Technology for enhancing water resistance and luminous intensity of SrAl2O4: Eu < 2 + >, Dy < 3 + > green long-afterglow material

Abstract

The invention discloses a technology for enhancing water resistance and luminous intensity of a SrAl2O4: Eu < 2 + >, Dy < 3 + > (SAO) long-afterglow material by an ammonium pentaborate combustion method, which is characterized in that CO (NH2) 2 is used as a fuel, NH4B5O8 is used as a reducing agent and a reactant, and a SrAl2B2O7 green long-afterglow material sample with good optical property and excellent water resistance is synthesized by a one-step combustion method. The SrAl2O4: Eu < 2 + >, Dy < 3 + > long-afterglow material treated by the method has ultrahigh brightness and excellent water resistance, the luminous intensity is only reduced by 16% after the material is soaked in water for 30 days, and the operation is simple and rapid.

Description

Technical Field

[0001] The present invention relates to a technique for enhancing the water resistance and luminescence intensity of SrAl 2 O 4 :Eu 2+ ,Dy 3+ green long afterglow materials by using ammonium pentaborate combustion method. This technique can enhance the water resistance and photoluminescence intensity of long afterglow luminescent materials, and belongs to the field of optoelectronic functional materials. Background Art

[0002] Rare earth luminescent materials can be made into luminescent ceramics, luminescent coatings, etc., and have a very wide range of applications. Among them, long afterglow materials with an alkaline earth aluminate structure, such as rare earth-doped strontium aluminate and calcium aluminate, are long afterglow materials with very excellent luminescence performance and afterglow performance. However, all these materials with an alkaline earth aluminate structure have a fatal common problem, that is, poor water resistance. After contacting with water, hydrolysis reaction will occur quickly, resulting in structural damage and the formation of aluminum hydroxide precipitate, which greatly affects the luminescence and afterglow performance of the long afterglow material.

[0003] At present, the treatment of the water resistance of this kind of alkaline earth aluminate long afterglow materials by researchers usually focuses on coating, hoping to isolate water by coating an organic or inorganic film in order to enhance the water resistance of the alkaline earth aluminate long afterglow materials. However, whether it is organic or inorganic coating, water will always be inevitably contacted during the coating process, resulting in a certain amount of loss. In 2005, Zhou Wenhua used SiO 2 and Al 2 O 3 to coat SrAl 2 O 4 :Eu 2+ ,Dy 3+ . The sol-gel method was used to coat SrAl 2 O 4 :Eu 2+ ,Dy 3+ . It was shown that an amorphous film was coated, but whether it was SiO 2 or Al 2 O 3 coating, it would affect the brightness of SrAl 2 O 4 :Eu 2+ ,Dy 3+ , and water was contacted during the coating process, resulting in loss. In 2011, Yang Qu used the boric acid combustion method to treat SrAl 2 O 4 :Eu 2+ ,Dy 3+ , greatly improving the SrAl 2 O 4 :Eu2+ , Dy 3+ 's water resistance, but has a weak impact on the luminescence intensity of the powder. In 2012, Hao Hu et al. used the liquid-phase deposition method to deposit a layer of MgF 2 O 4 :Eu 2+ , Dy 3+ on the surface of SrAl 2 . Although the liquid phase used in the coating process is anhydrous ethanol and will not cause hydrolysis of SrAl 2 O 4 , the film structure coated by the liquid-phase deposition method is not complete, and a large amount of SrAl 2 O 4 :Eu 2+ , Dy 3+ will still hydrolyze during actual use, resulting in waste. In 2022, Hu Liqun et al. used the organic coating method and used silane coupling agent to treat SrAl 2 O 4 :Eu 2+ , Dy 3+ for water resistance treatment. The water resistance of the treated powder is significantly improved, but the organic coating operation is complex and the economic applicability is not high.

[0004] Therefore, the present invention develops a technology for coating SrAl 2 O 4: Eu 2+ , Dy 3+ long afterglow material on SrAl 2 B 2 O 7 . While improving the water resistance of the powder, it enhances the luminescence intensity of the powder, which is of great significance for promoting the application of SrAl 2 O 4 :Eu 2+ , Dy 3+ long afterglow material. Summary of the Invention

[0005] In order to improve the water resistance and luminescence performance of SrAl 2 O 4 :Eu 2+ , Dy 3+ long afterglow material, the present invention proposes a technology for enhancing the water resistance and luminescence intensity of SrAl 2 O 4 :Eu 2+ , Dy 3+ long afterglow material by using the ammonium pentaborate combustion method.

[0006] The present invention uses SrAl 2 O 4 :Eu 2+ , Dy3+ Based on long-afterglow materials, using NH 4 B 5 O 8 as the reducing agent and reaction raw material, and CO(NH 2 ) 2 as the fuel, through the combustion method, make the surface of SrAl 2 O 4 :Eu 2+ ,Dy 3+ react with NH 4 B 5 O 8 to produce a continuous and dense amorphous SrAl 2 B 2 O 7 , improving the water resistance of the powder. At the same time, a large amount of reducing atmosphere is generated to reduce the residual un-reduced Eu 3+ to Eu 2+ , and the ultra-high temperature generated by combustion makes the crystallinity of SrAl 2 O 4 :Eu 2+ ,Dy 3+ increase again, enhancing the luminescence intensity of the powder. This technology uses SrAl 2 O 4 :Eu 2+ ,Dy 3+ , CO(NH 2 ) 2 , NH 4 B 5 O 8 as raw materials, CO(NH 2 ) 2 as the fuel, NH 4 B 5 O 8 as the reducing agent and reactant, and the ratio of the fuel CO(NH 2 ) 2 to SrAl 2 O 4 :Eu 2+ ,Dy 3+ is 1 - 3:1 of the theoretical dosage. The dosage of NH 4 B 5 O 8 is the amount of NH 4 B 5 O 8 reacting with SrAl 2 O 4 :Eu 2+ ,Dy 3+The mass ratio is 0.5 to 1.5:1. Reacting at an ignition temperature of 400 to 600 °C for 5 to 25 minutes can obtain a long afterglow material sample with good luminescence performance and excellent water resistance. The method of the present invention is simple and efficient. Compared with the traditional boric acid combustion, it not only improves the water resistance of the powder but also greatly enhances the luminescence performance of the powder. 2 O 4 :Eu 2+ ,Dy 3+ @SrAl 2 B 2 O 7 BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is the XRD pattern of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material before and after treatment.

[0008] Figure 2 is the scanning electron microscope image of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material treated with ammonium pentaborate.

[0009] Figure 3 is the excitation spectrum of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material before and after treatment.

[0010] Figure 4 is the emission spectrum of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material before and after treatment.

[0011] Figure 5 is the afterglow decay curve of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material.

[0012] Figure 6 is the comparison diagram of the excitation spectra of SrAl 2 O 4 :Eu 2+ ,Dy 3+ long afterglow material treated with ammonium pentaborate in water for 14 days.

[0013] Figure 7 is the SrAl treated with ammonium pentaborate in the present invention 2 O 4 :Eu 2+ ,Dy 3+ Comparison diagram of the emission spectra of the long afterglow material in water for 14 days.

[0014] Figure 8 is the SrAl treated with ammonium pentaborate in the present invention 2 O 4 :Eu 2+ ,Dy 3+ Comparison diagram of the excitation spectra of the long afterglow material in water for 30 days.

[0015] Figure 9 is the SrAl treated with ammonium pentaborate in the present invention 2 O 4 :Eu 2+ ,Dy 3+ Comparison diagram of the emission spectra of the long afterglow material in water for 30 days.

[0016] Figure 10 is the SrAl treated with ammonium pentaborate in the present invention 2 O 4 :Eu 2+ ,Dy 3+ The long afterglow material and the untreated SrAl 2 O 4 :Eu 2+ ,Dy 3+ XRD comparison diagram after soaking in water for 30 days. Specific embodiments

[0017] The specific process of the long afterglow powder with excellent luminescence performance and water resistance of SrAl 2 O 4 :Eu 2+ ,Dy 3+ @SrAl 2 B 2 O 7 is described as follows:

[0018] (1) Using SrAl 2 O 4 :Eu 2+ ,Dy 3+ , NH 4 B 5 O 8 , CO(NH 2 ) 2 as raw materials, according to NH 4 B 5 O 8With SrAl 2 O 4 :Eu 2+ ,Dy 3+ The mass ratio is 0.5 - 1.5:1, and CO(NH 2 ) 2 and SrAl 2 O 4 :Eu 2+ ,Dy 3+ is in the proportion of 1 - 3:1 of the theoretical dosage.

[0019] (2) To prepare 5 g of the sample, weigh the corresponding amounts of SrAl 2 O 4 :Eu 2+ ,Dy 3+ , NH 4 B 5 O 8 , CO(NH 2 ) 2 raw materials. Put the weighed raw materials into an agate mortar, grind for 20 - 60 min to mix the raw materials evenly, and then put them into a crucible with a volume of 300 ml.

[0020] (3) Put the 300 - ml crucible containing the raw materials into a muffle furnace preheated to 400 - 600 °C and react for 5 - 25 min.

[0021] (4) After sintering, cool down with the furnace. Wash the taken - out sample with alcohol, centrifuge, and dry it to obtain a long - persistent phosphor sample of SrAl 2 O 4 :Eu 2+ ,Dy 3+ @SrAl 2 B 2 O 7 with good luminescence performance and excellent water resistance.

[0022] Figure 1 XRD patterns of the SrAl 2 O 4 :Eu 2+ ,Dy 3+ long - persistent phosphor before and after treatment. It can be seen that no other impurity phases appear after the combustion treatment, and it is judged that the generated SrAl 2 B 2 O 7 is in an amorphous state, and the crystallinity of SrAl 2 O 4 becomes better.

[0023] Figure 2 For the SrAl treated with ammonium pentaborate prepared2 O 4 :Eu 2+ ,Dy 3+ Scanning electron microscope image of the long afterglow material. It can be seen that the particle size of the sample prepared by the present invention is about 1 μm, with good dispersibility and relatively fine particle size.

[0024] Figure 3 For SrAl prepared before and after treatment 2 O 4 :Eu 2+ ,Dy 3+ Excitation spectrum of the long afterglow material. The excitation spectrum of the sample is a broadband spectrum at 371 nm. Compared with that before treatment, the excitation spectrum of the powder after combustion treatment with ammonium pentaborate has been significantly improved.

[0025] Figure 4 For SrAl prepared before and after treatment 2 O 4 :Eu 2+ ,Dy 3+ Emission spectrum of the long afterglow material. The sample has the highest emission peak at 509 nm. Compared with that before treatment, the emission spectrum of the powder after combustion treatment with ammonium pentaborate has been significantly improved.

[0026] Figure 5 For SrAl prepared before and after treatment 2 O 4 :Eu 2+ ,Dy 3+ Afterglow decay curve of the long afterglow material. It can be seen that the afterglow decay change before and after treatment is not obvious, and the powder has good afterglow performance.

[0027] Figure 6 For SrAl treated with ammonium pentaborate prepared 2 O 4 :Eu 2+ ,Dy 3+ Comparison chart of the excitation spectra of the long afterglow material in water for 14 days. It can be seen that after soaking in water for 14 days, the excitation spectrum of the powder has not changed much and has decreased less.

[0028] Figure 7 For SrAl treated with ammonium pentaborate prepared 2 O 4 :Eu 2+ ,Dy 3+ Comparison chart of the emission spectra of the long afterglow material in water for 14 days. It can be seen that after soaking in water for 14 days, the emission spectrum of the powder has not changed much, and the luminous intensity has only decreased by 14.5%.

[0029] Figure 8 For SrAl treated with ammonium pentaborate prepared2 O 4 :Eu 2+ ,Dy 3+ Comparison chart of the excitation spectra of the long afterglow material in water for 30 days. It can be seen that almost no excitation spectrum can be detected for the untreated powder, while the excitation spectrum of the powder treated with ammonium pentaborate does not change much after being soaked in water for 30 days.

[0030] Figure 9 For the prepared SrAl treated with ammonium pentaborate 2 O 4 :Eu 2+ ,Dy 3+ Comparison chart of the emission spectra of the long afterglow material in water for 30 days. It can be seen that the untreated powder hardly emits light, while the light emission intensity of the powder treated with ammonium pentaborate only decreases by 16% after being soaked in water for 30 days.

[0031] Figure 10 For the prepared SrAl treated with ammonium pentaborate 2 O 4 :Eu 2+ ,Dy 3+ The long afterglow material and the untreated SrAl 2 O 4 :Eu 2+ ,Dy 3+ XRD comparison chart after soaking in water for 30 days. It can be seen that the XRD of the untreated powder is very chaotic and the SrAl 2 O 4 phase can no longer be detected, while the SrAl 2 O 4 phase can still be detected for the treated powder.

Claims

1. An ammonium pentaborate combustion method to enhance SrAl2O4:Eu 2+ ,Dy 3+ The technology of water resistance and luminous intensity of long afterglow materials is based on SrAl2O4:Eu 2+ ,Dy 3+ , CO(NH2)2, NH4B5O8 as raw materials, CO(NH2)2 as fuel, NH4B5O8 as reducing agent and reactant, fuel CO(NH2)2 and SrAl2O4:Eu 2+ ,Dy 3+ The ratio of the theoretical amount is 1 to 3:

1. The amount of NH4B5O8 is NH4B5O8 and SrAl2O4:Eu 2+ ,Dy 3+ The mass ratio is 0.5-1.5:

1. The SrAl2O4:Eu with good luminescence performance and excellent water resistance can be obtained by reacting at an ignition temperature of 400-600℃ for 5-25min. 2+ ,Dy 3+ @SrAl2B2O7 long afterglow material sample.

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