Traditionally, SWNTs have been prepared by electric arc-discharge, laser ablation, or chemical vapor deposition (CVD) methods, yielding tubes of various diameter and length distributions. However, without exception, as-prepared SWNTs are contaminated with a number of impurities, decreasing the overall yield of usable material. Impurities include transition metal catalysts, such as Fe, Co, and Ni, which are necessary for the growth of SWNTs as well as carbonaceous species such as amorphous carbon, fullerenes, multishell carbon nanocapsules, and nanocrystalline graphite. In this Feature Article, we highlight the role of microscopy in designing and facilitating the interpretation of the success of strategies, including (a) oxidative methods including liquid and gas phase oxidation, (b) chemical functionalization protocols, (c) filtration and chromatography techniques, and (d) microwave heating methods, aimed at rationally purifying single-walled carbon nanotubes.

Nanoscale structures, such as nanoparticles, nanorods, nanowires, nanocubes, and nanotubes, have attracted extensive synthetic attention as a result of their novel size-dependent properties. Ideally, the net result of nanoscale synthesis is the production of structures that achieve monodispersity, stability, and crystallinity with a predictable morphology. Many of the synthetic methods used to attain these goals have been based on principles derived from semiconductor technology, solid state chemistry, and molecular inorganic cluster chemistry. We describe a number of advances that have been made in the reproducible synthesis of various ternary oxide nanomaterials, including alkaline earth metal titanates, alkali metal titanates, bismuth ferrites, ABO₄-type oxides, as well as miscellaneous classes of ternary metal oxides.

We report on the M\"ossbauer spectra and magnetization properties of single-crystalline (BiFeO3)x-(BaTiO3)1$-${}x solid solution nanostructures in the form of nanocubes, measuring approximately 150 to 200 nm on a side, prepared by a molten salt solid-state reaction method in the compositional range wherein 0.5$\le${}x$\le${}1. Powder x-ray diffraction (XRD) and monochromatic synchrotron XRD studies indicate products of high purity, which undergo gradual, well-controlled structural transformations from rhombohedral to tetragonal structures with decreasing ``x.'' For all solid solution products, room-temperature magnetization studies exhibit hysteretic behavior with remnant magnetization values of Mr$\ge${}0.32$\hskip0.3em${}emu/g, indicating that the latent magnetization locked within the toroidal spin structure of BiFeO3 has been released. Room-temperature M\"ossbauer spectra show composition-dependent characteristics with decreasing magnetic hyperfine field values and increasing absorption linewidths due to a decrease in the magnetic exchange interaction strength with decreasing x. For the lowest x=0.5 composition studied, the M\"ossbauer spectra show paramagnetic behavior, indicating a N\'eel temperature for this composition below 300 K. However, room-temperature magnetization studies with applied fields of up to 50 kOe show hysteretic behavior for all compositions, including the x=0.5 composition, presumably due to field-induced ordering. Furthermore, hysteresis loops for all compositions exhibit smaller coercivities at 10 K than at 300 K, an observation that may suggest the presence of magnetoelectric coupling in these systems.

Multiferroic bismuth ferrite (BiFeO₃) nanotubes have been synthesized using a modified template methodology and characterized by a number of techniques, including XRD, SEM, TEM, HRTEM as well as EDX and SAED.