An upconversion luminescence and temperature sensor based on Yb³⁺/Er³⁺ co-doped GdSr₂AlO₅

GdSr₂AlO₅:Yb³⁺/Er³⁺ micro-particles were synthesized by a simple solid state method. The structure, morphology, size and upconversion luminescence features have been characterized. These results indicated that GdSr₂AlO₅ has a contracted tetragonal cell and has irregular block shaped particles with sizes of about 5 μm. During upconversion, green (²H_11/2, ⁴S_3/2 → ⁴I_15/2) (527 nm, 549 nm) and red (⁴F_9/2 → ⁴I_15/2) (665 nm) emissions had been observed, both of which occurred via a two-photon population process. In addition, green UC emission characteristics were studied, and it was found that its temperature ranged from 293 K to 473 K and the sensitivity was 0.0054 K^-1 at 473 K. This indicated that GdSr₂AlO₅:Yb³⁺/Er³⁺ micro-particles may have potential application in high temperature environments for safety signs.