Luminescence Properties Of M₃MgSi₂O₈: Eu²⁺, Mn²⁺ (M=Ba,Sr) Phosphors

ABSTRACT:The luminescent material with silicate as a substrate has good chemical, thermal and radiation stability, and synthetic process is simple. Its broad excitation spectra and emission spectra can change easily through the fine-tuning of rare earth ions doped. So people have taken note of the importance of the study of silicon matrix phosphor, and it also becomes a research focus of white LED phosphors.In this paper, M3MgSi2O8:Eu2+(M=Ba, Sr) and Ba3MgSi2O8:Eu2+, Mn2+ phosphors were synthesized by the sol-gel method and high temperature solid-state reaction method. The structure and emission spectrum excited by near violet light were investigated.Ba3MgSi2O8:Eu2+ was prepared by high temperature solid method, and samples were characterized by XRD (Powder X-ray diffraction), SEM (scanning electron microscopy) and other means. Samples were excited by 376 nm and the emission peak was located at 449 and 514 nm, and the emission peak was related to 4f65d1â†'4f7 in Ba3MgSi2O8 and Ba2SiO4. We changed the doped concentration of Eu2+ in range of 1-7 mol%. When the doped concentration of Eu2+ was more than 3 mol%, the concentration quenching was happened. We also experimentally studied at the effect on luminous intensity of Ba3MgSi2O8:Eu2+ sample caused by different densities fluxing agent H3BO3. The doped concentration of H3BO3 changed in range of 0-10 mol%, and the best carrier concentration was obtained,4 mol%.By the TG-DTA (Thermo Gravimetric-Differential Thermal Analyze) and FTIR (Fourier transform infrared spectroscopy) of sol-gel method Ba3MgSi2O8:Eu2+, Mn2+ samples, we studied the process of phase change in roasting and determined the approximate crystallization temperature of Ba3MgSi2Os:Eu2+, Mn2+ phosphors. The emission spectra monitored at 440,514, and 615 nm when excited by the 376 nm UV light. Our results demonstrate that 514 nm emission bands were from Eu ions replacing of the sites of Ba2+ in Ba2SiO4.440 nm emission bands originated from Eu2+ ions substituting the sites of Ba2+ in Ba3MgSi2O8, corresponded to 4f65d1â†'4f7 transition of Eu2+ ions.615 nm emission bands ascribed to Mn2+ ions taking place of the sites of Mg2+ ions, corresponded to 4Tâ†'6A red launch of Mn2+ ions, and when the doped concentration of Mn2+ ions was more than 15 mol%, concentration quenching occurred. The LED center's activation of 615 nm emission bands depended on the energy transfer of Eu2+ ions in the same lattice. We also compared the performance of samples prepared by high temperature solid state method and sol-gel method.Sr3MgSi2O8:Eu2+ was prepared by high temperature solid method, and samples were characterized by XRD, SEM and other means. The samples were excited by 362 nm, and the emission peaks related were 470 and 530 nm. These two emission bands were sourced by 4f65d1â†'4f7 of Eu2+ replacing Sr2+(â… ) and Sr2+(â…¡), (â…¢) lattice site. The doped concentration of Eu2+changed in range of 0.5-5 mol%, and the concentration quenching occurred when the doped concentration of Eu2+ ions was more than 2 mol%. Under the same condition, we also compared the emission spectrum of Eu2+(M=Ba, Sr).This paper contains figures 32, tables 3, reference 43.