Implementing Defects for Ratiometric Luminescence Thermometry.

In luminescence thermometry enabling temperature reading at a distance, an important challenge is to propose new solutions that open measuring and material possibilities. Responding to these needs, in the nanocrystalline phosphors of yttrium oxide YO and lutetium oxide LuO, temperature-dependent emission of trivalent terbium Tb dopant ions was recorded at the excitation wavelength 266 nm. The signal of intensity decreasing with temperature was monitored in the range corresponding to the D → F emission band. On the other hand, defect emission intensity obtained upon 543 nm excitation increases significantly at elevated temperatures. The opposite thermal monotonicity of these two signals in the same spectral range enabled development of the single band ratiometric luminescent thermometer of as high a relative sensitivity as 4.92%/°C and 2%/°C for YO:Tb and LuO:Tb nanocrystals, respectively. This study presents the first report on luminescent thermometry using defect emission in inorganic phosphors.