[en] Single crystalline α-Fe₂O₃ ellipsoidal nanoparticles were prepared by a simple hydrothermal method without any requirement of calcination step at high temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the ellipsoidal structure. The formation and evolution of these ellipsoidal nanoparticles were investigated by SEM, and the results showed that the ellipsoidal structure was achieved through aggregation of nanoparticles while the traditional Ostwald ripening mechanism also played an important role in formation of the initial particles before aggregation and smoothed the morphology of the ellipsoidal nanoparticles after attachment. The as-prepared α-Fe₂O₃ ellipsoidal nanoparticles could catalyze oxidation of almost 100% CO at a temperature of 330 deg. C. The present work shows that the nanostructures of catalyst are important to their catalytic performance besides the traditionally accepted factors, such as high BET surface area

[en] Magnetic MFe₂O₄ (M=Co, Ni, Zn) nanocrystals with a diameter about 30 nm and a nearly spherical shape were synthesized via a simple hydrothermal approach. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy have been used to investigate the as-prepared magnetic MFe₂O₄ (M=Co, Ni, Zn) nanocrystals. Magnetic properties of the as-prepared samples have been detected by a vibrating sample magnetometer at room temperature and the results show that the as-prepared magnetic MFe₂O₄ nanocrystals are a type characteristic of superparamagnetic materials. These superparamagnetic nanocrystals are believed to be promising for wide engineering applications, such as drug delivery, bioseparation, and magnetic resonance imaging