I am afraid that these rare earth minerals will not work in plastics. They are not soluble in organic compounds and the mixture would appear opaque. The particular metal oxide must be incorporated in a glass formulation.
Gerald , There are ways to dope polymer. Here is an part from an article , there are hundreds of them.
2.1. PMMA LAYERS
Fabrication process of PMMA layers doped with RE ions is following: Small pieces of PMMA (Goodfellow) were left to dissolve in chloroform for a few days before being used in the fabrication of PMMA layers. The layers were formed by the solution either being spin-coated onto silicon and glass substrates or by being poured into bottomless molds placed on a glass substrate and left to dry. For RE doping, solutions whose content ranged from 1.0 at. % to 20.0 at. % RE-ions were added to the PMMA. For RE co-doping rare earth chloride or Rare Earth fluoride were together dissolved in C5H9NO or C2H6OS. Samples containing 1.0 at. % erbium were co-doped with ytterbium in amounts also ranging from 1.0 at. % to 20.0 at. %.
2.2. EPOXY NOVOLAK RESIN
Commercially available polymer Epoxy Novolak Resin (NANOTM Su-8 10) supported by Micro Resist Technology GmbH was used for fabrication of the RE doped samples. Chemical structure of Epoxy Novolak Resin (ENR) polymer is shown in Fig.1.
Structure of the Epoxy Novolak Resin polymer
Polymer layers were formed by the solution either being spin-coated onto silicon or by being poured into bottomless molds placed on a quartz substrate and let to dry. After the deposition the samples were baked at 90 C for 45 min and then UV light was used for hardening. Finally hard baking at 90 C for 60 min was applied. The doping occurred using anhydrous RE chloride or RE fluoride dissolved in C2H6OS (Sigma-Aldrich). For the doping, solutions where the RE content ranged from 1.0 at. % to 20.0 at. % were added to the ENR polymer.
