Low temperature sensitivity of upconversion emission in Y2O3:Yb,Tm and Y2O3:Yb,Ho powders

Abstract

In recent years trivalent rare earth doped materials have received significant attention for optical temperature sensors. In these materials ratio of fluorescence emissions from different energy levels exhibit strong temperature dependence. Synthesized Y2O3:Yb,Tm and Y2O3:Yb,Ho powders were obtained via spray pyrolysis at 900 °C using 0.1 M nitrate precursor. Using laser excitation at 978 nm we investigated upconversion emission of these powders and recorded characteristic transitions: 1D2→3F4, 1G4→3H6, 1G4→3F4, 3F2,3→3H6, 1D2→3F3, 1G4→3H6, 3H4→3H6 for Tm3+ and 5F4, 5S2→5I8, 5F5→5I8, 5F4, 5S2→5I7 for Ho3+. Further we analyzed temperature dependence of fluorescence intensity ratios of different Stark components in the range from 10K to 300K. Several of these ratios exhibit significant temperature sensitivity, with the largest value of 0.08 K-1.