Peculiarities of the structural and optical properties of rare-earth-doped phosphate glasses for temperature sensing applications

Eu, Er, Yb-Er, and Dy-doped phosphate glasses were prepared by a wet-route processing of chemical precursors followed by melt-quenching and annealing. XRD measurements highlighted the amorphous nature of the investigated glasses. UV-Vis absorption spectra revealed peaks specific to f-f electronic transitions of the doping ions whereas FTIR and Raman spectroscopy proved the vitreous network forming role of phosphorous pentoxide. Luminescence spectra in the Vis domain, at RT, showed emission bands characteristic to the ion transitions from the excited states to the ground state. The luminescence spectra collected in the 25-160°C range exhibited a decrease of the emission intensity with temperature rise. In the case of Eu and Dy-doped glasses a relatively small decrease of the emission intensity with temperature is observed by comparison with Er and, respectively, Yb-Er-doped glass where a significant change of the emission intensity is noticed, which recommends the latter as promising candidate for sensing devices.