Temperature sensitivity based on Er³⁺ fluorescence fluctuation in Gd₂Ti₂O₇: Er³⁺-Yb³⁺ porous nanofibers

(Gd_1−x−yEr_xYb_y)₂Ti₂O₇ (GTOEY) fibers were synthesized by electrospinning technique and heat-treatment processes, in which nano-scale fibers vested with homogeneous porous morphology, high crystallinity and elevated temperature heat-resistance. Under 977 nm laser excitation, GTOEY nanofibers exhibit effective frequency upconversion (UC) fluorescence, therefore, the violent green and dimmed red UC emissions are identified as two-photon absorption processes, attributing to ²H_11/2/⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 radiation transitions of Er³⁺, respectively. Moreover, the temperature sensitivity based on UC emission fluctuation of Er³⁺ over a wide temperature range of 303–633 K has been derived. Thereby, having used a 980 nm laser and achieved green UC luminescence of GTOEY fibers centered at 525 and 545 nm, the maximum absolute and relative sensitivity values are obtained to be 0.382% K⁻¹ and 1.12% K⁻¹, respectively. These significant results demonstrate that the GTOEY nanofibers with distinct porous structure and admirable photothermal sensitivities can be regarded as a promising temperature sensing material used for overheating alarm and safety protection equipment.