Multicolor-tunable upconversion emission of lanthanide doped 12CaO·7Al2O3 polycrystals

A novel multicolor-tunable lanthanide doped 12CaO·7Al 2 O 3 (Ln 3+ :C12A7; Ln 3+  = Yb 3+ , Tm 3+ and Er 3+ ) synthesized by solid-state reaction method would greatly enhance the scope of its applications ranging from infrared solar cells to field emission display . The scanning electron microscopy (SEM) was used to characterize the morphology of Ln 3+ :C12A7. Under 980 nm excitation, the emission color was tuned from green-yellow to red region through adjusting the concentrations of Ln 3+ ions. The obtained near infrared upconversion (UC) emissions in Ln 3+ :C12A7 was corresponded to “window of optical transparency”. All blue, green and red UC emissions were populated by one-photon process, and the proposed UC mechanisms were studied in Ln 3+ :C12A7.