Luminescence properties of valorized and synthetic Tb³⁺ /La³⁺ co-doped natural Moroccan hydroxyapatite

This work reports a synthesized natural Moroccan hydroxyapatite (NHAP) phosphors doped by rare-earth elements using ion exchange technique. The objective of this technique lies in the generation of luminescence after UV excitation of the synthetized phosphors. Effects of doping and co-doping on the NHAP physicochemical properties were investigated using multiple characterization methods such as X-ray diffraction (XRD), scanning electron microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma and photoluminescence spectroscopy. The XRD results show that Tb³⁺/La³⁺ incorporated into NHAP does not change its structure. Under near-ultraviolet excitation at 405 nm, NHAP: xTb³⁺, yLa³⁺ samples show the advantage to obtain a single emission peak, which corresponds to the green colour characteristic of terbium. Moreover, the chromaticity coordinates of NHAP: 0.5%Tb, 1.5%La indicate the excellent cool green-emitting phosphors with a low correlated colour temperature. Overall, the obtained results suggest that NHAP (0.5%Tb:1.5%La) could be used as multifunctional bio-imaging materials or solid-state lighting for LEDs with high lighting efficiency. (author)