Ce³⁺/Tb³⁺ co-doped β-NaYF₄ dual-emitting phosphors for self-referencing optical thermometry

Traditional FIR (fluorescence intensity ratio)-based optical thermometers, requiring narrow energy gap between two thermally coupled states (TCS) of single rare-earth ion, have inherent drawbacks including low signal discriminability and large measuring error. To overcome the intrinsic limitation, a new thermometry strategy involving the usage of dual-emitting activators with diverse temperature-dependent emission behaviours has been proposed. Impressively, β-NaYF₄:Ce³⁺/Tb³⁺ phosphor exhibits good temperature sensing performance, excellent signal discriminability and superior thermal stability by using the linearly temperature-dependent FIR between Ce³⁺ and Tb³⁺ as detecting parameter. Hopefully, the developed dual-emitting sample could have a promising application in self-calibrated luminescent thermometry and this strategy provides a reference for developing high-performance optical thermometers.