Efficient upconversion and downshifting luminescence of CaIn2O4: Yb3+/Tm3+/RE3+ (RE=Er/Ho) phosphor: Temperature sensing performance in the visible and near-infrared range

In this paper, the upconversion(UC) and downshifting(DS) luminescence and thermal sensing performances of the CaIn2O4: RE3+/Tm3+/Yb3+(RE=Er, Ho) phosphors are investigated in detail. The bright UC emission bands from 450 to 900 nm and the DS luminescence bands from 1000 to 1700 nm are obtained under 980 nm excitation. The typical near infrared(NIR) emisson band(∼1550 nm) of Er3+ ions and the NIR emission band(∼1200 nm) of Ho3+ ions are gained. The temperature sensing features of CaIn2O4: RE3+/Tm3+/Yb3+ (RE=Er, Ho) phosphors are investigated with the luminescence intensity ratio (LIR) technique. The results indicate that the maximum relative sensitivity (SRmax) of CaIn2O4: Er3+/Tm3+/Yb3+ sample reaches 1.576% K-1 at 313 K, and the SRmax of CaIn2O4: Ho3+/Tm3+/Yb3+ sample reaches 0.797% K-1 at 353 K in UC range. In addition, the higher temperature measuring sensitivities have been obtained in NIR-II region with the DS luminescence of CaIn2O4: RE3+/Tm3+/Yb3+ phosphors. The above results indicate that the CaIn2O4: RE3+/Tm3+/Yb3+ phosphors show bright emission bands in visible and NIR-II, and higher sensitivity for temperature measurement. The CaIn2O4: RE3+/Tm3+/Yb3+ phosphors present great application in optical temperature measurement.