Improved optical thermometric sensitivity of Eu3+‐doped calcium niobate phosphor via nonstoichiometric control

Abstract

AbstractEu3+‐doped calcium niobate CaNbxO6 phosphors were successfully prepared by a solid‐state reaction, and the crystal structure, morphology, energy transfer process, and temperature‐dependent behaviors were systematically investigated. The CaNbxO6 host matrix presents the self‐activated characteristic emission at 470 nm due to the charge transfer transition of Nb5+–O2+, and the corresponding photoluminescence intensity reaches the maximum intensity when the nonstoichiometric ratio of Ca2+/Nb5+ ions is 1:1.9. Moreover, the energy transfer process from the host (470 nm) to Eu3+ (612 nm) ions in the CaNb1.9O6:Eu3+ phosphor is demonstrated, and the corresponding energy transfer efficiency is significantly enhanced compared with that of stoichiometric sample. Furthermore, it is observed that nonstoichiometric ratio of Nb5+ ions deteriorates the thermal quenching of the matrix while guaranteeing the thermal stability of the activators, resulting in the relative sensitivity (Sr) of CaNb1.9O6:Eu3+ being greatly improved from 2.235% to 3.673% K−1. Herein, these results provide an effective strategy for manipulating the sensitivity of optical thermometers of phosphors based on the induced modulation of the temperature‐response performance via nonstoichiometric control.