Effect of phase transition on photoluminescence of Er-doped KNN ceramics

The lead-free ceramics K0.5Na0.5NbO3 doped with x mol% Er3+ ions have been successfully manufactured and their photoluminescence properties, including the up-conversion visible (480-700 nm) emissions, down-conversion near infrared (1400-1680 nm) and middle infrared (2620-2850 nm) emissions, emission colors and lifetimes of the energy levels have been systemically investigated. The corresponding photoluminescence mechanism has been discussed in detail. Our results show that the Er-doping induces a phase transition from orthorhombic to cubic-like as well as inhibits the grain growth due to the donor-type nature. Both the change of crystallographic structures and concentration-quenching effect induced by Er3+ ions have great influences on the photoluminescence properties. Because of the wide emission ranges and long lifetimes, Er-doped K0.5Na0.5NbO3 ceramics are the promising candidates for optoelectronic applications.