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Abstract: La2Ce2O7 nanocrystals were prepared via hydrothermal method with polyethylene glycol (PEG) and cetyltrimethyl ammonium bromide (CTAB) as surfactants, respectively. X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, Raman spectroscopy, and Field emission scanning electron microscopy were utilized to characterize the phase structure, thermal decomposition, and morphology of the products. Qualitative analyses indicate that both samples have a cubic fluorite structure. The surfactants have an important effect on the specific surface area, lattice parameter, and average crystallite size of the products. The sample using CATB as surfactant has a higher activation energy of crystal growth than that with PEG. Moreover, the effects of surfactants on the sinterability of compacted body are also discussed. [Copyright &y& Elsevier]

Abstract: Nanopowders with cubic fluorite-type structure as well as uniform distribution in particle size were synthesized by hydrothermal method in the ternary oxide zirconia–yttria–ceria system with ceria content of 0–25mol%. X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimeter (TG/DSC), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (Raman), specific surface area (S BET) and high resolution transmission electron microscopy (HRTEM) were applied to characterize the structure, thermal decomposition, morphological characteristic and crystal growth of the produced powders. Qualitative analyses indicate that the as-synthesized nanoparticles are single-phase crystallites with an average particle size of 4–9nm. The specific surface area, lattice parameter and microstrain are closely related to Ce4+ concentration. Moreover, activation energy of crystal growth is significantly dependent on the dopant (CeO2) concentration. It firstly increased and then decreased with increasing dopant concentration, and the maximum value was observed at the dopant concentration of 5mol%. [Copyright &y& Elsevier]