Realization of sensible peak shift thermometry from multiple site occupied Eu 3+ ions in magnetically frustrated SrGd 2 O 4

Magnetically frustrated lattices even at low temperatures are well-known for not minimizing interaction energies. In a magnetically frustrated structure like strontium gadolinium oxide (SrGd 2 O 4 ), there exists more than one suitable site for rare-earth doping due to availability of two low Gd 3+ site symmetries. In the present work SrGd 2 O 4 doped with Eu 3+ ions were prepared by solid-state reaction method. Structural characterization confirms the nature of structure and bonding. Existence of different sites in the host lattice for the doped Eu 3+ ions were observed via excitation spectra. Photoluminescence studies with varying temperature (15–300 K) have been extensively used with high-resolution to distinguish different sites in this structure. Studies confirm that apart of the Gd 3+ sites, Sr 2+ could also accommodate the Eu 3+ ions. Variation of temperature that leads to shift in emission spectral peak positions has been thoroughly examined for line shift temperature sensing applicability. Low temperature uncovers emission peaks from 5 D 1 level that are unprovable at room temperature. Maximum relative sensitivity of 5 D 0 → 7 F 0 peak intensity to one of the multiple sites in SrGd 2 O 4 :Eu 3+ has been found to be 12.08 × 10 –3 % K −1 while using McCumber-Sturge equation to quantify line shift. Graphical abstract