A novel wide temperature range and multi-mode optical thermometer based on bi-functional nanocrystal-doped glass ceramics

Abstract

Novel nanocomposite glass ceramics (GCs), containing bi-functional NaYF₄:Yb³⁺/RE³⁺(RE³⁺ = Er³⁺, Nd³⁺) and NaAlSiO₄:Cr³⁺ nanocrystals, were synthesized by a melt-quenching process and subsequent heat-treatment. XRD and TEM results indicate that two types of nanocrystals, NaYF₄ and NaAlSiO₄, disperse homogeneously in the glass matrix. Photoluminescence (PL) spectra and lifetime measurements demonstrate that RE³⁺ and Cr³⁺ ions selectively enter into the precipitated NaYF₄ and NaAlSiO₄ nanocrystals, respectively, after crystallization, which restrains the potential energy transfer (ET) between the rare earth (RE) and transition metal (TM) ions. Significantly, there are three modes to carry out the optical thermometry based on the fluorescence intensity ratio (FIR) from two thermally coupled levels of Nd³⁺, the FIR from the Cr–Nd non-thermally coupled system and the fluorescence lifetime of Cr³⁺. Compared to standard temperature sensors based on a single mode technique, the Yb³⁺/Nd³⁺/Cr³⁺ codoped oxyfluoride GCs, with excellent sensitivity and high precision, open up a new path in the optical thermometry field.