A high-temperature solid-phase method

Preparation Materials 

Editor 

A high-temperature solid-phase method 

Afterglow prepared by high temperature solid material is a more traditional approach phase reaction, this method is used widely. In general, the general operation of the solid phase reaction is a solid powder material. glow in the dark dye‍ To achieve the required purity of the starting material by a certain percentage weighing and adding a certain amount of flux is homogenized thoroughly mixed, then under certain conditions (temperature, atmosphere, and time) for burning. Stoichiometric ratio of luminescent material according to the exact formula, placed in high-temperature resistance furnace in a protective gas atmosphere or a reducing atmosphere 900 ℃ ~ 1450 ℃ burning 2h-5h Serve. Burning process, the type and rate of co-solvent and doped with ions and so on structure and optical properties of long afterglow luminescent materials have a significant influence. 

Since the reaction conditions of high temperature solid-phase method of control, reducing agent, flux selection and preparation of raw materials aspects are becoming more optimized production processes mature, they have been widely used. For example: red afterglow material sulfide system is an alkaline earth metal carbonate, sulfur powder, and select the appropriate mix of rare earth oxides and flux calcined, but also the direct use of alkaline earth metal sulfates and rare earth oxides, flux mix baking process. [2] 

Sol - gel method 

For high-temperature solid-phase method ignition temperature is high, the preparation of luminescent material coarser particles by milling the crystalline material susceptible to damage shortcomings, it has developed a number of other glow in the dark material‍ ways. As a sol-gel method in which wet chemical methods in materials science community has attracted wide attention. This method originated in the 18th century, the application of this method has been very extensive. 

Sol-gel method is the use of specific materials in the precursor is hydrolyzed to form a sol, under certain conditions, and then the solvent was evaporated by a heat treatment, the sol into a gel network structure, and then into the post-treatment process through the formation of suitable nanomaterials a method for preparing the basic process of the nanomaterials used are as follows: 

Raw material -> dispersible system -> sol -> gel -> nanomaterials 

Prepared by the sol-gel technique is the use of luminescent material is mainly a metal alkoxide method, i.e., a metal alkoxide as a starting material into the perhydrolysis reaction, sol-gel polymerization reaction. Zhang Dong and his collaborators were prepared by sol-gel method ZnAl2O4: Mn material, the sintering temperature lower by 100 compared with the traditional method  200 ℃. [3] 

In recent years, inorganic complexes were prepared by the sol-gel gradually people's attention, which is mainly prepared by Pechin method is used, the use of citric acid and ethylene glycol esterified preparation Sol, this quick and easy method of experiment costs low compared with the metal alkoxide method. 

3 Combustion 

Combustion method is a method by means of combustion synthesis precursor material. When the reaction was allowed to reach the ignition temperature of the exothermic reaction, a method to ignite subsequent exothermic heat of reaction is maintained with the material prepared in the combustion products is proposed. The main principle of this method is the reaction of the corresponding raw material nitrate, urea was added as a fuel (reducing agent), is heated at a temperature a few minutes, by vigorous oxidation-reduction reaction, the overflow amount of gas, thereby burning, several after ten seconds to get fluffy foam-like material, not Jietuan easily crushed. This method has considerable applicability of gas generated during combustion is also used as protective gas. Operation is generally as follows to synthesize SrAl2O4: Eu, Dy, for example, the SrCO3, Al (NO3) 3, Eu2O3 and Dy2O3 nitrate solution was mixed by chemical, urea and adding the appropriate acid dissolved, has moved quickly warming to about 600 ℃ muffle furnace, with the evaporation of water, and after a few minutes, and the nitrate as an oxidizing agent of urea as a reducing agent the reaction occurs, and then burning the gas overflow, this process is very short, only ten seconds , the product was obtained after combustion. glow in the dark stones‍ After the product was taken out and cooled to obtain a product that is milled. When using this method can greatly reduce the oven temperature, is an energy efficient way. 

In addition to the persistence of several methods for material preparation methods, as well as hydrothermal synthesis, microwave-assisted synthesis, chemical precipitation method. By using these new synthetic techniques used, the research results show that to obtain luminescent materials breakthrough performance increase is also possible to obtain a light emitting material can not be obtained conventional preparation techniques, and to obtain a new kind of light emitting material, to further widen the long afterglow Research applications. ‍