Tailoring up-conversion luminescence for optical thermometry in K+/Er3+ co-doped oxyfluoride glass ceramics

In this work, a strategy of K⁺ ions doping was visited with the aim of enhancing up-conversion luminescence (UCL) and sensitivity for optical thermometer of β-PbF₂:Er³⁺ glass ceramics (GCs). Compared to K⁺-free β-PbF₂:Er³⁺ GCs, the UCL intensity of green (521, 552 nm), red (668 nm), NIR (825 nm) emissions and absolute sensitivity (S_a) for optical thermometer of the β-PbF₂:Er³⁺ GCs co-doped with 10 mol% K⁺ ions were increased by 176, 82, 18 and 1.5 times, respectively. Charge compensation and the distortion of the local symmetry around the Er³⁺ ions, when the K⁺ ions were introduced, were confirmed to be the origin of the enhancement. The results show that K⁺ ions simultaneous co-doping of β-PbF₂:Er³⁺ glass ceramics (GCs) very effective way to integrate this material for advanced photonic applications.