Real Time, Spectroscopic Monitoring of NaYF4 :Yb, Er Upconverting Nanocrystal Synthesis
Upconverting nanocrystals (UCNCs) have a wide variety of potential applications including security printing, solar energy, and bio-labels. One of the most efficient UCNCs known is ß-NaYF4 co-doped with Yb3+ and Er3+ ions. This type of UCNC has been synthesized using three main methods: hydrothermal, thermal decomposition and co-precipitation. Co-precipitation is the most convenient of these methods as it requires no special reaction apparatus as needed for the hydrothermal methods, nor does it require expensive and hazardous triflouroacetate precursors needed for the thermal decomposition method. Using real-time monitoring of the upconversion luminescence during UCNC synthesis, we were able to control the size and phase of the resulting nanoparticles, as well as elucidate key factors regarding the nucleation and growth mechanisms.