부산대학교 도서관

A series of LAGBPr phosphors of composition Li6AlGd(1–x)(BO3)4: x Pr3+ (0 ≤ x ≤ 2.0 mol%) were prepared by solid-state reaction method and characterized through thermal, structural, morphological and photoluminescence studies. Thermal investigation shows that the LAGBPr phosphors crystallize at 640 °C. The powder X-ray diffraction studies show that the size of crystallites is of the order of 77 nm. The excitation spectra reveal a charge transfer band due to O2– → Pr3+ (230–250 nm), host-related (Gd3+) bands from 205 to 315 nm and some f-f transitions of Pr3+ ions from 420 to 500 nm. The fluorescence properties were investigated by exciting within the host and within dopant (Pr3+) ions. A tunable fluorescence from orange-red to white to bluish-white was observed when excited at 274 nm and a bluish-white fluorescence at 449 nm excitation. Upon 449 nm excitation, a blue-shift is observed with increase of concentration of Pr3+ ions. The optimal concentration of Pr3+ ions for efficient fluorescence is confirmed to be 1.0 mol%, and a quenching in fluorescence was noticed and it was ascribed to the non-radiative transfer of energy through [3P0, 3H4] → [1D2, 3H6], [3P0, 3H4] → [3H6, 1D2] and [1D2, 3H4] → [3H4, 1D2] channels. The LAGBPr1.0 phosphor has more proficiency to be used in LED applications.