Luminescent Thermometry of (Y_1–xEr_x)₂O₃ Oxides

A fast and simple method for the synthesis of solid solutions based on erbium-doped yttrium oxide (Y_1–xEr_x)₂O₃ was developed. The crystal structures of the samples were determined by x-ray diffraction methods. The compounds exhibited greenish-yellow upconversion emission upon IR laser excitation (980 nm). An increase in the erbium concentration in (Y_1–xEr_x)₂O₃ caused a color change and a growth in the intensity of the upconversion luminescence. The maximum upconversion luminescence intensity was observed for the oxide with x = 0.05. A two-photon excitation mechanism was determined based on the dependence of the emission line intensities associated with ²H_11/2/⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions on the pumping power. The absolute and relative sensitivities were calculated from the temperature dependences of the ratio of emission lines corresponding to transitions from thermally coupled excited ²H_11/2 and ⁴S_3/2 levels and showed the promise of the oxides as materials for noncontact temperature sensing.