Long afterglow materials, commonly known as luminous materials or light storage luminescent materials, can maintain continuous luminescence ranging from tens of minutes to dozens of hours after being excited by visible light or ultraviolet light. This kind of material has a wide range of application values in low light lighting, emergency indication, information storage and display, energy-saving buildings, intelligent transportation and other fields. CaAl2O4:Eu,Nd is a typical long-lasting luminescent material that emits blue-purple light, and its persistence time can be as long as 19 hours. It is the longest persistence luminescent material found at present and has the widest application prospect. However, people’s understanding of its luminescent mechanism is still unclear, which restricts the development and application of new long-lasting luminescent materials. Recently, a breakthrough has been made in the study of luminescence mechanism of long afterglow luminescent materials.
Supported by the National Natural Science Foundation of China and the Natural Science Foundation of Anhui Province, the scientific research team of Hefei University of Technology systematically studied the electronic energy level structures of various impurities and defects in CaAl2O4:Eu,Nd by using the first-principles calculation method, which perfectly explained the luminescent mechanism of CaAl2O4:Eu,Nd and the reasons for its long afterglow.
In the foreseeable future, street lamps made of long afterglow materials can provide all-night illumination only by basking in the sun during the day. By analyzing the luminescence mechanism of CaAl2O4:Eu,Nd, scientists further put forward possible ways and methods to design and synthesize other new long-afterglow luminescent materials with excellent properties, and guide experimenters to synthesize these new long-afterglow luminescent materials. It is a traditional method to prepare long afterglow materials by high-temperature solid-state reaction, which is widely used. Generally speaking, the general operation of solid-state reaction is to use solid powder as raw material. The raw materials with required purity are weighed according to a certain proportion, and a certain amount of flux is added to fully mix and grind, and then burned under certain conditions (temperature, atmosphere, time, etc.).