Enhancing upconversion via constructing local energy clusters in lanthanide-doped fluoride nanoparticles

By introducing local energy clusters within the NaGdF 4 lattice, the optimal Er 3+ , Ho 3+ and Tm 3+ doping concentrations were increased to 8, 8, and 2 mol%, respectively. The UC intensity was enhanced approximately 54.3 times by doping Ca 2+ .