Optical temperature sensor based on Sm3+ emissions in a fluorotellurite glass

The temperature dependence of the visible luminescence of a fluorotellurite glass doped with 2.5 mol% of Sm3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the levels from (4)G(5/2) to H-6(J) (J = 5/2, 7/2, 9/2, 11/2) transitions were measured in a temperature range from 300 up to 650 K. The changes in the emission profiles were calibrated by means of the fluorescence intensity ratio technique. The maximum temperature value obtained for the thermal sensibility was 640 K which is in the range of other matrix glasses. The calibration curve was done by fitting the intensity ratio between the different peak emissions. Finally, a schematic design for the Sm3+ optical temperature sensor is presented and the calculations of the sensitivity have been obtained. In addition, the fluorotellurite glass has been structural characterized by SEM-EDX, Raman Spectroscopy and XRD in order to infer the local environment of Sm3+ ions. Furthermore, the Judd-Ofelt parameters have been calculated from the absorption spectra and derived branching ratios and transition probabilities have been computed as well.