An optical thermometry based on near-infrared luminescence of LiGaSiO4: Cr3+phosphors excited by red light

A near-infrared luminescent material LiGaSiO4:Cr3+ with triple temperature detection function was synthesized in this paper. The results show that the sample has the best Near-infrared luminescence (NIR) performance under the excitation of 620 nm red light when the concentration of Cr3+ is 0.05%. The emission peak in the near infrared region (705 and 721 nm) is due to the 2E -> 4A2 energy level transition of Cr3+, and the emission peak in the red region (670 nm) is due to the 4T2 -> 4A2 energy level transition of Cr3+. The obtained results show that the dependences of temperature on three fluorescence intensity ratio (FIR) models including 670/705, 705/721 and 721/605 all show excellent linearity, indicating that high temperature sensing sensitivity and accuracy can be obtained via the combination of three FIR models. Furthermore, FIR (705/721) can provide the highest tem-perature sensing performance and its relative sensitivity (Sr) is up to 4.32 K-1. All these results indicate LiGaSiO4: Cr3+ possessed great potential in the application of temperature sensing.