Luminescence thermometry below room temperature via up-conversion emission of Y_2O_3:Yb~(3+),Er~(3+) nanophosphors

摘要

This study explores potential of Er~(3+)-Yb~(3+) doped phosphors for up-conversion luminescence thermometry in the temperature range from 10 K to 300 K. Yttrium oxide nanopowder doped with trivalent ytterbium and erbium ions (Y_(1.97)Yb_(0.02)Er_(0.01)O_3) was prepared by hydrothermal synthesis as an example. The intensity ratios of up-conversion emissions from thermally coupled ~2H_(11/2) and ~4S_(3/2) levels of Er~(3+) show strong temperature dependence (in the range 150K-300K) with much higher relative sensitivity than those reported for thermometry above room temperature with Er~(3+)-Yb~(3+) based up-conversion materials. The maximal value of relative sensitivity is 5.28%K~(-1) at 150 K, with temperature resolution ranging from 0.81 K to 0.06 K. In addition, the intensity ratios of emission from thermally non-coupled Er~(3+) levels (~2H_(9/2) and ~4F_(9/2)) and from ~4S_(3/2) also show temperature dependence that can be approximated with an exponential function. With these up-conversion emission ratios, it is possible measure temperature in the range of 10 K to 300 K with excellent sensitivity and resolution.