Erbium Oxide

Erbium oxide (Er₂O₃) is a pink powdered rare earth oxide with stable chemical properties, excellent high-temperature resistance and thermal stability. Slightly hygroscopic, it should be stored in a sealed container. It is insoluble in water and slightly soluble in acids.  

Ytterbium(III) Oxide is a highly insoluble thermally stable Ytterbium source, which is a chemical compound with the formula Yb2O3. It is one of the more commonly encountered compounds of ytterbium. It is usually used for glass, optic and ceramic applications.