Morphology-controlled synthesis, characterization and microwave absorption properties of nanostructured 3D CeO₂

Nanostructured 3D CeO₂ have been synthesized by using PEG 2000 assisted simple hydrothermal technique. The impact of this novel approach on the structure, morphology, spectroscopy, complex permittivity and permeability was discussed. CeO₂ was studied by employing X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TG) and vector network analyzer. It can be seen that the microspheres of 1-3 μm in diameter were prepared at 600 °C with a mole ratio of 2:1, while the decreasing concentration of PEG-2000 resulted in the appearance of dim side-shape geometry. Obviously, the morphology of the synthesized CeO₂ gradually changed from sphere with relatively smooth to irregular side-shape annealed at 600 °C with the increase of mole ratio for reactants. The electromagnetic (EM) wave absorption properties of the synthesized CeO₂ were investigated over the range from 2 to 16 GHz, and minimum reflection loss (RL) with -19.3 dB was observed at 15.8 GHz with the thickness of 2.0 mm. This phenomenon may be attributed to both intrinsic characteristic of CeO₂ and preparation with the function of PEG-2000.