Ultra-sensitive luminescence thermometry based on MgNb2O6:Dy3+/Pr3+ thermochromic phosphors

Abstract

Luminescent materials have been explored for achieving highly sensitive and noncontact thermometry. Herein, a novel ratiometric luminescence thermometry strategy was proposed by combining the thermally induced redshift of the charge transfer band with the dramatic quenching of the intervalent charge transition in MgNb₂O₆ (MNO) phosphors doped with Dy³⁺ and Pr³⁺. The emission color of the resultant sample changes significantly from red to yellow as the temperature increases under single-beam irradiation, which is observable by the naked eye. Benefiting from the opposite thermal response of the luminescence of Dy³⁺ and Pr³⁺, the luminescence intensity ratio of Dy³⁺ and Pr³⁺ codoped MNO leads to excellent sensitivity. The maximum relative sensitivity and absolute sensitivity reached 7.61% K⁻¹ at 300 K and 0.61 K⁻¹ at 540 K, respectively. The investigated sample also exhibited excellent signal resolution, reversibility and temperature resolution. Consequently, Dy³⁺ and Pr³⁺ activated MNO phosphors are very promising in luminescence thermometry including visual temperature sensing and safety markers.