Design strategies for three highly sensitive multimodal optical thermometers based on diverse luminescence thermal-response in BaLu2Si3O10:Ln3+, Yb3+ phosphors (Ln3+=Er3+, Ho3+, Nd3+)

Abstract

Optical thermometer has gradually become a hotspot due to its contactless measurement, high spatial resolution and rapid response, while most of them currently used single-mode measurement without reference and calibration. Herein, three multimodal optical thermometers were designed in BaLu2Si3O10: Er3+/Ho3+/Nd3+, Yb3+ phosphors. Interestingly, both Er3+ and Ho3+ doped phosphors demonstrated thermochromic phenomenon, promising to be candidates for intelligent high-temperature alarms. Benefiting from diverse thermo-response of green and red emissions of above two phosphors, two visible two-mode optical thermometers were established by four fluorescence intensity ratio (FIR) modes. Besides, a near-infrared (NIR) multimodal optical thermometer was also proposed by three FIR modes in Nd3+-Yb3+ co-doped phosphor with continuous luminescence thermal enhancement. Because of efficient phonon-assistance energy transfer process, the 4F7/2 → 4I9/2 transition demonstrated super thermal enhancement over 2600 times. The method by integrating several independent optical addressed temperature readout modes provides diversified avenue toward the design of highly sensitive optical thermometers.