Views:266 Author:Site Editor Publish Time: 2020-08-20 Origin:Site
Luminous materials refer to materials that can absorb energy in a certain way and convert it into optical radiation. The process of absorbing energy inside a substance and converting it into light radiation is called luminescence. In practical applications, a solid that emits light when stirred by the outside world is called a luminescent material. They can be used in the form of powder, single crystal, thin film or amorphous. The main components are rare earth metal compounds and semiconductor materials, which are closely related to non-ferrous metals.
Humans have a long history of using luminous materials. For example, they are used on the dial surface of watches to make a luminous watch.
Luminous materials are divided into two types: self-luminous type and light storage type. The basic composition of self-luminous materials is radioactive materials, which can emit light continuously both at day and night without absorbing energy from the outside world. However, because it contains radioactive material, it is subject to greater restrictions when used, and disposal is also a major problem. If not processed properly, the substance will cause risk to human body. The Light-storage luminous materials rarely contain radioactive substances, and there are no restrictions while using, but they rely on absorbing external light energy to emit light, and they must store enough light energy to ensure a continuous light emission. Another shortcoming of the light-storage type luminous material is insufficient brightness. For example, zinc sulfide has been used as an afterglow phosphor before, but the light emission time is too short and the brightness is not enough. After doping the radioisotope 147, the effect of luminescence is ideal, but it does not meet the requirements of environmental protection.
The development of a highly efficient and pollution-free light-storage type luminescent material has become a subject of long-term research by scientists. In this regard, Japan ’s Yoshihiko Murayama is the world ’s first scientist to make a major breakthrough. He developed a light-emitting element that contains no radioactive substances and can maintain luminescence overnight, meanwhile the brightness is 100 times that of traditional luminous materials, which could be called an epoch-making luminous material.
Miyayama Yoshihiko uses strontium aluminate as the precursor crystal, blends high-purity alumina, strontium carbonate and other rare earth metals, sinters at high temperature, after forms raw materials, crushes them, and then selects among them. The material with small particles has good adhesion, but the brightness is low, and the particles with a diameter of about 50 microns are actually needed. Yoshihiko Murayama repeatedly tested the ratio of various components in the material to find the ideal composition of the best luminous body. This light-storage type luminescent material can be used in tunnels. For example, all kinds of display signs in subway stations use this kind of pollution-free light-storing material and the effect is very good. Subway trains passing by every few minutes, and the transit time is about 10 seconds. In such a short period of time, the light appeared is enough to make the light-emitting elements replenish energy.