Eu3+-based luminescence ratiometric thermometry.

Recently, luminescence ratiometric thermometry has gained ever-increasing attention due to its merits of rapid response, non-invasiveness, high spatial resolution, and so forth. For research fields relying on temperature measurements, achieving a higher relative sensitivity of this measurement is still an important task. In this work, we developed a strategy for achieving a more sensitive temperature measurement, one merely depending on the photoluminescence of Eu3+. We showed that using the 5D1-7F1 transition and the hypersensitive 5D0-7F2 transition of Eu3+ can boost the relative sensitivity compared with the method relying on the 5D1-7F1 and 5D0-7F1 transitions of Eu3+. The difference between these two strategies was studied and was explained by the hypersensitive 5D0-7F2 transition more steeply decreasing than the 5D0-7F1 transition with a rise in temperature. Our work is expected to help researchers design sensitive optical thermometers via proper use of this hypersensitive transition.