Low-temperature effects on up-conversion emission of Er3+/Yb3+-co-doped Y2O3

Over the past few years, rare-earth-ion-doped materials have attracted a great deal of interest due to their potential application as optical temperature sensors. The luminescence properties of these materials are sensitive and change with temperature. Here, we have investigated the properties of yttrium oxide powder co-doped with Yb3+ and Er3+, synthesized through the spray pyrolysis method at 900 degrees C and additionally thermally treated at 1100 degrees C for 24 h. The structural and morphological characterizations are carried out through x-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The obtained particles are spherical in shape and have cubic bixbyite structure with the space group Ia-3. Photoluminescent measurements (PL) are recorded in the temperature range from 10 to 300 K using 978 nm radiation. Emission spectra are assigned to the following trivalent erbium f-f electronic transitions: H-2(9/2) -> I-4(15/2) (blue: 407-420 nm), (H-2(11/2), S-4(3/2)) -> I-4(15/2) (green: 510-590 nm) and F-4(9/2) -> I-4(15/2) (red: 640-720 nm). The fluorescent intensity ratios of the blue, green and red areas under emission bands show significant temperature sensitivity, with the largest value of 2.3 K-1.