Transparent Na5Gd9F32:Er3+ glass-ceramics: enhanced up-conversion luminescence and applications in optical temperature sensors

Abstract

New rare earth ion-doped nanocomposite materials, Na₅Gd₉F₃₂:Er³⁺ glass-ceramics, were fabricated via a traditional melt-quenching technique and subsequent heat treatments. Their microstructural and optical properties were systemically investigated by XRD, TEM, HRTEM techniques, absorption, up-conversion spectra and luminescence lifetime measurements. Excited by 980 nm laser, both glass and glass-ceramic samples presented characteristic red and green up-conversion emissions of Er³⁺ ions. After crystallization, Er³⁺ ions were incorporated into the precipitated Na₅Gd₉F₃₂ nanocrystals. Compared with precursor glasses, the red up-conversion intensity of glass-ceramics was enhanced by 1300 times, and the luminescence lifetime was also prolonged. The fluorescence intensity ratio technique was utilized to carry out the optical thermometry based on the green up-conversion luminescence behavior of Er³⁺ ions. Results manifest that Na₅Gd₉F₃₂:Er³⁺ glass-ceramics would have potential applications in optical temperature sensors with high sensitivity.