Views:325 Author:Site Editor Publish Time: 2020-03-31 Origin:Site
The long-lasting self-luminous material is also called a light-storing luminescent material and a noctilucent material, which is essentially a photoluminescence material. Luminescence is the process by which matter converts energy absorbed in a certain way into light radiation. Long-lasting self-luminous materials are luminescent materials that emit light that is perceived by the human eye for more than 20 minutes after the excitation of the light source is stopped.
1. Sulfide Long-lasting Self-luminous material
The first generation of long-lasting self-luminous materials is sulfide, such as alkaline earth sulfide, zinc sulfide and so on. The outstanding advantages of sulfide long-lasting self-luminous materials are bright body color, various luminous colors, and fast light absorption in weak light. However, sulfide long-lasting self-luminous materials have obvious shortcomings, such as low afterglow brightness, short afterglow time, poor chemical stability, easy deliquescent, can't be used outdoors, and the production process has great environmental pollution. Its biggest disadvantage is that it is not resistant to ultraviolet rays, and will gradually become black under ultraviolet rays, which greatly limits its range of use.
2. Aluminate Long-lasting Self-luminous material
Since 1993, Matsuzawa synthesized Dy-doped SrAl2O4: Eu, and found that the afterglow decay time was as long as 2000min. Subsequently, a series of rare earth-activated aluminate long-lasting self-luminous materials have been successively developed. Although the aluminate's water resistance is not very good, the aluminate system long afterglow material has obtained huge commercial applications and is the main long afterglow material at this stage.
3. Silicate Long-lasting Self-luminous material
Long-lasting self-luminous material using silicate as a matrix. Because silicates have good chemical and thermal stability, and the raw material is cheap and readily available, they have received increasing attention in recent years and are widely used in lighting and display field.
4. Rare Earth Long-lasting self-luminous materials
Since the 1990s, in order to develop better long-lasting luminescent materials, people have tried to use rare earth, and successfully developed long-lasting luminescent materials doped with divalent europium and other rare earth ions. Its luminous intensity, afterglow brightness and afterglow time are all better than traditional alkaline earth metal sulfide luminescent materials, and its chemical stability in air is better than sulfide, but the disadvantage is that it is easy to decompose when immersed in water.
At present, the synthesis methods of long-lasting self-luminous materials mainly include high temperature solid phase method, chemical co-precipitation method, sol-gel method, microwave synthesis method, combustion method, hydrothermal synthesis method, microemulsion method, spray pyrolysis method, detonation method, etc.
It is generally believed that long afterglow emission is related to defects and trap levels. According to the general mechanism of long afterglow luminescence, long afterglow luminescence can be generated as long as a certain density trap level is generated in the matrix that can release the stored energy through thermal perturbation at room temperature.
1. Application in Fire Signs
Long-lasting self-luminous materials are widely used in fields such as low-light lighting, emergency instructions, building decoration and arts and crafts. In recent years, it has gradually expanded to applications such as information storage and high-energy ray detection. The light-storage type photoluminescent sign is a light-storage type sign made of rare earth long-lasting self-luminous material. It is non-toxic and harmless, has a long service life, can be reused within the service life, and has a high luminous safety factor.
2. Application in the Textile Industry
Luminous fiber is a light-light conversion functional fiber. As long as the luminescent fiber absorbs any visible light for 10 minutes, it can store light energy in the fiber. It emits light in the dark state, and the afterglow time lasts more than 10h. Luminous textiles use rare earth long-lasting self-luminous materials as the excitation source, which is non-toxic, harmless and radiation-free, and does not require electrical energy. The afterglow time is long, and the color light is generally gorgeous, which is very suitable for developing toys and embroidery art.
3. Application in Sensor
Long-lasting self-luminous materials together with optical fibers constitute a fluorescent optical fiber temperature sensor. The measurement system is generally composed of a sensor probe that excites the light source of the sensing element to emit a fluorescent signal, a photodetector that receives the fluorescent signal, and a processor for signal analysis. Afterglow luminescent materials detect the change in intensity or lifetime of the analyte to achieve the purpose of measurement.
4. Application in Coatings
The long afterglow material is applied to the coating after surface treatment. The most important performance of luminescent coatings is afterglow performance. The afterglow brightness and occlusion time are mainly related to the type and amount of long-lasting self-luminous materials, paint film thickness, and excitation light source.
5. Application in Biology
Long-lasting self-luminous materials do not contain toxic heavy metal elements, which can be excited before detection and imaging, and achieve biosensing and imaging under excitation-free conditions, thereby effectively avoiding background interference caused by in-situ excitation.
After a long period of development, long-lasting self-luminous materials have shown broad prospects for development and application. It is believed that by controlling the composition and structure of materials and improving the preparation process, long-lasting self-luminous materials will definitely be used in more and more extensive applications.