Synthesis and characterization of Nd3+-Yb3+ doped hydroxyapatite nanoparticles

The present work focuses on Nd-Yb co-doping of bare and Sr-substituted hydroxyapatite nanoparticles and their chemical, structural and optical characterization. An energy transfer between Nd and Yb centers was found, generating an efficient down-shifting process, where Nd absorbs at a low near-infrared wavelength and Yb emits at its characteristic F -> F transition. The energy transfer was found to be more efficient in Sr-substituted than in bare hydroxyapatite nanoparticles. The synthesized Nd-Yb doped hydroxyapatite nanoparticles can potentially find applications not only as diagnostic near-infrared down-shifting agent but also as nanosystem for near-infrared photoactivated treatment.