A borate glass with high stability for white LED and a rapid preparation method and application thereof

Abstract

The application provides a borate glass for high-stability white light LED, a rapid preparation method and application thereof, and the borate glass for white light LED is prepared from the following raw materials in terms of molar percentage: 49.9-50.1% of B2O3, 24.9-25.1% of SiO2, (20-x)% of Al2O3, 4.9-5.1% of PbO and x% of Dy2O3, wherein x=1-2. The borate glass for white light LED is prepared from B2O3, SiO2, Al2O3, PbO and Dy2O3 as base materials for the first time, and the borate glass has a good application prospect as up-conversion luminescent glass material in the field of white light LED.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of luminescent glass, and particularly relates to a borate glass for high-stability white light LED, and a rapid preparation method and application thereof. BACKGROUND

[0002] White light LED (W-LED) is one of many green energy-saving and environment-friendly materials, and has the advantages of small size, less heat generation, less power consumption, long service life, short response time, and easy development into short, small and thin products. The emergence of W-LED greatly improves the popularity of luminescent materials in the lighting field. Compared with general fluorescent powder luminescent materials, glass luminescent materials can emit light in multiple wavelength ranges, and have a wide spectral range, which is a great advantage for occasions requiring color effects, and can also solve the problem of color distortion. The service life of glass luminescent materials is greatly improved compared with fluorescent powder, which means that the luminescent materials do not need to be replaced frequently, reducing the use cost and maintenance difficulty. Glass luminescent materials are stable and easy to store.

[0003] The borate glass has attracted much attention due to its low melting temperature and stable physical and chemical properties, but the existing borate glass has relatively low fluorescence efficiency and unstable spectrum. After doping different rare earth elements in the borate glass, the luminescence wavelength changes, resulting in unstable spectrum of white light LED. Moreover, due to its low energy conversion efficiency and narrow emission spectrum range, the color temperature range is small, which limits its application in the field of optical devices. Therefore, it is of great significance to develop new borate glass for emitting white light and improve its energy conversion efficiency. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a borate glass applicable to the field of W-LED, and a preparation method and application thereof, which has high energy conversion efficiency, wide emission spectrum and wide color temperature range.

[0005] To solve the above technical problems, the technical solution provided by the present application is as follows:

[0006] The present application provides a borate glass for high-stability white light LED, which is prepared from the following raw materials in mole percentage: 49.9-50.1% B2O3, 24.9-25.1% SiO2, (20-x)% Al2O3, 4.9-5.1% PbO, and x% Dy2O3, wherein x=1-2.

[0007] Preferably, x=1.25.

[0008] The present application also includes a rapid preparation method of the above-mentioned borate glass for high-stability white light LED, and the specific steps are as follows:

[0009] 1) taking B2O3 powder, SiO2 powder, Al2O3 powder, PbO powder and Dy2O3 powder as raw materials, and preparing the raw materials according to the following molar ratio: 49.9-50.1% B2O3, 24.9-25.1% SiO2, (20-x)% Al2O3, 4.9-5.1% PbO, x% Dy2O3, wherein x=1-2;

[0010] 2) mixing the raw materials weighed in step 1) uniformly to obtain a uniform glass mixture, pressing the glass mixture into a round tablet by using a tablet press, and then sintering the round tablet in a muffle furnace to obtain a tablet sample;

[0011] 3) placing the tablet sample obtained in step 2) in a nozzle of a gas suspension furnace, passing oxygen to keep the tablet sample in a suspended state, heating the tablet sample to a molten state by using a laser when the suspension is stable, adjusting the size of the gas flow to keep the sample in a suspended state in the molten state, then keeping the suspension under constant laser and gas flow, turning off the laser when the molten sample is uniform, and rapidly cooling and solidifying the molten sample to obtain a glass ball, and then annealing the glass ball to obtain a borate glass for white light LED.

[0012] According to the above scheme, the purity of the B2O3 powder, SiO2 powder, Al2O3 powder, PbO powder and Dy2O3 powder in step 1) is greater than 99.99 wt%.

[0013] According to the above scheme, the method for uniformly mixing the raw materials in step 2) is as follows: adding a small amount of anhydrous ethanol to the raw materials, stirring and grinding until the anhydrous ethanol is completely volatilized, and then repeating the above steps 2-3 times.

[0014] According to the above scheme, the diameter of the round tablet in step 2) is 20-25 mm, the thickness is 2.5-3 mm, and the mass is 80-100 mg.

[0015] According to the above scheme, the sintering process conditions in step 2) are as follows: the sintering temperature is 200-400℃, and the sintering time is 2-4 h.

[0016] According to the above scheme, the gas flow of the gas suspension in step 3) is 2.4-2.6 NI / min.

[0017] According to the above scheme, the time for heating the tablet sample by using the laser in step 3) is 60-90 s, and the voltage of the laser is 1.0-1.2 V.

[0018] According to the above scheme, the annealing process conditions in step 3) are as follows: the annealing temperature is 200-300℃, and the annealing time is 2-3 h.

[0019] The application further includes the application of the above-mentioned high-stability borate glass for white light LED in a white light LED.

[0020] The application adopts a containerless gas suspension technology to prepare doped Dy 3+ The gas suspension technology can make the glass melt not contact with the wall, inhibit melt heterogeneous nucleation, and make the melt deeply undercooled to rapidly solidify, and is an effective method for preparing a glass with poor forming capacity, and the applicant has verified through a series of experiments that the sample with the raw material component ratio of 49.9-50.1 B2O3-24.9-25.1 SiO2-(20-x)Al2O3-4.9-5.1 PbO-x Dy2O3 is more likely to form a glass, has less raw material loss, and has good luminescent performance, and the sample with the raw material component ratio of 50 B2O3-25 SiO2-18.75 Al2O3-5 PbO-1.25 Dy2O3 has almost no bubble formation and has better white light emission.

[0021] The application has the advantages that: 1. The borate glass prepared by the application has low price, can emit white light, has high refractive index, good transmittance and good mechanical properties, is a good up-conversion luminescent glass material, and has good application prospects in white light LEDs. 2. The W-LED glass prepared by the application by taking the powder material as the base material and using the gas suspension technology has low requirements on the production environment, can inhibit heterogeneous nucleation, has good repeatability, short time consumption and high efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The photos of the samples prepared in examples 1-5 after grinding and polishing;

[0023] Figure 2 The Raman spectrum of the sample prepared in example 2;

[0024] Figure 3 The Fourier infrared spectrum of the sample prepared in example 2;

[0025] Figure 4 The absorption spectrum of the sample prepared in examples 1-5;

[0026] Figure 5 The photoluminescence spectrum of the sample prepared in examples 1-5 under the excitation of ultraviolet light with a wavelength of 347 nm;

[0027] Figure 6 The CIE chromaticity diagram of the sample prepared in examples 1-5 under the excitation of ultraviolet light with a wavelength of 347 nm;

[0028] Figure 7 The fluorescence lifetime diagram of the sample prepared in examples 1-5 under the excitation wavelength of 350 nm and the emission wavelength of 483 nm;

[0029] Figure 8The sample prepared in Example 2 is used to encapsulate the obtained device to draw the power-on light emission diagram. DETAILED DESCRIPTION

[0030] In order for those skilled in the art to better understand the technical solutions of the present application, the present application is further described in detail below with reference to the drawings.

[0031] The B2O3 powder, SiO2 powder, Al2O3 powder, PbO powder and Dy2O3 powder used in the embodiments of the present application have a purity of 99.99wt%.

[0032] Example 1

[0033] A borate glass for high-stability white light LED is prepared by the following method:

[0034] 1) The raw materials are weighed according to the target chemical formula 50B2O3-25SiO2-19Al2O3-5PbO-Dy2O3: 2.0690g of B2O3 powder, 0.8933g of SiO2 powder, 1.1522g of Al2O3 powder, 0.6635g of PbO powder, and 0.2218g of Dy2O3 powder;

[0035] 2) A small amount of anhydrous ethanol is added to the raw material powder weighed in step 1), and the mixture is stirred and ground until the anhydrous ethanol is completely volatilized. The above step is repeated 3 times to obtain a uniform glass mixture. The mixture is pressed into a circular sheet with a diameter of 25mm, a thickness of 2.5mm, and a mass of 100mg using a tablet press. The circular sheet is then placed in a muffle furnace and sintered at 400℃ for 2h to obtain a tablet sample;

[0036] 3) The tablet sample obtained in step 2) is placed in the nozzle of a gas suspension furnace, and oxygen (99.999vol%) is introduced to keep the sample in a suspended state. After the suspension is stable, the tablet sample is heated to a molten state using a laser. The size of the gas flow is adjusted to keep the sample in a suspended state in the molten state. Subsequently, the sample is kept in suspension for 1min under constant laser (voltage 1.1V) and gas flow (2.5NI / min). After the molten sample is homogenized, the laser is turned off, and the molten sample is rapidly cooled and solidified to obtain a glass sphere with a diameter of about 3mm. Subsequently, the obtained glass sphere is placed in a muffle furnace and annealed at 300℃ for 3h to obtain a borate glass for white light LED.

[0037] Example 2

[0038] A borate glass for high-stability white light LED is prepared by the following method:

[0039] 1) Weigh raw materials according to target chemical formula 50B203-25Si02-18.75Al203-5PbO-1.25Dy203: 2.053g B203powder, 0.8850g Si02powder, 1.1285g Al203powder, 0.6585g PbO powder, 0.2750g Dy203powder;

[0040] 2) Add a small amount of anhydrous ethanol to the raw material powder weighed in step 1), stir and grind until the anhydrous ethanol completely volatilizes, repeat the above step 3 times to obtain a uniform glass mixture, use a tablet press to press into a round piece with a diameter of 25mm, a thickness of 2.5mm, and a mass of about 100mg, then place it in a muffle furnace and sinter at 400°C for 2h to obtain a tablet sample;

[0041] 3) Place the tablet sample obtained in step 2) in the nozzle of a gas suspension furnace, pass in oxygen to keep the sample in a suspended state, and after the suspension is stable, use a laser to heat the tablet sample to a molten state, adjust the gas flow size to keep the sample in a suspended state in the molten state, then keep it suspended for 1min under constant laser and gas flow, turn off the laser after the molten sample is homogenized, and the molten sample cools and solidifies to form a glass ball with a diameter of about 3mm, then place the glass ball obtained in a muffle furnace and anneal at 300°C for 3h to obtain a borate glass for white light LED.

[0042] Example 3

[0043] A high-stability borate glass for white light LED is prepared by the following method:

[0044] 1) Weigh raw materials according to target chemical formula 50B203-25Si02-18.5Al203-5PbO-1.5Dy203: 2.0361g B203powder, 0.8794g Si02powder, 1.1042g Al203powder, 0.6529g PbO powder, 0.3277g Dy203powder;

[0045] 2) Add a small amount of anhydrous ethanol to the raw material powder weighed in step 1), stir and grind until the anhydrous ethanol completely volatilizes, repeat the above step 3 times to obtain a uniform glass mixture, use a tablet press to press into a round piece with a diameter of 25mm, a thickness of 2.5mm, and a mass of about 100mg, then place it in a muffle furnace and sinter at 400°C for 2h to obtain a tablet sample;

[0046] 3) Put the tablet sample obtained in step 2) into the nozzle of the gas suspension furnace, and pass oxygen to keep the sample in suspension. After the suspension is stable, heat the tablet sample to a molten state using a laser. Adjust the gas flow to keep the sample in suspension in the molten state. Then keep the sample in suspension for 1 min under constant laser and gas flow. After the sample in the molten state is homogenized, turn off the laser. The sample in the molten state is rapidly cooled and solidified to obtain a glass ball with a diameter of about 3 mm. Then put the glass ball into a muffle furnace and anneal at 300°C for 3 h to obtain the borate glass for white light LED.

[0047] Example 4

[0048] A high-stability borate glass for white light LED is prepared by the following method:

[0049] 1) Weigh the raw materials according to the target chemical formula 50B2O3-25SiO2-18.25Al2O3-5PbO-1.75Dy2O3: 2.021 g of B2O3 powder, 0.871 g of SiO2 powder, 1.081 g of Al2O3 powder, 0.648 g of PbO powder, and 0.379 g of Dy2O3 powder.

[0050] 2) Add a small amount of anhydrous ethanol to the raw material powder weighed in step 1), and stir and grind until the anhydrous ethanol is completely volatilized. Repeat the above step 3 times to obtain a uniform glass mixture. Use a tablet press to press into a round tablet with a diameter of 25 mm, a thickness of 2.5 mm, and a mass of 100 mg. Then put the tablet into a muffle furnace and sinter at 400°C for 2 h to obtain a tablet sample.

[0051] 3) Put the tablet sample obtained in step 2) into the nozzle of the gas suspension furnace, and pass oxygen to keep the sample in suspension. After the suspension is stable, heat the tablet sample to a molten state using a laser. Adjust the gas flow to keep the sample in suspension in the molten state. Then keep the sample in suspension for 1 min under constant laser and gas flow. After the sample in the molten state is homogenized, turn off the laser. The sample in the molten state is rapidly cooled and solidified to obtain a glass ball with a diameter of about 3 mm. Then put the glass ball into a muffle furnace and anneal at 300°C for 3 h to obtain the borate glass for white light LED.

[0052] Example 5

[0053] A high-stability borate glass for white light LED is prepared by the following method:

[0054] 1) Weigh raw materials according to target chemical formula 50B2O3-25SiO2-18Al2O3-5PbO-2Dy2O3: 2.0045g B2O3 powder, 0.8654g SiO2 powder, 1.0575g Al2O3 powder, 0.6428g PbO powder, 0.4297g Dy2O3 powder;

[0055] 2) Add a small amount of anhydrous ethanol to the raw material powder weighed in step 1), stir and grind until the anhydrous ethanol is completely volatilized, repeat the above step 3 times to obtain a uniform glass mixture, use a tablet press to press into a round tablet with a diameter of 20-25mm, a thickness of 2.5-3mm, and a mass of 80-100mg, then place in a muffle furnace and sinter at 400°C for 2h to obtain a tablet sample;

[0056] 3) Place the tablet sample obtained in step 2) in the nozzle of a gas suspension furnace, pass in oxygen to keep the sample in a suspended state, after the suspension is stable, use a laser to heat the tablet sample to a molten state, adjust the gas flow to keep the sample in a suspended state in the molten state, then keep suspended for 1min under constant laser and gas flow, after the molten sample is homogenized, turn off the laser, the molten sample cools rapidly to form a glass ball with a diameter of about 3mm, then place the glass ball obtained in a muffle furnace and anneal at 300°C for 3h to obtain a borate glass for white light LED.

[0057] Performance test

[0058] The materials obtained in Examples 1-5 were tested for the following performance:

[0059] (1) Basic performance test

[0060] The density of the borate glass samples prepared in Examples 1-5 was measured to be 2.70g / cm -3 , 2.73g / cm -3 , 2.74g / cm -3 , 2.77g / cm -3 , 2.94g / cm -3 , respectively, and the glass density increased with increasing Dy 3+ ion concentration, indicating that the structural tightness in the glass network increased.

[0061] Figure 1 From left to right are photos of the samples prepared in Examples 1-5 after grinding and polishing, it can be seen that the prepared samples are all transparent glass, the sample of Example 1 has a small amount of bubbles, and the remaining samples have no bubbles.

[0062] Figure 2 and Figure 3The Raman spectrum and the Fourier infrared spectrum of the borate glass prepared in Example 2 respectively show that the borate glass has a lower OH content, indicating that the prepared borate glass does not support too much non-radiative loss, but allows more radiative transitions, and can obtain better light emission intensity compared with traditional silicon-based glass.

[0063] (2) Optical performance test

[0064] When white light (containing light with a wavelength of 300-2100 nm) passes through the borate glass samples prepared in Examples 1-5, the spectrum of light produced after some wavelengths of light are absorbed by the samples is shown in Figure 4 , which is used to determine the absorption peak of the borate glass. From the figure, it can be observed that 6 H 15 / 2 There are 11 transitions from the ground state to different excited states, which are all characteristic peaks of Dy 3+ ions, confirming the doping of Dy ions. In addition, through the test of the absorption spectrum, it is confirmed that the glass has the strongest absorption peak at 347 nm, indicating that the best excitation light source of the borate glass is 347 nm.

[0065] Figure 5 The photoluminescence spectrum of the borate glass prepared in Examples 1-5 under the excitation of ultraviolet light with a wavelength of 347 nm is shown in the figure. It can be seen from the figure that the borate glass prepared in Example 2 has the highest light emission intensity, about 938030.

[0066] Figure 6 The CIE chromaticity diagram of the borate glass prepared in Examples 1-5 under the excitation of ultraviolet light with a wavelength of 347 nm is shown in the figure. It can be seen from the figure that the color coordinates (0.332, 0.344) of the borate glass prepared in Example 2 are most deviated from the CIE1931 best white light center coordinate point (0.333, 0.333), the color coordinates of the borate glass prepared in Example 1 are (0.3156, 0.3097), which is deviated to blue-white light, the color coordinates of the borate glasses prepared in Examples 3, 4 and 5 are (0.3913, 0.4258), (0.4051, 0.4359) and (0.4094, 0.4427) respectively, which are deviated to yellow-white light, and the borate glass prepared in Example 2 has better white light emission.

[0067] CCT is a basic element to explore the unique color of the light generated by the device, which can be estimated by the Kelvin scale. Using the CCT value, the emission properties of the light can be suggested as "warm" (<4000K), "neutral" (4000-5000K) or "cold" (>5000K). The CCT values of the borate glasses prepared in Examples 1-5 of the present application are 3772-6486K, which is a relatively wide range, so different glass samples can be prepared by adjusting the doping concentration, which can be used in different lighting fields.

[0068] Figure 7 The fluorescence lifetime of the borate glass prepared in Examples 1-5 is 0.235 ms, 0.168 ms, 0.164 ms, 0.092 ms, and 0.064 ms, respectively, at an excitation wavelength of 350 nm and an emission wavelength of 483 nm. 3+ The fluorescence lifetime decreases with the increase of the concentration of Dy3+ ions, and the longer the fluorescence lifetime, the more conducive to carrier separation, the greater the probability of photo-generated charges participating in photocatalytic reaction, and the more conducive to the fluorescence of the material. The fluorescence lifetime of the samples of Examples 1-3 is higher than that of Examples 4 and 5, indicating that the borate glass prepared in Examples 1-3 has better luminous intensity.

[0069] The borate glass sample prepared in Example 2 is packaged with an InGaN chip emitting ultraviolet light, and the light emission diagram of the device after being powered on is shown in Figure 6. Figure 8 After being powered on, the device can emit warm white light.

[0070] The above results show that the borate glass sample prepared in the examples of the present application has low price, can emit white light, has high refractive index, good transmittance and good mechanical properties, wide emission spectrum, wide color temperature range, and involves three properties of warm, medium and cold light, and is an excellent luminescent material, which has good application potential in the field of illumination under different conditions. Moreover, the preparation method used in the present application can quickly prepare a sample, and a sample can be prepared in 60 s, and has strong repeatability, can automatically sample and sinter after setting the parameters, can be quickly mass-produced, has high sample stability, short process time, and high efficiency.

[0071] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, some improvements and changes can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A high-stability borate glass for white LEDs, characterized in that, It is made from the following raw materials in the following molar percentages: 49.9-50.1% B2O3, 24.9-25.1% SiO2, (20-x)% Al2O3, 4.9-5.1% PbO, x% Dy2O3, where x = 1-2.

2. The high-stability borate glass for white LEDs according to claim 1, characterized in that, The x = 1.

25.

3. A rapid preparation method for high-stability borate glass for white LEDs as described in claim 1 or 2, characterized in that, The specific steps are as follows: 1) Using B2O3 powder, SiO2 powder, Al2O3 powder, PbO powder and Dy2O3 powder as raw materials, the following molar ratio is used for batching: 49.9-50.1% B2O3, 24.9-25.1% SiO2, (20-x)% Al2O3, 4.9-5.1% PbO, x% Dy2O3, where x = 1-2; 2) Thoroughly mix the raw materials weighed in step 1) to obtain a uniform glass mixture, press it into a disc using a press, and then sinter it in a muffle furnace to obtain a pressed sample. 3) Place the tablet sample obtained in step 2) into the nozzle of the air suspension furnace, introduce oxygen to keep the tablet sample in a suspended state, and after the suspension is stable, heat the tablet sample with a laser to make it into a molten state. Adjust the airflow to keep the sample suspended and stable in the molten state. Then keep it suspended under constant laser and airflow. After the molten sample is homogenized, turn off the laser. The molten sample is rapidly cooled and solidified to obtain a glass ball. Then anneal the obtained glass ball to obtain borate glass for white LEDs.

4. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, The purity of the B2O3 powder, SiO2 powder, Al2O3 powder, PbO powder and Dy2O3 powder mentioned in step 1) is above 99.99 wt%.

5. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, Step 2) The method for thoroughly mixing the raw materials is as follows: add a small amount of anhydrous ethanol to the raw materials, stir and grind until the anhydrous ethanol is completely evaporated, and then repeat the above steps 2-3 times.

6. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, Step 2) The disc has a diameter of 20-25 mm, a thickness of 2.5-3 mm, and a mass of 80-100 mg.

7. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, Step 2) The sintering process conditions are: sintering temperature of 200-400℃ and sintering time of 2-4h.

8. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, Step 3) The air suspension flow rate is 2.4 to 2.6 N / min; Step 3) The time for heating the compressed sample with a laser is 60 to 90 s.

9. The rapid preparation method of high-stability borate glass for white LEDs according to claim 3, characterized in that, Step 3) The annealing process conditions are: annealing temperature 200~300℃, annealing time 2~3h.

10. The application of the high-stability borate glass for white LEDs as described in claim 1 or 2 in white LEDs.

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