The role of precursor decomposition in the formation of samarium doped ceria nanoparticles via solid‑state microwave synthesis

摘要

The impact on the final morphology of ceria (CeO_2) nanoparticles made from different precursors (commercial: ceriumacetateitrate) and in house: cerium tri(methylsilyl)amide (Ce-TMSA)) via a microwave solid state reaction has beendetermined. In all instances, powder X-ray diffraction indicated that the cubic fluorite CeO_2 phase (PDF# 04–004-9150,with the space group Fm-3 m) had formed. Scanning electron microscopy (SEM) images revealed spherical nanoparticleswere produced from the Ce-TMSA precursor. The commercial acetate and nitrate precursors produced particles withirregular morphology. The roles of the precursor decomposition and binding energy in the synthesis of the nanocrystalswith various morphologies, as well as a possible growth mechanism, were evaluated based on experimental andcomputational data. The formation of spherical shaped nanoparticles was determined to be due to the preferentialsingle-step decomposition of the Ce-TMSA as well as the low activation energy to overcome decomposition. Due to thecomplicated decomposition of the commercial precursors and high activation energy the resulting particles adoptedan irregular morphology. Highly uniform samarium doped ceria (Sm_xCe_(1-x)O_(2-δ)) nanospheres were also synthesized fromCe-TMSA and samarium tri(methylsilyl)amide (Sm-TMSA). The effects of reaction time and temperature, on the finalmorphology were observed through SEM. The rapid single-step decomposition of TMSA-based precursors as observedthrough thermogravimetric analysis (TGA) and confirmed through the calculation of potential energy surfaces and bindingenergies from density functional theory (DFT) calculations, indicated that nanoparticle formation follows LaMer’sclassical nucleation theory.