Study of composite Al₂O₃-Ce:Y₃Mg_1.8Al_1.4Si_1.8O₁₂ ceramic phosphors

The nominal composition of Al₂O₃-Ce:Y₃Mg_1.8Al_1.4Si_1.8O₁₂ (A-Ce:YMASG) ceramic phosphors was fabricated by the vacuum sintering technique. The introduction of Al₂O₃ as a second phase partially enters the crystal lattice, which was confirmed by the composition changing of the samples through x-ray diffraction measurement. An impurity phase of Y₄MgSi₃O₁₃ was observed in Ce:YMASG and disappeared with the introduction of Al₂O₃ at the concentration of 10 wt. %. When the content of Al₂O₃ increased to 30 and 50 wt. %, the second phase of Al₂O₃ was measured with actual weight ratios of 7.72 and 20.55 wt. %, respectively. The third phase of MgAl₂O₄ was found with the further addition of Al₂O₃at 70 wt. %; the weight ratios of Ce:YMASG, Al₂O₃, and MgAl₂O₄ were 68.756, 18.457, and 12.787 wt. %, respectively. The luminescent characters of the samples were measured by the photoluminescence spectra and electroluminescent spectra. With the increase of Al₂O₃ from 0 to 30 wt. %, the emission wavelength of Ce³⁺ plummeted from 610 to 552 nm, and the luminous efficacy of the samples increased from 35 to 65 lm/W.