Eu3+ Single-Doped Phosphor with Antithermal Quenching Behavior and Multicolor-Tunable Properties for Luminescence Thermometry

Abstract

To date, non-contact luminescence thermometry methods based on fluorescence intensity ratio (FIR) technology have been studied extensively. However, designing phosphors with high relative sensitivity (S_r) has become a research hotspot. In this work, Eu³⁺ single-doped Ca₂Sb₂O₇:Eu³⁺ phosphors with a high S_r value for dual-emitting-center luminescence thermometry are developed and proposed. The anti-thermal quenching behavior of Eu³⁺ originating from the energy transfer (ET) of host → Eu³⁺ is found and proved in the designed phosphors. Interestingly, adjustable color emission from blue to orange can be achieved. Surprisingly, the degree of the anti-thermal quenching behavior of Eu³⁺ gradually reduces from 240 to 127% as the Eu³⁺ doping content increases from 0.005 to 0.05 mol, attributed to most Eu³⁺ being located in the low symmetrical [Ca1O₈] dodecahedral site. According to the differentiable responses of the host and Eu³⁺ to temperature, the maximal S_r value reaches 3.369% K^-1 (383 K). Moreover, the ambient temperature can be intuitively predicted by observing the emitting color. Owing to the excellent performance in optical thermometry, color-tunable properties, and outstanding acid and alkali resistance for polydimethylsiloxane (PDMS) films, the developed Eu³⁺ single-doped Ca₂Sb₂O₇:Eu³⁺ phosphors are expected to be prospective candidates in luminescence thermometers and LED devices in various conditions.