Upconversion nanocrystals (NCs) of NaY F4: Yb,Ln (Ln=Er and Tm) in cubic and hexagonal phases were synthesized in oleic acid (OA) and/or trioctylphosphine (TOP) with octadecene (ODE) via a thermolysis method. Only cubic-phase NCs were obtained in OA/ODE and TOP/ODE solvents; on the other hand, the hexagonal-phase NCs resulted in OA/TOP/ODE. The phase transition from cubic to hexagonal was induced by a ligand formed between oleate and TOP at high temperature. Moreover, the addition of OA/TOP in high and low ratios produced hexagonal nanoparticles and nanorods, respectively. The formed NCs were coated by Si O2 using microemulsion reactions for further biofunctionalization in biological applications.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)