Synthesis and Characterization of Luminescent Er3+-Doped Natural Fluorapatite

Abstract

Ca10(PO4)6F2:xEr3+ (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 Er2O3 peaks is becoming more evident as Er-doped increases. In the SEM microstructure images, non-diffused Er2O3 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 2H11/2 to 4I15/2 emission bands of Er3+ at ∼530 nm are seen in all samples. The maximum average lifetime was obtained in 125 μs 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.