Upconversion luminescence of YbVO4: Er3+/K+ for multimode optical temperature measurement

The effect of K + ions doping on YbVO 4 : Er 3+ was studied under the excitation of a 980 nm laser. The intensity of multiple emission peaks increased was found to be enhanced at 527 nm ( 2 H 11/2 → 4 I 15/2 ), 553 nm ( 4 S 3/2 → 4 I 15/2 ), 654 nm ( 4 F 9/2 → 4 I 15/2 ), and 803 nm ( 4 I 9/2 → 4 I 15/2 ), including green, red, and near-infrared spectra. The optimal doping concentration was 0.1 K + ions in YbVO 4 : 0.02Er 3+ . The enhancement of upconversion luminescence is attributed to the presence of defect bands, which facilitate the absorption of excited photons and enable effective energy transfer from abundant electrons to Yb 3+ ( 2 F 5/2 ) and Er 3+ ( 4 I 11/2 ) ions. YbVO 4 : Er 3+ /K + was utilized in a three-mode temperature sensor, employing TCEL modes of 2 H 11/2 / 4 S 3/2 , NTCEL modes of 2 H 11/2 / 4 F 9/2 and 4 S 3/2 / 4 F 9/2 , and single luminescence intensity at I 803 . It exhibited maximum relative sensitivities of 1.36 % (298 K), 0.77 % (398 K), 0.44 % (298 K), and 1.69 % (623 K), respectively, highlighting its potential in high-precision optical temperature sensing applications.