High-brightness gayag fluorescent powder and preparation method thereof

Abstract

The application provides a high-brightness GAYAG fluorescent powder and a preparation method thereof, and belongs to the technical field of fluorescent materials. The preparation method comprises the following steps: weighing GAYAG fluorescent powder raw materials, cerium raw materials and an activator according to proportions; mixing the GAYAG fluorescent powder raw materials and the cerium raw materials, preheating to 200-300 DEG C, and then adding the activator for the first time, uniformly mixing, and then heat preservation; heating to 1000 DEG C + / - 10 DEG C, and then adding the activator for the second time, uniformly mixing, and then heat preservation; heating to 1200 DEG C + / - 10 DEG C, and then heat preservation; heating to 1400-1800 DEG C, and then heat preservation; naturally cooling to room temperature; the GAYAG fluorescent powder raw materials comprise yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide; and the activator is europium oxide. The application adds the europium element in steps, controls the synthesis temperature and the heat treatment ladder steps, makes the fluorescent powder brightness crystal form multiple light emitting centers, increases the absorption light source range, makes the fluorescent powder reach the brightening effect, and thus improves the quality of LED lighting.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fluorescent materials, and particularly relates to a high-brightness GAYAG fluorescent powder and a preparation method thereof. BACKGROUND

[0002] The GaYAG fluorescent powder is one of aluminate system fluorescent powders, can realize large-scale adjustment of peak wavelength in the range of 515-540 nm, has excellent quantum efficiency and chemical stability, is one of the most important fluorescent powders for providing light efficiency in general lighting, and is an important luminescent raw material in the field of LED.

[0003] At present, the solid phase method is one of important methods for synthesizing the GAYAG fluorescent powder, and the GAYAG powder is generally synthesized at a high temperature of 1600 DEG C for more than 20 h. The synthesis temperature of the LED fluorescent powder is a key parameter, which directly affects the synthesis efficiency, purity and final luminescent performance of the fluorescent powder. Proper high temperature can promote the chemical reaction and ensure that the raw materials are fully reacted to generate the fluorescent powder with high purity. However, too high temperature may cause side reactions, affecting the purity and performance of the product. In the existing solid phase method, single high temperature heat treatment or reduction reaction at 500 DEG C-800 DEG C + crystallization reaction at more than 1600 DEG C is generally adopted.

[0004] In the GaYAG fluorescent powder product prepared by the existing solid phase method, the luminescent center is a single body, and only a small part of the chip energy can be absorbed. SUMMARY

[0005] In view of this, the present application aims to provide a high-brightness GAYAG fluorescent powder and a preparation method thereof, and aims to solve at least one technical problem in the background art.

[0006] The present application is realized in the following manner:

[0007] The present application provides a preparation method of a high-brightness GAYAG fluorescent powder, which comprises the following steps:

[0008] The GAYAG fluorescent powder raw material, cerium raw material and activator are weighed according to the proportion;

[0009] The GAYAG fluorescent powder raw material and the cerium raw material are mixed and preheated to 200 DEG C-300 DEG C, and then the activator is added for the first time, mixed uniformly, and then heat preserved for a first time;

[0010] The temperature is raised to 1000 DEG C±10 DEG C, and then the activator is added for the second time, mixed uniformly, and then heat preserved for a second time;

[0011] The temperature is raised to 1200 DEG C±10 DEG C, and then heat preserved for a third time;

[0012] The temperature is raised to 1400 DEG C-1800 DEG C, and then heat preserved for a fourth time;

[0013] Subsequently, naturally cool to room temperature;

[0014] The GAYAG fluorescent powder raw material comprises yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide; and the activator is europium oxide.

[0015] Preferably, the GAYAG fluorescent powder raw material comprises the following molar percentage composition:

[0016] Yttrium oxide 25% to 38%;

[0017] Aluminum oxide 30% to 55%;

[0018] Gallium oxide 0% to 20%;

[0019] Terbium oxide 0.1% to 8.0%;

[0020] Bismuth oxide 0.01% to 4.0%;

[0021] Antimony oxide 0.01% to 3.0%.

[0022] Preferably, the first amount of the activator is 2wt% to 4wt% of the GAYAG fluorescent powder raw material; and the second amount of the activator is 3wt% to 6wt% of the GAYAG fluorescent powder raw material.

[0023] Preferably, the cerium raw material is cerium oxide, and the amount of the cerium oxide is 2wt% to 5wt% of the GAYAG fluorescent powder.

[0024] Preferably, the first time is 2h to 3h; the second time is 50min to 70min; the third time is 3.5h to 4.5h; and the fourth time is 5h to 7h.

[0025] The second aspect of the present application provides a high-brightness GAYAG fluorescent powder prepared by the above method.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The present application optimizes the performance of the fluorescent powder by adding the activator europium element in steps and controlling the synthesis temperature and heat treatment steps, thereby improving the quality of LED lighting.

[0028] 2. The fluorescent powder prepared by the method of the present application has multiple light-emitting centers due to the brightness of the crystal, and the use of the fluorescent powder increases the range of light sources, thereby achieving the brightening effect of the fluorescent powder.

[0029] 3、The application analyzes the raw material mass transfer law of the nucleation and growth of the phosphor crystal grains, improves the viscosity of the sintering system melting state, adjusts the migration rate difference of the homogeneous grains in the high-temperature system, achieves the grain effect of mutual adhesion of the grains, develops the GAYAG phosphor adhesion preparation technology of high-brightness and homogeneous grains, and effectively improves the packaging brightness of the GAYAG phosphor under the same conditions. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The GAYAG phosphor electron microscope graph prepared for the embodiment 1 of the application;

[0031] Figure 2 The spectrum graphs of the light emitting devices respectively prepared by the GAYAG phosphor of the embodiment 1 of the application and the conventional GAYAG phosphor. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the application more clear and explicit, the application is further described in detail below in combination with the embodiments. It should be understood that the specific implementation cases described here are only used to explain the application, and are not used to limit the application.

[0033] A preparation method of a high-brightness GAYAG phosphor, comprising the following steps:

[0034] S1, proportionally weighing GAYAG phosphor raw materials, cerium raw materials and activators;

[0035] The GAYAG phosphor raw materials can adopt any components and ratios allowed in the art. In the specific implementation, the GAYAG phosphor raw materials include the following molar percentage composition: yttrium oxide 25% to 38%; aluminum oxide 30% to 55%; gallium oxide 0% to 20%; terbium oxide 0.1% to 8.0%; bismuth oxide 0.01% to 4.0%; antimony oxide 0.01% to 3.0%; the GAYAG phosphor raw materials used in the following embodiments are: yttrium oxide 33%; aluminum oxide 48%; gallium oxide 10%; terbium oxide 5%; bismuth oxide 2.5%; antimony oxide 1.5%, but are not limited to the listed values, and other values not listed in the value range are also applicable;

[0036] The cerium raw material is cerium oxide, and the amount is 2wt% to 5wt% of the GAYAG phosphor;

[0037] The activator is europium oxide, and the total amount is 5wt% to 10wt% of the GAYAG phosphor raw materials.

[0038] S2, the GAYAG phosphor raw materials and the cerium raw materials are mixed and preheated to 200℃ to 300℃, and then the activator is added for the first time, mixed uniformly, and then heat preserved for 2h to 3h;

[0039] The first amount of the activator is 2wt% to 4wt% of the GAYAG fluorescent powder raw material; for example, it can be 2wt%, 3wt%, 4wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0040] S3, after being heated to 1000℃±10℃, the activator is added for the second time, and after being mixed, it is kept for a second time for 50min to 70min, preferably 60min;

[0041] The second amount of the activator is 3wt% to 6wt% of the GAYAG fluorescent powder raw material; for example, it can be 3wt%, 4.5wt%, 6wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable; in this step, the raw material and the two added activators are preliminarily reacted.

[0042] S4, after being heated to 1200℃±10℃, it is kept for 3.5h to 4.5h, preferably 4h; in this step, the raw material and the two added activators are fully reacted, and during the reaction process, the homogeneous grains have different migration rates in the high-temperature system, achieving the effect of grains adhering to each other, and then the final fluorescent powder has multiple light-emitting centers.

[0043] S5, after being heated to 1400℃ to 1800℃, it is kept for 5h to 7h, preferably 6h, and after high-temperature sintering, the raw material and the activator are crystallized.

[0044] S6, then naturally cooled to room temperature.

[0045] The synthesis temperature of the LED fluorescent powder is a key parameter, which directly affects the synthesis efficiency, purity and final luminescent performance of the fluorescent powder. Appropriate high temperature can promote the chemical reaction and ensure that the raw materials are fully reacted to generate fluorescent powder with high purity. However, too high a temperature may cause side reactions, affecting the purity and performance of the product. The present application can optimize the performance of the fluorescent powder by controlling the synthesis temperature and the heat treatment step, thereby improving the quality of LED lighting.

[0046] Example 1

[0047] A method for preparing a high-brightness GAYAG fluorescent powder, comprising the following steps:

[0048] S1, the GAYAG fluorescent powder raw material, cerium raw material and activator are weighed according to the proportion;

[0049] The GAYAG fluorescent powder raw material comprises the following molar percentage composition: yttrium oxide 33%; aluminum oxide 48%; gallium oxide 10%; terbium oxide 5%; bismuth oxide 2.5%; antimony oxide 1.5%;

[0050] The cerium raw material is cerium oxide, and its weight is 3.5wt% of the GAYAG fluorescent powder;

[0051] The activator europium oxide has a weight of 5wt% of the GAYAG fluorescent powder raw material;

[0052] S2, the GAYAG fluorescent powder raw material is mixed with the cerium raw material, preheated to 200℃, and then the europium oxide is added for the first time, mixed uniformly, and then heat preserved for 2h; the amount of europium oxide is 2wt% of the GAYAG fluorescent powder raw material;

[0053] S3, the temperature is raised to 1000℃, and the europium oxide is added for the second time, mixed uniformly, and then heat preserved for 1h; during this process, the temperature is stable within ±10℃; the amount of europium oxide is 3wt% of the GAYAG fluorescent powder raw material;

[0054] S4, the temperature is raised to 1200℃ and heat preserved for 4h; during this process, the temperature is stable within ±10℃;

[0055] S5, the temperature is raised to 1400℃ and heat preserved for 6h, and then crystallization is performed;

[0056] S6, then naturally cooled to room temperature to obtain the GAYAG fluorescent powder.

[0057] Example 2

[0058] The difference between this example and Example 1 is that the first amount of the activator europium oxide is 3wt% of the GAYAG fluorescent powder raw material; other reaction conditions and parameters are consistent with those of Example 1.

[0059] Example 3

[0060] The difference between this example and Example 1 is that the first amount of the activator europium oxide is 4wt% of the GAYAG fluorescent powder raw material; other reaction conditions and parameters are consistent with those of Example 1.

[0061] Example 4

[0062] The difference between this example and Example 1 is that the second amount of the activator europium oxide is 4wt% of the GAYAG fluorescent powder raw material; other reaction conditions and parameters are consistent with those of Example 1.

[0063] Example 5

[0064] The difference between this example and Example 1 is that the second amount of the activator europium oxide is 5wt% of the GAYAG fluorescent powder raw material; other reaction conditions and parameters are consistent with those of Example 1.

[0065] Example 6

[0066] The difference between the embodiment and the embodiment 1 is that the second amount of the activator europium oxide is 6wt% of the GAYAG fluorescent powder raw material; the other reaction conditions and parameters are consistent with the embodiment 1.

[0067] Embodiment 7

[0068] The difference between the embodiment and the embodiment 1 is that the temperature adjustment of the preheating stage S2 is 250℃; the other reaction conditions and parameters are consistent with the embodiment 1.

[0069] Embodiment 8

[0070] The difference between the embodiment and the embodiment 1 is that the temperature adjustment of the preheating stage is 300℃; the other reaction conditions and parameters are consistent with the embodiment 1.

[0071] Embodiment 9

[0072] The difference between the embodiment and the embodiment 1 is that the temperature adjustment of the crystallization stage is 1600℃; the other reaction conditions and parameters are consistent with the embodiment 1.

[0073] Embodiment 10

[0074] The difference between the embodiment and the embodiment 1 is that the temperature adjustment of the crystallization stage is 1800℃; the other reaction conditions and parameters are consistent with the embodiment 1.

[0075] Comparative example 1

[0076] The difference between the comparative example and the embodiment 1 is that the activator is added once in step S2; the other reaction conditions and parameters are consistent with the embodiment 1.

[0077] S2 and S3 are specifically:

[0078] S2, the GAYAG fluorescent powder raw material and the cerium raw material are mixed and preheated to 200℃, then the europium oxide is added, and after mixing, it is kept for 2h; the amount of the europium oxide is 5wt% of the GAYAG fluorescent powder raw material;

[0079] S3, the temperature is raised to 1000℃ and kept for 1h, and during this process, the temperature is stable within ±10℃.

[0080] Comparative example 2

[0081] The difference between the comparative example and the embodiment 1 is that the activator is added once in step S3; the other reaction conditions and parameters are consistent with the embodiment 1.

[0082] S2 and S3 are specifically:

[0083] S2, the GAYAG fluorescent powder raw material and the cerium raw material are mixed and preheated to 200℃, then the europium oxide is added, and after mixing, it is kept for 2h; the amount of the europium oxide is 5wt% of the GAYAG fluorescent powder raw material;

[0084] S3, temperature is raised to 1000℃, europium oxide is added, and after mixing, it is preserved for 1h, and during this process, the temperature is stabilized within ±10℃; the amount of europium oxide is 5wt% of the GAYAG fluorescent powder raw material.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 1 is that the activator is added at once before preheating in step S2; other reaction conditions and parameters are consistent with Example 1.

[0087] S2 is specifically: the GAYAG fluorescent powder raw material, cerium raw material, and europium oxide are mixed and preheated to 200℃, and then preserved for 2h; the amount of europium oxide is 5wt% of the GAYAG fluorescent powder raw material.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that S3 and S4 are adjusted to one heat treatment stage, i.e., the heat treatment of the 1200℃ stage is all adjusted to 1000℃; other reaction conditions and parameters are consistent with Example 1.

[0090] After S3 and S4 are combined, it is specifically:

[0091] S3, temperature is raised to 1000℃, europium oxide is added for the second time, and after mixing, it is preserved for 5h, and during this process, the temperature is stabilized within ±10℃; the amount of europium oxide is 3wt% of the GAYAG fluorescent powder raw material.

[0092] Comparative Example 5

[0093] The difference between this comparative example and Example 1 is that S3 and S4 are adjusted to one heat treatment stage, i.e., the heat treatment of the 1000℃ stage is all adjusted to 1200℃; other reaction conditions and parameters are consistent with Example 1.

[0094] After S3 and S4 are combined, it is specifically:

[0095] S3, temperature is raised to 1200℃, europium oxide is added for the second time, and after mixing, it is preserved for 5h, and during this process, the temperature is stabilized within ±10℃; the amount of europium oxide is 3wt% of the GAYAG fluorescent powder raw material.

[0096] The GAYAG fluorescent powder of the conventional single crystal structure (conventional group) purchased, the fluorescent powder prepared in Example 1 to Example 10 and Comparative Example 1 to Comparative Example 5 respectively as powder 1, the nitride red powder as powder 2, the phenyl silicone glue with the refractive index of 1.54 and the viscosity of 8300 mPa·s and 1000 mPa·s respectively as A glue and B glue (mixed according to the mass ratio of A glue:B glue = 1:10), the powder 1, the powder 2, the A glue, the B glue mixed uniformly as the LED packaging glue, the LED chip packaged by the packaging glue is sequentially subjected to 100 ℃ baking for 1 h and 150 ℃ baking for 1 h to obtain the LED light emitting device.

[0097] Figure 1 The GAYAG fluorescent powder prepared in Example 1 is shown in the electron microscope graph. Figure 1 It can be seen that the brightness crystal of the fluorescent powder prepared in Example 1 forms multiple light emitting centers.

[0098] Figure 2 The spectrum of the light emitting device prepared by the GAYAG fluorescent powder of Example 1 and the conventional GAYAG fluorescent powder (conventional group) respectively is shown in the following figure. Figure 2 It can be seen from the comparison that the fluorescent powder prepared in Example 1 has higher light intensity than the conventional GAYAG fluorescent powder, and the polycrystal structure fluorescent powder emits more light source after receiving the blue light source, so as to achieve the brightening effect. The luminous flux and the apparent indicator performance test of the LED device after packaging are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] It can be seen from the data in Table 1 that the packaging brightness of the GAYAG fluorescent powder prepared in Example 1 to Example 10 is improved.

[0103] The first addition of the activator and the raw materials are mixed to produce a preliminary reaction, and the contact probability and the reaction activity between the activator and the raw materials are enhanced. It can be seen from the comparison of the conventional group, Example 1 to Example 3 that the luminous flux of the LED device of Example 1 to Example 3 is higher than that of the conventional group, and with the increase of the amount of the first added activator europium oxide, the luminous flux of the LED device increases after decreasing. In view of the data in Table 1 and based on the cost consideration, the amount of the first added activator europium oxide is preferably 2wt% to 4wt% of the GAYAG fluorescent powder raw material, and the optimal value is 2wt%.

[0104] The secondly added activator reacts with the first added activator and raw materials, and the first added activator and raw materials are in a certain degree of reaction preparation state. When the amount of europium oxide added in the second time is increased, the increase of the concentration of the activator makes the reaction move towards the direction of generating products. Moreover, the high temperature (1000℃) provides sufficient energy for these active sites, and the chemical properties of europium oxide itself also become more active at high temperature, enhancing the interaction with other raw materials. As can be seen from the comparison of the conventional group, example 1, example 4 to example 6, the luminous flux of the LED device of example 1, example 4 to example 6 is higher than that of the conventional group; and with the increase of the amount of europium oxide added in the second time, the luminous flux of the LED device decreases and then increases. In view of the data in table 1 and based on cost considerations, the amount of europium oxide added in the second time is preferably 3wt% to 6wt% of the GAYAG fluorescent powder raw materials, and the optimal value is 3wt%.

[0105] The first added activator and raw materials are in a certain degree of reaction preparation state in the S2 preheating stage, and then the migration rate difference between the crystal grains formed in the subsequent high temperature heating stage and the crystal grains in the high temperature system is caused, so that the raw materials and the first added activator fully react with the secondly added activator, the crystal grains adhere to each other, and multiple light emitting centers of the fluorescent powder brightness crystal are formed. As can be seen from the comparison of the conventional group, example 1, example 7 to example 8, the luminous flux of the LED device of example 1, example 7 to example 8 is higher than that of the conventional group; and with the increase of the temperature in the S2 preheating stage, the luminous flux of the LED device decreases and then increases. In view of the data in table 1 and based on cost considerations, the temperature in the S2 preheating stage is set to 200℃ to 300℃, and the optimal value is 200℃.

[0106] As can be seen from the comparison of the conventional group, example 1, example 9 to example 10, the luminous flux of the LED device of example 1, example 9 to example 10 is higher than that of the conventional group, and with the increase of the temperature in the S5 crystallization stage, the luminous flux of the LED device decreases and then increases. In view of the data in table 1 and based on cost considerations, the temperature in the S5 crystallization stage is set to 1400℃ to 1800℃, and the optimal value is 1400℃.

[0107] As can be seen from the comparison of example 1, comparative example 1 to comparative example 3, the luminous flux and apparent performance of the one-time addition of activator europium oxide before or after the preheating stage or after the first temperature rising reaction are far lower than those of example 1, because the raw materials, activators and the like do not fully mix and react.

[0108] As can be seen from the comparison of example 1, comparative example 4 and comparative example 5, the luminous flux and apparent performance of the one-step heat treatment of combining S3 and S4 reduction reaction stages are far lower than those of example 1, because the one-step heat treatment makes the fluorescent powder raw materials form a single light emitting center structure of the crystal.

[0109] The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a high-brightness GAYAG fluorescent powder, characterized in that, The preparation method comprises the following steps: The GAYAG fluorescent powder raw material, cerium raw material and activator are weighed proportionally; The GAYAG fluorescent powder raw material and cerium raw material are mixed and preheated to 200-300 DEG C, and then the activator is added for the first time, mixed uniformly and kept for 2-3 hours; The temperature is raised to 1000 DEG C ± 10 DEG C, and then the activator is added for the second time, mixed uniformly and kept for 50-70 minutes; The temperature is raised to 1200 DEG C ± 10 DEG C and kept for 3.5-4.5 hours; The temperature is raised to 1400 DEG C-1800 DEG C and kept for 5-7 hours; Then it is naturally cooled to room temperature; The GAYAG fluorescent powder raw material comprises yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide; the cerium raw material is cerium oxide, and its amount is 2-5 wt% of the GAYAG fluorescent powder; the activator is europium oxide, and the first amount of the activator is 2-4 wt% of the GAYAG fluorescent powder raw material; the second amount of the activator is 3-6 wt% of the GAYAG fluorescent powder raw material.

2. The method according to claim 1, wherein the method is characterized by, The GAYAG fluorescent powder raw material comprises the following molar percentage composition: Yttrium oxide 25-38%; Aluminum oxide 30-55%; Gallium oxide 10-20%; Terbium oxide 0.1-8.0%; Bismuth oxide 0.01-4.0%; Antimony oxide 0.01-3.0%.

3. A high-brightness GAYAG fluorescent powder prepared by the preparation method of claim 1 or 2.

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