Temperature sensing characteristics of Bi3+/Eu3+ co-activated SrGa2B2O7: Phosphor for dual-mode optical thermometry

SrGa 2 B 2 O 7 : Bi 3+ , Eu 3+ phosphors were synthesized through high temperature solid-state method successfully. The structure, luminescent characteristics and temperature sensing properties of the phosphors are studied. Under the excitation at 363 nm, several bands of Sr 0.935 Ga 2 B 2 O 7 : 0.015Bi 3+ , 0.05Eu 3+ phosphor appeared in the blue and red regions and the emission peaks of Bi 3+ and Eu 3+ ions can be well separated. For the SrGa 2 B 2 O 7 : Bi 3+ /Eu 3+ samples, the maximum absolute temperature sensitivity ( S a ) reaches about 0.181 K −1 at 473 K and the relative temperature sensitivity ( S r ) of that is up to 1.549% K −1 at 423 K. The results originated from the characteristic transitions of Bi 3+ ( 3 P 1 → 1 S 0 ) and Eu 3+ ( 5 D 0 → 7 F 1 , 5 D 0 → 7 F 2 , 5 D 0 → 7 F 4 ) ions are based on the fluorescence intensity ratio (FIR). Furthermore, the maximum of S a is 4.66 K −1 and the maximum of S r is 0.538% K −1 at 293 K based on the fluorescence lifetime temperature measurement method. All these investigations indicate that the SrGa 2 B 2 O 7 : Bi 3+ /Eu 3+ phosphors can be a promising optical thermometric material in the field of temperature sensing.