Phosphors (commonly known as noctilucent powder) are usually divided into two categories: photoinduced energy storage noctilucent powder and radioactive noctilucent powder. Luminous powder for storing light energy is a kind of phosphor that stores light energy after being irradiated by natural light, sunlight and ultraviolet rays. Then it is slowly released in the form of fluorescence after the light is stopped, so it can still shine at night or in the dark, lasting for several hours to more than ten hours. Radioactive noctilucent powder is a kind of luminescent powder, which is doped with radioactive substances, and excites the phosphor to emit light through the continuous radiation of radioactive substances. This luminous powder has a long luminous time, but its application range is small because of its toxicity and environmental pollution.

In real life, people use the long-term luminous characteristics of noctilucent powder to make weak lighting sources, which have special uses in military departments. This material can be coated on aviation instruments, clocks, windows, various switch signs on machines, door handles, etc. , can also be pressed into various symbols, components, items (such as power switches, sockets, hooks, etc. ) and various transparent plastics. After being irradiated by light, these light-emitting elements continue to emit light at night or when they get up after unexpected power failure or lightning, so that people can identify the surrounding direction and bring convenience to work and life. Ultrafine particles of luminescent materials are mixed into textiles to make the colors brighter, so that children can wear luminescent textiles and reduce traffic accidents.

At present, luminescent materials at home and abroad are mainly made of ZnS (zinc sulfide), SrS (strontium sulfide) and CaS (calcium sulfide), which emit green light and yellow light. However, SrS and CaS materials are easy to deliquesce, which brings difficulties to their wide application. Therefore, the market is dominated by ZnS luminescent materials. However, the rest glow time is only 1 ~ 3 hours, which is easy to deteriorate and turn black in strong light (such as sunlight), ultraviolet light and humid air, and its application in many fields is limited. Although ZnS luminous powder activated by diamond and copper * * * has a long afterglow, it has infrared quenching phenomenon, and the afterglow will be extinguished quickly under the irradiation of electro-optic light (containing more red light).