Preparation and upconversion luminescence of YAG(Y3Al5O12): Yb3+, Ho3+ nanocrystals

Cubic YAG: Yb3+, Ho3+ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials. After calcining the precipitates at 800 °C, the resultant YAG: Yb3+, Ho3+ nanocrystals were nearly spheric and the particle size was about 40 nm. Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2 (5F4)→5I8, 5F5→5I8, and 5S2 (5F4)→5I7 transitions, respectively.