Microemulsion process synthesis of lanthanide-doped hydroxyapatite nanoparticles under hydrothermal treatment

Luminescent lanthanide-doped hydroxyapatites (Eu:HA and Eu–La:HA) were successfully fabricated via the (cyclohexane/polyxyethylene (TX-100)/n-butanol/water solution) microemulsion mediated hydrothermal process. The structure, morphology, and optical properties were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) spectra, respectively. The XRD results reveal that the obtained Eu:HA and Eu–La:HA nanoparticles also show the characteristic peaks of hydroxyapatite in a hexagonal lattice structure. It is observed that the as-prepared luminescent samples exhibit sphere-like morphology with well dispersed and non-aggregated size distribution. Upon excitation by UV radiation, the Eu:HA samples demonstrate the characteristic 5D0–7F1–4 emission lines of Eu3+. Moreover, the PL emission intensity of Eu3+ can be tuned by importing La3+ ions into the structure of europium-doped hydroxyapatite nanocrystals within some Eu3+:La3+ doping contents, and altering the doping concentration of Eu3+.