[en] Full text: Rare earth (RE³⁺)-doped Y₂O₃ have interesting optical properties due to the capable of converting photons into higher and/or lower energy from excitation, ultraviolet (UV) or infrared (IR) regions, respectively. In this sense, materials which can convert absorbed energy in the UV region and IR after double and simultaneous excitation, originating emission in visible region, Y₂O₃:Er³⁺/Yb³⁺/Eu³⁺ were synthesized via precursor citrate. The materials were heat-treated at 900, 1000 and 1100 °C for 4 h. By XRD it was observed reflections with peaks related to the Y₂O₃ cubic phase. There are no additional diffraction peaks assigned to the impurities, confirming the successfully preparing of the Y₂O₃:Er³⁺/Yb3⁺/Eu³⁺. Based on the most intense (222) reflection (2θ: 29.22°) the average crystallite sizes were estimated using Scherrer’s formula. The annealing temperature increases the crystallite size. From the Williamson-Hall”s equation was found to decrease the microdestrains with increasing heat-treatment temperature. Under excitation at 980 nm there are emission bands in the range between 510 – 590 nm and 630 –700 nm attributed to f-f transitions of Er³⁺, assigned to the upconversion process. The lifetime measurements of the excited state of Eu³⁺ in the triply-doped system varied between 1.54 and 1.57 ms. The SEM images present material with morphology spherical micrometric particle, not being detrimental to the photoluminescent properties of the material. Therefore, Y₂O₃:Er³⁺/Yb³⁺/Eu³⁺ becomes a very promising material, with features suitable for possible electronic applications, to be effective in absorbing UV and IR energy simultaneously converting it to visible. [1] Kumar, V., Singh, S., Chawla, S. Superlattices and Microstructures 79 86–95 (2015). [2] Mayrinck, C., Ferrari, J.L., et.al. Ceramics International. 41 1189–1195 (2015). (author)