Synthesis, structure, and luminescence properties of Europium/Cerium/Terbium doped strontium-anorthite-type green phosphor for solid state lighting

Novel phosphor exploration and luminescence property regulation are two important strategies in pursing high performance phosphors for white light emitting diodes, and have attracted great attention from the researchers. Herein, novel green phosphors Sr2Ga2SiO7:Eu2+ and Sr2Ga2SiO7:Ce3+,Tb3+ had been obtained by high-temperature solid-state reactions and their luminescence properties had been investigated in detail. Powder X-ray diffraction and Rietveld structure refinement results verified the phase purity and gave the crystal structure of the prepared samples. Due to the electric dipole transition between inter configurations of 4fN and 4fN-15d1, Sr2Ga2SiO7:Eu2+ and Sr2Ga2SiO7:Ce3+ exhibited intense broad excitation and emission bands, giving out green and blue emitting light under UV excitation, respectively. By codoping Tb3+ with Ce3+ in the host and utilizing the energy transfer, tunable blue to green emission had been obtained. The energy transfer mechanism had been determined to be electric dipole-quadrupole interaction through dynamic luminescence analysis using I-H model. The prepared phosphors exhibited good thermal stability with integral emission intensity at 150 degrees C remaining more than 80 % of the emission intensity at 25 degrees C. Moreover, by coating Sr2Ga2SiO7:Eu2+ and Sr2Ga2SiO7:Ce3+, Tb3+ on UV chips, green LED devices had been obtained. The investigation results indicated that the Eu2+ singly doped and Ce3+-Tb3+ codoped Sr2Ga2SiO7 might be potential UV excited green phosphors for solid state lighting.