How to prepare long afterglow luminescent materials(2)

3 Combustion method

Combustion method is a method of synthesizing materials by combustion of precursors. When the reactants reach the ignition temperature of the exothermic reaction, ignition in some way, the subsequent reaction that is maintained by the heat released, the combustion products are the materials to be prepared. 

The main principle of this method is to make the reaction raw materials into the corresponding nitrate, add urea (reductant) as fuel, heat at a certain temperature for a few minutes, after a violent redox reaction, overflowing a large amount of gas, and then burning, a few dozen seconds to get fluffy foam-like material, not to join the group easy to crush. This method has considerable applicability, and the gas produced by the combustion process can also be used as a protective gas. The general operation is as follows, to synthesize SrAl2O4:Eu,Dy for example, the nitrate solution of SrCO3, Al(NO3)3, Eu2O3 and Dy2O3 is mixed in chemical proportions, and appropriate urea and boric acid are added, and after dissolution, it is quickly moved into a muffle furnace that has been heated to about 600°C. 

With the evaporation of water, after a few minutes, the nitrate as an oxidizer and the urea as the evaporation of water, after a few minutes, the nitrate as an oxidizing agent and the urea as a reducing agent react, and then burn, overflowing gas, this process is very short, only a dozen seconds, the product is obtained after combustion. After the product is removed, the product is obtained by cooling and grinding. When using this method, the furnace temperature can be greatly reduced, which is an energy efficient method.

In addition to the above methods for afterglow material preparation methods, there are hydrothermal synthesis method, microwave-assisted synthesis method, chemical precipitation method, etc.. Through the use of these new synthetic technology, scientific research results show that improve the luminous properties of the material breakthroughs, but also may obtain the traditional preparation technology can not get the luminous material, so as to obtain new types of luminous materials, further broaden the research applications of long afterglow materials.