Synthesis and characterization of terbium-doped fluorine-substituted hydroxyapatite (HAp-F-Tb)

Abstract

This work investigates the luminescent properties of fluorapatite doped with Tb³⁺ ions (HAp–F:Tb) to determine the nature of the luminescent centers and the excitation features. Biohydroxyapatite was obtained from cattle bone raw material by rapid pyrolysis followed by annealing at 750^◦C ; doping was carried out by the solvation–precipitation method. The samples were characterized by X-ray diffraction analysis, IR spectroscopy, and photoluminescence spectroscopy in the 200–700 nm range. It was established that the main active center is Tb³⁺ : intense emission bands corresponding to the 5D4 → 7F5 , 5D4 → 7F4 , and 5D4 → 7F3 transitions were recorded in the 490–620 nm region. The maximum intensity was observed under excitation at 220–260 nm and 355–377 nm, indicating direct excitation of Tb³⁺ and/or energy transfer from the matrix and defect levels. The obtained results demonstrate the promise of HAp–F-Tb as a luminescent material and the possibility of targeted modification of its optical properties through doping with rare-earth ions