Research On Preparation Of Nano Oxide By Arc-discharge In Solution And In-situ Reaction Of Pt Nanocrystals

Nano metaloxides play an important role in the physics ,chemistry and material science.Nano metaloxides have a lot of unique functions and they are widely used in micro-electrics, fuel cells, petrol industry, pollution controlling and semiconductor manufacture. So it is of great value for the preparation of nanoparticles, nanorods and nanoplatelets.In this work, rodlike and spherical Fe2O3 nanoparticles, Fe3O4 nanoparticles, ZnO nanoparticles and nanoplatelets, NiO nanoparticles were prepared by arc-discharge in solution. The products were characterized by means of TEM, SEM, XRD, TGA and magnetization measurements. Experiment results indicate that solution concentration and calcination temperature ,which determine the size and character of nanoparticles are the most important factors in this experiment.TEM images showed that two morphologies ofα-Fe2O3 nanoparticles including rodlike and spherical were obtained by calcining at 450, 600℃,respectively. The rodlikeα-Fe2O3 nanoparticles with a diameter of about 20 nm and an average length of 50 nm have been obtained by calcining at 450℃and the sphericalα-Fe2O3 nanoparticles with a mean diameter of 51 nm can be obtained by calcining at 600℃. Magnetization measurements indicate that the magnetic property of the sample is very sensitive to the shape and size. The rodlike nanoparticles are superparamagnetic, whereas the spherical nanoparticles exhibit weak ferromagnetic behaviors. During the preparation of ZnO and NiO process, the best solution concentration and calcination temperature were explored. A possible formation mechanism of the nano metaloxide is proposed. Endohedral metallofullerenes have been the subject of increasing interest due to their unique structures, properties and wide applications in physics, chemistry, and material science. Endohedral metallofullerenes and C60 were discovered at the same time. However the research about the synthesis of Endohedral metallofullerenes got along slowly . The formation mechanisms for various Endohedral metallofullerenes were speculated by theoretical calculation.Therefore, the experimental proofs for formation mechanisms of Endohedral metallofullerenes are important.In this work, the formation of Pt/ C core-shell nanostructures has been investigated by a real-time transmission electron microscope under electron irradiation. Pt nanocrystals catalyzed amorphous carbon around them and maked amorphous carbon to form ordering carbon.Then order carbon transformated into graphite fragments, formed layers and closured shells.During this process, Pt catalyst particle (111) facets played an important role on nucleation. In addition, congregation and coalescence of two or many Pt nanocrystals irradiated by electron beams were observed.