Inherently Eu2+/Eu3+ Codoped Sc2O3 Nanoparticles as High‐Performance Nanothermometers

Abstract Luminescent nanothermometers have shown competitive superiority for contactless and noninvasive temperature probing especially at the nanoscale. Herein, we report the inherently Eu 2+ /Eu 3+ codoped Sc 2 O 3 nanoparticles synthesized via a one‐step and controllable thermolysis reaction where Eu 3+ is in‐situ reduced to Eu 2+ by oleylamine. The stable luminescence emission of Eu 3+ as internal standard and the sensitive response of Eu 2+ emission to temperature as probe comprise a perfect ratiometric nanothermometer with wide‐range temperature probing (77–267 K), high repeatability (>99.94%), and high relative sensitivity (3.06% K –1 at 267 K). The in situ reduction of Eu 3+ to Eu 2+ ensures both uniform distribution in the crystal lattice and simultaneous response upon light excitation of Eu 2+ /Eu 3+ . To widen this concept, Tb 3+ is codoped as additional internal reference for tunable temperature probing range.