Luminescence properties of Ca0.65La0.35F2.35:Yb3+, Er3+ with enhanced red emission via upconversion

Yb3+/Er3+ codoped Ca0.65La0.35F2.35 materials with intense red emission via upconversion were prepared by a high temperature solid-state method. Based on the upconversion luminescence properties investigations, it was found that, under 980 nm excitation, Ca0.65La0.35F2.35:20 mol.%Yb3+, xEr3+ showed intense red upconversion luminescence, which was ascribed to 4F9/2 → 4I15/2 transition of Er3+, although both green and red emissions could be detected. It was also found that the green and red emissions originated the two photon processes, and the ground-state absorption (GSA), excited-state absorption (ESA) and energy transfer (ET) processes between Er3+/Yb3+ ions and Er3+/Er3 ions were involved in the enhanced red emission mechanism.