Dual-mode optical thermometry based on intervalence charge transfer excitations in Tb³⁺/Pr³⁺ co-doped CaNb₂O₆ phosphors

Self-calibrated temperature measurements combined with luminescence intensity ratio (LIR) and luminescence lifetime are more accurate. A dual-mode self-calibration optical thermometer was designed based on CaNb2O6: Tb3+/Pr3+ phosphor. The obtained sample has excellent sensitivity, with the maximum values of absolute sensitivity (S-a) and relative sensitivity (S-r) being 0.69 K-1 at 612 K and 2.50% K-1 at 532 K for LIR mode, and 0.0059 K-1 at 475 K and 2.62% K-1 at 535 K for luminescence lifetime mode, respectively. These results indicate that CaNb2O6: Tb3+/Pr3+ phosphor has valuable potential application for self-calibration optical temperature measurement.