Luminescence properties of Sr2Ga2GeO7:Bi3+ phosphors and temperature sensing characteristics of co-doped Sm3+

As one of the fundamental physical quantities, temperature is extremely important in various fields. In order to study the temperature sensing characteristics of dual-emitting center phosphors, Bi³⁺-doped and Bi³⁺/Sm³⁺-doped Sr₂Ga₂GeO₇ phosphors were synthesized by high-temperature solid-phase method. Under 312 nm excitation, the Sr₂Ga₂GeO₇:Bi³⁺ phosphor exhibits a blue broadband emission corresponding to the ³P₁ → ¹S₀ transition of Bi³⁺ ions. By testing the temperature change spectrum of phosphors, it was found that Bi³⁺ exhibited strong thermal sensitivity. However, due to the fact that single ion doped phosphors are easily affected by other factors when applied to the field of temperature sensing, based on the thermal sensitivity of Bi³⁺, Sm³⁺ with low temperature sensitivity was selected as the co-doped ion, and it was found that the two ions had different thermal quenching characteristics when the temperature change spectrum was tested. Using the temperature detection method based on the fluorescence intensity ratio (FIR) of the dual emission centers, it was found that the best absolute sensitivity S_a was 3.125% K⁻¹ and the maximum relative sensitivity S_r was 1.275% K⁻¹ in the range of 303–423 K. These results show that Sr₂Ga₂GeO₇:Bi³⁺/Sm³⁺ phosphors have broad application prospects in the field of optical temperature sensing.