Constructing new thermally coupled levels based on different emitting centers for high sensitive optical thermometer

Due to the competition between thermalization and non-radiative/radiative process, high-sensitive optical thermometer are designed based on two new thermally coupled levels (Bi3+/Eu3+, Tb3+/Eu3+). [Display omitted] •The New-TCLs are constructed based on different luminescent centers.•The steady-state equations confirm stronger thermalization process among New-TCLs.•The high absolute/relative temperature sensitivities are achieved simultaneously. In multi-emitting and thermochromic Bi3+-Tb3+-Eu3+ co-doped garnet type Ca3Sc2Si3O12 phosphor, new thermally coupled levels (New-TCLs) are firstly constructed based on 3P1(Bi3+)/5D0(Eu3+) and 5D4(Tb3+)/5D0(Eu3+). And the relative electron population of New-TCLs obeys similar Boltzmann type distribution rules owing to stronger thermalization process with the increase of temperature, which can be elaborated by steady-state rate equations. Hence, a novel self-calibrated non-invasion optical thermometer with high absolute/relative temperature sensitivities (0.094 K−1 at 498 K; 1.0% K−1 at 448 K) and good signal discrimination (Δλ ≈ 158 nm) can be achieved by taking advantage of fluorescence intensity ratio of such New-TCLs. This work exhibits a novel strategy to design high-performance optical thermometer in high temperature environment.