Infrared-to-visible upconversion luminescence of Er3+ doped barium-natrium-yttrium-fluoride phosphor

► A kind of fluoride upconversion phosphor was synthesized by the LCS method. ► The phosphor synthesized by the LCS method is with the particle size of 40-70 nm. ► This phosphor can be used in the phosphor-coated CCD sensitive to ∼1.5 μm.