关键词: Sr_2MgSi_3O_9, Eu~(3+), 发光, 凝胶-燃烧法, 白光LED

Abstract: Novel phosphors Sr_2MgSi_3O_9:Eu~(3+) synthesized by gel-combustion method in weak reductive environment.The as-synthesized phosphors were investigated by XRD, SEM and Fluorescence spectrophotometer. The results show that Sr_2MgSi_3O_9: Eu~(3+) phosphor possesses the similar tetragonal crystal structure as that of Sr_2MgSi_2O_7. The initial particles of as-synthesized phosphors are nearly spherical in shape, and the particle size is about 100 nm in diameter. The excitation spectrum of Sr_2MgSi_3O_9:Eu~(3+) sample presents wide band absorption between 220～300 nm, which is ascribed to the charge transfer between Eu~(3+)-O~(2-). The sharp peaks after 300 nm belong to f→f transition of Eu~(3+), and the strongest sharp peak is located at 400 nm, which is ascribed to the transition from the ground state of Eu~(3+) to ~5L_6 excited state. Therefore, samples can be efficiently excited by ultraviolet radiation from InGaN chip. The emission spectrum consists of two emission peaks at 592 nm and 618 nm, which are ascribed to ~5D_0→~7F_1 and ~5D_0→~7F_2 respectively. Moreover, it is found that co-doped Ti~(4+) with the proper content can make the emitting colour shift from orange-red to red, and improve intensity of luminescence effectively.

Key words: Sr_2MgSi_3O_9:Eu~(3+), luminescence, gel-combustion method, WLED