Upconversion from fluorophosphate glasses prepared with NaYF(4):Er(3+),Yb(3+) nanocrystals

The direct doping method was applied to fabricate upconverter fluorophosphate glasses in the system (90NaPO(3)-(10-x)Na(2)O-xNaF) (mol%) by adding NaYF(4):Er(3+),Yb(3+) nanocrystals. An increase in the network connectivity, a red shift of the optical band gap and a decrease in the thermal properties occur when Na(2)O is progressively replaced by NaF. To ensure the survival and the dispersion of the nanocrystals in the glasses with x = 0 and 10, three doping temperatures (T(doping)) (525, 550 and 575 °C) at which the nanocrystals were added in the glass melt after melting and 2 dwell times (3 and 5 minutes) before quenching the glasses were tested. Using 5 wt% of the NaYF(4):Er(3+),Yb(3+) nanocrystals, green emission from the NaYF(4):Er(3+),Yb(3+) nanocrystals-containing glasses was observed using a 980 nm pumping, the intensity of which depends on the glass composition and on the direct doping parameters (T(doping) and dwell time). The strongest upconversion was obtained from the glass with x = 10 prepared using a T(doping) of 550 °C and a 3 min dwell time. Finally, we showed that the upconversion, the emission at 1.5 μm and of the transmittance spectra of the nanocrystals-containing glasses could be measured to verify if decomposition of the nanocrystals occurred in glass melts during the preparation of the glasses.