Up-conversion luminescence of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 poly-crystals

The optical properties of Er 3+ -doped and Yb 3+ /Er 3+ co-doped 12CaO·7Al 2 O 3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er 3+ -doped and Yb 3+ /Er 3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er 3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the intensity ratio of red to green up-conversion emission had an increase in Yb 3+ (1.0 mol.%, 2.0 mol.%, 10. 0 mol.%)/Er 3+ (fixed at 1.0 mol.%). This detailed study of the up-conversion processes allowed us to identify the dominant up-conversion mechanisms in Er 3+ -doped and Yb 3+ /Er 3+ co-doped C12A7 poly-crystals.