Rare-earth doped yttria and scandia sesquioxides have been widely used as host materials for solid-state lasers due to their high refractive index, wide bandgap, and high melting point. Both yttria and scandia crystallize in cubic bixbyite structure under ambient conditions with octahedral (C3i) and trigonal-prismatic (C2) cation sites. Specifically, the C2 sites have larger space for the cations due to their low symmetry. Sc3+ has a smaller size compared with rare earth ion dopants, which creates a strong crystal field at the dopant sites. As such, the larger rare-earth ions occupying the trigonal-prismatic sites are expected to have higher luminescence intensity. Here, we are investigating the selective doping of Er3+ in a YxSc2-xO3 host in order to improve its upconversion performance by optimizing the concentration of C2 sites. In this work, Er3+ doped YxSc2-xO3 nanoparticles were synthesized using hydrothermal chemistry with Er3+ as a photoluminescent probe to study the effect of site position and size on the upconversion performance. Co-doping the Sc2O3 system with Y3+ allows for manipulating lattice site sizes to concentrate Er3+ in the of lower symmetric C2 sites. These systems are quantified using a combination of XRD and Raman spectroscopy along with structural refinement to affirm the substitutional doping of Er3+ into Sc/Y C2-sites. Photoluminescence spectroscopy shows that the size of C2 sites of Er3+ directly affects the vibrational relaxations resulting in improved lifetimes and modification of the green to red emission ratio. To extract the luminescent efficiency, Judd-Ofelt calculations were performed to extract theoretical lifetimes and luminescent efficiency of Er3+emission. Overall, this work allows controlling the spatial location of luminescence centers in the host material in order to optimize the luminescence performance of phosphor materials.

Upconversion performance of Er3+ in YxSc2-xO3 hosts

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.