Synthesis and Characterization of Luminescent Er 3+ -Doped Natural Fluorapatite

Ca 10 (PO 4 ) 6 F 2 :xEr 3+ (x = 0.1, 0.3 and 0.5) was synthesized using solid-state powder process (1150 °C, 1h), conventional sintering (1150 °C, 1h), and spark plasma sintering (SPS) techniques (1150 °C, 10 min, and 50 MPa). XRD analysis revealed that all samples are generally composed of fluorapatite (FAP) containing quartz as a minor phase, and the presence of Er 2 O 3 peaks is becoming more evident as Er-doped increases. In the SEM microstructure images, non-diffused Er 2 O 3 particles also increase with doping in powder and pellet samples. However, the PL analysis showed that the luminescence intensity did not increase proportionally with the doping content caused by the concentration quenching effect. FAP samples doped with 0.3 mol Er have higher luminescence intensity than 0.1 and 0.5 mol Er-doped samples. In addition, powder samples have the highest luminescence intensity due to increased luminescence intensity with increasing crystallite size. The characteristic 2 H 11/2 to 4 I 15/2 emission bands of Er 3+ at ∼530 nm are seen in all samples. The maximum average lifetime was obtained in 125 μ s in the powder sample with 0.3 mol Er. CIE color coordinates demonstrate the standard green color under ∼ 275 nm excitation; eventually, these phosphors can be utilized as green phosphors for optical applications. A comparison of emission intensities of Er 3+ -doped FAPs produced with different techniques was performed. Green phosphors with ultrahigh emission intensity were produced by doping 0.3 mol Er 3+ in natural fluorapatite. The dipole-dipole interaction causes a concentration quenching mechanism after 0.3 mol Er. Characteristic Er 3+ emissions at 530 nm ( 2 H 11/2 → 4 I 15/2 transitions) were achieved under UV excitation.