Thermometer of stable SrAl2Si2O8: Ce3+, Tb3+ based on synergistic luminescence

Non-contact optical thermometer appears to be excellent alternative for traditional contact thermometer. Fluorescence intensity ratio (FIR) via thermally-coupled energy levels (TCELs) of one certain lanthanide ion is most adopted method to measure temperature. However, there is an inevitable dilemma in this method that large energy gap (EG) of TCELs is required for gaining highly relative sensitivity (S-r) while small EG is needed for achieving highly absolute sensitivity (S-a). Meanwhile, the EG of TCELs cannot exceed a certain value for achieving thermal equilibrium. To solve this issue, in this work, a new strategy based on synergistic luminescence from Ce3+ and Tb3+ codoped in SrAl2Si2O8 (SASO) has proposed for obtaining highly sensitivity over a wide temperature range. FIR of Ce3+ to Tb3+ in this self-referencing and dual-emitting phosphor shows remarkable contrary temperature dependence and has well fitted linear relationship, owing to resonance energy transfer (ET) from Ce3+ to Tb3+. Meanwhile, the emitting color of the phosphor is gradually shifted from blue to green with temperature, which means it is also potential candidate as colorimetric luminescent thermometer. These results could provide useful inspiration for designing stable and highly sensitive optical thermometer based on ET induced by synergistic luminescence.