Contactless Visible Luminescence Thermometry Based on β-Phase Zinc Silicate Confined in Silica Glass Matrix

Abstract

Nanophosphors zinc silicate β-phase in glass matrix with adequate manganese concentration were synthesized by a sol–gel method in three steps. In the first one, a sol-gel process was used for the synthesis of ZnO:Mn nanopowder. In the second one, the elaborated nanopowder was incorporated in silica aerogel monolith using supercritical conditions of ethanol and in the third step, a simple solid-solid reaction under natural atmosphere for 2 h at 1500 °C was performed. The obtained samples are composed by grains with an average size of about 70 nm in a triclinic phase dispersed in silica host matrix. This protocol leads to a very stable 15 at.% Mn doped zinc silicate β-phase at high temperature. The analysis of the obtained nanophosphor material showed a strong broad yellow emission at 584 nm attributed to 4T1(4G) to 6A1(6S) transition. The intensity and the time decay of this yellow emission depend on the measurement temperature. In fact, the decreases rate of the PL intensity is of 12.7% and the rate of lifetime change is of about 2.7%. These results are considered as promising values compared to those obtained until now. These two potential behaviours make it possible to predict the use of this material in various technological applications, particularly in contactless luminescence thermometry.