EuF₃/Ga₂O₃ Dual-Phase Nanostructural Glass Ceramics with Eu²⁺/Cr³⁺ Dual-Activator Luminescence for Self-Calibrated Optical Thermometry

Abstract

To circumvent the requirement of small energy gap between thermally coupled levels of lanthanide probes in optical thermometry, a strategy using dual-activator fluorescence intensity ratio as temperature signal in dual-phase nanostructural glass ceramics was reported. Specifically, oxyfluoride glass with specially designed composition of SiO2–Al2O3–LiF–EuF3–Ga2O3–Cr2O3 was fabricated, and subsequently glass crystallization was used to induce homogeneous precipitation of hexagonal EuF3 and cubic Ga2O3 nanocrystals among the glass matrix. Impressively, Eu2+ activators were produced after glass crystallization in an air atmosphere, and the Cr3+ emitting center was evidenced to incorporate into Ga2O3 crystalline lattice. As a result, temperature determination with high sensitivity of 0.8% K–1, large energy gap of 8500 cm–1, and superior thermal stability were realized by taking advantage of the fluorescence intensity ratio between Eu2+ and Cr3+ as detecting parameter, which exhibited a linear dependence on temperature. We believe that this preliminary investigation will provide a practical approach for developing a high-performance self-calibrated optical thermometer.