Synthesis of single-phase gd-doped ceria nanopowders by radio frequency thermal plasma treatment

Gd-doped ceria nanopowders were synthesized using Radio Frequency (RF) thermal plasma. The powders were prepared by ball-milling Gd₂O ₃ and CeO₂ powders of several tens of μm in size at the cation ratio of 8:2 and 9:1. The prepared precursors were treated by RF thermal plasma at a plate power level of ∼140 kVA, and then, small-sized powders (∼50 nm) were retrieved by filtration. Transmission Electron Microscopy, Electron Energy Loss Spectroscopy, and Selected-Area Electron-Diffraction images of the as-synthesized powders showed that Gd atoms were incorporated into the CeO₂ particles. In addition, no crystalline peak for Gd ₂O₃ appeared in the X-ray diffraction patterns of the as-synthesized powders, which is attributed to the solid solution of Gd ³⁺ into the CeO₂ lattices. Finally, Inductively Coupled Plasma-Optical Emission Spectrometry analysis data revealed relatively small changes within 3 at.% in the cation composition between the ball milled powder mixtures and the nanoscale powders prepared from these mixtures.