Enhancing the luminescence of Eu³⁺/Eu²⁺ ion‐doped hydroxyapatite by fluoridation and thermal annealing

Abstract

This paper reports a novel way for the synthesis of a europium (Eu)-doped fluor-hydroxyapatite (FHA) nanostructure to control the luminescence of hydroxyapatite nanophosphor, particularly, by applying optimum fluorine concentrations, annealed temperatures and pH value. The Eu-doped FHA was made using the co-precipitation method followed by thermal annealing in air and reducing in a H₂ atmosphere to control the visible light emission center of the nanophosphors. The intensities of the OH^- group decreased with the increasing fluorine concentrations. For the specimens annealed in air, the light emission center of the nanophosphor was 615 nm, which was emission from the Eu³⁺ ion. However, when they were annealed in reduced gas (Ar + 5% H₂ ), a 448 nm light emission center from the Eu²⁺ ion of FHA was observed. The presence of fluorine in Eu-doped FHA resulted in a significant enhancement of nanophosphor luminescence, which has potential application in light emission and nanomedicine.