Infrared to visible upconversion luminescence in Er3+:Y2O3 transparent ceramics

Er3+:Y2O3 transparent ceramics have been fabricated successfully via nanocrystalline powder technology and hydrogen atmosphere sintering method. Under the excitation of 980 nm diode laser, very strong green emission centered at 562 nm and red emission centered at 660 nm were observed, which were assigned to the transitions of 4S3/2/2H11/2→4I15/2 and 4F9/2→4I15/2 energy levels of Er3+ ions, respectively. The excited state absorption mechanism played an important role in the upconversion processes and cooperative energy transfer (CET) processes between two nearby Er3+ ions cannot be ignored. By changing the doping concentration of Er3+ ions, the color of upconversion emissions can be tuned from green to red, gradually.