High-brightness GAYAG fluorescent powder and preparation method thereof

Abstract

The invention provides 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 a GAYAG fluorescent powder raw material, a cerium raw material and an activating agent in proportion; mixing a GAYAG fluorescent powder raw material and a cerium raw material, preheating to 200-300 DEG C, adding an activating agent for the first time, uniformly mixing, and preserving heat; heating to 1000 + / -10 DEG C, adding the activating agent for the second time, uniformly mixing, and keeping the temperature; raising the temperature to 1200 + / -10 DEG C, and preserving the heat; the temperature is increased to 1400-1800 DEG C, and then heat preservation is conducted Naturally cooling to room temperature; the raw materials of the GAYAG fluorescent powder comprise yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide. The activating agent is europium oxide. Through step-by-step europium element adding, synthesis temperature control and heat treatment, the fluorescent powder brightness crystal forms a plurality of light emitting centers, the light source absorption range is increased, the fluorescent powder achieves the brightening effect, and therefore the LED lighting quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent materials, and in particular relates to a high-brightness GAYAG fluorescent powder and a preparation method thereof. Background Art

[0002] GaYAG phosphor is a type of aluminate system phosphor. It can achieve a large adjustment of the peak wavelength in the range of 515-540nm. It has excellent quantum efficiency and chemical stability. It is one of the most important phosphors for providing light efficiency in general lighting and an important luminous raw material in the LED field.

[0003] At present, the solid phase method is one of the important methods for synthesizing GAYAG phosphors. Generally, GAYAG powder is synthesized at a high temperature of 1600℃ for more than 20 hours. The synthesis temperature of LED phosphors is a key parameter, which directly affects the synthesis efficiency, purity and final luminescence performance of the phosphors. Appropriate high temperature can promote the chemical reaction, ensure that the raw materials react fully, and generate high-purity phosphors. However, too high a temperature may cause side reactions, affecting the purity and performance of the product. In the existing solid phase method, most of them use a single high-temperature heat treatment or a reduction reaction at 500℃ to 800℃ + a crystallization reaction above 1600℃.

[0004] In the existing GaYAG phosphor products produced by the solid phase method, the luminescent center is a single body and can only absorb a small part of the chip energy. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a high-brightness GAYAG phosphor and a preparation method thereof, aiming to solve at least one technical problem in the background technology.

[0006] The present invention is achieved in that:

[0007] A first aspect of the present invention provides a method for preparing a high-brightness GAYAG phosphor, comprising the following steps:

[0008] Weigh GAYAG phosphor raw material, cerium raw material and activator according to proportion;

[0009] The GAYAG phosphor raw material and the cerium raw material are mixed and preheated to 200°C to 300°C, and then the activator is added for the first time, and then the mixture is mixed and kept warm for the first time;

[0010] After heating to 1000℃±10℃, add the activator for the second time, mix well and keep warm for the second time;

[0011] Heat to 1200℃±10℃ and keep warm for the third time;

[0012] After heating to 1400°C to 1800°C, keep warm for the fourth time;

[0013] Then naturally cool to room temperature;

[0014] The GAYAG phosphor raw materials include yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide; and the activator is europium oxide.

[0015] Preferably, the GAYAG phosphor raw material comprises the following composition in molar percentage:

[0016] Yttrium oxide 25% to 38%;

[0017] Alumina 30% to 55%;

[0018] Gallium oxide 0%~20%;

[0019] Terbium oxide 0.1%~8.0%;

[0020] Bismuth oxide 0.01%~4.0%;

[0021] Antimony oxide 0.01%~3.0%.

[0022] Preferably, the first dosage of the activator is 2wt% to 4wt% of the GAYAG phosphor raw material; the second dosage of the activator is 3wt% to 6wt% of the GAYAG phosphor raw material.

[0023] Preferably, the cerium raw material is cerium oxide, and its usage is 2wt% to 5wt% of the GAYAG phosphor.

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

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

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

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

[0028] 2. The phosphor brightness crystals prepared by the method of the present invention form multiple luminous centers. When the phosphor is used, the range of absorbing light sources is increased, so that the phosphor achieves a brightening effect.

[0029] 3. The present invention analyzes the mass transfer rules of raw materials for the nucleation and growth of phosphor grains, improves the viscosity of the molten state of the sintering system, adjusts the migration rate difference of homogeneous grains in the high-temperature system, achieves the effect of grains adhering to each other, and develops a high-brightness, homogeneous grain GAYAG phosphor attachment preparation technology. Under the same conditions, the present invention effectively improves the brightness of the GAYAG phosphor package. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an electron microscope image of the GAYAG phosphor prepared in Example 1 of the present invention;

[0031] Figure 2 Spectra of light-emitting devices made of the GAYAG phosphor of Example 1 of the present invention and conventional GAYAG phosphor. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] A method for preparing a high-brightness GAYAG phosphor comprises the following steps:

[0034] S1. Weigh GAYAG phosphor raw material, cerium raw material and activator according to proportion;

[0035] The GAYAG phosphor raw material can be any component and ratio allowed in the art. In a specific implementation, the GAYAG phosphor raw material includes the following molar percentage composition: 25% to 38% yttrium oxide; 30% to 55% aluminum oxide; 0% to 20% gallium oxide; 0.1% to 8.0% terbium oxide; 0.01% to 4.0% bismuth oxide; 0.01% to 3.0% antimony oxide; In the following embodiment, the GAYAG phosphor raw material is: 33% yttrium oxide; 48% aluminum oxide; 10% gallium oxide; 5% terbium oxide; 2.5% bismuth oxide; 1.5% antimony oxide, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

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

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

[0038] S2, preheating the GAYAG phosphor raw material and the cerium raw material to 200°C to 300°C, adding the activator for the first time, mixing and keeping warm for 2h to 3h;

[0039] The first dosage of the activator is 2wt% to 4wt% of the GAYAG phosphor raw material; for example, it can be 2wt%, 3wt%, or 4wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] S3, after heating to 1000°C ± 10°C, add the activator for the second time, mix well and keep warm for the second time of 50min to 70min, preferably 60min;

[0041] The second dosage of the activator is 3wt% to 6wt% of the GAYAG phosphor raw material; for example, it can be 3wt%, 4.5wt%, 6wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; in this step, the raw materials initially react with the activators added twice.

[0042] S4, heating to 1200℃±10℃ and keeping warm for 3.5h~4.5h, preferably 4h; in this step, the raw materials react fully with the activators added twice respectively, and homogeneous grains have a difference in migration rate in the high temperature system during the reaction, achieving the effect of grains adhering to each other, and then the brightness crystals of the phosphor finally obtained form multiple luminescence centers.

[0043] S5. After heating to 1400°C to 1800°C and maintaining the temperature for 5h to 7h, preferably 6h, the raw materials and the activator are crystallized and formed after high-temperature sintering.

[0044] S6. Then cool naturally to room temperature.

[0045] The synthesis temperature of LED phosphor is a key parameter, which directly affects the synthesis efficiency, purity and final luminous performance of the phosphor. Appropriate high temperature can promote the chemical reaction, ensure that the raw materials react fully, and generate high-purity phosphor. However, too high temperature may cause side reactions, affecting the purity and performance of the product. The present invention can optimize the performance of the phosphor 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 phosphor comprises the following steps:

[0048] S1. Weigh GAYAG phosphor raw material, cerium raw material and activator according to proportion;

[0049] The GAYAG phosphor raw material includes the following molar percentages: 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 phosphor;

[0051] The weight of the activator europium oxide is 5wt% of the GAYAG phosphor raw material;

[0052] S2, preheating the GAYAG phosphor raw material and the cerium raw material to 200°C, adding europium oxide for the first time, mixing and keeping warm for 2 hours; the amount of europium oxide used is 2wt% of the GAYAG phosphor raw material;

[0053] S3, heating to 1000°C and adding europium oxide for the second time, mixing and keeping warm for 1 hour, during which the temperature is kept stable within ±10°C; the amount of europium oxide used is 3wt% of the GAYAG phosphor raw material;

[0054] S4, heating to 1200℃ and keeping it for 4h, during which the temperature is kept stable within ±10℃;

[0055] S5, heating to 1400°C and keeping the temperature for 6 hours to perform crystallization;

[0056] S6. Then naturally cool to room temperature to obtain GAYAG phosphor.

[0057] Example 2

[0058] The difference between this embodiment and embodiment 1 is that the first dosage of the activator europium oxide is 3 wt % of the GAYAG phosphor raw material; other reaction conditions and parameters are consistent with those in embodiment 1.

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the first dosage of the activator europium oxide is 4 wt % of the GAYAG phosphor raw material; other reaction conditions and parameters are consistent with those in embodiment 1.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 1 is that the second dosage of the activator europium oxide is 4 wt % of the GAYAG phosphor raw material; other reaction conditions and parameters are consistent with those in embodiment 1.

[0063] Example 5

[0064] The difference between this embodiment and embodiment 1 is that the second dosage of the activator europium oxide is 5wt% of the GAYAG phosphor raw material; other reaction conditions and parameters are consistent with those in embodiment 1.

[0065] Example 6

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

[0067] Example 7

[0068] The difference between this embodiment and embodiment 1 is that the temperature of the S2 preheating stage is adjusted to 250° C.; other reaction conditions and parameters are consistent with those of embodiment 1.

[0069] Example 8

[0070] The difference between this embodiment and embodiment 1 is that the temperature in the preheating stage is adjusted to 300° C.; other reaction conditions and parameters are consistent with those in embodiment 1.

[0071] Example 9

[0072] The difference between this embodiment and embodiment 1 is that the temperature in the crystallization stage is adjusted to 1600° C.; other reaction conditions and parameters are consistent with those in embodiment 1.

[0073] Example 10

[0074] The difference between this embodiment and embodiment 1 is that the temperature in the crystallization stage is adjusted to 1800° C.; other reaction conditions and parameters are consistent with those in embodiment 1.

[0075] Comparative Example 1

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

[0077] S2 and S3 are specifically:

[0078] S2, preheating the GAYAG phosphor raw material and the cerium raw material to 200°C, adding europium oxide, mixing and keeping warm for 2 hours; the amount of europium oxide is 5wt% of the GAYAG phosphor raw material;

[0079] S3. Raise the temperature to 1000℃ and keep it for 1h. During this process, the temperature should be kept stable within ±10℃.

[0080] Comparative Example 2

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

[0082] S2 and S3 are specifically:

[0083] S2, preheating the mixture of GAYAG phosphor raw material and cerium raw material to 200°C and keeping the mixture warm for 2h;

[0084] S3. Raise the temperature to 1000°C and add europium oxide. Mix well and keep warm for 1 hour. During this process, the temperature is kept stable within ±10°C. The amount of europium oxide used is 5wt% of the GAYAG phosphor raw material.

[0085] Comparative Example 3

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

[0087] S2 specifically comprises: preheating the mixture of GAYAG phosphor raw material, cerium raw material and europium oxide to 200° C. and then keeping the mixture warm for 2 hours; the amount of europium oxide used is 5wt% of the GAYAG phosphor raw material.

[0088] Comparative Example 4

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

[0090] The specific details after S3 and S4 are merged are:

[0091] S3. Raise the temperature to 1000°C and add europium oxide for the second time. Mix well and keep warm for 5 hours. During this process, the temperature is kept stable within ±10°C. The amount of europium oxide used is 3wt% of the GAYAG phosphor raw material.

[0092] Comparative Example 5

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

[0094] The specific details after S3 and S4 are merged are:

[0095] S3. Raise the temperature to 1200°C and add europium oxide for the second time. Mix well and keep warm for 5 hours. During this process, the temperature is kept stable within ±10°C. The amount of europium oxide used is 3wt% of the GAYAG phosphor raw material.

[0096] The purchased conventional single crystal structure GAYAG phosphor (conventional group), the phosphors prepared in Examples 1 to 10, and Comparative Examples 1 to 5 were respectively used as powder 1, the nitride red powder was used as powder 2, and phenyl silica gel with a refractive index of 1.54 and a viscosity of 8300 mPa·s and 1000 mPa·s respectively was used as glue A and glue B (mixed in a mass ratio of glue A: glue B = 1:10), powder 1, powder 2, glue A, and glue B were evenly mixed as LED encapsulation glue, and after encapsulating the LED chip with the encapsulation glue, the LED light-emitting device was successively baked at 100°C for 1h and 150°C for 1h to obtain a LED light-emitting device.

[0097] Figure 1 is an electron microscope image of the GAYAG phosphor prepared in Example 1; Figure 1 It can be seen that the brightness crystals of the phosphor prepared in Example 1 form multiple luminescence centers.

[0098] Figure 2 The spectrum diagram of the light-emitting device prepared by the GAYAG phosphor of Example 1 and the conventional GAYAG phosphor (conventional group) is shown in FIG. Figure 2 By comparison, it can be seen that the luminous intensity of the phosphor prepared in Example 1 of the present invention is higher than that of the conventional GAYAG phosphor, and the polycrystalline phosphor emits more light after receiving the blue light source, achieving a brightening effect. The luminous flux and CRI performance test of the encapsulated LED device are shown in Table 1 below.

[0099] Table 1

[0100]

[0101]

[0102] It can be seen from the data in Table 1 that the brightness of the GAYAG phosphor packages prepared in Examples 1 to 10 of the present invention is improved.

[0103] After the first addition of the activator and the raw materials are mixed, a preliminary reaction occurs, and the contact probability and reaction activity between the activator and the raw materials are enhanced. From the comparison between the conventional group and Examples 1 to 3, it can be seen that the luminous flux of the LED devices of Examples 1 to 3 is higher than that of the conventional group. As the amount of the first addition of the activator europium oxide increases, the luminous flux of the LED device decreases significantly and then increases. In view of the data in Table 1 and based on cost considerations, the amount of the first addition of the activator europium oxide is preferably 2wt% to 4wt% of the GAYAG phosphor raw material, and the optimal value is 2wt%.

[0104] The activator added for the second time reacts with the activator and raw materials added for the first time. The activator and raw materials added for the first time are already in a reaction preparation state to a certain extent. When the amount of europium oxide added for the second time increases, the increase in the concentration of the activator causes the reaction to move in the direction of generating products. Moreover, the high temperature (1000°C) provides sufficient energy for these active sites, and the chemical properties of europium oxide itself become more active at high temperatures, enhancing the interaction with other raw materials. From the comparison of the conventional group, Example 1, and Example 4 to Example 6, it can be seen that the luminous flux of the LED devices of Example 1, Example 4 to Example 6 is higher than that of the conventional group; and as the amount of europium oxide added for the second time increases, the luminous flux of the LED device decreases significantly and then increases. In view of the data in Table 1 and based on cost considerations, the amount of europium oxide added for the second time is preferably 3wt% to 6wt% of the GAYAG phosphor raw material, and the optimal value is 3wt%.

[0105] The activator and raw material added for the first time in the S2 preheating stage are already in a reaction preparation state to a certain extent, which makes the migration rate of the grains formed in the subsequent high-temperature heating stage and the grains in the high-temperature system different, so that the raw materials and the first activator react fully with the second added activator, so that the grains adhere to each other, and the phosphor brightness crystals form multiple luminous centers. From the comparison of the conventional group, Example 1, and Example 7 to Example 8, it can be seen that the luminous flux of the LED devices of Example 1, Example 7 to Example 8 is higher than that of the conventional group; and as the temperature of the S2 preheating stage increases, the luminous flux of the LED device decreases significantly and then increases. In view of the data in Table 1 and based on cost considerations, the temperature of the S2 preheating stage is set to 200℃~300℃, and 200℃ is most preferred.

[0106] From the comparison between the conventional group, Example 1, and Example 9 to Example 10, it can be seen that the luminous flux of the LED devices of Example 1, Example 9 to Example 10 is higher than that of the conventional group. As the temperature of the S5 crystallization stage increases, the luminous flux of the LED device decreases significantly and then increases. In view of the data in Table 1 and based on cost considerations, the temperature of the S5 crystallization stage is set to 1400°C to 1800°C, and 1400°C is most preferred.

[0107] From the comparison between Example 1 and Comparative Examples 1 to 3, it can be seen that when the activator europium oxide is added once before or after the preheating stage or after the first heating reaction, the luminous flux and the display index performance are much lower than those of Example 1. The reason is that the raw materials, the activator, etc. are not fully mixed and reacted.

[0108] From the comparison between Example 1, Comparative Example 4 and Comparative Example 5, it can be seen that the luminous flux and display performance of combining the S3 and S4 reduction reaction stages into a one-step heat treatment are much lower than those of Example 1. The reason is that the one-step heat treatment causes the phosphor raw material to form a crystalline single luminescent center structure.

[0109] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a high-brightness GAYAG phosphor, characterized in that: The preparation method comprises the following steps: Weigh GAYAG phosphor raw material, cerium raw material and activator according to proportion; The GAYAG phosphor raw material and the cerium raw material are mixed and preheated to 200°C to 300°C, and then the activator is added for the first time, and then the mixture is mixed and kept warm for the first time; After heating to 1000℃±10℃, add the activator for the second time, mix well and keep warm for the second time; Heat to 1200℃±10℃ and keep warm for the third time; After heating to 1400°C to 1800°C, keep warm for the fourth time; Then naturally cool to room temperature; The GAYAG phosphor raw materials include yttrium oxide, aluminum oxide, gallium oxide, terbium oxide, bismuth oxide and antimony oxide; and the activator is europium oxide.

2. The method for preparing a high-brightness GAYAG phosphor according to claim 1, characterized in that: The GAYAG phosphor raw material comprises the following molar percentage compositions: Yttrium oxide 25% to 38%; Alumina 30% to 55%; Gallium oxide 0%~20%; Terbium oxide 0.1%~8.0%; Bismuth oxide 0.01%~4.0%; Antimony oxide 0.01%~3.0%.

3. The method for preparing a high-brightness GAYAG phosphor according to claim 1 or 2, characterized in that: The first dosage of the activator is 2wt% to 4wt% of the GAYAG phosphor raw material; the second dosage of the activator is 3wt% to 6wt% of the GAYAG phosphor raw material.

4. The method for preparing a high-brightness GAYAG phosphor according to claim 1, characterized in that: The cerium raw material is cerium oxide, and its usage is 2wt% to 5wt% of the GAYAG phosphor.

5. The method for preparing a high-brightness GAYAG phosphor according to claim 1, characterized in that: The first time is 2 hours to 3 hours; the second time is 50 minutes to 70 minutes; the third time is 3.5 hours to 4.5 hours; and the fourth time is 5 hours to 7 hours.

6. A high-brightness GAYAG phosphor prepared by the preparation method according to any one of claims 1 to 5.

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