Non-contact thermometry with dual-activator luminescence of Bi3+/Sm3+: YNbO4 phosphor

Based on the luminescence of Bi3+, novel temperature sensing materials YNbO4:Bi3+ and YNbO4:Bi3+/Sm3+ were successfully synthesized by solid state reaction. The XRD patterns show that the synthesized materials have a pure phase of YNbO4. With the excitation of 314 nm, the YNbO4:Bi3+ material shows intense temperature-dependent luminescence in the range of 303 K–463 K. Based on the temperature-dependent luminescence of Bi3+ in YNbO4, the maximum relative sensitivity can be obtained at 434 K (1.72% K−1). Under the excitation of 406 nm, the YNbO4:Sm3+ material shows the characteristic emission peaks of Sm3+. In YNbO4:Bi3+/Sm3+ phosphor, the large overlap between the emission spectra of Bi3+ and the excitation spectra of Sm3+ leads to a significant energy transfer from Bi3+ to Sm3+. With the excitation of 314 nm, the emission spectra of YNbO4:Bi3+/Sm3+ material shows the characteristic peaks of Bi3+ and Sm3+. The luminescence intensity ratio of Sm3+ and Bi3+ shows a strong temperature dependence. Based on the luminescence intensity ratio, a large relative sensitivity is obtained at 455 K (1.57% K−1).