Synthesis and luminescence properties of CaAl2O4:Mn4+ phosphor
CaAl 2 − y O 4 : y Mn 4+ ( y = 0–1.6 mol%) phosphors are synthesized by a solid-state reaction method in air, and their crystal structure and luminescence property are investigated. To compare luminescence property, CaAl 3.99 O 7 :1%Mn 4+ and SrAl 1.99 O 4 :1%Mn 4+ phosphors are also synthesized at the same condition. Broad band excitation spectra are observed within the range 220–550 nm, and emission spectra cover from 600 to 720 nm with the strongest emission peak at ∼658 nm owing to the 2 E → 4 A 2 transition of Mn 4+ ion. The influence of crystal field to luminous intensity is discussed, and the possible luminous mechanism of Mn 4+ ion is explained by using energy level diagram of Mn 4+ ion. CaAl 1.99 O 4 :1%Mn 4+ , CaAl 3.99 O 7 :1%Mn 4+ , and SrAl 1.99 O 4 :1%Mn 4+ phosphors under excitation 325 nm light emit red light, and their CIE chromaticity coordinates are (0.7181, 0.2813), (0.7182, 0.2818), and (0.7198, 0.2801), respectively. These contents in the paper are helpful to develop novel and high-efficient Mn 4+ -doped phosphor for white LEDs.
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