Nd3+ doped TZPN glasses for NIR operating single band ratiometric approach of contactless temperature readout

Abstract

The most commonly applied luminescent thermometry (LTs) approach, which are based on the luminescence intensity ratio (LIR), requires integration of the analyzed emission bands. This analysis is often cumbersome and technically challenging due to spectral overlap and vicinity of the two emission bands. These limitations can be overcome by a new, single emission band ratiometric (SBR) approach which involves excitation through thermally induced excited state absorption (ESA) and ground state absorption (GSA). What is more, the frequent problem of low intensity of one of the radiative transitions, which are analyzed in conventional luminescent thermometry, is overcome owing to the involving of the SBR approach. Due to the opposable behavior of the emission intensity with temperature changes upon these two excitation schemes, improved thermal sensitivity can be achieved. In this work, the suitability of Nd3+-doped oxyfluorotellurite (65-x)TeO2–20ZnF2–12PbO–3Nb2O5–xNd2O3 (x = 0.1, 1, 2, 5 and 10) glasses (TZPN) was analyzed for SBR-based luminescent thermometry. To excite Nd3+ ions, the 808 nm and 1060 nm wavelengths, which are related to GSA and ESA, respectively, were involved. In the biological temperature range the relative sensitivity reached SR = 2.95%/°C. The highest value of SR = 6.15%/°C was obtained at low temperature range for the 10%Nd3+:TZPN glass LT and decreased below 1%/°C only at temperatures above 200 °C.