Reddish-orange-emitting Ca 12 Al 14 O 33 : Sm 3+ phosphors with high color purity

Samarium (Sm)-doped Ca 12 Al 14 O 33 (CAO) phosphors were synthesized using solid-state reaction method. Crystal structure of Sm 3+ -doped CAO was investigated using X-ray diffraction and Raman spectroscopy analysis. Raman active peaks at 320 cm −1 , 512 cm −1 and 754 cm −1 and 773 cm −1 were attributed to Ca–O, vibration between Al–O–Al, and ν3 mode of AlO 4 5− groups, respectively. The optical band-gap for pure and Sm 3+ ion-doped CAO was calculated to be 4.55 eV and 4.50 eV, respectively. Field emission scanning electron microscope (FESEM) image of synthesized phosphors exhibited agglomerated coin-like structure spread with voids. Luminescence properties were analyzed by photoluminescence (PL) spectra. The emission of reddish-orange light due to transition of 4 G 5/2 - 6 H 7/2 was observed, which was confirmed by the Commission Internationale de l’Eclairage (CIE) chromatic coordinate graph. The maximum intensity of orange-red light was observed in 0.5% Sm 3+ -doped CAO, and the calculated color purity was 95.2%.