In this work, we synthesized ZnO nanorods by a wet chemical process. By varying different parameters of the synthesis process like precursor concentration, solvent used, surfactant, temperature, and reaction time, we were able to control the aspect ratio (l/d) and sharpness factor (S f ) h/b) of the rods. Rods with an aspect ratio of ∼20 and a sharpness factor of 10 were repeatedly obtained and characterized from scanning electron microscopy. High-resolution transmission electron microscopy and dark field analysis revealed that nanorods grow as a single crystal along the c axis [0001]. UV and visible emission was obtained in both flat-and sharp-terminated rods. According to the XPS analysis, rods present an excess of Zn 2+ of ∼4% that is responsible for the strong yellow emission band. Such defects were removed by annealing of the sample at 200 °C for 2 h. Possible mechanisms of changes in the morphology produced by changes in the synthesis process are also discussed.

SiO 2-coated Fe nanoparticles were synthesized using a wet chemical method, and their structural and magnetic properties were studied. The SiO 2 material was in an amorphous state. The Fe nanoparticles were in a bcc state and contained an inner ferrihydrite core whose size decreased with increasing calcination temperature. The nanoparticles were basically in the ferromagnetic state. Their saturation magnetization increased with increasing calcination temperature, whereas their coercivity decreased with increasing calcination temperature. Different from bulk Fe, the nanoparticles exhibited strong temperature-dependent magnetic behaviors. The Bloch exponent fell from 1.5 to smaller values and decreased with increasing ferrihydrite content, while the Bloch constants were much bigger than that for bulk and increased significantly with ferrihydrite content. The value of coercivity decreased notably with increasing temperature. The exchange anisotropy arising from the exchange coupling across the Fe/ferrihydrite interfaces was examined and was used to interpret the observed temperature behaviors.

It is shown that, during electron irradiation of a thin carbon film in the presence of gold nanoparticles, fullerene onion structures are produced at a much higher rate than in the case in which no nanoparticles are present. We conclude that steps on the gold nanoparticle act as catalytic sites to promote the rearrangement of carbon atoms into caged structures. Once being nucleated, onion structures are ejected from the surface.

The image quality in electron microscopy often suffers from lens aberration. As a result of lens aberrations, critical information appears distorted at the atomic scale in high-resolution transmission electron microscopy (HRTEM). In scanning TEM (STEM), the spatial resolution of images and the quality of spectroscopic data are greatly reduced. With the recent introduction of aberration-corrected lenses and monochromators, new and exciting images with sub-0.1-nm spatial resolution are now recorded routinely, and electron energy loss data has been used to determine the location of a single atom in an atomic column. As a result of the decreased focal depth of an aberration-corrected lens used in STEM, the dream of three-dimensional (3-D) atomic resolution is one step closer and for HRTEM it was shown that 3-D imaging with atomic resolution is feasible. However, understanding imaging and spectroscopy in HRTEM and STEM still requires refined modeling of the underlying electron scattering processes by multislice image simulation. Since research into the physics and technology of nanoelectronic devices has already moved into sub-10-nm transistor gate lengths, the need for well-understood imaging and spectroscopy at nanoscale dimensions is already upon us. Fortunately, nanowires and other nanotechnology materials serve as useful test samples as well as being potential materials for future nanoelectronics. This enables early development of microscopy methods that will be used to investigate future generations of integrated circuits.

The reaction of carbon with hydrogen to form methane in the presence of platinum particles is studied. Kinetics studies are combined with TEM techniques that allow particle shape and structure to be obtained. The methane production has two peaks at 800 and 950 ·C. The reaction always involves pitting or channeling by particles moving along the substrate surface. The most active particles are found to be platelets with a (110) surface in contact with the basal plane of the graphite. Those particles have a very rough surface containing many kinks.