Insight into site occupancy of cerium and manganese ions in MgAl2O4 and their energy transfer for dual-mode optical thermometry

Abstract

The cerium, manganese solely and co-doped MgAl2O4 have been synthesized via traditional solid-state reaction. XRD refinement and the first-principle calculation indicate that the Mn2+ preferentially substitutes for Mg2+ while Ce3+ is more preferential for the substitution of Al site in MgAl2O4 matrix. Effective energy transfer enables the photoluminescence spectra of the co-doped phosphors to show both ultraviolet (UV) emission of Ce3+ at around 359 nm and green emission of Mn2+ peaked at 516 nm. The separated emission bands of Ce3+ and Mn2+ indicate the good signal resolution. Due to relative thermally stable of Mn2+ and huge thermal quenching of Ce3+, the temperature sensing performance of the prepared phosphor was evaluated by measuring fluorescent intensity ratio (FIR) of Ce3+ to Mn2+ and lifetime of Ce3+. The maximum of the Sr values is 0.59%K−1 at 448 K for FIR mode and 0.40%K−1 at 523 K for lifetime mode, respectively. Satisfactory repeatability makes it suitable for dual-mode optical thermometry.