; the rotation speed of the rotating table is 60~70 r / min, and the rotation time is 30 min; In step 4, the hot air blower heats the air at a temperature of 120~150°C for 2 minutes. In step 5, the muffle furnace heating temperature is 180~200°C, and the holding time is 10 minutes.

2. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that, In step 2, the stirring rate is 60~70 r / min and the stirring time is 30 min.

3. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that, In step 3, the substrate is an aluminum substrate with a size of φ30~60 mm.

4. An inorganic bulk luminescent material prepared by the preparation method according to any one of claims 1 to 3, characterized in that, It includes an inorganic matrix, phosphor dispersed inside, and a substrate at the bottom, wherein the quantum efficiency of the inorganic bulk light-emitting material is 95-98% of that of the phosphor, and the light decay at 150°C is 0.9-8.1%.

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