A new mechanism for temperature sensing based on the thermal population of 7F2 state in Eu3+

The thermal coupling property of the ground state 7F0 and its adjacent thermally-excited state 7F2 of Eu3+ ion was firstly discussed and a new temperature sensing mechanism was proposed based on the thermal population of 7F2 state in Y2O3: 5% Eu3+ powder sample. Under a constant 611.2 nm excitation, the fluorescence originating from 5D0 state increases monotonously as the temperature rises in the region from 150 K to 300 K. The reason leading to this temperature-dependent fluorescence behavior was analyzed in detail. It is demonstrated that this present work provides a new mechanism for non-contact optical thermometry.