Self-referenced luminescence thermometry with Sm3+ doped TiO2 nanoparticles

The performance of Sm3+ doped TiO2 nanoparticles for luminescence temperature sensing was tested over a temperature range from room to 110 degrees C. The Sm3+ ions were incorporated into TiO2 nanocrystals using hydrolytic sol-gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and x-ray diffraction measurements. Luminescence emission spectra of Sm3+ doped TiO2 nanoparticles consists of two distinct spectral regions: the high energy region associated with the trap emission of the TiO2 host, and the low energy region with well-resolved emission peaks of the Sm3+ ions. The ratio between Sm3+ emission and TiO2 trap emission shows strong temperature dependence, and is tested for temperature sensing. The relative sensor sensitivity was found to be higher than 1% degrees C-1 over given temperature range with the maximum value of 10.54% degrees C-1 at 57.5 degrees C. Lifetime data derived from the Sm3+ emission decay revealed that time-resolved measurements provide comparable quality of temperature sensing as corresponding ratiometric measurements, with a maximum relative sensitivity of 10.14% degrees C-1 at 66.5 degrees C.