Research On The Synthesisand Luminescence Properties Of The Rare Earth Doped Silicate Phosphors

Silicates are perfect matrix material because of the stable physical and chemicalproperties, abundant raw materials and simple preparation technology. Silicates phosphor isan important part of W-LED phosphors, and its excitation and emission spectra could bechanged by the microstructure. Therefore, the rare earth doped silicate luminescentmaterials have been attracted attention.Eu2+ions doped metasilicate BaSiO3: Eu2+phosphors were prepared by conventionalsolid-state reaction and sol-gel method. The phosphors prepared by solid-state reactionmethod could be excited efficiently by ultraviolet and emitted green light with a peakposition at540nm. The phosphors prepared by sol-gel method could be excited efficientlyby ultraviolet or blue light and emitted green light with a peak position at540nm.Thecritical concentration of quenching concentration for BaSiO3: Eu2+phosphors prepared bysol-gel method was higher than that of solid state reaction method. Both of these greenemissions were originated from the4f65d1â†'4f7transition of Eu2+ion.A series of samples Ba2SiO4matrix doped with Sm3+/Ce3+were prepared by conventionalsolid-state reaction method. Three emission bands peaked at562nm,598nm and645nmwere observed in Sm3+doped Ba2SiO4phosphors under a402nm excitation wavelength,which were corresponded to transitions4G5/2â†'6H5/2,4G5/2â†'6H7/2,4G5/2â†'6H9/2transitions ofSm3+, respectively. The optimal doping concentration of Sm3+was2mol%andconcentration quenching occurred when the concentration was large than2mol%. Underdifferent excitation wavelength, the emission peaks of Ce3+doped Ba2SiO4phosphors werelocated at380nm,490nm and750nm. In addition, there was an upconversionluminescence under650nm excitation. The luminescence originated from Sm3+ionsreduced and Ce3+ions was opposite, which indicated that there was energy transfer betweenCe3+and Sm3+ions. In addition, the Sm3+ion resulted in the peak of Ba2SiO4: Ce3+locatedat490nm disappeared. The first possible reason is that the effect of adding Sm3+ions onlattice structure changed the degree of Ce3+splitting in Ba2SiO4. Another possible reason isthat the codoping of Sm3+and Ce3+restrained the formation vacancies and Ce4+ion.