Novel Fluoride Matrix for Dual-Range Optical Sensors and Visualization

Novel tetragonal matrix Ba0.5-xLn0.5NaxF2.5-x with x = 0.08, doped by Yb3+, Ho3+, Er3+, was synthesized by molten salt synthesis (MSS) from nitrate flux. XRD data show that the tetragonal phase with a = 4.122(1) angstrom, c = 17.672(1) angstrom is stable in an argon atmosphere up to 960 degrees C. Luminescence spectra recorded in 500-900 nm and 1050-1700 nm upon 974 nm pumping demonstrated the characteristic luminescence at 1550 nm (4I13/2 -> 4I15/2) for Er3+ and 1150 nm (5I6 -> 5I8) for Ho3+. The relative thermal sensitivity (Sr) at 296-316 K were 0.3%xK-1 and 5.5%xK-1 in shortwave infrared (SWIR) and visible range, respectively. Synthesized luminophores can be used as dual-range optical temperature sensors, which simultaneously operate in visible and SWIR ranges.