Views:355 Author:Site Editor Publish Time: 2020-03-30 Origin:Site
Long-lasting self-luminous materials are also known as luminous materials. It is a type of substance that absorbs sunlight or artificial light sources to emit visible light, and can continue to emit light after excitation stops. Long-lasting self-luminous materials do not consume electrical energy, but can store the absorbed natural light, and present bright and visible light in a dark environment. It is a green light source material.
The decay of luminescence depends on the behavioral trap of electrons after entering the conduction band, which plays a very important role in the relaxation process of luminescence.
1) In the process of material preparation, doped elements form luminescent centers and trap centers in the matrix. When excited by external light, the ground-state electrons of the light-emitting center transition to the excited state. When these electrons transition from the excited state back to the ground state, they emit light.
2)Some electrons fall into the trap center when they are excited and are disturbed by ambient temperature after being removed by the bound light. The electrons bound to the trap jump out of the trap and fall to the ground state. The released energy excites the luminous center to form light.
3) The electrons bound to the trap gradually jump out of the trap, so the light emission appears as a long process, that is, a long process is formed.
There are two forms of lighting.
1) When the temperature is increased, the light emitted by the luminous body is called thermoluminescence. The relationship between the luminous intensity and the temperature is called the thermoluminescence curve.
2) Under the action of long-wave light, the light emitted by the luminous body is called photoluminescence. The resulting light sum is called photoluminescence sum.
1) Traditional Luminous Powder
Long-lasting self-luminous materials can be called luminous powders in general because they can emit light for a long time in the dark after removing light. There are two main types of traditional luminous powder, sulfide type and radiation excited type. Sulfide types include ZnS, CaS, etc. The chemical properties of these materials are relatively unstable, and they are easily hydrolyzed or photolyzed under the action of moisture and ultraviolet rays.
The afterglow time of this material is generally two or three hours, and the service life is short. The radiation-excitation type uses radiant energy emitted by a radioactive substance incorporated in the material as an excitation source, and excites the luminous center to emit light. Such materials are harmful to the environment and human health because they contain radioactive materials and have been banned from use in most countries.
2) New Luminescent Materials
New types of long-lasting self-luminous materials were discovered in the 1990s. For example, it can be mixed with transparent porcelain powder, coated and sintered to make light-emitting ceramics. If added to plastic particles as light-emitting masterbatch, it can be made into light-emitting plastic sheet or film. Mixed with transparent resin or binder, it can be used to make various paint. It does not contain any harmful elements and it is with stable performance, long afterglow time. There are two main characteristics.
1) The aluminate ceramic material is used as the matrix, and the rare earth material is used as the doping element forming the luminous center and the trap center, which has a good display function at night.
2）Based on this new type of long-lasting self-luminous materials and various bonding materials, various forms of night display or decoration devices can be made.
At present, research on long-lasting self-luminous materials is still very active, and its materials and related luminescent species have been industrialized and commercialized. It is of great theoretical significance and practical value to carry out the basic research and application research of new long-lasting self-luminous materials.