Eu-doped barium strontium silicate phosphor particles prepared from spray solution containing NH₄Cl flux by spray pyrolysis

Eu-doped barium strontium silicate phosphor particles with high photoluminescence intensity under long wavelength ultraviolet were prepared from the spray solution containing NH₄Cl flux by spray pyrolysis. It was found that the addition of NH₄Cl to the spray solution makes it possible to greatly improve the photoluminescence intensity of Ba _1.488Sr_0.5SiO₄:Eu_0.012 phosphor particles under long wavelength ultraviolet of 410 nm. The highest photoluminescence intensity, which was achieved when the NH₄Cl content was 5 wt.%, was about 150% of Ba_1.488Sr_0.5SiO ₄:Eu_0.012 particles prepared from the spray solution without flux material at the post-treatment temperature of 1050°C. The particle size of Ba_1.488Sr_0.5SiO₄:Eu _0.012 phosphor particles were enlarged by using the NH₄Cl flux in the spray solution because of the large grain growth which was identified from the sharpening of the XRD peaks. Adding the NH₄Cl flux into the spray solution was found to lower the optimal post-treatment temperature at which the Ba_1.488Sr_0.5SiO ₄:Eu_0.012 phosphor particles are fully crystallized and have the maximum photoluminescence intensity. The phosphor particles prepared from spray solution containing 5 wt.% NH₄Cl flux had the maximum photoluminescence intensity at post-treatment temperature of 1100°C.