Synthesis and spectroscopic characterization of Ce0.90Eu0.07Sm0.03O2 phosphors for luminescence-based thermometry applications

Uniform nanoparticles of Eu3+/Sm3+ co-doped CeO2 phosphors were prepared through a hydrothermal method assisted with ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The pH values of the precursor solution were varied to obtain uniform morphology of Eu3+/Sm3+ co-doped CeO2 phosphors and the most uniform morphology of Eu3+/Sm3+ co-doped CeO2 phosphors was obtained at pH 10. The maximum photoluminescence efficiency was observed at 7 mol% of Eu3+ and 3 mol% of Sm3+ ions of Eu3+/Sm3+ co-doped CeO2 phosphors. The emission spectra for Ce0.9Eu0.07Sm0.03O2-δ phosphors consisted of a host (450–560 nm) and dopant (570–700 nm) emissions. The ratio between the intensity of host and dopant emissions showed strong temperature dependence and the variation of intensity ratio was utilized for temperature sensing. Within the studied temperature range (298–523 K), the value of absolute sensor sensitivity for Ce0.9Eu0.07Sm0.03O2-δ phosphors was elevated from 0.0026 to 0.025 K−1. The maximum relative sensor sensitivity of Ce0.9Eu0.07Sm0.03O2-δ phosphors was 2.8% K−1 at 373 K. The high sensor sensitivity and uniform morphology of Ce0.9Eu0.07Sm0.03O2-δ phosphors could be used for luminescence-based thermometry applications.