The Enhancement of Upconversion Luminescence of Gd2O3:Yb,Er Nanoparticles by Ca2+ Codoping for Temperature Sensing at Room and High Temperatures

Abstract

We prepared a series of Gd2O3:Yb,Er,Ca (3/1/[Formula: see text][Formula: see text]mol.%, [Formula: see text] represents the nominal concentration of Ca element including 0, 2, 3, 4, 5, 7, 10) upconversion nanoparticles (UCNPs) with regular morphology via a wet-chemical route. We observed a simultaneous enhancement of upconversion luminescence (UCL) emission of Gd2O3:Yb,Er after Ca[Formula: see text] ions were doped. When the doping level of Ca[Formula: see text] reaches its optimal concentrate at 5[Formula: see text]mol.%, the red and green emissions increased by 6.3 and 11 times, respectively. The potential application of Gd2O3:Yb,Er,Ca material as a noninvasion optical thermometry based on FIR technique was investigated. The sensing of temperature at both high and room temperatures was realized by choosing different parameters. The absolute temperature sensitivity ([Formula: see text]) of Gd2O3:Yb,Er nanoparticles at 293[Formula: see text]K reached 0.0875[Formula: see text]K[Formula: see text], whereas Gd2O3:Yb,Er, 5[Formula: see text]mol.%Ca was chosen as sensor of high temperature due to its considerable Sa of 0.0060[Formula: see text]K[Formula: see text] at 573[Formula: see text]K. The resultant UCNPs provided a new way for sensitive thermal detection at various target temperatures.