Luminescence properties and thermometric performance of Bi3+/Sm3+-codoped BaLa2ZnO5 phosphors

A zincate material, BaLa 2 ZnO 5 was successfully synthesized by a high-temperature solid-state method as a host for Bi 3+ . All the peaks in the X-ray diffraction patterns of the obtained material could be attributed to single phase BaLa 2 ZnO 5 . The BaLa 2 ZnO 5 host exhibited strong band-to-band absorption in the range of 200–290 nm. After the doping of Bi 3+ , the absorption band due to band-to-band transition decreased, and three new absorption bands appeared. Upon monitoring the luminescence of Bi 3+ at 407 nm, three excitation peaks were observed for BaLa 2 ZnO 5 : Bi 3+ , which could be attributed to A, C and metal-to-metal charge-transfer states by analyzing its excitation and absorption spectra . When codoped with Bi 3+ and Sm 3+ , BaLa 2 ZnO 5 : Bi 3+ /Sm 3+ exhibited strong energy transfer process from Bi 3+ to Sm 3+ . Variable-temperature emission spectra revealed that the luminescence intensity of Bi 3+ decreases rapidly with the increase in temperature, while that of Sm 3+ ions decreases slowly. The relative sensitivity ( S R ) values of the BaLa 2 ZnO 5 : Bi 3+ and BaLa 2 ZnO 5 : Bi 3+ /Sm 3+ phosphors to temperature (1.77 and 1.12% K −1 , respectively) were high and extremely stable in the range of 293–423 K. Therefore, the Bi 3+ -doped BaLa 2 ZnO 5 phosphor has great application potential for biological temperature sensing.