Temperature sensing of Sr₃Y₂Ge₃O₁₂:Bi³⁺,Sm³⁺ garnet phosphors with tunable sensitivity

In this study, a novel temperature-sensitive material, Sr₃Y₂Ge₃O₁₂:Bi³⁺,Sm³⁺ phosphor, was successfully synthesized by a solid-state reaction method. Under 376 nm light excitation, the as-prepared phosphor presents both blue emissions of Bi³⁺ and orange red emissions of Sm³⁺ due to energy transfer from Bi³⁺ to Sm³⁺. Owing to the significant difference in thermal quenching properties and the distinguishable emission between Bi³⁺ and Sm³⁺ ions, the temperature sensing performance of the prepared phosphor was evaluated by measuring the fluorescence intensity ratio (FIR) of Sm³⁺versus Bi³⁺. More importantly, for the first time, it was found that the absolute and relative sensitivities of Sr₃Y₂Ge₃O₁₂:Bi³⁺,Sm³⁺ could be tuned by changing the concentration of activators to determine the optimal temperature measurement conditions, which opened up the possibility of improving the performance of fluorescence temperature sensing materials.