Upconversion Luminescence and Temperature Sensing of InNbO4:Er3+/Yb3+ Phosphors

Abstract

Er3+/Yb3+ co-doped InNbO4 phosphors were synthesized using solid state reaction method. Crystal structure was characterized using X-ray diffraction (XRD), which confirm all obtained phosphors had a monoclinic-wolframite structure and no impurity phase was introduced upon doping. Upon 980 nm excitation, upconversion (UC) emission from Er3+ ions was observed in green and red range. UC emission was obviously enhanced after co-doping Yb3+ ions and reached the maximum for 10 mol% Yb3+ ions. The relation between emission intensity and pump power was performed, revealing that the UC emission result from two-photon processes. Optical temperature sensing property was investigated by exploiting fluorescence intensity ratio (FIR) between 2H11/2 and 4S3/2 levels of Er3+ ions. Its maximum value of absolute sensitivity obtained was 0.0091 K-1, suggesting InNbO4:Er3+/Yb3+ phosphors show potential application in optical thermometry.