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

Infrared-to-visible upconversion luminescence has been investigated in Er3+-doped barium–natrium–yttrium–fluoride phosphor (BaxNayYzF2x+y+3z+3m:Erm) with different cation concentrations. Intense upconversion emissions around 530, 550, and 660 nm corresponding to the 2H11/2, 4S3/2, and 4F9/2 transitions, respectively to the 4I15/2 ground state were observed when excited by CW laser radiation at 1550 nm. We adopted the low-temperature combustion synthesis (LCS) method to decrease the phosphor particle size to 40–70 nm in order to couple to the photosensitive surface of CCD. The effect of the amount of carbamide on the particle size and the upconversion luminescence intensity was analyzed. The upconversion luminescence mechanism was studied by the log–log plot of intensity–power.