(39c) Cubic or Monoclinic Y2O3:Eu Nanoparticles by Flame Spray Pyrolysis

Monocrystalline cubic and/or monoclinic Y₂O₃:Eu³⁺ nanoparticles (10-50 nm) were synthesized continuously without post-processing by single-step flame spray pyrolysis (FSP). These particles were characterized by X-ray diffraction (XRD), nitrogen adsorption (BET) and transmission electron microscopy (TEM). Photo-luminescence (PL) emission was measured as well as the time-resolved PL-intensity decay. Synthesis of single and mixed crystal phase (monoclinic and/or cubic) Y₂O₃:Eu³⁺ nanoparticles was achieved by controlling the precursor combustion conditions in the flame, hence the temperature profile (maximum flame temperature, cooling rate) as well as high temperature residence time which resulted in different particle growth histories which in turn affected particle characteristics as crystal phase, size and morphology. Longer high temperature residence time of the particles resulted in cubic nanoparticles with lower maximum PL-intensity than measured by commercial micron-sized bulk Y₂O₃:Eu³⁺ phosphor powder.