Preparation And Characterization Of Silicon Nitride-based Luminescent Materials

In recent years, rare earth-doped Sialon phosphors have attracted increasing interest due to their outstanding luminescence properties and excellent thermal and chemical stabilities.During Sialon phosphors, research about β-Sialon phosphors is much less. The conventional method to synthesize β-Sialon phosphors requires expensive raw materials （such as high-purity silicon nitride, aluminium nitride, aluminium oxide）, high reaction temperature and a long reaction time. Moreover, the synthesized powder also requires tedious post-treatment to obtain high-purity phosphor. In this thesis, we explore a new synthetic method to β-Sialon phosphors, compared with the conventional method to obtain β-Sialon phosphors, lower cost raw materials, simpler post-reatment and a relatively short reaction time are achieved. It is anticipated that these new raw materials developed here could find broad applications for synthesizing β-Sialon: Eu²⁺ phosphors.（1） High-purity silicon nitride-based luminscnet materials were successfully synthesized from nano-SiO2 （Aladdin, 99.5%）, nano-Carbon （Aladdin, 99.5%）, AI （Aladdin, 99.95%） and EU2O3 （Sinopharm Chemical ReagentCo, Ltd） powders. The amount of a phase will become larger along with more dopant concentration of Eu2O3. All the materials exhibit yellow emission under excitation at 405nm.（2） On the basis of （1）, aluminium powder is added in the raw materials. Eu²⁺-dopedê-Sialon phosphors were synthesized in a high-frequency induction furnace. The phosphors exhibit an intense green emission under UV radiation. Concentration quenching and a blue shift of the emission peak appear with increasing dopant concentration of Eu2O3. The ê-Sialon phosphor has smaller thermal quenching than a commercial green-emitting silicate phosphor.（3） Phase-pure Ce³⁺-doped β-Sialon phosphors were also synthesized in a high-frequency induction furnace, but it is in a lower reaction temperature. The phosphors exhibit violet emission under excitation at 300nm. Intensity of the emission peaks enhances along with more dopant concentration of CeO2. Meanwhile, a red shift of the emission peak is observed.Compared with the commercial blue phosphors, the phosphor has smaller thermal quenching from 150℃ to 250℃.