Synthesis and Luminous Characteristics of Ba_2SiO_3Cl_2:Eu~(2+), Mn~(2+) Phosphor for White LED

摘要

Ba_2SiO_3Cl_2:Eu~(2+), Mn~(2+) phosphor was synthesized by high-temperature solid state reaction at 900～1200°C in a slightly reducing atmosphere for 2.0～8.0 hours. The raw materials were the mixture of BaCO_3, SiO_2, MnCO_3, NH_4Cl, and Eu_2O_3 in the mol ratio of 3, 2, 0.004, 2 and 0.02. Ba_2SiO_3Cl_2:Eu~(2+), Mn~(2+) phosphor's absorption and luminescence spectra were studied. The results indicated that the emission band consists of three peaks located at 425 nm, 492nm and 608nm, respectively. The emission peaks at 425 and 492nm originate from the transition 5d → 4f of Eu~(2+) ions that occupy the two Ba~(2+) sites in the crystal of Ba_2SiO_3Cl_2, while the 608nm emission is attributed to the energy transfer from Eu~(2+) ions to Mn~(2+) ions. The white light can be obtained by mixing the three emission colors of blue (425 nm), green (492 nm) and red-orange (608 nm) in the single host. When the concentrations of the Eu~(2+) ions and Mn~(2+) ions were 0.02mol and 0.004mol respectively, the sample presented intense white emitting. The excitation spectra of the three emissions extending from 300 nm to 460 nm indicated that Ba_2SiO_3Cl_2:Eu~(2+) phosphor can be excitated by InGaN chip UV emission effectively, and it is a single-phase white phosphor with low-cost and high brightness for white LEDs.