Effects of doping content and crystallite size on luminescence properties of Eu3+ doped fluorapatites obtained from natural waste

Abstract

In this study, Eu 3+ doped natural fluorapatites [Ca 10 (PO 4 ) 6 F 2 :xEu 3+ (x = 0.1, 0.3 and 0.5)] were produced from a natural waste by solid-state powder synthesis, conventional sintering, and spark plasma sintering techniques. The effects of doping content and crystallite size on luminescence properties of fluorapatite were investigated by XRD, SEM, and PL analysis. The obtained results showed that luminescence emission's intensity significantly increased with doping content, but no effect was observed on the density and crystallite size. For the samples produced with different methods, emission intensity was the lowest for sintered samples by SPS (1150 °C, 10 min, 50 MPa) with the smallest crystalline size. In contrast, emission intensity was found much higher for synthesized powders with the largest crystallite size. Furthermore, upon excitation under UV radiation, the Eu doped fluorapatites demonstrated the characteristic 5 D 0 – 7 F 2 and 5 D 0 – 7 F 4 emission lines of Eu 3+ at 618 nm and 704 nm (red region) with an ultrahigh intensity that has been firstly observed in the literature. Therefore, Eu doped fluorapatites, quickly produced from a natural waste in an eco-friendly and cost-effective way, carry a potential to be used in biological applications and lightning applications.