Anti-thermal quenching of YNbO4:Eu3+/Er3+ for multi-functional applications

At present, many researchers are focusing on Er 3+ ions doped thermally enhanced upconversion luminescent materials. However, the anti-thermal-quenching downshifting emissions of the activator in a phosphor have not yet been studied in sufficient depth. Herein, Eu 3+ /Er 3+ co-doped YNbO 4 phosphors prepared are explored for selectively enhanced red emission (Eu 3+ : 5 D 0 → 7 F 2 and 5 D 0 → 7 F 4 ) due to the defect-mediated thermal enhancement of emission by thermal compensation mechanism. Moreover, the coexistence of intrinsic luminescence centers ([NbO 4 ] 3- ), Er 3+ and Eu 3+ ions enables tunable emission color shifting from red to green and red under excitation at 250 nm, 379 nm, and 395 nm, respectively. This multi-wavelength excitation approach ensures the material's application in anti-counterfeiting. Based on the different thermal response of [NbO 4 ] 3- and Eu 3+ ions, an optical temperature sensing is achieved. The relative sensitivity of YNbO 4 :2%Eu 3+ /8%Er 3+ sample could reach 2.466% K −1 at 323 K. The above results indicate that the sample is a promising candidate for multi-functional applications.