LAUSR

Abstract The Er 3+ , Yb 3+ co-doped cerium(IV) oxide powders were synthesized by inverted co-precipitation method and calcined at 1000 °C and 1500 °C, respectively. The influence of dopant concentration and calcination temperatures on the luminescence efficiency under excitation with 980 nm laser light was systematically investigated. The maximum intensity of upconversion luminescence (UCL) was observed for CeO 2 :Yb 5 Er 2 calcined at 1000 °C and CeO 2 :Yb 2 Er 0.5 calcined at 1500 °C, respectively. Luminescence intensity ratios (LIR) in two Stark sub-levels in green and red regions were used for the determination of temperature sensitivity of CeO 2 :Yb 2 Er 0.5 sintered at 1500 °C for 1 h. The sensitivity increased for the investigated coupled sub-levels from 0.001 K -1 to 0.003 K -1 (green region) and from 0.0011 K -1 to 0.0025 K -1 (red region). Thus Er 3+ /Yb 3+ doped CeO 2 phosphors with high temperature stability seem to be promising materials for low temperature optical measurement under vacuum.