Flux-Aided Synthesis of Lu₂O₃ and Lu₂O₃:Eu-Single Crystal Structure, Morphology Control and Radioluminescence Efficiency.

Li₂SO₄ or (Li₂SO₄ + SiO₂)-mixture fluxes were used to prepare a Lu₂O₃:Eu powder phosphor as well as an undoped Lu₂O₃ utilizing commercial lutetia and europia as starting reagents. SEM images showed that the fabricated powders were non-agglomerated and the particles sizes varied from single microns to tens of micrometers depending largely on the flux composition rather than the oxide(s)-to-flux ratio. In the presence of SiO₂ in the flux, certain grains grew up to 300-400 μm. The lack of agglomeration and the large sizes of crystallites allowed making single crystal structural measurements and analysis on an undoped Lu₂O₃ obtained by means of the flux technique. The cubic structure with = 10.393(2) Å, and Ia space group at 298 K was determined. The most efficient radioluminescence of Lu₂O₃:Eu powders reached 95%-105% of the commercial Gd₂O₂S:Eu.