Study On Preparation And Thermal Stability Of MAlSiN₃:Eu²⁺（M=Ca、Sr） Red Phosphor

Because of meeting the requirements which means energy-saving, environmental protection, and pollution-free, white LED becomes the fourth generation light source. The white light generated by combination of InGaN blue chip and YAG:Ce3+yellow phosphor is short of the red ingredient. It’s a great test on the thermal stability for red phosphor with the development trend of high-power white LED devices.Based on the thinking to repair lattice distortion and physical surface coated phosphor technology this study has been carried out. The thermal stability of the phosphors has been improved by two different ways, doped with ions and coated with inert materials. In the mean time, the preliminary exploration of the impact between doped different ions and thermal stability, and also the impact among the phosphors coated with different materials have been study in this research.With increasing in ion concentration of Eu2+ and the proportion of alkaline earth metal of Ca2+, the Samples’ emission peak red-shift occurred and luminous intensity showed a change of first increase and then decrease. Concentration quenching occurred when the concentration of activator Eu2+>0.01mol%. It can improve relative brightness of samples when the doping amount of B or Si is not greater than 0.008 mol·mol-1. Single ion doped to improve thermal degradation best is B, dosage 0.004 mol·mol-1; Followed by is Mg and Si, the addition amount is 0.010 mol·mol-1; 0.004 mol·mol-1 respectively. Ga element does not serve to the effect to improve thermal degradation, but the addition of Ga enables blue shift of the emission peak. The best element of effect on increasing the thermal quenching performance is Si, the addition amount is 0.010 mol·mol-1; B Secondly, the addition amount is 0.004 mol·mol-1; Mg has no significant effect on improving the performance of the thermal quenching. The samples’thermal quenching performance becomes worse when added Ga. The series samples of Sr(0.79-x)LaxCa0.2Al(1+x)Si(1-X)N3:0.01Eu2+red phosphors, with the increase of the added amount x, the relative brightness decreased rapidly, and and the effect to improve the thermal performance of the recession and the thermal quenching is not as good as expected.The amount coated in phosphor samples by MgF2, SiO2,Al2O3 three coating materials is of 8wt%, coating technology has no effect on the chromaticity coordinates, the emission spectrum of the phosphor powder.Compared with the uncoated sample, the order of the relative brightness is:MgF2> SiO2> uncoated sample> Al2O3,which responses that phosphor power coated with MgF2, SiO2 materials could improve the sample relative brightness. All of these three materials are effective to improve thermal degradation, MgF2> SiO2> A12O3. However, the effect to improve thermal degradation is not obvious because of severely reduced A12O3 coated phosphors relative performance. Phosphor sample coated with SiO2 or Al2O3 to improve the performance of the thermal quenching is not obvious, Phosphor sample coated with MgF2 can raise the thermal quenching performance to some extent. The improvement of nitrides red phosphors on the performance of thermal stability can promote extensive development and application of high-power white LED device greatly.