Preparation of europium(III)-doped hydroxyapatite nanocrystals in the presence of cationic surfactant

Europium (III) (Eu^3 +)-doped hydroxyapatite (HAp) nanocrystals were synthesized in the presence of a cetyltrimethylammonium bromide (CTAB) to investigate the states of Eu^3 + ions in the structure. The HAp structure was preserved with the doping as well as the CTAB existence, and the carbonate ions were included in the structure. The uniform shapes and mono-dispersion of the nanocrystals were observed by adding CTAB. The transitions of ⁵D₀–⁷F₁ and ⁵D₀–⁷F₂ in the photoluminescence spectra indicated the presence of the Eu^3 + in an environment of a low symmetry before the calcination. The Eu^3 + was effectively positioned in the Ca sites in the HAp structure. The CTAB addition would prevent the Eu^3 + ions from aggregating each other, inducing the effective substitution and resultantly showing the efficient luminescence. Therefore, the interactions between the Eu^3 + ions and HAp structure were successfully enhanced in the presence of CTAB.