Triple-temperature readout in luminescence thermometry with Cr3+-doped Mg2SiO4 operating from cryogenic to physiologically relevant temperatures

Abstract

Cr3+-doped Mg2SiO4 orthorhombic nanoparticles are synthesized by a combustion method. The 3d3 electron configuration of the Cr3+ ion results in the deep-red emission from optical transitions between d–d orbitals. Two overlapping emissions from the Cr3+ spin-forbidden 2Eg→ 4A2g and the spin-allowed 4T2g→ 4A2g electronic transitions are influenced by the strong crystal field in Mg2SiO4 and, thus, are suitable for ratiometric luminescence thermometry. The temperature-induced changes in Cr3+-doped Mg2SiO4 emission are tested for use in luminescence thermometry from cryogenic to physiologically relevant temperatures (10–350 K) by three approaches: (a) temperature-induced changes of emission intensity; (b) temperature-dependent luminescence lifetime; and (c) temperature-induced changes of emission band position. The second approach offers applicable thermometry at cryogenic temperatures, starting from temperatures as low as 50 K, while all three approaches offer applicable thermometry at physiologically relevant temperatures with relative sensitivities of 0.7% K−1 for emission intensity, 0.8% K−1 for lifetime and 0.85% K−1 for band position at 310 K.