Syntheses and luminescent properties of CaAl2Si2O8:Eu2+, Mn2+ phosphors for white LED

Aluminosilicate-based luminescent materials, a series of CaAl 2 Si 2 O 8 :Eu 2+ samples were prepared by using a solid-state reaction method. The X-ray diffraction patterns of the samples confirmed their triclinic structure after annealing at 1100 °C. The excitation spectra of CaAl 2 Si 2 O 8 :Eu 2+ exhibited a broad band ranging between 220 to 420 nm with a point peak at a longer wavelength. Moreover, a shift in the broad band was also recorded with increasing Eu 2+ concentration. The emission spectrum of CaAl 2 Si 2 O 8 :Eu 2+ consists of a broad band from 390 to 550 nm with a maximum intensity at about 438 nm, which can be ascribed to the electric-dipole-allowed 4f 6 5d 1 - 8 S 7/2 (4f 7 ) transition of the Eu 2+ ions. A series of Eu 2+ and Mn 2+ co-activated CaAl 2 Si 2 O 8 samples were synthesized at 1400 °C. The CaAl 2 Si 2 O 8 :Eu 2+ , Mn 2+ samples had a wide emission band ranging from blue to yellow and peaking at 438 and 550 nm under an excitation wavelength of 352 nm. The PL spectrum of the CaAl 2 Si 2 O 8 :Eu 2+ , Mn 2+ samples reveal an effective energy transfer from Eu 2+ to Mn 2+ in CaAl 2 Si 2 O 8 . By utilizing the principle of energy transfer, we also demonstrated that with appropriate tuning of the activator content, CaAl 2 Si 2 O 8 :Eu 2+ , Mn 2+ phosphors exhibit great potential as a phosphor for white-light-emitting diodes.