Synergistic luminescent thermometer using co-doped CaGdSbO:Mn/(Eu or Sm) phosphors.

Luminescent thermometers provide a non-contact method of probing temperature with high sensitivity and response speed at the nanoscale. Synergistic photoluminescence from different activators can realize high sensitivity for luminescent thermometers by finely selecting ions with specific crystallographic sites. Herein, the more temperature-sensitive Mn and the less-sensitive Eu (or Sm) activators are co-doped into a CaGdSbO matrix to form an effective thermometer, where Mn and Eu (or Sm) ions occupy the Sb and Gd sites, respectively. The co-doping of Eu ions or Sm ions leads to lattice expansion of CaGdSbO matrix and a tuned narrow emission from deep-red to orangish-red. According to the ratio of luminescence intensity, the maximal and values are 0.19 K (347 K) and 1.38% K (420 K) for CaGdSbO:Mn/Eu probe and 0.26 K (363 K) and 1.55% K (430 K) for CaGdSbO:Mn/Sm probe thermometers, respectively. In addition, thermometers based on Mn emission lifetimes can provide the highest relative sensitivity of 1.47% K at 425 K. Thus, the highly-temperature-sensitive CaGdSbO:Mn/(Eu or Sm) phosphor is a promising candidate for practical luminescence thermometers.