Research Article
Improving Upconversion Photoluminescence of GdAlO3:Er3+, Yb3+ Phosphors via Ga3+, Lu3+ Doping
Figure 9
Schematic diagram of energy levels of Er3+, Yb3+ ions and possible transitions under 980nm excitation. EBT: energy back transfer; ET: energy transfer; NR: nonradiative transfer.